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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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PARALLEL Twincharging, whatever....
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Sat, 20 August 2005 14:40
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Heya Ppl,
i've been pretty disappointed at the small amount of work that has gone into twincharge designs. so i thought it would be nice if i could share some of my ideas, and with a big collective group hug, get a workable design.. i haven't had the time to think through these designs thoroughly, so at first i'll just present the case for acceleration.
The basic reason you would twin charge something, is so that you can use a much bigger turbo than would otherwise be practical from a lag or power delivery point of view. the drawbacks, apart from cost, are the complexity of having an arrangement that allows the SC to be turned off and still have a good transition from SC to turbo.
there have been a few kits and installs that have them in series, with the turbo blowing into the SC. This works, but you stll have the parasitic SC loss, as well as the Roots blower inefficiency to deal with in terms of heat (I'm assuming use of SC12/14 etc).
Ideally, you would have them in a parallel arrangement, whereby you could turn the SC off and have a great topend charge from the turbo, but still have bottom end torque from the SC. as i said, the issue of transition is the biggest hurdle to this setup.....
So, my thinking cap went on, with the basic requirements that the transition from SC to be turbo had to be absolutely smooth, the SC must be able to be switched off, and that it could be MECHANICALLY controlled with minimal electronics.
so first, i present the case for pure acceleration, the simplest case in terms of transitions. As shonw in dodgy diagram below, we have SC, turbo, and three throttles:
one to throttle SC input, T1
one to throttle turbo output, T2
and one to throttle the air recirculating through the SC, T3.
i will also assume that we have an ECU with programmable output to allow switching on, and perhaps off, of SC. IC will refer to any air that is after the chargers, ie from the IC.
so we start from idle at WOT, and assume the SC is switched on
T1 is open to allow SC to draw in air, T3 is closed to stop air recirculating from IC to before the SC. T2 is also closed because we don't want to force air out backwards thru the turbo..
so basically it runs like a normal SC car.
for the transition, the problem is that the SC is positive displacement, ie it either pushes it's maximum volume, or none at all, whereas the turbo is a variable volume system, it can provide full pressure with nearly no flow. what we need to do is to balance the flow of both chargers so that at the transition there is a continuous increase in both flow AND pressure.
we can use this at the transition point by referencing T2 to the pressure at the turbo exit, R1, and use some kind of wastegate actuator to open T2. we could either have the actuator as an absolute
reference... to maybe 2psi above SC pressure, or as a relative reference, so that it begins to open when R1 is 2psi above R2 (the IC pressure)
so basically, the turbo starts to spool, and the pressure between the turbo and T2 rises past the IC pressure (ie SC output) then T2 begins to open a little, bleeding air into the IC. we _could_ just leave the SC on also and be done with it, but what i want is to be able to switch the SC off, and turn higher rpm with the turbo alone... if we just switch it off now, the pressure drops as the turbo is not flowing any volume..
so what we do is to start throttling the SC's intake via T1, and allow an amount of air to recirculate back past the SC via T3. These could also be actuated by the turbo outlet pressure, and indeed for a rough effort, could be mechanically linked to T2 also!!!
so what we would have is a system where the turbo reaches SC pressure and starts to contribute to the volume of the system. at the same time, the SC input is throttled and to allow SC to pump a constant amount, air is recirculated to the SC intake... by slowly closing T1 and opening T3, you can have the SC still turning full speed, yet not contribute any air to the system.
in fact this is what we want.. by the time the turbo is properly spooled, and is providing almost all the air at a couple of Psi above SC pressure, T1 will be almost closed, and T2 fully open... so now, the SC is providing no new air to the system and can be swithced off completely, possibly using a microswitch on T1....
so now, only the turbo is providign air, T3 can remain open as long as T1 is closed (as both sides of SC are at equal pressure), and T2 is fully open...
car is now running in turbo only mode
so thats the basic idea for acceleration.
initially only SC is running.
turbo starts to kick in and SC is throttle back, but intake manifold pressure and flow continue to increase, but with the turbo providing an increasing proportion of air.
the SC is throttled back and recirculated to the point where it has no contribution and is switched off.
we are now in turbo only mode...
i see that these three throtles can be simply actuatd using something like wastegate actuators, and given the right sizing/bell crank gemoetry, could even be mechanically linked so that only one actuator is needed. the only electronics needed are ECU signal to switch SC on (or manual switch), and then microswitch at T1 to turn the SC off when it is no longer contributing....
so... i'd like constructive comments and criticisms. this is not a thread to bitch and whine about the benefits or not of twin charging, but simply a "let's make it work" thread.
Cya, Stewart
[Updated on: Wed, 24 August 2005 05:47]
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 15:04
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nope i hadn't but i noticed he's running a megasquirt  (on MSnSe code of course)
the main difference to his setup is that i don't like one way valves (had this in a previous iteration), and i would prefer to recover the 50-60hp that the SC sucks at high rpm.. his idea of using massive J-pipe for turbo is not bad, since lag is no longer a problem
i am thinking along the lines of a turbo that can support 30psi or more, and so havign SC running at the same time is not a good idea..
thanks for the link 
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Location:
Hobart, Tas
Registered:
May 2002
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 15:33
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Just a thought: what if you instead had a pair of parallel turbos of different sizes, one small for response & one big for top end power?
I guess if it was a good idea, it would already be used, but it jus toccured to me 
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Location:
Sydney
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 15:39
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A number of cars already use a sequential turbo setup, the 2JZ-GTE for example, it works pretty well.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 16:18
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indeed they do.. but there is still lag, and you still have low boost at low rpm..
for me the problem with turbos is not at what rpm they kick in at, but how slow they are to get to that rpm... great to have boost by 4000rpm, but if you floor it from 2000rpm.. how long to get there??
anyways, this thread is not about sequential turbo setups, as they have been done, but to me the excessive plumbing on the hot side is a drawback. i'd rathr have more cold piping.
as an extra thought to controlling the SC, you could just have a switch on the pedal/manifold throttle (which if course is the same as normal throttles) such that SC turns on at sayyy 50% throttle? 75% throttle? and will be turned off by T1 when not needed by turbo.. so it's almost enough to control it for accel conditions...
next we go to mild acel, cruise, and decel conditions. lastly we get to transitions between these states....]
Cya, Stewart
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Location:
The Shire
Registered:
May 2005
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 17:01
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in issue 90 of Zoom there is a 13bt in a 323 that is running a 1g supercharger. The supercharger is used below 5000rpm to improve the response until the turbo kicks in.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 17:03
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and how does it switch over? does it just turn off? does it stay on? i don't exactly have access to Zoom atm
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Location:
The Shire
Registered:
May 2005
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 18:07
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When the turbo comes up to speed, a solenoid-controled TB is opened and the electromagnetic clutch on the SC is disengaged.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sat, 20 August 2005 18:14
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thanks for the pics ( a little better than mine )
so the SC blows through the turbo, and when the SC shuts off, there will be a sudden drop in the turbo inlet pressure....
i wonder if that will be seen as a manifold pressure drop?
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Location:
brisbane
Registered:
October 2004
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 02:14
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how about checking out some oem setups like the nissan march super turbo and lancia,
'nissan march on autospeed'
At low-to-mid revs, the 930cc four is boosted by a positive displacement blower (see Supercharger Steal - Part One for details). At higher revs, however, a relatively large turbo kicks in to give great top-end performance. Note that the transitional stage is very smooth thanks to a relatively simple supercharger/turbo control system. At low rpm the turbo blows through the supercharger which is effectively free-wheeling. Then, at high rpm, the supercharger is disengaged by an electro-magnetic clutch and the turbo feeds the engine via a supercharger bypass passage. Airflow through this passage is controlled by a differential pressure valve which begins to open as the turbocharger nears operating speed
http://www.nissanperformancemag.com/august03/ask_s arah/
Known as twinchargers, the Lancia rally cars employed both a turbo and a supercharger. HKS even offered an upgrade for the Toyota MR2 with a supercharger-into-turbo kit.
[Updated on: Sun, 21 August 2005 02:17]
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Location:
townsville NQLD
Registered:
February 2004
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 03:43
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this is from some website. i think its a forum member's
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I am lucky enough to have a friend that is a Japanese parts & engine importer, and one day he brought back a rather odd engine, one that I've never seen before or since. It's a Toyota 1G-GZTE, which means it's a 2 litre, twin cam, four valves-per-cylinder, 6 cylinder, supercharged AND turbocharged 450hp monster! Take a look at a couple of pictures of it - This is looking at it from the front, and on the right hand side you can see where the turbo bolts on to the exhaust manifold, and the supercharger on LHS the supercharger. You can also see part of the complex inlet plumbing ...
This shows a good view of the inlet pipes. All of the darn things! It took me a while to figure out how it all works, but I think I've got it under control. You also get a better view of the supercharger, and also the two inlet manifolds - The upper one and the lower one.
(apologies for the scratch in the picture)
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The engine is a rather clever device - when driving slowly (Yes, I DO believe that it's possible!) the turbo is not spinning fast enough to make any boost, and also the supercharger isn't spinning. This is because it has an electronic clutch on the front of the blower, much like an air-conditioner, and so can be turned on & off as needed. This means that while driving around on the road the car is quite docile.
Ok, put your foot down a little. The supercharger cuts in, making up to about 12psi of boost, thus giving a fair kick in the tail. And also helping spin up the turbo faster...
So the turbo (Which is a LOT bigger than what you'd normally put on a 2 litre engine) spins up quicker and I expect it to be making more boost than the blower at around 4,000rpms or so.
Once the turbo is making more boost than the blower, the blower turns off and thus loses all the mechanical drag required to spin it. The turbo then runs up to 20-something psi. I haven't worked out just how much yet, but I reckon it'll be about 25psi boost.
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[Updated on: Sun, 21 August 2005 03:45]
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 04:01
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my thoughts on it is this!there is a izusu or similar diesel that has a belt driven turbo{i came up with the idea and found they already did it!}!it must disconnect once the exhaust has the pressure to spin it! id be running along the line of a one way clutch system on a turbo that is belt driven till you have the pressure at say 3000rpm that the turbo needs,be easy to do and save alot of weight compared to having a blower and a turbo.i have always wanted to do this as a commercial concern and have done research and a little development into it.i think it is the ultimate street setup as you have the low end and as high an end, as a street car could ever want.lmao please save the applause until i have it 100% sorted,thats if i get around to it.
hahahaha
mick
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Location:
townsville NQLD
Registered:
February 2004
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Location:
Rocky Mountains, Canada
Registered:
May 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:10
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I think i know the answer to this already, but to be sure...
Why not just supercharge?
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:12
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Thanks Styler,
the march idea works, and is relatively smooth, but not completely smooth
Brett, looks like your pic is basically what the nissan march idea is..... but if you slowly close the SC's input, it's going to be pulling a massive vacuum... enough to bend throttle plates? maybe..
that 1GGZTE was Bill SHerwoods, and i believe it's in different hands now.. is kinda hard to see how thats connected..
Mick, i don't really want to get into centrifugal and belt assisted turbos here..
WHAT I WANT PEOPLE TO DO... is to look at the diagram in the first post and see if they can see ways to improve it..
there are many many ways to twincharge, but as i said, I AM NOT HAPPY WITH THEM  ... i want to discuss SPECIFICALLY THIS way of doing it
Cya, Stewart
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:16
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| M.W.P. wrote on Sun, 21 August 2005 15:10 |
I think i know the answer to this already, but to be sure...
Why not just supercharge?
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FFS because most ppl are too stingy to buy a real supercharger.. end of story..
SC12/14 are what? $200.. real SC is about $2500.. no-one here (nearly) will pay that..
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:19
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to drive the superchager on the 780hp at the wheels comdomdore i do the engine on you are talking 140hp to drive the charger up top.hence why a turbo will always make more power things being equal!
mick
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:22
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why stewart you prefur complex heavy systems!hahaha
mick
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Location:
Campbelltown
Registered:
November 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:26
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I'd kill for a robbie start kit on a commodore whipple supercharger but its like 18K for the full kit, but 800Nm of torque at like 1900rpm muhuhahahahahaha  .
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:32
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Corona RT142 a good setup you can do for around the 14k mark!one of the ones i do he has spent over $50k on the engine bay setup.
mick
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Location:
Campbelltown
Registered:
November 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:35
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who needs a top end when you have that much torque down low  . I'll see if i can drag pics up of an RB26DETTSC
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 05:37
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so anyway back to topic.. thanks everyone for looking at the first post
on performance forums earlier this year. Niscort posted some pics, which are basically the same, except i am throttling the SC input also..
http://pforums.company-hosting.com/forums/showthre ad.php?t=67184522&highlight=twincharged
but as like this thread so far.. everyone just wants to talk about other systems....
i think this idea is the way to go for twincharge. it can be made to work, just needs some actual thought time..
Cya, Stewart
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Location:
Campbelltown
Registered:
November 2003
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Location:
Canberra
Registered:
July 2005
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 06:18
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Yeah, the idea of sucking all the inlet air through the turbo seems like an unnecessary restriction. Your idea, oldcorollas, has these in parallel, which seems like a significantly better idea, although a greater amount of pipework will result. Throttling the supercharger seems like it would be a good idea, but maybe unnecessary? perhaps this is something that could be investigated in a modular R & D setup.
As far as the three throttle bodies are concerned, yes, these will be subject to quite a bit of pressure, but the butterflies should handle it, and if not, it probably wouldn't be too much of a challenge to retrofit reinforced butterflies in standard throttles (again saving a bit of money in using pre-existing parts).
In a ideal world, one way valves would be perfect, but existing models don't come close to ideal, especially in extreme circumstances, so I think utilising throttles over one way valves is wise.
It would be interesting to get such a setup running and compare it to a good PD supercharger, 'cos basically they do the same thing. The systemic losses incurred in the form of flow restriction (throttles/valves/bends) and excess piping (loss of charge pressure/boost response) could cause some issues, but I'm sure there is nothing insurmountable.
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Location:
MELBOURNE
Registered:
December 2004
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 07:00
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| tricky wrote on Sun, 21 August 2005 16:18 |
Yeah, the idea of sucking all the inlet air through the turbo seems like an unnecessary restriction. Your idea, oldcorollas, has these in parallel, which seems like a significantly better idea, although a greater amount of pipework will result. Throttling the supercharger seems like it would be a good idea, but maybe unnecessary? perhaps this is something that could be investigated in a modular R & D setup.
As far as the three throttle bodies are concerned, yes, these will be subject to quite a bit of pressure, but the butterflies should handle it, and if not, it probably wouldn't be too much of a challenge to retrofit reinforced butterflies in standard throttles (again saving a bit of money in using pre-existing parts).
In a ideal world, one way valves would be perfect, but existing models don't come close to ideal, especially in extreme circumstances, so I think utilising throttles over one way valves is wise.
It would be interesting to get such a setup running and compare it to a good PD supercharger, 'cos basically they do the same thing. The systemic losses incurred in the form of flow restriction (throttles/valves/bends) and excess piping (loss of charge pressure/boost response) could cause some issues, but I'm sure there is nothing insurmountable.
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good points..
more pipework ys, but filling pipework with air will not really be an issue, since the SC can provide nearly full boost from idle in just a few revolutions.
the idea if throttling the SC actually came form some of my SC only ideas ... ie you still have a plenum throttle, but for first maybe 30% of pedal travel, there is no boost, then from 30% to 100% throttle, the pedal just moderates the amount of boost in a linear fashion (maybe a modern EBC will be required here).... this does two things, reduces pumping losses (but may make more heat due to double pumping..), and makes thr throttle much more reliable as a source of control...
i hate the way my stock turbo car will sometimes hit boost halfway thru an intersection in first gear if the pdal is too far down.... i like NA linearity .. i guess i want a linear boosted car
i looked at one way valves very closely, but in the end decided that with fast throttle cahnges, they will end up falling to bits... they will work tho, in fact the turbo putput throttle is effectively just that, since it is both volume and pressure based.. but the SC must be controlled by throttle plates as you are restricting it, not just waiting till it does something..
i totally agree.. there will be losses, but it's hard to compare to a Lysholm SC... the lysholm seems to be good up to around 2:1 pressure ratio, sometimes 2.5, but they get hot (IC will help this), but they certainly cannot do 3:1 ratio.... the twincharge is for the peson that wants a little bit more.. ie 30-40psi range.... we are not talking sensible numbers here...
ie a 4AG with 30psi will have around about 400-450Nm of torque.. maybe from about 5000rpm up.. close to what a 5L motor does, but will have around 250-300Nm below 5000rpm..
the lysholm will give you a good 300Nm from low to high rpm...
so.. basically, it's all about the top end charge... i'm not sure what you would do with a 450Nm 1.6L engine.. maybe put it in a dragster
but yes.. an R&D setup is planned. eventually..
Cya, Stewart
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I Supported Toymods
Location:
Sydney
Registered:
December 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 07:02
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Your idea's seem reasonable OC but how do you plan to control 3 throttle bodies?
What if you replaced T1 with a wastegate with the boost feed coming from where you have R1?
Maybe chuck in another wastegate with the spring removed instead of T2 (read: massif 1 way valve!!!)
Then maybe you could invest in 1 x fly by wire throttle body for your T3 position and let the ECU control it.
Seems like a lot of work for what you plan to achieve though... why not just bolt on your massif turbo and then use nitrous to get you going.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 07:31
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| Toobs wrote on Sun, 21 August 2005 17:02 |
Your idea's seem reasonable OC but how do you plan to control 3 throttle bodies?
What if you replaced T1 with a wastegate with the boost feed coming from where you have R1?
Maybe chuck in another wastegate with the spring removed instead of T2 (read: massif 1 way valve!!!)
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well... T1 and T3 are connected... since they basically just control the volume of the SC.... which by default can also control the pressure... i think this hooked to to a snazzy EBC (ie the ones that have RPM/TPS/Boost mapping) and a wastegate actuator, would work very well. i guess in theory this is basically what a wastegate is.. so yes .. i was thinking throttle body for reduced flow restriction, but a wastegate, if properly sized would also work..
T2 is effectively a one way valve... and it may well be better to actually use one, if it could be made reliable enough.. there have been suggestions before of using a massive old AFM as a one way valve!! that could work too!
thing is, none of this needs to work exactly.. since there is still the pedal conrolled throttle/s at the manifold, all this garbage is just a boost control system... and what's a few psi between friends i guess in the long run, all this is meant to do is to stop and boost DIPS during transitions...
i'll have to look into wastegates and actuators more
| Toobs wrote on Sun, 21 August 2005 17:02 |
Then maybe you could invest in 1 x fly by wire throttle body for your T3 position and let the ECU control it.
Seems like a lot of work for what you plan to achieve though... why not just bolt on your massif turbo and then use nitrous to get you going.
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well... i guess thats what the EBC will do... linear control of boost via the T1/T3 actuator... of course if the ECU can do it also.. saves buying some colour screened crapp electronic box
yes it is a lot of work... but no-one seems to have bothered to go down this path because it is "too complex/difficult"... i reckon i might just be the person to bother.... at least in theory
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Location:
Canberra
Registered:
July 2005
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 07:42
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| oldcorollas wrote on Sun, 21 August 2005 17:00 |
the idea if throttling the SC actually came form some of my SC only ideas ... ie you still have a plenum throttle, but for first maybe 30% of pedal travel, there is no boost, then from 30% to 100% throttle, the pedal just moderates the amount of boost in a linear fashion (maybe a modern EBC will be required here).... this does two things, reduces pumping losses (but may make more heat due to double pumping..), and makes thr throttle much more reliable as a source of control...
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So you plan on having a mechanical linkage from your plenum throttle to the supercharger throttle? Mechanical linkages could prove to be a bit of a bitch, since they are so linear. As you said, I think an EBC would make life easier, and enhance that linearity across the rev range which you seek.
As Toobs says, T2 replaced by an unsprung wastegate could be a good option, so the second the turbo makes boost, it goes into the intake. Perhaps the same ECU signal that controls the SC clutch could control the throttle T3, but you probably want to control the bypass in a more linear fashion, which could be tricky.
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why not just bolt on your massif turbo and then use nitrous to get you going.
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That's limiting a bit. especially in a street setup, and nitrous doesn't last forever... What happens if you drop below 5000rpm or wherever the turbo is boosting? If you give it another shot of N2O, it's hardly a linear response.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 08:17
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| tricky wrote on Sun, 21 August 2005 17:42 |
So you plan on having a mechanical linkage from your plenum throttle to the supercharger throttle? Mechanical linkages could prove to be a bit of a bitch, since they are so linear. As you said, I think an EBC would make life easier, and enhance that linearity across the rev range which you seek.
As Toobs says, T2 replaced by an unsprung wastegate could be a good option, so the second the turbo makes boost, it goes into the intake. Perhaps the same ECU signal that controls the SC clutch could control the throttle T3, but you probably want to control the bypass in a more linear fashion, which could be tricky.
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initially i wanted them seperate... i guess by using differently phased bellcranks, you could make it work... but the result would not be boost that is linear with TPS..
the more i think about it, the more i think a TPS based EBC is the way to go... as you could have the EBC hooked up to both the SC via T1/T3, and to the turbos wastgate.. when the turbo is not boosting (ie not WOT) doesn't matter if wastegate is open or not.. (well, having it open in cruise conditiosn reduces backpressure, but..)
hmm, a lightly sprung wastegate could work for T2.. you want a bit of resistance, since you don't want it staying open because of reverse flow.. i had vague ideas at opening T2 during cruise conditions, which is why i wanted to retain T2 a a throttle, but but... hmmmmm
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 08:39
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quick lock thread!to insightful and intelligent for toymods!
lmao
mick
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Location:
Hobart, Tas
Registered:
May 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 09:13
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| Alchemist wrote on Sun, 21 August 2005 01:39 |
A number of cars already use a sequential turbo setup, the 2JZ-GTE for example, it works pretty well.
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I was talking about 2 very different turbos in parralel, not 2 the same in series.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 09:26
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| Stefan wrote on Sun, 21 August 2005 19:13 |
| Alchemist wrote on Sun, 21 August 2005 01:39 |
A number of cars already use a sequential turbo setup, the 2JZ-GTE for example, it works pretty well.
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I was talking about 2 very different turbos in parralel, not 2 the same in series.
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that is done often, ie rotaries.. but thats not what we are talking about here... sorry... you can start another thread if you wish
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 09:37
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why not just have a valve that works of the turbo pressure,when the turbo makes full boost the pressure valve closes the throttlebody for the superchager intake etc
mick
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Location:
Bundaberg, Qld.
Registered:
May 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 09:59
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s/c blowing through the turbo is exactly how i would do it if i ever decide to try a twin charge set-up.
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Location:
Bundaberg, Qld.
Registered:
May 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 10:07
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| kingmick wrote on Sun, 21 August 2005 14:01 |
my thoughts on it is this!there is a izusu or similar diesel that has a belt driven turbo{i came up with the idea and found they already did it!}!it must disconnect once the exhaust has the pressure to spin it! id be running along the line of a one way clutch system on a turbo that is belt driven till you have the pressure at say 3000rpm that the turbo needs,be easy to do and save alot of weight compared to having a blower and a turbo.i have always wanted to do this as a commercial concern and have done research and a little development into it.i think it is the ultimate street setup as you have the low end and as high an end, as a street car could ever want.lmao please save the applause until i have it 100% sorted,thats if i get around to it.
hahahaha
mick
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hrmm.. like a viscuos hub driven turbo of sorts.. i like the idea.
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Location:
Newcastle
Registered:
July 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 10:15
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feral: exactly..
why not use the the charger to blow through the compressor housing of the turbo. yes it will offer some restriction however the plus is that you will be aiding the spooling of the turbo buy forcing air through both sides.then use a electronic controllable butterfly valve in a second pipe that bypasses the SC. as the turbo is at a point where it can/is making boost then open the electronic throttle (SC bypass) and turn off the charger.
my tuner and i considered this. the upwards transition is pretty straight forward to tune. its the downwards transition and partial throttle higher revs ie a sweepiong corner etc that will be difficult to tune.
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Location:
Rosanna, Melb
Registered:
June 2002
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 10:36
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| toof wrote on Sun, 21 August 2005 20:15 |
feral: exactly..
why not use the the charger to blow through the compressor housing of the turbo. yes it will offer some restriction however the plus is that you will be aiding the spooling of the turbo buy forcing air through both sides.then use a electronic controllable butterfly valve in a second pipe that bypasses the SC. as the turbo is at a point where it can/is making boost then open the electronic throttle (SC bypass) and turn off the charger.
my tuner and i considered this. the upwards transition is pretty straight forward to tune. its the downwards transition and partial throttle higher revs ie a sweepiong corner etc that will be difficult to tune.
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but it has already been done.. that 13B for example.. anyway.. this is not the thread to discuss those ideas sorry.. make your own thread
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Location:
Melbourne
Registered:
January 2003
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Location:
Bundaberg, Qld.
Registered:
May 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 10:50
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| oldcorollas wrote on Sun, 21 August 2005 20:36 |
this is not the thread to discuss those ideas sorry.. make your own thread
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my appologies, best of luck finding out what you want then.
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Location:
Melbourne
Registered:
January 2003
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 10:51
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| Henn wrote on Sun, 21 August 2005 20:30 |
I'm not a big fan of three throttles and having to control them all. Also I feel that the throttle T3 and the feedback around the SC could be ditched. The SC shouldn't have a problem sucking vacuum and T1 shouldn't bend. This is how ZEs come setup from the factory.
My best idea so far uses one way valve. I haven't thought too much about their reliability but I'm sure something strong enough could be made/sourced.
It will still run into the problem of how to turn the SC off smoothly. I'd be interested in seeing how much of a jerk would be produced if you simply held the SC on for a little longer, to a point where the turbo was producing most of the air volume then just dropped the magnetic clutch.
Or you could throttle the SC input to smoothly lose the SC air input. Setup right this could also negate the need for the SC one way valve.
Hen
PS - ImageShack.us is way cool
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hmm.. three throttles is easy if they have one actuator
the feedback around SC is to keep it alive and to be able to control its output.. otherwise it is all or nothing, and that will NEVER give a smooth transition.. pulling vac was also a concern for sucking oil thru the bearings....
SC using one way valve such as that will mean it is ALWAYS pushing maximum volume.. and where is the air going to go?
you could blow it off, but thats just wasted air... why not recirculate and reduce pumping losses of SC?
well, say SC is providing 1bar boost,,, for a 2L engine, that measn when you turn off SC, you lose 2L of air per engine rev.... thats a lot of air to loose...
if the SC was providing 1bar of boost and the turbo is also providing 2 bar total.. thats a big drop from 3 bar total boost to 1 bar total boost...
throttling SC to reduce its input is what this is all about
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 11:00
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| feral4mr2 wrote on Sun, 21 August 2005 20:50 |
| oldcorollas wrote on Sun, 21 August 2005 20:36 |
this is not the thread to discuss those ideas sorry.. make your own thread
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my appologies, best of luck finding out what you want then.
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LOL, all i'm saying is that blowing SC into turbo.. or turbo into SC, ie in series, has been done many times, and there is little you can do to improve the transition becasue it is in series....
there are no surprises there, it's pretty straightforward..
but the parallel route is not really that well developed... esp not by manufacturers as it is too costly...
is all i'm sayin
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Location:
Newcastle
Registered:
July 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 11:34
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| oldcorollas wrote on Sun, 21 August 2005 20:36 |
| toof wrote on Sun, 21 August 2005 20:15 |
feral: exactly..
why not use the the charger to blow through the compressor housing of the turbo. yes it will offer some restriction however the plus is that you will be aiding the spooling of the turbo buy forcing air through both sides.then use a electronic controllable butterfly valve in a second pipe that bypasses the SC. as the turbo is at a point where it can/is making boost then open the electronic throttle (SC bypass) and turn off the charger.
my tuner and i considered this. the upwards transition is pretty straight forward to tune. its the downwards transition and partial throttle higher revs ie a sweepiong corner etc that will be difficult to tune.
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but it has already been done.. that 13B for example.. anyway.. this is not the thread to discuss those ideas sorry.. make your own thread
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internal combustion has been done before and kinda works ok too
if you were going for the sequential the SC blowing through the turbo i imagine would be preferable to the turbo blowing through the SC. at least i would imagine it is.. since you can regain the SC's parasitic losses when the turbo is producing boost.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 11:37
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| toof wrote on Sun, 21 August 2005 21:34 |
internal combustion has been done before and kinda works ok too
if you were going for the sequential the SC blowing through the turbo i imagine would be preferable to the turbo blowing through the SC. at least i would imagine it is.. since you can regain the SC's parasitic losses when the turbo is producing boost.
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but it has already been done.. there's no technical challenge here...
i'm not looking for EASIEST way to do it. i'm looking for BEST way to do it ;P
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Location:
brisbane
Registered:
October 2004
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: PARALLEL Twincharging, lets make it work
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Sun, 21 August 2005 12:48
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i imagine the static compression would have to be relatively low to be able to run between 30psi and 40psi of boost...
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Location:
Brisbane
Registered:
May 2002
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Re: Twincharging, lets make it work
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Sun, 21 August 2005 13:05
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| oldcorollas wrote on Sun, 21 August 2005 15:12 |
Brett, looks like your pic is basically what the nissan march idea is..... but if you slowly close the SC's input, it's going to be pulling a massive vacuum... enough to bend throttle plates? maybe..
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Slide throttles?
Cheers
Wilbo
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Location:
Rosanna, Melb
Registered:
June 2002
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Re: PARALLEL Twincharging, lets make it work
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Sun, 21 August 2005 23:29
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Yes, just dropping the SC might be a bit drastic, but if you just throttle the input to smoothly take out any SC air input then it should work fine.
What I'm now thinking is:
Which is basically what Old Rolas posted first off minus the SC feedback and with a 1way valve rather than T2. I still think the SC will be fine without the feedback, if its input is throttled its output volume will be controlled. Sucking vacuum shouldn't damage it, as many modified ZEs work fine just like this and in this setup you can just switch the entire SC off once the turbo comes on hard.
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Location:
brisbane
Registered:
December 2004
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 06:14
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and what is the problem of running the s/c whilst the turbo is also on boost (sorry if the answer is staring me in the face) haha
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Location:
Central Coast, NSW
Registered:
February 2005
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 06:30
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| berad wrote on Mon, 22 August 2005 16:14 |
and what is the problem of running the s/c whilst the turbo is also on boost (sorry if the answer is staring me in the face) haha
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I may be way off the mark here, but if theyre not in series (ie, one is not restricting the other) Then what DOES it matter if the s/c continues providing boost?
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Location:
Rosanna, Melb
Registered:
June 2002
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 06:31
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Superchargers get very inefficient once they start spinning too fast. This puts a big drain on engine power for little gain, especially when the turbo could be producing the air instead for very little loss.
Hen
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 06:35
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exactly.. an SC12 pushing maybe 15psi, will draw maybe 50hp ie 40kW!! this is free power if the turbo can make that boost and more anyway...
Henn, i see what you are saying with the recirculation... i vaguely remember reading something about an SC pulling on vacuum still draws a lot of power, but freewheeling, it won't..
i may have remembered incorrectly tho, and would be happy to simplify the situation if there is no power gain..
edit: even so, the control of T1 and T3 could simply a mechanical connection... if T1 is closed, T3 is open and vice versa
[Updated on: Mon, 22 August 2005 06:42]
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 06:46
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| Merudo wrote on Mon, 22 August 2005 16:30 |
| berad wrote on Mon, 22 August 2005 16:14 |
and what is the problem of running the s/c whilst the turbo is also on boost (sorry if the answer is staring me in the face) haha
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I may be way off the mark here, but if theyre not in series (ie, one is not restricting the other) Then what DOES it matter if the s/c continues providing boost?
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to put it into perspective, think of it this way.. if you want to make 250kw at the wheels with a 1.6L... you need what? 280?290kw at the tailshaft..
if you leave the SC connected, that means you actually need 320-330kw at the crank to make 250kw at the wheels.
i'd rather have a (slightly) lower stressed motor pushing 290kw, than one needing 330kw to have the same rwkw...
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Location:
Rosanna, Melb
Registered:
June 2002
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 06:51
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| oldcorollas wrote on Mon, 22 August 2005 16:35 |
i vaguely remember reading something about an SC pulling on vacuum still draws a lot of power, but freewheeling, it won't..
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Having a think about it that seems right. If it is vacuum at the input and 1bar boost at the output (thanks to the turbo) it'll be very hard to spin the SC. If the pressure each side is equal then it should take very little to turn it.
Looks like that original (high-quality) sketch in the first post could well be the BEST way to do it.
Hen
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Location:
Brisbane
Registered:
July 2005
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 08:05
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This is more what you are looking towards right?
It is a bit cumbersome but could be workable.
It allows the charger to basically freewheel while still being ready to contribute to the system at any time. The turbo is pumping at all times there is no need for a wastegate on the exhaust. A big turbo like that is going to do very little until it comes on hard at say 5500rpm. The blow off valve(s) bleeds off air while they are both producing boost, then at 6000rpm both wastegates switch to block the charger outlet and allow it to recirculate. The turbo is already producing enough air to feed the motor the blow off valves just stop bleeding it off.
Something that occured to me while I typed this out.
What happens to the air that's circulating through the charger, how hot will it get? It shouldn't be being pressurised but it will be picking up a bit of heat from the whole process.
Interested to hear what you think.
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Location:
Canberra
Registered:
July 2005
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Re: PARALLEL Twincharging, lets make it work
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Mon, 22 August 2005 08:27
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Do you mean when the turbo is on full boost and the SC is no longer the primary source of boost?
At this stage, T1 is fully closed, T3 is open and the SC clutch is free spinning. Thus the SC will not be pumping, and no air will be forced through the charger because there is no pressure differential in the feedback loop, so essentially, it will appear as a length of pipe to the inlet charge. That's how I see it anyway> You could shut T3 if you wanted, but it shouldn't be an issue really.
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