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Location:
Sydney
Registered:
March 2003
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20v VVT tech question
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Tue, 04 January 2005 03:50
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Dumb ques re the cam timing, when the VVT cuts in does it retard or advance the cams? Where does it cut in as stock? Is it similar to the SR16 where you can select the cam timing for intake & exhaust seperately, or can you only do both at the same time?
We'll be using an EMS ECU so can cut cams over whenever we want, which depends on what the dyno tells us, Im just not sure of roughly where to start as I dont know which direction the VVT moves the cam.
Final question, is the 20v like the 100kw 16 where if you lose the belt the valves still wont touch the piston crown?
Cheers,
Riv.
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Location:
sydney
Registered:
March 2003
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Re: 20v VVT tech question
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Tue, 04 January 2005 05:03
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i came across a 20v at a workshop once and it didnt make much more hp when it was on
but might have been bad tune
what you do is turn it on always and do a dyno run
then turn it off fully and do a dyno run
then u look at both graphs and see where the cross over point is in hp and that is about where it should come on
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Location:
Gympie Qld
Registered:
December 2004
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Re: 20v VVT tech question
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Tue, 04 January 2005 12:03
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Riv, on a slightly side note what load sensor are you using with the EMS. AFM, MAP or TPS.
I'm using a 20 valve but was looking to run ram tubes and individual air cleaners. Was going to use Microtech but found out the other day they can't tune it off MAP as I first thought. Can only tune it off TPS which I am worried will be a bit rough. Apparently can't run it off AFM so I can't een go back to a factory like settup.
Gavin
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Location:
Sydney
Registered:
March 2003
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Re: 20v VVT tech question
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Tue, 04 January 2005 23:56
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I hadnt really stopped to put that much thought into it... I'd also like to use MAP, the same setup we had with the 16v. We used MAP as its an offroad buggy and the TPS can get bounced around alot and give back inacurate readings, besides having to recalibrate it constantly. Bit hard to use MAP without a plenum chamber though...
I guess you could run a line into the mani in each runner after the TB's to accurately measure vaccum and do it that way - but I have no experience with it. Has anyone out there tried it?
Nobody I know races using AFM - I'll be steering clear of it.
In regards to TPS, I'll be looking into whether there is a more accurate sensor through Motec that could be used as a possible solution.
Not really much help, I hadnt started thinking about it yet!
cheers Sideshow - a simple idea which I would never have thought of!
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Location:
nth ringwood, Victoria
Registered:
August 2002
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Re: 20v VVT tech question
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Wed, 05 January 2005 02:47
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what engine silver or blacktop they are both different and in both cases its only the inlet that retards and advances
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Location:
nth ringwood, Victoria
Registered:
August 2002
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Re: 20v VVT tech question
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Wed, 05 January 2005 02:49
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just another thought i have a friend that has a silver top with a black top ecu and it runs fine try that if you can no afm at all ,and in the motec case they use tps as the map is used as atmospheric pressure
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Location:
nelson, new zealand
Registered:
October 2004
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Re: 20v VVT tech question
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Wed, 05 January 2005 02:56
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celicara45... you have a mate running a blacktop ecu on a silver top?
how did he do that? theres quite a few difference...
map, the vvt is different....
the cross over is around 4500-5000 but it depends on a few things.
the 20v in non interferance, i just dont recomend testin git at 8000 rpm...
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Location:
Sydney
Registered:
May 2002
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Re: 20v VVT tech question
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Wed, 05 January 2005 03:19
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Dont really know much about the VVTi settings, as im not allowed to run a 20V in the sprinter,
But im using an EMS on a 16V 4AGE with 20V throttle body, and some big cams in TPS only mode, it runs fine, i havnt had any throuble with TPS bounce, even down Watagan road 
Ben.
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Location:
sydney
Registered:
March 2003
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Re: 20v VVT tech question
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Wed, 05 January 2005 03:29
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when you run multiple throttle bodies and fit an aftermarket ecu there are afew work arounds
autronic has a good setup and i think mottec has it now aswell
it uses throttle off boost and map on boost
with a 20v being n/a i cant see why you cant run a microtech and run the map signal off the tiny vac lines under the manifold
there is a vac line that connects to all 4 runners so its a common one
i would even ring microtech and ask them if there is any majors probs when running a microtech on a 20v
20vs have been out for awhile so im sure microptech have done somehting about it
at the worst all u get is not the smoothest idle
once you start to accel;erate its all good
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Location:
Sydney
Registered:
March 2003
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Re: 20v VVT tech question
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Wed, 05 January 2005 03:39
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Ahh! there's the answer to that q - if there is already a line connecting all four runners after the TBs I' be using that for MAP.
We had all sorts of problems using only TPS - the worst of which was having to callibrate it after every jump, creek rut or big rock... basically after every run... but it might have been a dodgy TPS...
To throw another log into the fire (dumb question time) - EMS (and I assume other ECU's) have 2 tables for fuel and ig. 0kpa and -50kpa. Without a vaccum line how does the ECU pick the right load point without knowing mani pressure?
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Location:
nelson, new zealand
Registered:
October 2004
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Re: 20v VVT tech question
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Wed, 05 January 2005 03:43
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isnt there a vacuum cross over line after the t/bs on the 20vs?
its internal on the blacks but i think its external on the silvers, you could tap in to that
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Location:
nth ringwood, Victoria
Registered:
August 2002
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Re: 20v VVT tech question
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Wed, 05 January 2005 04:34
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on my 3sge it is running TRD quads and uses a toyota 20 v tps that the motec runs fine ,that is all im using and with 520 thou lift cams and 260 at 50thou and 12to 1 comp it still idles at 750 rpm and as i said the map sensor is to atmoshpere only and this year im going to use vvti in the beams engine as well so i can move both cams in either direction
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Location:
Gympie Qld
Registered:
December 2004
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Re: 20v VVT tech question
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Wed, 05 January 2005 11:34
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I suggested straight away to Microtech guys, both local and head office (web site contact) about equalising the vacuum signal but both still said it won't work properly and onyl real way is TPS. One can only assume this means there is an issue with the Microtech MAP sensor or programming. Autronic guys say yeah no problem.
Was also told that TPS mode was very crude and only good for race cars as they are generally reading on or off. Eg great at WOT but get similar fueling at part throttle under certain circumstances. Hard to distinguish between constant part throttle and constant WOT for example.
I'm after as close to factory running as I can get. Before you say use factory computer, I don't have one or loom and it would complicate conversion.
IF you are only going to use TPS mode why would you even spend the dollars on a new Microtech. You may as well just buy any old second hand Wolf, Digi 1/2 etc.
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