| Author | Topic |
|---|
Location:
Hobart, tassie
Registered:
December 2003
|
|
Carby supercharging
|
Tue, 10 August 2004 23:09
|
 |
Not really that interested in doing just want to find out whether you can use an Sc12 on say a 2t with a webber
Obviuosly there would be fabrication of some sort involved but are these charges able to be used
Cheers Josh
|
|
|
Location:
Brisbane
Registered:
May 2002
|
|
Re: Carby supercharging
|
Tue, 10 August 2004 23:15
|
|
Yes, it can be done and it's quite easy. Just mount the carby in front of the supercharger (ie a "suck-thru" setup) and Bob's yer uncle. The downside is you can't use an intercooler, so you'd have to keep the boost pretty low.
|
|
|
Location:
Hobart, tassie
Registered:
December 2003
|
|
Re: Carby supercharging
|
Tue, 10 August 2004 23:33
|
|
so'd there be nothing that needs to be modified with inside the supercharger being originally off of an efi motor
Cheers josh
|
|
|
Location:
Montrose, VIC
Registered:
May 2002
|
|
Re: Carby supercharging
|
Wed, 11 August 2004 00:09
|
|
Just make sure you connect the pressure balance hoses correctly 
|
|
|
Location:
brisvegas
Registered:
August 2004
|
|
Re: Carby supercharging
|
Wed, 11 August 2004 11:52
|
|
no!!!! the sc12 wasn't designed to compress liquids! i was going to do this on my 18r, the best way i saw, was to have the filter - sc12 - intercooler - sealed airbox - to the carbies, all you have to modify on the carbies are the floats, make sure there non-collapsable brass type, not the plastic ones.
happy boosting!
mat
|
|
|
Location:
Ballarat, Vic.
Registered:
February 2004
|
|
Re: Carby supercharging
|
Wed, 11 August 2004 12:21
|
|
hrrm, ive heard this elsewhere.
in reality, you will need an efi fuel pump, rising rate fuel regulator, and a BOV to go blow through carby supercharging, as well as a carby box ect. this is because as you close the throttle at higher rpm, the supercharger is still producing boost, placing unneeded strain on the carby butterflies. the bov will vent this excess pressure, insuring correct operation and longer life to your carbie.
as for the fuel side, you need to remember that for every 1psi boost, the fuel should be at least 3psi greater in pressure, otherwise it'll get blown back down into the fuel tank.
the toyota superchargers as far as i know have teflon coated rotors, so using it for draw-thru should be ok.
just remember that with draw through, as the fuel/air is compressed together, you get a chemical intercooling effect as the petrol can absorb a lot of latent heat, meaning you can use a little more boost than you think....
any help?
M.
|
|
|
Location:
Brisbane
Registered:
May 2002
|
|
Re: Carby supercharging
|
Wed, 11 August 2004 23:32
|
|
Using an SC12 supercharger in a blow-through setup is a BAD idea (I don't know how many times I've said this). If you think a little BOV is enough to vent excess pressure when the throttle is snapped shut, think again!
AFAIK the rpm limit for an SC12 is around 10k rpm. The SC12 is a positive-displacement pump which means it displaces exactly 1.2 litres per air every revolution. So, imagine your at max revs and you lift off the throttle - all of a sudden, you have 12,000 litres per minute (approx 420cfm) of air with nowhere to go except out the 1" outlet of a BOV! Hmmm, what's wrong with this picture?
Running fuel through an SC12 is no problem, plenty of people have done it before. Just think of how many old-school supercharged V8's run fuel through their roots blowers, no problems there either!
|
|
|
I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
|
|
Re: Carby supercharging
|
Wed, 11 August 2004 23:39
|
|
| Norbie wrote on Thu, 12 August 2004 09:32 |
AFAIK the rpm limit for an SC12 is around 10k rpm. The SC12 is a positive-displacement pump which means it displaces exactly 1.2 litres per air every revolution. So, imagine your at max revs and you lift off the throttle - all of a sudden, you have 12,000 litres per minute (approx 420cfm) of air with nowhere to go except out the 1" outlet of a BOV! Hmmm, what's wrong with this picture?
|
Yeah, but will get that cool flutter noise like the WRC rally cars?
|
|
|
Location:
Ballarat, Vic.
Registered:
February 2004
|
|
Re: Carby supercharging
|
Thu, 12 August 2004 05:06
|
|
well, as with most sane people, i doubt that you would run a supercharger-fed engine to 10,000 rpm, unless it's a race car.
but if you want to get silly, you could use some of those stupidly large HKS BOVs used on 30+ psi drag/racecars.....or use more than 1 BOV.
but the best idea is to go efi with the T/B before the charger, an intercooler and some large injectors controlled by an MTX-8.
but why bother with something as restrictive as a supercharger?
use a gt30 BB instead. boost can come on as low as 2800rpm in a 1600.
turbo is the way to go.
M.
|
|
|
Location:
Brisbane
Registered:
August 2003
|
|
Re: Carby supercharging
|
Thu, 12 August 2004 05:11
|
|
|
He wasn't talking about the reving the engine to 10k, he was talking about the supercharger.
|
|
|
Location:
Brisbane
Registered:
May 2002
|
|
Re: Carby supercharging
|
Thu, 12 August 2004 05:15
|
|
That's correct; the SC12 is overdriven on the 4A-GZE, and its max rpm limit is something like 10k rpm (I think).
Even if you use a hugh BOV or multiple BOV's to vent enough air, it's still a really silly idea. Think of how much time you spend at WOT - maybe 1% of the time you drive the car? So the rest of the time your BOV(s) will be venting shiteloads of air. Not only will your fuel economy go to shit, the car will sound like an industrial air conditioning unit.
In short, if you're using a positive-displacement blower like the SC12, you need to mount the throttle plate pre-blower. There's a reason Toyota set up the GZE engines like that.
|
|
|
Location:
Vic
Registered:
May 2002
|
|
Re: Carby supercharging
|
Thu, 12 August 2004 05:29
|
|
I have used a SC14 with a blow through setup usings LPG. I also know of a few that run carbies without problems.
I used a BOV venting back to the intake & had a switch to turn the blower on & off. You can also buy a supercharger bypass valve for this exact application or some poeople have used 2 BOV's.
I used 1 & only blew my hoses off a couple of times using 15psi.
|
|
|
Location:
Brisbane
Registered:
May 2002
|
|
Re: Carby supercharging
|
Thu, 12 August 2004 06:19
|
|
| bmak wrote on Thu, 12 August 2004 15:29 |
I used 1 & only blew my hoses off a couple of times using 15psi.
|
Obviously it's a good idea then.
|
|
|
Location:
Castle Hill, Sydney
Registered:
February 2004
|
|
Re: Carby supercharging
|
Thu, 12 August 2004 07:48
|
|
im not sure on the suck through menthod, but the BOV would go after the sc right? and the carb b4 it, so wouldnt u not only be blowing off tonnes of air but fuel also!
and blowing fuel floating around ur engine does not sound like a good idea!
|
|
|
Location:
Hackham South Australia
Registered:
July 2004
|
|
Re: Carby supercharging
|
Thu, 12 August 2004 08:54
|
|
Go EFI as the ultimate, LPG works well too. I would tend to go for suck through, it'll be handy if a friend can weld alloy, moddify the manifold and make an adapter plate for the blower, Keep the the intake for the SC on and make an adapter for a SU as these are the easiest when it comes to this method, some thing like a 2" SU should do it. Using an SU as some are aware, will not kill the engine as fuel is sucked through the diaphram as apposed to being forced as with webers and alike. Eldred Norman, from NSW wrote a small book on this some 30 or so years ago. He had been using a vane type with twin su's on a GT cortina running 15 psi and running methanol, sure it had the worst economy you can think of and then times it by 10, but it worked.
If you are interested in hearing more i can try and get the relevant info that you need for this conversion. SC is an interesting way to make power and a hell of a lot of torque, i am only too willing to help out if it is required. Try using the SC off the soarer rather than the corolla, it has more puff. and costs about the same.
Big motor conversions, turbos' SC 'ing, Is there nothing kids won't do today! ( im only 21.7)
|
|
|
