Anyone done it before with success? It looks like a good solution for Challenge boost, if you're fine with running overly rich. I read this Hot Rod article and it looks easy enough. Asking for a friend...
Anyone done it before with success? It looks like a good solution for Challenge boost, if you're fine with running overly rich. I read this Hot Rod article and it looks easy enough. Asking for a friend...
We tried to do it on the Triumph spitfire with a Weber years ago and could never get the thing running right. It would have about 200 rpms of power and the rest of the time it would cough and spit. I'd advise staying away unless you can find a cheap method to implement a rising rate fuel pressure regulator.
If I were to do it again, I would do a pull through setup like the old F1 cars utilized... Of course that comes with throttle response issues among others.
In reply to NordicSaab:
i dont think you can run an intercooler on draw through set ups due to fuel pooling in the intercooler, but it depends on how you want to do things if you'd need an intercooler
another good source of info i've found on blow through carb's is here.
Just say no.
Port injection is the path of enlightenment.
The Blow through path is littered with melted pistons.
Lotus did it with Del Orto's. They are not identical to the regular Del Orto's. There's a few differences that I don't recall as I never had them. Look up like mid-80's Turbo Esprits. Not Esprit Turbos, those are EFI. The other way is like the Maser Biturbos, build an air tight box around the whole carb and pump air through it. Yeah, you'll have to do something with the fuel pressure regulator to index it to the intake pressure.
In reply to NordicSaab:
It's my understanding that a boost referenced regulator is a requirement to make a blow though work, otherwise it will starve for fuel as the vacuum/boost gauge swings past 0.
I don't think it's a matter of swinging past 0, but more of changing the effective pressure from something like 3 PSI at a vacuum to say -3 PSI when you are at 6PSI of boost. If the pump is trying to push fuel in at 3PSI and the box or carb is pressurized at 6 PSI, it isn't going to flow very well.
Dr. Hess wrote: I don't think it's a matter of swinging past 0, but more of changing the effective pressure from something like 3 PSI at a vacuum to say -3 PSI when you are at 6PSI of boost. If the pump is trying to push fuel in at 3PSI and the box or carb is pressurized at 6 PSI, it isn't going to flow very at all.
Edited for emphasis.
In reply to Dr. Hess:
Right, unless you have a referenced regulator fuel flow will gradually drop off to 0 as boost pressure approaches fuel pressure.
Fordsix has great info about it, specificlly lincs thread. 28psi through a one barrel!
I have no experience with a DIY blow thru but I know quite a bit about how Yamaha did it in the early '80s with their Seca Turbos. I still ride the one I bought new as a leftover in '88 when I was working at a Yamaha dealer. They used CV carbs and a boost referenced fuel pressure regulator with an electric fuel pump.
BrokenYugo wrote: In reply to Dr. Hess: Right, unless you have a referenced regulator fuel flow will gradually drop off to 0 as boost pressure approaches fuel pressure.
I know when they do blow through's on Corvair's they run a line from the intake to the backside of the mechanical fuel pump to compensate for the rising pressure. The floats in the carbs also need to be reinforced otherwise they will tend to collapse.
If you do the box around the carb you can put the pressure regulator inside the box to reference it. You just have to make sure to use one that can handle choking down the 15psi or so the fuel pump will have to put out at boost to the 3psi or so the carb will need at idle. It also wouldn't be a bad idea to have a check valve between the box and the air filter so that if you are not in the boost the box stays near atmospheric pressure with clean air.
I studied how to do this back in the 80's and looked at all of the issues, the kits that were available, etc. I never did go this route since at about that time EFI was starting to be offered on more & more cars. It became a moot point to design a custom "blow through" turbo system when it can be dome so much easier and with better performance and reliability using EFI.
It can be done but for the "Challenge" I think that adding a NOS system would help more.
Did a search on Mc Culough(sp) super chargers.
Tells you just what to do.
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