Parallel Carburator ???

[Edub1]

This is so crazy it just might work!

I've been looking for a good, cost efficiant tune for my SOHC-T project and have been coming up short - or should I say expensive.

Would it be plausible to hook up a parallel carburator that would open just to feed the turbo? I'm thinking it would hook up just like a second MAF and remain completely closed when not needed. That way I could keep my stock injectors, fuel pump, MAF and ECU. That's about $1000 including JWT tune. The car would have all the benefit of EFI except at say 70-80% load when the carb would open.

I'd also use a BTM for timing.

Anybody see any reason that this wouldn't work?

[SeVa-S13]

Why not just get an FMU? They're semi-decent for low power and undoubtedly a ton easier than trying to hook whatever system you have in your mind.

[Dark-Hawk]

Cost efficiency and reliability often times do not go hand in hand, just keep this in mind. In the long run I think it'd just be better to get a Walbro 255 fuel pump (~!$100 shipped on EBay), DSM injectors (can get them for like $45 and they're 450cc just need to bore your fuel rail out), and an S-AFC II which can be had for a couple hundred off EBay, a FPR would be wise as well. In total you're looking at about $500-$600 and it seems much safer than the setup you'd like to do right now.

[C-Kwik]

This is so crazy it just might work!

I've been looking for a good, cost efficiant tune for my SOHC-T project and have been coming up short - or should I say expensive.

Would it be plausible to hook up a parallel carburator that would open just to feed the turbo? I'm thinking it would hook up just like a second MAF and remain completely closed when not needed. That way I could keep my stock injectors, fuel pump, MAF and ECU. That's about $1000 including JWT tune. The car would have all the benefit of EFI except at say 70-80% load when the carb would open.

I'd also use a BTM for timing.

Anybody see any reason that this wouldn't work?

For all the work you would need to do to make this work, it would likely be simpler and probably cheaper to even add additional injectors in front of the throttle body.

According to Corky Bell, you'ld be limited to about 5-10 PSI of boost, and to a blow-through set-up. As it would be ideal to have a carb throat dedicated for each cylinder, it would be rather difficult to fit such a system in parallel with the existing plenum.

I'll give you a cookie for thinking out of the box, but this would have no benefit over and EFI system and if cost and simplicity is a factor, this is not something you want to get into. Most Carbs are not designed to work under positive pressure and need some level of prep work to allow it to work under pressure. I would recommend reading maximum boost on the carburetion section before thinking about this further. If you're not that familiar with fuel injection, read that part too. You'll quickly realize how much simpler fuel injection is. It shouldn't be hard to find a system that can add an injector or 2 that runs off a boost and RPM sensor. Or if you're not looking for a lot of boost, a FMU would be a cheap and reliable option, even with a higher flow fuel pump.

[Edub1]

I was thinking of a y pipe that would split one side to the MAF and the other to a draw through carb that would only open under boost conditions. Can gas be put through a turbo? Anyway, I guess it would probably be real tough to calibrate.

I just noticed that the blue emanage should do just about everything I want at a good price on ebay. I'm going to check into that further. Too bad there are so few options for the SOHC. JWT is the only one who offers tunes for this motor and it's $600 to say hello.

[C-Kwik]

I was thinking of a y pipe that would split one side to the MAF and the other to a draw through carb that would only open under boost conditions. Can gas be put through a turbo? Anyway, I guess it would probably be real tough to calibrate.

I just noticed that the blue emanage should do just about everything I want at a good price on ebay. I'm going to check into that further. Too bad there are so few options for the SOHC. JWT is the only one who offers tunes for this motor and it's $600 to say hello.

Again, Read Maximum Boost on this topic. It will discourage a draw-through carb set-up even more so than a blow-through one. Fuel will tend to liquify over a long area of plumbing. Intercooling will become nearly impossible without fuel puddling in it as well as any other low spot in the plumbing. Carburators generally need to be fairly close to the cylinders and usually want them to flow down from the carburator to the cylinders. You can get away with some horizontal airflow(side drafts), but turbo systems usually do not lend the most ideal set-up in plumbing to facilitate a draw-through set-up effectively.

[Edub1]

Again, Read Maximum Boost on this topic. It will discourage a draw-through carb set-up even more so than a blow-through one. Fuel will tend to liquify over a long area of plumbing. Intercooling will become nearly impossible without fuel puddling in it as well as any other low spot in the plumbing. Carburators generally need to be fairly close to the cylinders and usually want them to flow down from the carburator to the cylinders. You can get away with some horizontal airflow(side drafts), but turbo systems usually do not lend the most ideal set-up in plumbing to facilitate a draw-through set-up effectively.

I didn't consider the effect of the intercooler. With our super cold winters that would probably condense all of my fuel into liquid. I think I've decided to go emanage anyway.

Is maximum boost a good source for info on tuning or are there others that may be more complete in this area. I've already chosen the T3/T4 hybrid so I'm good on that. I might however have some questions on a hose or two but I'm mainly looking to learn about tuning.

[C-Kwik]

Maximum Boost is just a good read on turbocharging. While it doesn't go into all the fine details of tuning, it goes over a broad view of it including some detail about how to properly size your injectors, the different turbo options, their strengths and weaknesses, and some info about how not to blow up your motor.