so as you all know i want to redo my 2002 ... and my HP goal is 200ish. now ... i could do a motor swap ... or switch to a stand alone fuel injected system, but that would kind of take away from the old school nature of the beast. i think it would be really nifty to build the block up to take boost, and then come up with an old fashioned carb/turbo setup.
so i was thinking just now, what if i fab'd up a mount to put a carb (like a holley or something) on the intake side of a turbo (so it was sucking air through the carb) and then make a tubular intake system????
here are my questions:

1. think it would be hard to tune?
2. think it would get an even dispersion of air/fuel to all cylinders?

i know that VW bugs run a similar situation, but they're kinda' all together different anyway.
here is a rough diagram of what i propose:

http://img219.imageshack.us/img219/2489/carbturbosetuprf0.jpg
think it could work? or just a pipe (bending) dream????

i know i didn't include the exhaust/turbo manifold side in the diagram ... but that's not really the part i have in question.

Do a Google search for this. I know some of those wild Scandanavians have done this. I remember one with the carb sticking through the grill where the cold air intake is on an M2

i <3 your diagram and i in no way contribute to your thread

Hi Jonny,

What you're talking about is an 'old school', carbureted forced induction system!!! (Using either a supercharger or turbocharger for boost, in combination with a carb set-up.)

They're designed either as draw-through (like your diagram) or blow-through (where the position of the carb and the turbo/supercharger are swapped).

Of the two, blow-through is supposed to be the MUCH better set-up - according to the 'forced induction' bible, "Maximum Boost" by Corky Bell. So much so that he calls the system you've diagramed a "dead fish"... ;-)

I've attached his diagram of the two set-ups, and a snippet of his assessment of the two systems for you. If you're interested at all in designing/fabbing/installing a forced induction set-up on your 02, you've gotta get and read this book.

Hope this helps!

Tom

I have seen this setup before and it is referred to as "drawn through". There was also a popular setup known as "blown through" where the position of the turbo and carb are reversed.

The reason these configurations went away is most likely because they were difficult to tune. The situation you have illustrated is probably least desirable because any fuel that comes out of suspension is going to puddle in the compressor. Not sure about you, but I would hate to have fuel puddling in my turbo, sounds like a recipe for disaster!

thanks for the input guys ... especially visionaut ...

thanks for the input guys ... especially visionaut ...

Ditto on reading Corky's book. I have recommended "Maximum Boost" to numerous people as it is well written and easy to understand even if you are not an engineer.

Ok guys I'll order up that book ... and start looking more into the blowthrough system, as it seems the best. I'm sure that an modern egine swap and/or updated EFI system would work better and be easier to tune. but, i'm thinking that keeping as much on the car low-tech as i can would be cool as well.

so how was the factory turbo setup? was it mechanical fuel-injection and if so how difficult are those items to aquire?

what about something like this on VW's ....

http://www.vwtrendsweb.com/tech/0211vwt_turbo_volkswagens/photo_01.html

The only drawback to a blow through system is, you have to fabricate a pressurized airbox around the carb. The fuel bowl vent must be at the same pressure as inlet air. Otherwise the boost will blow the fuel out of the carb...lol duh...

IOW, it's more fabrication. If you are going to the trouble of turbocharging, think about a MegaSquirt EFI system. Way easier, and better results in the long run.

Yeah ... I was also thinking about TWM Induction EFI conversion on a dual carb style setup. Then just have to fab up a intake box for the throttle bodies and do everything else like a standard turbo setup.

I suggest that you find a 2002tii or early 320 intake manifold and simply re-sleeve it for electronic injectors.

That is basically what I did to convert the mechanically fuel injected hardware to utilize modern EFI.

I have zero experience with the Megasquirt controller but everyone who has used it seems to like it.

FYI -- I'm personally exploring doing a Blow-through system with a supercharger as the next major mod to my 02. I like the old school aspect to it, and I'm only looking for a moderate additional performance increase (~7psi boost, maybe an additional 30 or so HP) on my already highly modded motor. I already have the ignition set-up and dual DCOEs, so if I do it, I'm planning to build around that vs switching to EFI.

I've found that Weber DCOEs are a perfect carb for a blow-through application from my research. I will need to fab a sealed airbox to them that is supplied via the 'charger (looking at enhancing a Pipercross airbox). I haven't picked a supercharger yet, I'm still evaluating options.

If I end up doing it, it'll be a spring project, and I'll document it for any who might be interested.

Tom

^ yeah i'd be interested that ... let me know how it goes. if all is well, maybe we could work out an arrangment to just get both intake boxes done at the same time and share some of the cost???

btw i've got a 44mm setup now.