Cascade Crew

[scott in wa.]

Ok, We have been playing with the idea of doing a single or twin junk yard turbo set up on a 305 88 camaro tbi

what turbo's do I need?
we did one on a honda civic this weekend and it turned out good. small turbo, I asume I need a bigger one. it was a custom setup but hav'nt put intercooler in yet. the civic starts to boost at about 3,000 rpm's with about 6psi. kinda cool, with blow off valve.

what ones ???
thanks
scott

[Dewey316]

The biggest issue with TBI and boost, isn't fitting the turbos. Youc omputer is going to have a nightmare of a time trying to deal with fueling. There are a few "hack" style mods you can do to try and get it to work.

You will need to put some sort of check-valve in line with the MAP sensor, so that it will not read boost, but it will probably read vacume at part throttle.

You will also need some sort of rising rate fuel pressure regulator, that also raises fuel pressure proportional to boost.

Then you have to deal with trying to tune the computer, to fuel close to what you are looking for.

As for turbos.... for twins, some mid-sized T3's would probably work well (maybe .64 A/R), maybe a pari of K26, from a merc, audi or porche, maybe a pair of smallish T04's.

The best bet here, is to do the math on the motor, and then look at the compressor maps from OEM turbo's, and find ones that fit well. With the smaller turbo's, you have to be carefull of the surge limit, and also make usre you are in a descently effeciant range when you are using lots of air.

For twins, you are also going to need to sync the waistgates, so that you get even boost output from both turbo's.

[scott in wa.]

Ya sound about right.
Would the same problems occur on the TPI vs TBI one being MAP and the other MAF.

Also its the same type of stuff if trying to set up a blow threw supercharger vs Turbo except not boost on the low rpm rang on the turbos right.


scott

[Dewey316]

Computer wise, the issues are the same.

MAF is going to have some slightly diffrent issue. again, without reading boost, you will have issues. With a N/A MAF engine, once you max the 255gm/m limit, the fuel consumption will be the same at any RPM.

With a turbo/supercharger application, you have to fuel according to boost, so you have a problem with a computer system that is not able to read pressure bast atmospheric.

NOW, with TPI there are some options (maybe with TBI also, you would need to get creative though.

You can swap to a MAP system, and use the $58 code from the sy/ty application. This will have the factory turbo code in the computer, when you use a 2bar MAP, it will work right.

You might be able to run a 749 ECU, with the quad4 code (not sure of the mask), and get it to work with TBI. the 749 should be capable of running TBI injectors, when it is in the quad4 application setup. You would hten need to set your BPW and constantants for the V8, and adjust accordingly.

You could also consider an aftermarket computer. The Holley Commander 950, should run TBI, and Port injection, and have 2bar or 3bar MAP compatability to handle boost fueling.

[scott in wa.]

I got to tell you, you are an amazing sorce for information on this stuff.
You must live eat and breath this stuff.\
Thanks

Has any one in the Crew, done a turbo on there v8's??? was it TBI or TPI ???
Dual turbos or single

Maybe the blow threw supercharger???
thanks

[Dewey316]

I don't think any of the current active members have done it. I am going to do the twin eatons blow thru style, but I need a good amount of money, before I can take on that project.

[Twilightoptics]

[aaron_sK]

http://www.turbomustangs.com/smf/

They have an entire forum dedicated to GM turbo builds. It's a pretty good read if you're looking for ideas.