Nope I dont have one, but my head is ringing from sifting through all the about tbi's. Some people are saying that no tbi can support 400hp. It appears that if you want a truly performance tbi you need a holley 900 or 950 model. What are the cold hard facts on using a centrifugal supercharger with these?
Can a 85pph injector support the boost?
Does a 900cfm tbi actually flow about 700?
I dont want to use this system if I will be at the upper limits with it. Does anyone have some useful info?? If anyone knows its the guys on this board.

 

Stock ECM wont pick up the boost...use a later model truck ECM and use a 454 TBI with the 454 injectors and you could use the aftermarket TBI supercharger not sure who makes it but summit has it.

No reason why that wouldnt work.

 

The holley system comes with its own ecm and its a four barrel so the 454 injectors wouldnt work. I doubt there is a pod that would accept them if you used four.

 

Depends on what 454 injectors your reffering to. None the less, the 61 pph late model units can be had if you spec them at the time of purchase, or buy them from a GM supplier.

The 900 CFM tbi will flow 900 CFM @ 1.5 inHg, the 670 unit will flow around 670 CFM @ 1.5 inHg. IMO, though, the same, or nearly the same result could be had by getting a good old big block and getting a cam that gives you a powerband from idle to around 5500 RPM. With good heads, cam, and a properly prepped short block it should easily belt out 400+ horspower, or more. Itll probably be less $$$ wise as you wont be buying a supercharger in addition and you can get around the whole boost issue. As for the power issue, with that motor you can just turn the fuel pressure up to around 30-40 psi as itll need more fuel across the board. There are people here making this much power already.

 

That would be an awesome way to go but I already have the supercharger. And Im in Germany right now so the big block is definitely out of the question. The holley 900 projection or the 950 commander sounds like the way to go if I keep it efi. Now I understand that you cant program any boost into the holley ecm. Is this true? If not I can do it the shady way using an FMU. But will the injectors be able to support 450-500hp under boost? Thanks for the replies.

 

Well, in that case, the best thing to do would be to call holley and see what the capabilities of their ECUs are. The other alternative would be to use a 7749 from a cyclone or typhoon. Those are set up for boost.

What bars the use of a big block in Germany? Granted it weighs more so itll cost extra over a small block to have it shipped over from the US.

 

Im thinking that a blown (centrifugal) 350 would have better low end gas mileage vs a bb. Plus I already scooped up the vortech charger for $2000. The only reason I want to keep the tbi is for emissions purposes, but I really want to go carb. Having a 500hp car would justify the work to swap the carb back to tbi at inspection time when I go back to the states (no emissions inspections here), and to make all the emissions equipment appear to be functional. I know it will be a lot of work. But if this holley setup isnt going to satisfy me, then thats what ill be doing. If I was doing this to my 74 nova, the last year of any emissions requirements in my state, I would definitely be putting a bb in.

 

The syclones and typhoons were mpfi if I remember correctly, im not skilled enough to dive into converting that to tbi.

 

Yes, they where MPFI, but the ecms can be wired to provide enough firings for use with tbi. The same ecm also came in other cars as well.

 

It "might" be possible to run a 2-bbl TBI via the 7749 ECM. I'm trying that now. I *think* Grumpy on DIY-PROM has run in this configuration on a bench a while back. However, I don't believe you'd be able to run this, or any other GM ECM, with 4 TBI-style injectors without some external circuitry or internal modification.....

 

I'm pretty sure Grumpy ran a TBI vehicle on a 7749 a few years ago, that's why he always told people to try making the switch over. I'm almost positive he had it running in an application though. Someone else on the PROM board also ran a 749 on a TBI motor, he posted about it maybe 6 months back i want to say.

 

The commander 950 950-21s model is for 450-600hp. It uses four 85 lb/hr injectors. Could I use an FMU instead of programming in boost? I know its not the clean way, but I dont have the time for experiments right now. Could low boost in any way harm these injectors?

 

Boost wont hurt them. It would be better if whatever computer you used could see boost. Would require less work to get it to work correctly. It may be easier and cheaper to build a 383 or 400+ and sell the supercharger, especially if you havnt built the motor yet. Youll get the same results with 1/10 the effort. That commander system should have no trouble on a hot motor.

 

Right now I'm going to put this on a vortec headed 305. If I aquire a 350 here, I'll stroke it and put in forged parts and raise the boost and run it until the tranny or the rear gives. But chances are ill wait until I get back to the states and redo my whole drivetrain. That will be a must with a supercharged 383. With the 64cc vortec heads, the stock internals on the 305 should be ok with low boost.

 

The holley Commander 950 ECM is setup up to run boosted applications. All you need to do is supply it with a 2 bar map sensor. I am using that ecm to run my 77 vette with a 142 roots supercharger and the holley 4bbl TBI. It sit on top of a 383 chevy small block. The car is a ton of fun to drive, and tuning the commander 950 could not be any easier.

 

If teh commander supports boost then your good to go.

 

Sweet, sounds like I'm set then. Thanks for the help guys.