Ok i have a 88' Blazer L05 in my camaro, i have installed 9906 Vortec heads with a comp cams 12-262-4 camshaft from Summit also matching valve springs and retainers, I have installed new crank bearings and the motor only has about 64,000 miles on a rebuild, it has a SUM-226018 Intake from Summit, a square bore carb to TBI adaptor plate, and a Ultimate TBI mods 350 tbi unit with 350 injectors, I am working with Brian from TBI chips to get the correct burn, i already have one he burned for me but didn't do much good, he told me to run 454 injectors with my setup, well i did that and it sputters if given 75-100% throttle (runs really rich, blows out a little black smoke). my base timing is 0 degrees right now, I am wondering what you guys think is the problem..... Its slower than it used to be... bottom line. didn't gain any hp apparently.... Could it be the TBI unit not flowing enough cfm for the engine? like maybe i need the 454 unit or any other ideas? i'm stumped..... I'm close to going carbureted....... ****Mods in Sig****

 

Mostly in the tuning, but you can also check fuel pressure. Smaller injectors might helpto since it's running rich.

 

I am running the 350 injectors at what i think to be not very high but about halfway up the slit where the tab slides. SO stock pressure maybe? but shouldn't the Vortec heads and cam take a lot more fuel in?

 

I have tried 454 injectors at low and high pressure, and the 350 at high and low pressures and still doesn't make much of a difference. only the 454 injectors make it run rich...

 

These problems don't seem to be getting solved so i'm going to throw a carb on there and be done with the EFI bull.

 

Carb may not be too cost friendly as i already have $300+ into the EFI.... any ideas ppl?

 

As strange as this may sound, have you tried running the stock 350 chip to see what happens? It is a pretty mild cam, so it might run a little better. If it does it could give a better base line.

The outer part of the harmonic balancer can slip too, which would have your timing way off. Neither may help, but both are free to check. I hope it helps.

 

Did I read right? You are running the 350 TB unit with 454 injectors? Shouldn't you be running the 454 TB with 454 injectors? The 454 TB has 2 inch barrels. The 350 TB has 1 3/4 inch. You are choking the engine with that set-up. Get a 454 TB and injectors. This will allow more cfm for that cam to inhale more fuel/air.

 

I asked that before and no one said it was a problem.... i think i probably will get a 454 tb... what does the 454 tb flow vs ultimate tbi modded 350 unit?

 

I don't know what either one flows, but a 454 has 1/4 inch bigger barrels. They must flow more. WHen you add the bigger injectors to the smaller TB it will probably cram too much fuel into the engine.

 

Its not the small block TBI, its not the 454 injectors. Its not the TBI setup. Its the LACK of TUNING that is killing you.

 

Ok i have tuning done and Brian the guy who is doing my tuning says my exhaust is killing my hp, i have Flowtech Headers 2 1/2 collectors into Flowtech Y-pipe 2 1/2 out into 2 1/4" Magnaflow cat (2 1/4 inlet and 2 1/2 oulet cat) and goes into a 3" midpipe back to the 3" flowmaster 80 series into duel 2 1/2 out... is that a terrrible setup? He says it can limit my power up to even 100hp.... any ideas?

 

anyone?

 

The most restrictive part of your exhaust you mentioned is 2-1/4, so if we treat it like your entire system was 2-1/4 then that should handle ruffly
300-325 HP
They say 2-1/2 can handle 326-400.
Some factors can change this, but this is ruff.

With the setup you mentioned I think you should be fine exhaust wise.
At least it should not be causing you to lose 100 HP.

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I think the issue is probabily more about tune than anything else.
Are you running a stock 305 chip, or a 350 chip and waiting for your custom tuned chip?
If so, I would make sure you are matching your intake to your injectors.
Which might help some, but until you get the right chip, it might not perform the best.

 

i am on my 2nd tuned chip, from brian from TBIcips.com, hes the one who says my exhaust is killing me.