what i the most HP possible with TBI some one said that the 454 TBI i wanna get with #90 injectors will only support 360 horses. so is there anything else to do?

 

you can get a ton of power out of tbi. one thing to remeber with all the traditional hp support calculators, they are more designed to deal with mechanical parts. you can support more with digital controls. you will be able to create about 10-15% more power with tbi than those formulas come up with. taht means goign well over 400hp.

later
tim

 

*To keep people off my a$$, I'm going to start by saying this is only what I have heard from others on this site.*

The stock 305 TBI unit is supposed to be able to handle 300 hp. I believe that is without ultimate TBI, though not sure. Now, people have claimed to have 400+ TBI engines (I hope to have one myself!!...383 style), which leads me to believe it can be done when using the Holley 670 or GM 454 TBI.
All the mods listed in Ultimate TBI give you more power, and I would assume they also up the maximum hp the TBI can shell out. And though the mods are based around the stock 305 TBI, I'm sure they can be applied to the larger TBI units as well.
You could always spray it........

 

well what do u mean by digital controls...i want to try ad gt it to support 425HP or maybe a little more...so what would have to do other than ultimate TBImods

 

The 2" TB versions (454 and holley 670) can support up to about 450 n/a hp. You can get even more hp if you do a power adder (duh). Heck, this summer, when I get the chance. I'm going to design a SIMPLE injector driver add on board for the 7747 and 8746 ecms. This way if you want to make mega hp and keep the stock GM ecm (if you are already burning eproms and like good gas milage), you can run a holley pro-jection system with 4 injectors. The holley 900cfm system can support 600+hp.
I want to swap to a 4 barrel TB setup after I do the hot cam swap. It would be the cheapest way for me to keep EFI and make lots of hp AND have good gas milage with the highway mode, closed loop blah blah yadda yadda.
I have the plans from the www.diy-efi.org site if you're interested. I just need to find where to tap into the injector drivers on the board. I thought I had an idea but doesn't look right to me. The total cost of parts for controlling 4 injectors would cost maybe $20 all depending on parts, resources, help.
Just remember the most important part of TBI is that it's still a speed density system so do NOT skip the custom eprom unless you want an excuse to go to a carb!