i might be getting a car with a 350 and TBI on it now. my question is how much do the stock TBI's flow and can you get any better ones like at least 600cfm, 750 would be better.

how good are TBI's for power? i want to get it over 300-350hp and was wondering if i should swich to carb or get a better TBI or how good the stock one does.

 

I think the 454 throttle body's (when ported) with cranked up big block injectors can support over 400 ponies. I don't think any has pulled good numbers on a dyno yet. I plan on hitting a dynoi this summer, and I'm hopping for over 300 at the wheels.

 

It all depends on what size the TBI thats on the motor is, there are two: 400 and 670 cfm. The 400cfm will have 1 11/16 inch bores and the 670 will have 2 inch bores. If you're wondering about power, well a TBI can run on any motor, just depends on how much cfm and how big the motor. For instance, 400cfm was stock on the 305s, 670cfm for the 350s, and then Holley makes a 900 or 1000, can't remember which, for big blocks. For that fact Holley makes aftermarket 400 and 670 units that are capable of delivering much more fuel at higher pressures and much much more efficient air flow characterisitics. You can get them from Jeg's at:
http://www.jegs.com/cgi-bin/ncommerc...search=on&ns=Y

Hope that helps!

 

Nope. 4.3L, 305 and 350 all came with the same Rochester 220 TBI. Only the 454 got the 2" bore TBI.
Only differences between the small block (and 4.3L) TBIs are the injectors.

 

ball park estimate of the flow rates of the two tbi's are around 375/500 CFM @ 1.5 inches. You wont have too much air to play with and youll be working with speed density so youll have to choose teh components of your combo carefully to really get something that performs. With some, more like alot of prom burning and a good deal of research into what parts to run i feel that 300+ or maybe even 375HP is obtainable. I have yet to really see any good hard dyno numbers yet, though. Im going to be trying out running vortec heads with a XE256-12 cam, edelbrock s-victor intake, and a bb tbi. It should be interesting to see what i get out of it.

 

Heres what desktop dyno says about my motor running a 454 tb.