I am currently running a Holley TBI on a 5.7 but I do own an 86 TPI system off of a Trans Am. Should I swap and use the TPI, I have the ECM for the TPI also. I know I would have to swap for splayed center bolt heads since they are pre-87 but would all that be worth the effort?

 

Just curious what ecm are you using for your tbi ?

 

The factory ecm, the last owner put a chip in but it's not programmed by an individual or anything it's just off the shelf

 

In less your looking to gain alittle low end torque I wouldn’t bother changing from tbi to tpi.
You would need to change your fuel pump too.
The only tbi 350 that was used with the 89-92 tbi 1228746 was the caprice.

 

TBI allows you to retain the "looks like a carb" style of intake however TBI does have a lot of limitations. Only 2 injectors to flow fuel into the engine is a big restriction. It's unlikely, the 2 injectors could flow enough fuel to feed a 300 HP. Probably limited to 200-250 HP. Trying to put an open air filter onto it usually means using a drop base air cleaner or putting on a low cowl hood for clearance.

TPI however has a lot of advantages. With a typical front mounted throttle body, it allows for a low hood profile and it's easier to get cool air from the front of the car. The 8 injectors and throttle body can easily be upgraded to provide more fuel and air into the engine than what a TBI system is capable of doing so there's a lot more potential available.

 

The engine did come from a Caprice, I bought it from the E.Peoria, IL police auction. When they switched to the front wheel drive Impala's years ago. I do have a cowl hood for the air cleaner to fit. And given the HP limitations of TBI and the complexity of adding TPI a carb is becoming attractive. There is already a hole in the trunk for a fuel pump to be easily swapped though. This engine with the Holley 2 barrel 670CFM is making what, maybe 220 HP?

 

There have been some strong builds with TBI. I'm sure Fast355 or Robert Frank can steer you in the right direction. I plan to keep mine TBI but I'm only looking for somewhere between 250-285 hp. But yeah, if you wanted a 400hp build I wouldn't go TPI or TBI.. I would go carb it would be MUCH easier. A set of Vortecs with upgraded springs and retainers and the right cam with your roller 9c1 engine would be a strong performer.

 

Thanks! I think illI start with the heads and work up.

 

"This was a bargain. I picked it up at the Mount Prospect city police auction last spring. It’s an old Mount Prospect police car. They were practically giving ’em away."

 

Haha! Nice! Anyone know if they are steel crank motors or not?