I recently bought a 86 Yellow IROC with a TPI 305 and and auto. My original plan was to get a fourth gen camaro and swap the LT1 and t-56 into the IROC. I was looking at the HP and torque ratings for the two engines. A 93-95 Z/28 (which is probably what i would get) has 275 HP and 325 for torque. Then i looked at a 87-92 350 TPI and they had more than 225 hp and 330 foot lbs of torque. The LT1 has 50 more hp and 5 foot pounds of torque less than the 350 TPI. I am hoping to get 325-350 HP from one of these engines, Which is the best one for me to start with? I would also not want to use NOS or a supercharger unless neccesary.

 

well.....that amount of hp is achievable by both enginees, and not too difficult to get with out a supercharger and nitrous. But the TPI will always have more torque. I myself am building a 350TPI and am looking for a 6-speed to bolt up to it.

 

I would say the LT1 would be the best basis, and Im not just being biased. For one, to reach you goal of 325-350 is going to be easier with the LT1 since you are already starting out higher. Second, you are going to have to spend more on the TPI since it starts falling flat above certain RPM's that are going to be necessary to reach that horsepower level, so you would have to upgrade runners, probably TB, injectors, etc. The LT1 injectors, at 24 lbs, are good up to about 450 hp. TPI, 19 lbs, or 21 lbs, not real sure, are going to be near maxxed out in their duty cycle at 350 hp. For each mod that you do to the engine, the LT1 will have more horsepower since it starts out with more, and therefore, theoretically, should cost less to acheive the desired horsepower level. theres more to it, but I would say that covers the basics.