I have a 305 from an 81 chevy van that was rebuilt 10,000 miles ago that i'm putting in my 82 z28. I want to add hedman shorty headers, have an exhaust shop make me a 3 in. y-pipe, hopefully get rid of the cat., and get a 3 in. hooker cat-back. How much h.p. and torque could i expect from this. Would this exhaust even be much improvement since it'll be a stock engine?I want to just add exhaust and gears to my car for now and not throw money into the weak 305. I want to just give this a little more power for now and then eventually just get a 350tpi iroc. Thanks in advance

 

Anybody?

 

I'd say about a 15% increase in HP, I believe that is the figure for full exhaust, or about 30hp or so.

 

I would agree with Mark. I got about 30 HP out of my headers and exhaust. Add in a fuel pressure regulator and a good tuneup with a good ignition system and you get another 15-20. Check the sig.

 

I agree that an improved exhaust will help, but probably not that much. If the heads are the typical truck 305 heads, they'll have small valves and ports, so the actual improvement from normal "hot rod" bolt-ons will be less than they would be if applied to a 3rd gen 305.

 

I agree with Five7, your starting platform is a dog 145hp with 8.5:1cr most likely a pissy cam and heads your dog wouldn't chew on.

but you should gain some power out of it. I would guess a best of 20-25 out of the whole thing. Good for when you drop the 5.7 in.

Way to start it off