I have an 87 IROC with a T5 tranny, 305 TPI K&N Air filters modded air box, modded MAF sensor, Hooker Shortie headers into 3" collectors into 3" exhaust with a dynomax muffler, I also have a cut out installed, a chip and a 160 thermostat, 8mm plug wires and NGK vpower plugs. I only want to know because people alwase ask me how much i have. thanks guys

 

probably about 15 rwhp more than stock. but don't take my word for it... go get it dynoed. what are you running in the 1/4 mile?

 

I haven't ever run it in the 1/4 i was going to but it rained on the only day i had available.

 

What is the stock rearend gear on an 87 iroc?

 

Standard rear axle ratio was 3:08 with 305TPI, unless you have RPO option G92 which was a BW 9-bolt 3:45. And this option is RARE!

My guess on your HP, since you have not done anything major would be about 10 over stock numbers. Your mods do not ADD any big increases.

 

My buddy had a 89 305-5 speed G92 car... Had little bolt ons (MSD 6AL, AFPR, 3"exhaust w/ no cat, airfoil, K&N's and a cut filterbox) he went 14.0 at 100MPH with a 2.0 60ft. I couldn't believe it if I didn't see it with my own eyes! The engine also had over 100,000 miles!

Tell me 305's can't be fast!

 

i gained about a half second my on 91 RS 305 with a 3" cat and I-pipe,which go into a flowmaster 80 series muffler.i also still have the stock Y-pipe and manifolds.with your exhaust plus the headers youll should easily gain about .7 seconds in the 1/4 mile.what that equals to in HP i dont know.of course every motor is different.you could get more you could get less than what i did.i know headers and exhaust on an average 305 add about 30hp,if not more.the system as a whole is so restrictive its rediculous.stupid GM

 

305's can't be fast!

 

tell me about it