nicholas1978

I'm about to buy a 1990 5.0 auto IROC w about 90,000 miles on it. This was the previous owners 3ed car, and it was babied. He installed a K&N air filter system, headers and a magnaflow cat back system. I don't know any more details than that. My question is, approx. how much horse power does the engine produce now with the current setup?

VincentZ28

iTrader: (2)

220-230whp

nicholas1978

Is whp measured at the crank or the rear wheels? If it's measured at the crank, what percentage would be lost at at the rear wheels?

VincentZ28

iTrader: (2)

At the wheels

NowhereFast

I don't know about that. That would be about 260 at the crank. Full exhaust won't add 50hp.

VincentZ28

iTrader: (2)

Wanna bet? With a tune, yes. It almost made 50whp in a 5.7 G92 car.

gmstrong

240 to the flywheel.

NowhereFast

His is a 305. The gains won't be as large, because the engine is moving less air, therefore, the stock exhaust is less of a restiction and the better flowing system will net less gain.

VincentZ28

iTrader: (2)

Well how do you know? What headers did you use? I've seen a 89 Iroc with a full exhaust system run 13.80's @ 102mph 20 years ago

nicholas1978

Ok, I'm new to all this. Air intake, headers, cat back exhaust and tune should add about 50whp? When you say "tune", are you talking about adding a chip and running the car on a dyno, or just changing the spark plugs and so forth, or what? Also, how much should it cost?

VincentZ28

iTrader: (2)

Depends on the condition of the engine, it's possible. On the SoCal board we do a lot of Dyno testing and we also tune on the Dyno for the results. If notice I said up to 50whp. A good running 1989-92 305TPI will make around 190whp stock. A full exhaust system and tune will get it up to 220-230whp with Dyno Don headers. Without the tune it will be around 210-220whp.

VincentZ28

iTrader: (2)

If you haven't cut out the bottom of the air box, do it. It's worth about 5hp and the engine is breathing better.

vistageek92

iTrader: (2)

Whooaa. 50HP? That sounds excessive. People do complete head or header swaps to get that kinda power.

I always thought that a good re-run of exhaust is like a 10-20hp kinda deal. Not 50...

Not saying it isn't possible. Just stunning.

VincentZ28

iTrader: (2)

That's because they don't use 1 3/4 Dyno Don's headers, dual cats, 3in cat-back, 89-92 G92 5.7 350, free flowing intake and a tune. Get it?

vistageek92

iTrader: (2)

For instance...I am running hookers, with true dual out on 2.5in to two Thrush mufflers..your opinion? (I ranged that about 25hp)

jwdomino

iTrader: (12)

wow the fail is strong in this thread...

vistageek92

iTrader: (2)

VincentZ28

iTrader: (2)

Your car is not stock so I wouldn't know!