How much HP. Really?

[jiangtao]

I have a '90 coupe and am looking to put on a K&N air filter with high flow exhaust mufflers. I am looking for an unbiased opinion on how much HP to expect from the combo. Everything else on the car is stock. I did this combo on one of my previous Vettes and felt a difference in HP, but never did a dyno on it. Thanks in advance!

 

[92ghost]

That's a tough question to answer. What type of High Flow muffler (brand) are you talking about, and do you have an open air lid for the K&N. I'd venture to say you would get between 10 and 15 HP at most with just the basics you have mentioned.

 

[jiangtao]

I was thinking about going with some Flowmasters and keeping the air filter lid stock.

 

[Tuna]

You might want to check out CORSA as they are supposed to be making a cat-back system for early C4's now.

I dyno'ed my 92 LT1/4 car before and after CORSA were added and saw 22 HP gain. CORSA advertises a 15 HP gain. I believe it.

The K&N filter will not add much of anything over a brand new paper filter but the K&N will not lose any HP as it ages. I have K&N filters in all my cars for that reason.

 

[92ghost]

Hey Tuna, you need to tell him that you have atleast 400 HP at the crank with your LT1/4 engine. Your 22 HP gain is right along the lines of performance percentage "%" for your HP baseline. A stock L98 has 250 HP at the crank. Using your percentage gain of about 5.5 %, it puts the stock L98 at around 263.75 or 13.75 HP gain, which is still respectable and right with CORSA's estimation.

Take my stock LT1 at 300 HP and adding a CORSA will give me roughly 16.5 HP. Not bad.... IF only I would pull the trigger and do the LT4 upgrade...

 

[Rogue]

I don't know how much horsepower the Corsas add. However, I do love the way they look and sound.

I've tried other exhausts on my L98 and hated their droning.

The Corsas are perfect in everyway. The quality, looks, sound, without ANY resonance whatsoever. In fact, they are almost as quiet as stock when cruising. But they sound awesome when you get on it.

The car feels powerful enough.