daanbc

Realistically what kind of increase will there be/ can there be from installing true duals. I will be having them installed next week. Actually I am not doing it for performance as much as I just like the sound/feel of a V8 idling with no smog equipment on it. I feel the engine will breath alot better then having the "Y" pipe and cat. But there are those that say the company did this for a reason "back pressure" and you should leave well enough alone. So last night I searched the www. and found articles from every point of view. I honestly don't believe there will be an increase of 40-50 hp like some of those articles said. But I am hoping I am right about letting the engine breath, and therefore maybe seeing a 5-8 hp increase. Is this possible? Or is all this just for sound. Either way Im going ahead and getting them. To me a real V8 should have duals. Thanks.

wnmech

I honestly doubt if you will be able to feel any difference in your performance at least I couldnt. I am pretty sure the GM designers designed the factory exhaust for maximum performance back then. I put corvette centrals pure 2 and 1/2 inch exhaust on my 77 and it sure sounds like more power but I am not that concerned about haveing a super car only to have a head turner.

daanbc

Yeah I was not expecting to feel the hp. I do expect to hear/feel a little rumble from the sound.

NHRalph

I believe you will gain 20 to 30 horsepower by switching from single to duals. I base this on the difference between the 74 and 75 Vettes. 74 having duals with the L-48 and L-82 and single in 75. That was the biggest difference between those years.

daanbc

That would be a sweet plus, but that's alot of gain for just changing an exhaust. I would think them kind of #'s you would see from a head change or cam, not an exhaust. But I'll take what it gives me.

NHRalph

I got that info from the 'Corvette Black Book'. Don't forget, a single exhaust by itself decreases horsepower, then add on the Cat and it goes down even further. The more emmission controls they threw on a car, the less power. You could gain as much as ten horsepower with just a good ignition advance curve. When the L-48 first came out, it was considered one of GM's performance motors. 295 horse but it had 10.25 compression ratio too. It doesn't take much to get the horsepower up on those engines, just go back to where it all began!

daanbc

Yeah I've been reading up on the timing thread. I need to get the parts for my HEI Dist. then I'll do the timing.