ZL1 exhaust pipe diameter?

[Juiced1]

Originally Posted by stieger

Hmm I wonder why they recommend not getting LT headers.

Probably so they can sell him a cam package they can make more money on. The LSA is a supercharged beast. Adding a set of headers will probably add 50rwhp

[paul2010]

Originally Posted by Juiced1

Probably so they can sell him a cam package they can make more money on. The LSA is a supercharged beast. Adding a set of headers will probably add 50rwhp

I already have a camaro to race with built by them with every available extra power option. Actually the package that they offer for a very reasonable price with ported heads, cam, pulley and tuned right will make the ZL1 well over 700hp. At that level 50 more hp for around 2k for the headers and a little for labor is just not worth the added cost. The other thing is I really like my 2010 with headers but it is almost too loud. Not gonna be good for my ZL1.

[Unobtainium]

Headers on a s/c car are not great value. At or near stock power levels, the gains are minimal vs cost. A pulley change is way cheaper and easier. The GT500's have gone through the same thing for years. I've seen very little gain until they are wound-up pretty good, like 600whp good. Then, you see about 20-30whp over factory manifolds. The big benefit is that they lower boost for the same power, and sound better.

[ADM PERFORMANCE]

Originally Posted by Juiced1

Probably so they can sell him a cam package they can make more money on. The LSA is a supercharged beast. Adding a set of headers will probably add 50rwhp

NOPE

[radz28]

They didn't on CTS-V...

I'll be pecking at low- hanging fruit, like shorties, X-pipe, and maybe those tight bends just fore of the mufflers. I have to appear smog-legal, FWIW...

[2012ZL1]

Kinda wondering why people are saying headers don't make power on a supercharged engine.
Boost is made in the intake manifold not the exhaust. The scavenging affect of headers may draw some pressure out during overlap, but the backpressure that creates more boost costs hp.
Long tube headers will need a tune to optimize the benefits of better flow, but they are definately not going to lose power over a set of manifolds, that is just ridiculous.
LT's will make more power even if boost is dropped slightly by scavenging. This can be countered with a pully up, with even more hp without increasing boost from stock.
Add in a tune to richen up the leaner environment and there is more power at your disposal.
Headers are ALWAYS better than manifolds for more power, cooler temps, and better sound, there's just some extra stuff to do to realise the full impact of the gains possible.

[radz28]

Originally Posted by 2012ZL1

Kinda wondering why people are saying headers don't make power on a supercharged engine.
Boost is made in the intake manifold not the exhaust. The scavenging affect of headers may draw some pressure out during overlap, but the backpressure that creates more boost costs hp.
Long tube headers will need a tune to optimize the benefits of better flow, but they are definately not going to lose power over a set of manifolds, that is just ridiculous.
LT's will make more power even if boost is dropped slightly by scavenging. This can be countered with a pully up, with even more hp without increasing boost from stock.
Add in a tune to richen up the leaner environment and there is more power at your disposal.
Headers are ALWAYS better than manifolds for more power, cooler temps, and better sound, there's just some extra stuff to do to realise the full impact of the gains possible.

I've noticed comments that LTs don't help on SC'd motors more than just our Community. I've seen similar comments on last generation Cobras and ZR1s. That is obviously up to a certain power-level, but it seems up to around where the majority of these might be turned up to, that the power-to-dollar ratio is not quite as high with some of these motors.

I'd like to know, too...

[2012ZL1]

Another clue to the fact that with proper application headers are better choice than other upgrades is that cam timing for blown motors generally have designed in less intake duration than exhaust duration respective to NA cams.
This is because blown motors do not need to rely on inertia to fill cylinders. The intake charge is under pressure, waiting to burst into the cylinder. The exhaust timing is generally longer duration to allow the engine to pump out the larger volume of exhaust created by the higher pressure relative to an naturally asperated exhaust charge. Some help is afforded by the overlap, but this method of gaining exh flow is at a cost to cylinder pressure and only logical purpose would be to cool the exhaust valve.
Headers have the bonus of cooler running generally speaking than manifolds, so in turn headers help with keeping temps down on the exhaust side.
Generally speaking and within reason, headers with the proper cam and more boost and fuel will help produce more power on a blown motor than a set of heads unless said original heads are extremely restricted.

Blower motors are more immune to head mods at least on the intake side, because if you are forcing the charge in under pressure, port design has little effect on volume within a reasonable range.

If you want to do anything to heads, port the exhaust as big as possible and as straight as possible with as large a valve as possible, with springs to match the cam.

I would spend the money on these other mods WELL in advance of spending money on heads.

[Gene Culley]

FYI the cat-back is the 2 1/2". I have one at the shop and am going to install it in my SS shortly.

[radz28]

It's 2.5" stock?

Thanks

[Unobtainium]

Well 3" is an easy upgrade. Won't give much power, but most cat backs don't.
Just was involved with a GTR build that made 650whp. Changing the cat back from factory was worth 8whp on one run, but couldn't be repeated. All others showed 0-2 whp better. Exhaust is mostly for sound and weight on these FI cars.
The factory dual-mode is cool, but heavy.

[Mr. Wyndham]

3" cat back may be difficult so I hear....the differential cooler lines that run down that way become awful close to the hot exhaust at that larger diameter....