Stainless LS4 Headers
TECH Enthusiast
Joined: Jun 2008
Posts: 621
Likes: 1
From: Zeeland, MI
It all comes down to time vs. skill vs. money....
If I had the time, the skill and the shop/parts to bend up a set of pipes and try out the LS6 shorty's it would be done.
But I think everyone here doesn't have access to all the variables needed to get it done.
If someone actually had a pipe bender, a mig or tig welder, some extra dough and some extra time it would be done. But until those variables all line up with one person we wont know how the exhaust will work....i still like the under the trans idea with a different oil pan....look around it was talked about a few months ago.
If I had the time, the skill and the shop/parts to bend up a set of pipes and try out the LS6 shorty's it would be done.
But I think everyone here doesn't have access to all the variables needed to get it done.
If someone actually had a pipe bender, a mig or tig welder, some extra dough and some extra time it would be done. But until those variables all line up with one person we wont know how the exhaust will work....i still like the under the trans idea with a different oil pan....look around it was talked about a few months ago.
Registered User
Joined: Dec 2008
Posts: 5
Likes: 0
I think I stumbled across the answer when I sifted through some old stuff in my garage, and found the original exhaust from my 2002 Corvette Coupe, running a 5.7 liter LS1. The Coupe ran dual exhaust on its 5.7, and each pipe was 2.5 inches - the diameter which handles the flow for the entire LS4. My Coupe benefited from going to a GHL exhaust, indicating that the 2.5 pipes were not a detriment to its power potential.
Given that the LS4 is a similar engine to the LS1 (with regard to valve timing, compression, etc.), I believe that it too, would find dual 2.5" pipes comfortable to breathe through. The slightly lower displacement (the LS1 has 7.5% more) would be insignificant in realizing similar flow velocities and back pressure through the system. Given that the Coupe would pick up about 7-9 more HP by bolting on a set of shorty headers, my guess is that there is room for improvement in the LS4's power potential also.
Peace.
Moe
Given that the LS4 is a similar engine to the LS1 (with regard to valve timing, compression, etc.), I believe that it too, would find dual 2.5" pipes comfortable to breathe through. The slightly lower displacement (the LS1 has 7.5% more) would be insignificant in realizing similar flow velocities and back pressure through the system. Given that the Coupe would pick up about 7-9 more HP by bolting on a set of shorty headers, my guess is that there is room for improvement in the LS4's power potential also.
Peace.
Moe
Last edited by Richiec77; Jan 5, 2009 at 11:11 PM.
Staging Lane
Joined: Jul 2008
Posts: 52
Likes: 0
From: Philadelphia, PA
Guys,
Here's a couple of possibilities;
1) Leave the stock exhaust manifolds in place, but give the car *TRUE* dual exhaust (Yes folks, our cars are actually single exhaust beasts, and just that one change of going from single to dual might net you 20 HP *easy*. Recall that Chevy gets 6-8 HP from a cheesy dual-mode muffler on the 'Vette.). Unless you're planning to run serious times with your car, you might come to find that the current exhaust manifolds are not too bad. They are very similar to the style which AMC used between 1971-1974, with much success, and are far better than some monstrosities currently in production.
GM uses a system similar to what Chrysler uses to help damp out some of the low-frequency droning which rears its ugly head at low RPM and 4-cylinder mode: that huge resonator under our cars. In contrast to the Chrysler's twin-exhaust DOD resonator, it is from this point back that the LS4 runs a fundamentally single exhaust. If we kept our current manifolds, but split the left and right sides of the exhaust into separate runs, rather than using the current single run which cosmetically splits into two at the end, we would not only see a world of improvement, but the car would also start to sound like a V-8, which would really be nice.
2) This next tactic for moar power might be a bit sketchy, as it requires untried items. One of the lesser known facts about our engines, is that we run the same heads as the LS6, and as a result (unless all LS heads have exactly the same port dimensions anyway, making this part of my post redundant), it would reason that LS6 cylinder head accessories would fit our engines too. Looking at our cars and their engine installations, it would seem to me that a pair of C-5 Z06 Shorty Headers would just barely squeeze in (they run about $550, depending on source). They are just slightly larger that the stock manifolds, and would certainly provide a less turbulent flow than stock units do. The approach would require a muffler shop to fabricate pipes from both the "front" and "back" exhaust manifolds, to cats, and ultimately, mufflers. While more expensive, this would be a complete solution, giving the car true dual exhaust, a decent manifold, and free-flow mufflers. The large center resonator/cat combo would be ditched, and in its space, the pair of pipes would be installed, coursing back to the mufflers. One would have to install two catalytic converters, but realistically, practically any pair would work, or, they might be removed completely - but only for off-road use, of course.
Fabrication rates vary according to locality, but plan for the majority of the work to be allocated to bending the "front" manifold pipe around the motor, and running it back to the stock muffler pipes (these can be re-used, so there's no need to replace them). The collector/pipe on the "back" cylinder bank will be much easier, as it needs only be fabricated, and run back. Again, given Chevy's experience with dual-mode exhaust on the Corvette, you might be able to net another 7-8 moar H.P. by replacing the fiberglass-stuffed stock pieces, with free-flowing, parabolic-resonator designs from companies such as Dynomax, Flowmaster, GHL, or whatever you prefer. The end result would be a racier exhaust note, as well as moar power - for the extra cost of the mufflers ($125 each), and their installation ($depends on locality$). Parts aside, I can't see a legit muffler shop charging moar than about 4 hours at their established rate to do the job. However, on the other end of that spectrum, I know a local shop that would probably tackle a job like that with a two-hour time estimate......
Even if you figure in for large discrepancies in the price of labor across the nation, I can't see how the entire job would come out to much moar than $1,600, including Z06 shorty headers, piping, generic cats, and a pair of DynoMax or Flowmaster mufflers (about $125 each), all including labor. If you have *REALLY* expensive shops in your areas, I can see the price going to maybe $2,000, but no moar. If the number gets too much higher than that, somebody is smelling blood in the water....
I consider my 2008 GXP to be a gorgeous car, as it is loaded to the hilt with extras, including Nav, sunroof, suede, etc., and is a beautiful shade of midnight blue, with a black and tan interior. I bought the car as a replacement to my mythical 2007 Z06, and I plan to have it as my daily driver when I re-acquire another Z06 - possibly an '09. My plans are to attempt a mild upgrade to the car, either item #1), or #2), above, along with a free-flowing air-filter, a throttle body, thermostat/temperature reduction, a programmer, and a set of Crane 1.8:1 rocker arms. I checked my horsepower kinematically, and I got 297 max - not bad for a machine rated at 303 tops! I prefer kinematic measurements as they let you see what is happening on the road, both for the better, such as the effects of ram air, etc, and the worse, such as the effects of heat soak, and chassis limitations.
Peace.
Moe
Here's a couple of possibilities;
1) Leave the stock exhaust manifolds in place, but give the car *TRUE* dual exhaust (Yes folks, our cars are actually single exhaust beasts, and just that one change of going from single to dual might net you 20 HP *easy*. Recall that Chevy gets 6-8 HP from a cheesy dual-mode muffler on the 'Vette.). Unless you're planning to run serious times with your car, you might come to find that the current exhaust manifolds are not too bad. They are very similar to the style which AMC used between 1971-1974, with much success, and are far better than some monstrosities currently in production.
GM uses a system similar to what Chrysler uses to help damp out some of the low-frequency droning which rears its ugly head at low RPM and 4-cylinder mode: that huge resonator under our cars. In contrast to the Chrysler's twin-exhaust DOD resonator, it is from this point back that the LS4 runs a fundamentally single exhaust. If we kept our current manifolds, but split the left and right sides of the exhaust into separate runs, rather than using the current single run which cosmetically splits into two at the end, we would not only see a world of improvement, but the car would also start to sound like a V-8, which would really be nice.
2) This next tactic for moar power might be a bit sketchy, as it requires untried items. One of the lesser known facts about our engines, is that we run the same heads as the LS6, and as a result (unless all LS heads have exactly the same port dimensions anyway, making this part of my post redundant), it would reason that LS6 cylinder head accessories would fit our engines too. Looking at our cars and their engine installations, it would seem to me that a pair of C-5 Z06 Shorty Headers would just barely squeeze in (they run about $550, depending on source). They are just slightly larger that the stock manifolds, and would certainly provide a less turbulent flow than stock units do. The approach would require a muffler shop to fabricate pipes from both the "front" and "back" exhaust manifolds, to cats, and ultimately, mufflers. While more expensive, this would be a complete solution, giving the car true dual exhaust, a decent manifold, and free-flow mufflers. The large center resonator/cat combo would be ditched, and in its space, the pair of pipes would be installed, coursing back to the mufflers. One would have to install two catalytic converters, but realistically, practically any pair would work, or, they might be removed completely - but only for off-road use, of course.
Fabrication rates vary according to locality, but plan for the majority of the work to be allocated to bending the "front" manifold pipe around the motor, and running it back to the stock muffler pipes (these can be re-used, so there's no need to replace them). The collector/pipe on the "back" cylinder bank will be much easier, as it needs only be fabricated, and run back. Again, given Chevy's experience with dual-mode exhaust on the Corvette, you might be able to net another 7-8 moar H.P. by replacing the fiberglass-stuffed stock pieces, with free-flowing, parabolic-resonator designs from companies such as Dynomax, Flowmaster, GHL, or whatever you prefer. The end result would be a racier exhaust note, as well as moar power - for the extra cost of the mufflers ($125 each), and their installation ($depends on locality$). Parts aside, I can't see a legit muffler shop charging moar than about 4 hours at their established rate to do the job. However, on the other end of that spectrum, I know a local shop that would probably tackle a job like that with a two-hour time estimate......Even if you figure in for large discrepancies in the price of labor across the nation, I can't see how the entire job would come out to much moar than $1,600, including Z06 shorty headers, piping, generic cats, and a pair of DynoMax or Flowmaster mufflers (about $125 each), all including labor. If you have *REALLY* expensive shops in your areas, I can see the price going to maybe $2,000, but no moar. If the number gets too much higher than that, somebody is smelling blood in the water....
I consider my 2008 GXP to be a gorgeous car, as it is loaded to the hilt with extras, including Nav, sunroof, suede, etc., and is a beautiful shade of midnight blue, with a black and tan interior. I bought the car as a replacement to my mythical 2007 Z06, and I plan to have it as my daily driver when I re-acquire another Z06 - possibly an '09. My plans are to attempt a mild upgrade to the car, either item #1), or #2), above, along with a free-flowing air-filter, a throttle body, thermostat/temperature reduction, a programmer, and a set of Crane 1.8:1 rocker arms. I checked my horsepower kinematically, and I got 297 max - not bad for a machine rated at 303 tops! I prefer kinematic measurements as they let you see what is happening on the road, both for the better, such as the effects of ram air, etc, and the worse, such as the effects of heat soak, and chassis limitations.
Peace.
Moe
