Corvette exhaust versus truck exhaust

[Matthew Jeschke]

I have a C5 corvette in addition to my 2001 Tahoe w/ built LQ9. My Corvette is nicely equipped too... but my question is I wonder if any of the exhaust parts are feasible on the truck.

Specifically, the LS1/LS6 manifold design looks a bit better? I noticed GM seems to have discontinued the part went to a log style exhaust manifold, pictures below.

I wonder if anybody has tried these LS1 style exhaust manifolds on the truck? It appears the down pipe would have to be modified in the least... The older exhaust manifold design more closely resembles a shorty header. My vette has an exhaust on it minus headers. I looked into it and was told the LS1 manifolds were very well designed and wouldn't get as big of gains as I'd expect. And long tubes barely fit in that thing.

I have limitless projects in mind, but ultimately I want to get another set of exhaust manifolds for my truck build, polish, and port the manifolds. Then I have some of the dual exhaust parts from a Denali. Rig up the complete dual exhaust system on my truck build. Would be awesome if these LS1 manifolds are in deed better than the newer log castings. In which case I could add them to the project.

Anybody have experience fiddling with the older LS1/LS6 manifolds?


LS1/LS6 style manifold...



Newer log style manifold.

 

[iamdub]

I have a C5 corvette in addition to my 2001 Tahoe w/ built LQ9. My Corvette is nicely equipped too... but my question is I wonder if any of the exhaust parts are feasible on the truck.

Specifically, the LS1/LS6 manifold design looks a bit better? I noticed GM seems to have discontinued the part went to a log style exhaust manifold, pictures below.

I wonder if anybody has tried these LS1 style exhaust manifolds on the truck? It appears the down pipe would have to be modified in the least... The older exhaust manifold design more closely resembles a shorty header. My vette has an exhaust on it minus headers. I looked into it and was told the LS1 manifolds were very well designed and wouldn't get as big of gains as I'd expect. And long tubes barely fit in that thing.

I have limitless projects in mind, but ultimately I want to get another set of exhaust manifolds for my truck build, polish, and port the manifolds. Then I have some of the dual exhaust parts from a Denali. Rig up the complete dual exhaust system on my truck build. Would be awesome if these LS1 manifolds are in deed better than the newer log castings. In which case I could add them to the project.

Anybody have experience fiddling with the older LS1/LS6 manifolds?


LS1/LS6 style manifold...

View attachment 412710

Newer log style manifold.

View attachment 412711

I think it's simply the application and later, packaging. The LS1/6 style is a tri-Y which can be tuned for satisfying flow requirements across a wide or narrow range of engine operations. Those runners being equal length and not crossed over to match firing order tells me they're more for "all-RPM use with an emphasis on upper-RPM flow". So, not really sacrificing any low-end power capability but also catering to the upper-end flow requirements. The log style used on trucks doesn't really choke it on the upper end, but helps to build the low-end.

My guess is they found later that the log style also supported the LS1/6 needs just fine. The rough napkin math makes sense- a 5.7 probably breathes in the peak of its power band what a 6.0 breathes at the peak of its power band. Since it's a simpler and more compact design, it was a sensible replacement mechanically and financially.

Of course, this is all stock for stock. If your 6.0 is modded and moves more air (cam, etc.), then you might could benefit from a higher flowing manifold. It's hard to pass up stock cast iron manifolds for their engineered design and properties for sound and heat insulation. So, if you can get complementary flow from cast iron "headers"- why not? If your LQ9 is cammed, it's likely making more mid- and high-RPM power and could use exhaust mimicking the high performance car variant. If there's any low-end power sacrificed, it's probably nothing you'd feel. You might notice an upper-end gain.

 

[Mudsport96]

The early F body LS1 manifolds flow worse than the truck manifolds. My nova forum has been down that route for LS engine swaps.
As for the pictured vetted manifold, packaging issues. I would almost bet that style manifold would interfere with engine/front diff crossmembers or the front driveshaft on the driver's side.
And the newer log style is almost the same as the truck manifolds.
I would have to look for the video again. But depending on how much power you are looking for, the truck manifolds are decent until you get high enough in power that you are sacrificing low-end torque. And in reality, we need as much of that as we can get in these tanks.

 

[Matthew Jeschke]

I looked closer at my C5. It's a 1999. It doesn't have that one I put in the picture. It's slightly different...

I asked Richard Holdener on one of his videos. He got back with me and said the late style LS1 manifolds flow better than the log style. They are essentially shorty headers (just cast). Although, there's more to the equation (tube length / tuned for what power / RPM). They at least look like they scavenge.

Another person said they thought part of the reason for shifting from the LS1 style was packaging and redesign of the air pump / EGR system. I also thought they might interfere with the frame and driveline stuff. If I found a pair on the cheap would be fun to fiddle with though.

The newer log style do look "cheap" in comparison / IMO. I don't really like the log design either. I don't think it could scavenge that well. Unless there's some compromise I'm missing?

I'm running a cam w/ LSR 2116 lifters, full shaft mount roller rockers... don't think the trim makes too big a difference but the cam specs are more than that of the stock cam. I don't recall them off top of my head. It was custom ground for my application by Roger Vinchi. It's like a hybrid RV cam that doesn't cut off top end power. He said I should have gains across the whole torque curve over stock. I then went with a moderate dual valve spring setup, nothing with crazy spring pressure but enough to support the cam.

Currently have a mess. I tuned with an AEM wideband. Never EVER buy anything AEM. It was junk, gave me erroneous data. Long story. I have an innovate motorsports setup on order now.

 

[Mudsport96]

AEM first... yeah used some of their products a long time ago. And while it has been almost two decades... I would never recommend them after the poor help I received from the company.

As for the vette manifolds. It would be cool to test them. I personally think they will fall somewhere between shorty headers and long tubes. But, that is based on my understanding of primary tube length.
But again, unless you are in the 450 to 550 range you will only see gains in the 5 to 15(17) hp range. And that is with long tubes, on a 6.0.
I am all for trying different mods. If this is your daily, it may not be worth the hassle. If it is a play thing I'd probably try it myself. Hell, on my nova I went from the late 60s hipo iron manifolds to the tubular center dump "vette" style manifolds. Some serious tweaking and flange redesign had to be done to clear the 4th gen X-body engine mounts.
Did it make a difference on a 300hp car that is done making power at 5600 rpm? Idk, haven't been back to the dyno. It SEEMS to run better, but how much of that is me trying to justify the price of parts and time spent? Lol. BUT. It is a conversation piece at a carshow, and that is fun in and of itself.

So, yeah. I'd say I'd it is just a toy and you have plenty of down time, and can find some cheap go for it. I would ask though. Once you get it tuned well, do a before and after dyno. So we can have data to add to the forum for future knowledge.

 

[Matthew Jeschke]

Thanks, it is a mostly a toy but I do use it frequently. I had same trouble AEM support. My meter came with a bad sensor and they didn't want to send me a new one... so I bought a new one for $30. Turns out they "modify" the sensor a d you have to buy any replacements direct from them. So costs 125$ for same sensor. Really dumb... took me forever to figure that out too. I would have thought a bosch 4.9 sensor is a 4.9 sensor. Nope not if it is a AEM guage. Could have blown my motor. It just real 14.6 to 14.7 when I did my WOT pulls before I figured that out. Thank god i didnt.