C6 Corvette "8-4-1" exhaust system: VERY NICE

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NewbVetteGuy
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C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by NewbVetteGuy »

From "Celeritech" in the Netherlands.

They've released an EngMod4T-designed full exhaust system for C6 Corvettes that uses a 4:2:1 tri-y stainless header, a titanium 2:1 mid pipe and a titanium BAAAARELY muffled Axelback. They're changing the header designed to fit better on ZR1 Corvettes and to fit with 6 bolt LS3 heads, but what a gorgeous, fantastic exhaust system that seems very much in the "Calvin Elston SCHOOL".

If someone made this for a C3 Corvette, I'd be very, VERY tempted...

https://celeritechusa.com/
https://celeritechusa.com/products/c6-8-4-1-headers

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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by NewbVetteGuy »

You can listen to it here: https://youtu.be/yKvi0-UiZ6Y?t=587

I'd love to here this and a 180 degree header on the same car side-by-side.

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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by RevTheory »

That's just all kinds of badass.
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by Rick! »

Going through the gears it sounds proper, at idle it's a bit too spicy. Either way, it's way better than nearly all late model vette exhaust notes.
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by NewbVetteGuy »

Rick! wrote: Wed Aug 02, 2023 6:30 pm Going through the gears it sounds proper, at idle it's a bit too spicy. Either way, it's way better than nearly all late model vette exhaust notes.
It's using the Texas Speed "Chop Monster" LS3 cam. 110 LSA, a lot of extra exhaust duration; no idea on adv or seat-to-seat durations, though.
https://www.texas-speed.com/p-9019-tsp- ... 3-cam.aspx


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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by BOOT »

Interesting note. LT headers can cause wiring problems in Corvettes, due to the underhood temps making it brittle. Drifters have this issue with the C6 and I've read of C4 guys(not drifters) also having the problem over time but don't think they made the connection. Local climate factors I'm sure and it's just not Covettes.

Still those are cool 8)
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by BLSTIC »

BOOT wrote: Thu Aug 03, 2023 1:24 pm Interesting note. LT headers can cause wiring problems in Corvettes, due to the underhood temps making it brittle. Drifters have this issue with the C6 and I've read of C4 guys(not drifters) also having the problem over time but don't think they made the connection. Local climate factors I'm sure and it's just not Covettes.

Still those are cool 8)
I remember having related problems with a speedway car. Bolt on turbo kit on an I6 without heat shields and melted some wiring. Then I made heat shields that were *too* good (not really, I just forgot that the wastegate needed airflow). Turns out if you're forgetful about that sort of thing and race the car you can turn your wastegates diaphragm into ash, retemper the spring so it has zero preload, and turn blue anodising into gold anodising... in about four minutes...

Modified a factory heat shield, hid the pretty* turbo adapter behind another, wrapped selected pipes, and nothing caught fire any more...

*ok... it was the kind of pretty only a mother could love... net increase in looks hiding it behind a heat shield

Moral of the story: Sometimes you just gotta hide your sexy go fast parts if you want the car to actually work as a whole
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by Orr89rocz »

Great. Now i need a C6
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by BOOT »

Orr89rocz wrote: Thu Aug 03, 2023 6:16 pm Great. Now i need a C6
C6 is one of my fav gens but after the drifters started to use them prices will not drop near as much.
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by FpcDreams »

Hey

That’s me (the USA part). Thanks for the praise.

Guess where the idea came from.

I’ve talked to Calvin about this and he only did it once on a low HP engine. We’re venturing into new waters.

Neels from EngMod4T actually added in the ability to do the 8-4-1 due to my request.

It has never sounded so bad at free-revs before. I did not expect the titanium to produce such a pronounced difference.
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by NewbVetteGuy »

How did the sound change between the stainless and titanium versions?

Did the sound change significantly with just the mid-pipe and the 8:4:2:1 merge vs. adding the axel back that splits it back into 2 / 4 pipes? Or does just merging those two banks smooth out the sound and then splitting it back into 2/4 pipes again doesn't change the sound much?

Did EngMod4T show the exhaust velocity slowing down as it goes through the axel back system because of the 1:2:4 through there? (Essentially a slight velocity / performance vs. aesthetics / packaging trade-off?)

This is TECHNICALLY an 8:4:2:1:2:4 exhaust system, isn't it? (Couldn't help with the ridiculous naming...) ;-)

Also curious if you tried different muffler combinations. I'd be interested in how a muffler that didn't cancel out the lower-end frequencies changed the sound.

I'm assuming that Calvin recommended just having one big rear exit tube and you guys went added the axel back just because the "Corvette guys" wanted to see those 4 exhaust tips out the center?



There's so many conversations on here that this is mostly how a max performance, broad powerband exhaust SHOULD be done, but then it's so painful and so expensive to actually do it, so almost no one does and there's no real off-the-shelf headers or exhaust systems that someone can purchase for most cars (Except for the Calvin-designed Mustang headers that I know are out there.). Awesome to see someone bring such a product to the market. I hope they're wildly successful.

It would be so great to see dyno results on a car that had a cam properly matched to the high velocity system, too.



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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by FpcDreams »

NewbVetteGuy wrote: Wed Aug 09, 2023 12:15 pm How did the sound change between the stainless and titanium versions?
The underload sound didn't really change. The free rev sound went from "throaty" exotic to Honda like. We have to find the right muffler for the titanium

Did the sound change significantly with just the mid-pipe and the 8:4:2:1 merge vs. adding the axel back that splits it back into 2 / 4 pipes? Or does just merging those two banks smooth out the sound and then splitting it back into 2/4 pipes again doesn't change the sound much?
It sounds the same if was just just dumped at the 8:4:1 vs splitting back out

Did EngMod4T show the exhaust velocity slowing down as it goes through the axel back system because of the 1:2:4 through there? (Essentially a slight velocity / performance vs. aesthetics / packaging trade-off?)
I only modeled the 8:4:1 portion. I didn't model the rest of the exhaust. And it's really only going to two instead of four. The tips are just a Y

This is TECHNICALLY an 8:4:2:1:2:4 exhaust system, isn't it? (Couldn't help with the ridiculous naming...) ;-)
I would say 8:4:1:2

Also curious if you tried different muffler combinations. I'd be interested in how a muffler that didn't cancel out the lower-end frequencies changed the sound.
We tried a few different mufflers. OEM Z06 mufflers sound like a civilized OEM Ferarri. Corsa sounded like a Honda. StainlessWorks muted highs and lows. A lot more testing to do

I'm assuming that Calvin recommended just having one big rear exit tube and you guys went added the axel back just because the "Corvette guys" wanted to see those 4 exhaust tips out the center?
You know it. Calvin loves his single ( I do too). I actually didn't get the chance to talk to Calvin until recently.



There's so many conversations on here that this is mostly how a max performance, broad powerband exhaust SHOULD be done, but then it's so painful and so expensive to actually do it, so almost no one does and there's no real off-the-shelf headers or exhaust systems that someone can purchase for most cars (Except for the Calvin-designed Mustang headers that I know are out there.). Awesome to see someone bring such a product to the market. I hope they're wildly successful.
Thanks! That what I hope to change. Invest everything into R&D so I can without a doubt speak facts. I really want in-cylinder pressure transducers and an engine dyno

It would be so great to see dyno results on a car that had a cam properly matched to the high velocity system, too.
Absolutely. But, who really knows what that is at this point. I've spent hours thinking about how the cam would be adjusted.



Adam
If you thought the C6 system was cool, wait until you see the C8 system. We hope to debut them at SEMA
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by NewbVetteGuy »

FpcDreams wrote: Thu Aug 10, 2023 12:38 am
NewbVetteGuy wrote: Wed Aug 09, 2023 12:15 pm It would be so great to see dyno results on a car that had a cam properly matched to the high velocity system, too.
Absolutely. But, who really knows what that is at this point. I've spent hours thinking about how the cam would be adjusted.


Adam
Mike Jones is just a phone call and a custom cam order form away...


There's a couple of ST threads where he's given away a couple juicy nuggets of information on general changes when someone moves from a 4:1 to a tri-y header, but I apparently did NOT save them in one of my notebooks and I couldn't find them with a few targeted google searches today.



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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by Orr89rocz »

Technically based on firing order shouldnt this design pair the outer cyls together 1/7 2/8 and pair the inners 4/6 3/5? Then come together with a set of outers on one bank into inners on the other?

That way each one is actually 180 deg apart? Guess it be much harder to fabricate
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Re: C6 Corvette "8-4-1" exhaust system: VERY NICE

Post by FpcDreams »

NewbVetteGuy wrote: Thu Aug 10, 2023 1:05 pm
Mike Jones is just a phone call and a custom cam order form away...


There's a couple of ST threads where he's given away a couple juicy nuggets of information on general changes when someone moves from a 4:1 to a tri-y header, but I apparently did NOT save them in one of my notebooks and I couldn't find them with a few targeted google searches today.



Adam
I did contact CamKing. He suggested I port the intake side of the heads, dyno test, then port the exhaust, dyno test.

Heres the extra fun part about doing R&D. After buying a C6 for testing the engine blew up ( valve dropped) shortly after the only dyno test I got to do. Also even finding dyno shops that were willing to even do testing as a normal paying customer was 1/10.

So a few thousand here, several thousands there, thousands everywhere before even making a dollar. It just doesn't make sense to pursue finding the optimum combination at the time.

I absolutely would love to and hope to in the future.


Orr89rocz wrote: Thu Aug 10, 2023 4:01 pm Technically based on firing order shouldnt this design pair the outer cyls together 1/7 2/8 and pair the inners 4/6 3/5? Then come together with a set of outers on one bank into inners on the other?

That way each one is actually 180 deg apart? Guess it be much harder to fabricate
I see what you are saying. The tri-y order prioritizes time between each cylinder firing. Doing it in that manner would result in another cylinder firing down the same secondary only 90 degree apart. It seems that works with 180 degree headers because those cylinder are firing into seperate larger collectors where these still have to travel down the secondaries.

It would be interesting to see how that would affect everything in EngMod4T.
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