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Shop says I have to junk my old 1 3/4 LG Long Tube Pros and go bigger to make the car run right and get a proper tune. I really (really) like these headers due to the true merge collectors and 32 inch primaries and they make good power. Unless I am mistaken there is no other option with those features that will package under a C5. Bigger diameter headers necessitates shorter primaries right ?
Question, I am in real deep on this build...so if cost was no object what headers do you guys recommend for the build in sig ? (Note that we are also downsizing the cam).
I was under the impression that gains via larger headers (even on a 434) were negligible and not worth the expense. Although this sounds like more of a tuning issue.
Shop says I have to junk my old 1 3/4 LG Long Tube Pros and go bigger to make the car run right and get a proper tune. I really (really) like these headers due to the true merge collectors and 32 inch primaries and they make good power. Unless I am mistaken there is no other option with those features that will package under a C5. Bigger diameter headers necessitates shorter primaries right ?
Question, I am in real deep on this build...so if cost was no object what headers do you guys recommend for the build in sig ? (Note that we are also downsizing the cam).
I was under the impression that gains via larger headers (even on a 434) were negligible and not worth the expense. Although this sounds like more of a tuning issue.
Thanks for any input !
since u have some cubes there and if you're trying to get every once of hp go with a 2 headers. If it's worth the price for some gain but don't know how much then for sure and your going to have to retune it. Total price for say 50 hp worth over a 1k.
Nah, not worried about squeezing every ounce out of it (at all) but the shop is adamant about upsizing. I am ONLY concerned with drivability and bigger headers will help with the getting the tune right I am told. I have an old computer and these are some pretty big heads on top of a lot of cubes so I kind of get it.
I definitely wouldn’t agree that you “have to junk your headers”.
You may lose some top end power compared to bigger headers, but there shouldn’t be any issue tuning it or getting it to run right with the headers you have
Here’s an interesting thread regarding header size on an ls7. Ideal exhaust size depends on a few things though, not just displacement. Maybe post up your build specs for better advice.
Either way, I find it hard to believe they wouldn’t be able to get your car running fine with the headers you have.
Nah, not worried about squeezing every ounce out of it (at all) but the shop is adamant about upsizing. I am ONLY concerned with drivability and bigger headers will help with the getting the tune right I am told. I have an old computer and these are some pretty big heads on top of a lot of cubes so I kind of get it.
Shop may be adamant because they want to sell you the "upgraded" headers!! The LG LT headers are as good as any header made, and better than most. My opinion, see who else chimes in....
Sounds a little iffy to me, shop/tuner should be able to get 434 running great on existing headers even if it leaves a little power on the table - but I am no expert.
Curious how it works out, I have a LS2-based 427 with Kooks 1-3/4 headers.
OK Back to reality ARH 1 & 7/8" and Catted X With 3" Back to Axles to your C5 Z06 Titanium Exhaust is what you
Want/Need IMO!
I did the 1 7/8" ARH & Catted X on my bolt on 99 C5 LS1 and drove for many years before my
Custom 396" was built and installed. Will change my 2 1/2" for 3" eventually and 2" Headers although
better maybe 6-8 HP more for me, the 1 7/8" upgrade for you would be ~+12-15 VS 1 3/4" for you
even with a smaller cam.
With 4.10s and a smaller Cam Motion Cam (something like ~ 236/248 on a 114*) would drive so Mild,
and tune MUCH BETTER with your 1999 Computer,
Ask me how i know LOL
This would Make a Much Bigger difference VS Primary Header Size.
I would contact Pat G. for a cam spec, and if needed a remote tune also.
I never saw what Rocker Arms you were using.
Always thought a .720" Lift Cam was Aggressive for your Reliability Goals.
Who is doing the rebuild?
Has an Autopsy been done?
For the amount of $$ you have invested in your Project/Build I would expect
Top Shelf Concierge Service.
Just my .02
Good Luck
Agreed man and thanks for the header advice I have been out of the loop for a while and am having to “dive back in”. Yells Terra’s are the rockers used. The computer is a 2000 if that makes any difference and yea I 100% agree with that particular expectation.
Agreed man and thanks for the header advice I have been out of the loop for a while and am having to “dive back in”. Yells Terra’s are the rockers used. The computer is a 2000 if that makes any difference and yea I 100% agree with that particular expectation.
I know someone besides Burns (FWIW-I've never heard of them, which doesn't matter) makes 1-7/8"-2" stepped headers, ARH, Stainless Works, Kooks, I've forgotten. However, that LG 1-3/4" header you have is probably as good as some 1-7/8" setups. I'd run them. No reason the tune can't be made to work with them.....
What part of the tune are they having trouble with?? Wot or driveable. Those are to different monsters. Most of the novice that do their own tune will get wot pretty decent including me. But driveable is where u separate the men from boys. Then they start pointing to mechanical problems because they can't figure it out. Many of my friends had problem. When to a different tuner and car drives good. Obviously it u have a big cam they do their best
I also think the ARH 1 7/8 would be a good choice. 2” on a C5 would not be fun to install unless you have a C6 pan.
That said, I don’t agree that what you have won’t work.
The actual ecu on C5’s is the same from 99-03. What’s different is the operating system. 99/00 are the same, not user friendly in SD mode due to the abbreviated VE table. 01-03 are much better in that respect.
All work fine in MAF only mode.
Helga is exactly correct about the drive around tuning. Way harder than the dyno part. Cam overlap dictates that.
If u look around u will find them but it’s not gonna be stuff u can find at summit and are gonna be a bit more costly...and u can match whatever length U want. I’d say going 10 inches out the side roughly is what u will need to prevent burning the panels ....and ur motor will run top notch with those style of headers...
Throw on a welded outlet with 4 equal length pipes and u got it made
Last edited by Speedy007; Apr 23, 2021 at 12:35 PM.
If there was a way to reasonably package side exit exhaust I would do it.
Once you cross the $40k number on a C5 build nothing is off the table.
Ya I’ve crossed that hump a while back lol , but I don’t see why a 1 7/8 side mount heat wrapped with a custom end wouldn’t work ..total prob a 2-3k set up all said and done
What part of the tune are they having trouble with?? Wot or driveable. Those are to different monsters. Most of the novice that do their own tune will get wot pretty decent including me. But driveable is where u separate the men from boys. Then they start pointing to mechanical problems because they can't figure it out. Many of my friends had problem. When to a different tuner and car drives good. Obviously it u have a big cam they do their best
The car was very difficult to cold start. Very difficult. It ran perfect once warmed up but unfortunately with < 500 miles the engine has to come out and apart for an unrelated issue and we are going to recam and retune at this time. I dropped the car off in January at their request it was smoking bad upon cold start, leaking some kind of fluid on my new pavers and low oil light came on (they rufused to cover the tow). I was informed of all of this just last week. I think they just want to get it right and feel bigger headers will assist in the tune. Thanks everybody for the inputs.
The car was very difficult to cold start. Very difficult. It ran perfect once warmed up but unfortunately with < 500 miles the engine has to come out and apart for an unrelated issue and we are going to recam and retune at this time. I dropped the car off in January at their request it was smoking bad upon cold start, leaking some kind of fluid on my new pavers and low oil light came on (they rufused to cover the tow). I was informed of all of this just last week. I think they just want to get it right and feel bigger headers will assist in the tune. Thanks everybody for the inputs.
Good luck buddy! sounds like multiple issues going on. Hope it all gets right.
BEST headers for 434 build...
The LG LT headers are as good as any header made, and better than most. My opinion, see who else chimes in....
