Headers Vs. Downpipe?

[trewyn15]

I'm looking into getting to the exhaust part of performance now and Milzy just came out with these Headers for the 3400, which have an outrageous price but look really good, I think Ben can even agree they look alright, but I'm not looking to pay that price no matter how good they are.

I'm wondering how much of a loss in HP i'll be taking if I decide to get a Downpipe instead of Headers.

Also, do ported exhaust manifolds help anything out?

[onefastV6]

If you are talking on an N body, I don't think you are going to gain alot with just the down pipe.

[trewyn15]

Sorry, Monte Carlo so W-Body

[bob442]

no its n body, they are not equal length at all

[trewyn15]

what's n body?

how much power could I be looking to get from a downpipe compared to headers? I know obviously headers are better but I want to know if I'll still feel a bit of power there.

Also, what will exhaust manifolds being ported do for me?

[montess408]

if you have a 3400 monte carlo pace setters use to have headers(idk if they still) that will be your best bet

[eckoxl]

no its n body, they are not equal length at all

monte carlo is not a n body.

[trewyn15]

monte carlo is not a n body.

right, it's w-body which is why im confused now lol

i want to know how much power im looking to gain from downpiipe compared to headers.

i'm looking to do a custom downpipe into an electric cutout for the sound... would like to know power differences before i decide to do this tho

[bszopi]

A downpipe may gain you 3-5hp. Headers will most likely gain you +20hp.

[WrathOfSocrus]

I doubt anyone has done a lot of dyno work comparing all the different possible setups. The thing about it is that it is a cumulative upgrade. If you had a car with a completely opened up intake and porting, bigger cam, and better flowing exhaust from the cat back, then you would see the most gains. No doubt you could get 20-25 HP from headers in that situation. Maybe a little less maybe more but I wouldn't expect it to be 40+ HP like headers can do for some V8 engines. If you have any major bottlenecks like a restrictive intake or a clogged cat and you wont get much out of headers.

With a W-body you probably have the 'header' style rear exhaust manifold. I don't think you really want to go crazy hogging it out but you can clean up the casting and the opening out the back is a decent diameter (i forget exactly, somewhere between 2 and 2.5"). The inside of the stock downpipe goes to roughly 1.75". Just like the headers, if you have everything else upgraded you can see some decent gains and probably the best HP per dollar spent (if you can make it yourself), and virtually no gains with any bad bottlenecks.

[bszopi]

Its been several years since I remember reading this, but when S&S headers came out, otherwise stock GAGTs were seeing ~20hp gains by just installing the headers.

[trewyn15]

I doubt anyone has done a lot of dyno work comparing all the different possible setups. The thing about it is that it is a cumulative upgrade. If you had a car with a completely opened up intake and porting, bigger cam, and better flowing exhaust from the cat back, then you would see the most gains. No doubt you could get 20-25 HP from headers in that situation. Maybe a little less maybe more but I wouldn't expect it to be 40+ HP like headers can do for some V8 engines. If you have any major bottlenecks like a restrictive intake or a clogged cat and you wont get much out of headers.

With a W-body you probably have the 'header' style rear exhaust manifold. I don't think you really want to go crazy hogging it out but you can clean up the casting and the opening out the back is a decent diameter (i forget exactly, somewhere between 2 and 2.5"). The inside of the stock downpipe goes to roughly 1.75". Just like the headers, if you have everything else upgraded you can see some decent gains and probably the best HP per dollar spent (if you can make it yourself), and virtually no gains with any bad bottlenecks.

Has anyone else heard about the 3500 exhaust manifolds? I hear they're better flowing, I was planning on snagging those and self porting and polishing them just to clean up the casting a bit.

Does anyone have any idea about that? Sounds like a good way to go for my mild build.

[trewyn15]

Has anyone else heard about the 3500 exhaust manifolds? I hear they're better flowing, I was planning on snagging those and self porting and polishing them just to clean up the casting a bit.

Does anyone have any idea about that? Sounds like a good way to go for my mild build.

bump, i posted in the chat about this, will this work without much modification or do you guys know how much work will be involved?

[WrathOfSocrus]

Do a search for it I remember a couple threads mentioning it. The W body has a motor mount on the bottom where they run the exhaust to the back using those shorty style manifolds on stock applications. You need to use a large radius U-bend to have it run over the trans and get a 2-1 merge. I vaguely remember seeing a pic of the front manifold with the U-bend on it.

[trewyn15]

http://www.v6z24.com/jbodyforum/little-side-project-t108940,highlight,side+project,start,45.html

I think that's the one, doesn't look like anything I could do, Ben should look into producing a crossover pipe ha anyone able to possibly make one and sell it?