Generation IV External Engine - 416 Headers L92

Iam looking at geting new headers to replace my passeter headers that are 1-3/4 for my 416 with ported l92's are 1-7/8 to 2 inch step headers to big??

1 7/8 - 2 are way to big. 1 7/8 max if it drives on the street.

im probably going with the 1 7/8 stepped to 2 inch on my 402, but my car is going to be on the bottle

AR 1 7/8 with 3" X-pipe on mine (403, L92/L76)

my car also will be on the bottle like a 200 hit

Kooks 1-7/8" here....

Kooks 2'' all the way. its not too big if your cam is like mine 248/254dur.

More details needed, but on "most" 400-418 cubic inch motor's a quality 1 7/8" is enough header. Even on most 427 setup a 1 7/8" header is a nice fit.
I would do a 1 7/8" with a 3" Y pipe stepped to a 3 1/2" outlet. Should be a very nice combo. Now if you’re going crazy on spray or trying to make HUGE power with LS7 style heads, huge cam etc then that could be a different story. Maybe then you would want a 1 7/8" header with a custom 3 1/2" "Y" pipe to a 4" outlet.
We can get you whatever you need from American Racing, and more than likely have it in stock.
We are having a sale right now on their product. Check it out below.
Thanks
Jeremy


http://ls1tech.com/forums/showthread.php?t=806949

More details needed, but on "most" 400-418 cubic inch motor's a quality 1 7/8" is enough header. Even on most 427 setup a 1 7/8" header is a nice fit.
I would do a 1 7/8" with a 3" Y pipe stepped to a 3 1/2" outlet. Should be a very nice combo. Now if you’re going crazy on spray or trying to make HUGE power with LS7 style heads, huge cam etc then that could be a different story. Maybe then you would want a 1 7/8" header with a custom 3 1/2" "Y" pipe to a 4" outlet.
We can get you whatever you need from American Racing, and more than likely have it in stock.
We are having a sale right now on their product. Check it out below.
Thanks
Jeremy


http://ls1tech.com/forums/showthread.php?t=806949

does American Racing make a stepped header, and do they make a 3 1/2" to 4" y-pipe too, and if they do do you have any pics of the y-pipes, cause if i go back to a y-pipe i dont want a sloppy merge to give me the rasp again

American Racing does have stepped headers. And custom built "Y" pipe's. I don't have any pictures of what your asking for but I will put a call into Nick at ARH to see if he can send me a few.
They do make a 3 1/2" to 4" "Y" pipe and are making one right now for a customer that ordered last week.
They do a custom merge so you don't have that raspy sound, leaks, etc and the product is top notch. The price however is much greater when you get into the 1 7/8" stepped and the custom "Y" pipe's.

If you are making the power to need this kind of header/Y pipe then I believe ARH will be the best system you could choose. The product is unbeatable.
Send me a email @ JZ@mphparts.com and I will do my best to get a few pictures for you and go over cost on these systems.
Thanks
Jeremy

my car is a gto 3 inch x pipe to 3inch magnaflows

my car is a gto 3 inch x pipe to 3inch magnaflows

You alreay run some real impressive times. What kind of power are you making? What MPH did you run in the 1/4?
I still feel 1 7/8" is a great headers do go with and enough for your NA motor. We have done 3 ported heads/ L92 motor's now and the best power was 551.7... He has 1 3/4" ARH headers, which just goes to show that the combo is working and I doubt the 1 3/4" are holding him back much.
Jeremy

mine did 505whp when it was a 6 speed and 445 whp with the th400. 124mph with a 1.50 60 foot, iam trying to get my numbers up were they should be iam changing the cam and headers to help i hope, looking to get 470 whp with the th400, when my car was a 6speed it just did not make no were near 551 whp looking for the missing hp

Well I will give you the breakdown of his combo and you can do the math however you believe it works best.
2003 Z06
12:1CR
TEA ported L92's with a L76 intake, and a ported LS2 TB.
250/258 duration cam, 620ish lift on a 113+0
ARH LT's with non catted X pipe, and Borla Exhaust
Ele Water pump, vararam, cometic .045 gaskets.
93 octane. Dynoed on a dynojet 248C with a spec stage 3+ and alunimum flywheel.
He now has a steele flywheel and a heavier rear time and made 533 a few weeks back.
But says it feel's stronger. HAHA go figure.

hate to do this to you as you already have a strong running car but have you considered the 4" bore ETP LS7 heads? You will gain between 15-30 CFM's through the manifold using the LS7 style ETP heads and a ported LS7 intake manifold over what you have now. The manifold is really a killer of power, especially past 6,200 RPM's.

dont want to change heads yet because i want to build another motor next fall using a tall deck lsx block, his cam is all most like my new one from texas speed 251-259 661-663 on a 112 i hope it helps over what i got now, thanks for your help