The title should have read "LSx stock exhaust manifold options"

I have been trying to find this information and since I am not yet to the point of my LS6 swap to see what kind of room is available - the exhaust is my last and only concern. I know the 4th gen manifold fits but if it restricts an LS1 how much will it restrict an LS6 (dynoed at 427hp). I know Hawks headers fit but I refuse to lose ANY ground clearance and since I am using a 4L60E trans all the pictures I have seen with Hawks and Auto have led to ground clearance loss.

Oh, and I using a Spohn k-member.

What I would like to know is what stock manifolds do we know, for certain, wont work and which ones might. Both LS2 and corvette LS6 stock manifolds will support 400hp but are they usable? Truck manifolds do not work? Where do GTO manifolds come in? CTS?

My car will be a weekend show car and will not see the strip. I want to maintain roughly 400hp. I cannot lose ground clearance. I am open to having custom headers made but I am having a hard time finding someone to do it - if you know anyone around Charlotte, NC that will do it and does quality work let me know.

 

I just got dont with my ls1 swap this week. I'm using the factory exaust manifolds. They came from a 2002 Trans Am. I Bought 6 U shaped mandral bends 2.5" to make my pipes to make my Y. The driver side one come down and bends to the front of the car between the spohn k-member abd oil pan it runs right and than runs to over by the frame does another zig zag than to the y. The passenger side some straight down than curves right than to the back of the car and into the y to my 4"exaust. Took a lot of time but have lost really no ground clearance. tucks nicely. Also.. the flanges for the hot pipes ...I did not get. So i took my flange gaskets to a welding shop and they made a computer program and cut them out with a plasma cutter. Only cost like twenty for two sets. I was told that the factoy maniflods flow as good as shorty headers. And theres plenty of room for them. Well thats all I know. Good luck

 

How many hp will I lose using 4th gen headers on an LS6? Some aftermarket headers report ~25hp gain from a stock 4th gen LS1 and those are putting out ~325hp (crank)...so bump it to ~415hp (crank) and how much restriction are we talking? Guestimating of course.

Does anyone have a picture of an LSx engine mounted with no exhaust on it? Perhaps I can guess which manifolds will fit. Or maybe I'll have to wait 4 weeks till I am ready to bolt it up and see for myself

 

i make about 300hp and 425tq through stock manifolds. they flow just about the same as shorties, so the only thing that is going to help you is getting longtubes. you'll probably gain 15 hp and like 25 ft-lbs for 800 bucks.


to save some face on the 300hp number, the throttle cable wasnt apparently open all the way. so its more now =D

 

i have a thread on here somewhere showing my exhaust setup. with a dual 2.5 " exhaust going to manifolds. i have the spohn th350 cross-member and alston sfc's, NOT a fun combo for exhaust. the lowest point is where it crosses the sfc bar on the driver side. it is called my lq4 swap.

 

I thought I would post my results of some fitting tests.

LS6 (2004? vette) Drivers side: will not work with fbody engine mounts
LS6 (2004? vette) Passengers side: will not work with fbody engine mounts

Next I tried some LS2 headers. I do not know what year they are off of or anything, just that they came from a gmpp ls2.

LS2 Drivers side: hits the top of the engine mount but just barely and the mount could easily be trimmed to fit. Brake line has to be rerouted. May work but would be difficult.
LS2 Passenger side: actually fits fine. have to reroute brake line. I think routing the y-pipe could be difficult

LS1 (2001 fbody) Drivers side: fits very well, gonna use it
LS1 (2001 fbody) Passenger side: fits very well, gonna use it

Truck Manifolds : hit the frame rails

I have a bunch of pictures (of the ls2 and ls1) but nowhere to host them right now. One problem with both of them is I still cannot use my A/C. Still working on that solution.

btw, I am using the Spohn k-member.
Hope someone finds this useful.

 

truck manifolds hit the frame rails. can add that :P

 

Ok, added it

 

If you find a manifold that fits well, but doesn't support the desired power level, you could also consider having it extrude honed... (Just another possibility.)

 

I am just guessing, you are having this problem with a Spohn-Kmemeber and A/C becuause your using a LS6 engine with LS1 manifolds.

But no issues with Spohn with LS1 engine and LS1 manifolds ?

 

If they fit, I have a couple of sets of GTO manifolds. Both sets have less than 1500 miles. I can get pics of them when I find which box I packed them in when we moved.

 

does anyone have pictures of how stock manifolds would be placed with a y pipe?

 

A buddy of mine has the hawks thirdgen Ls-x long tube 3rdgen conversion header setup with y-pipes and cats brand new, never been bolted on anything...for sale if you are interested. They clear thirdgen frame rails etc... and are specifically made for this swap.

 

By that I am assuming you mean the stock 4th gen f-body ls manifolds. If that is the case my plan is do the same as Blownz28man and follow the original route of the factory 3rd gen exhaust. Of course from engine to y-pipe will be custom but from cat to muffler will be aftermarket. I do not have pictures yet (its not done) but once I am complete they will be posted.

 

Reading this made me think, what the hell am i gonna use for the l92 heads i have on my 4th gen block

 

I have a set of extrude honed LS1 manifolds I picked up on LS1tech. From what I recall back in the day a set of extrude hone cast iron manifolds were worth about ~3 to 5rwhp and about the same for torque on a stock/bolt on LS1 over the stock cast iron manifold.

 

so how are people using these 4th gen manifolds or truck manifolds routed down with a y pipe?? i havent seen to many. majority people use hawks headers and fabricated y pipe

 

There is actually no physical external difference between the LS6 and LS1 except the cam and heads, the later year model LS1s were actually LS6 blocks (that had the extra webbing) with the LS1 241 casting heads and cam, plus the 2000+ manifolds flowed just about as much as the headers for an LS1 and can be ported since they're cast instead of stainless like the 97-99 manifolds are.

 

Forget stock manifolds, atleast go with the edelbrock shorties, they fit just fine, i used the ti-tec version and they are a direct replacement for stock manifolds. part 65732 on jegs.

 

that's why I went with the manifolds. all the dyno tests I have seen show no gain.

 

I used the stock 2002 manifolds on my LS1 swap. My engine is from a 2002 SS Camaro. All the research I did showed that the stock manifolds for 2001/2002 LS1's were as good as any shorty headers. Honestly if you use the long tubes from stainless works, and the trans crossmember from Skulte.com you wont lose any ground clearance. Skultes x member has two raised points for the y pipe to go through. I am going to switch to it after I get long tubes this summer. I just wanted to get my swap done quickly, and was going to go over my orginal budget if I had of bought them then.

I have the 2002 Manifolds with a 2.5 inch y pipe going into a 3 inch pipe back to a 2 chambered flowmaster.