Guys I can fit 2.25" TTI headers into my car easily enough.

My question is: will a 3.5"collector be enough for a 6500rpm max 572" N/A Hemi ? Engine makes 845HP/770TQ on pump gas.

TTI make a 4" collectored header but that is only for the Indy 426-1RA head, and Im running a set of Indy 426-1 head.

So, am I better off with a 4" collector or will 3.5" be sufficient ?

Any experience with this would be great !

Thanx

are you running mufflers ? if so what size pipe and mufflers

in my opinion, 3.5 is way too small for a 572. with a 426/7200 rpm/765 hp motor w 2.25 primaries, we saw 8HP improvement w 4" vs 3.5"

I went with 4 inch stanless with an X pipe and out the back bumper.

Hey can we see the rest of that 63 ? That looks really nice . Gary

Thanx pretty much confirmed what I suspected.Here's my plan....

Since TTI don't make a 4" collectored header for the 426-1 heads I think Im gonna have to mod them and add the 4" collector.

Then dual 4" pipes from the collector to the X (or H) then muffs - 4" IN and 3.5" OUT. The reason for 3.5" out is by then the exh gases would have cooled sufficiently to allow a reduction in pipe diameter and to enable it to be easier to get over the diff.

After they go over the diff Ill run another 2 x 3.5" IN/OUT muffs at the rear to keep the noise to an acceptable level. The tank is in the trunk so I have the room to do it. The dual 3.5" pipes out to the bumper.

For you 4" collector guys, how is your ground clearance with them?

Thanx...

With all the trouble to go threw you think you will ever feel that maybe 8 HP loss on a street car???? You already have more than you need!!!! Just my 2cents.

Jake just want to optimize the combo amigo - thats all.



BTT

I'd run it as is. My engine's headers are 2 sizes small on the primaries and 1/2" or better to small on the collectors. It still makes more power than I've been able to stick to the ground. The only time I can notice the difference is with the mufflers and pipes hooked up, I loose 117hp then. As Fred said, you'll never see the difference in 8hp. Dave

Hey thank you , very nice lookin car . has it seen the track ? Or just a weekend cruiser . Gary

Thats just it Fred.

I want to run thru the exhaust at the track as well.

Another vote for 4".

Unless you are trying all different exaust combo's and measuring results you have no idea what your gains or losses are. That 8 hp loss was on someone else's combo. you dont have a clue what yours are. It may make less but make more torque. Unless you are running a heads up class just adjust the hp loss with the dial in on the window. That is allot of expence for the small gain.

We have to run full exhaust in our KOS series here, so we have played around a lot with our exhaust. Not to say we know everything, but in my experience the exhaust system is way more of a power robber than the headers themselves.

We have tried a lot of different exhaust combos on the Cuda and in the end I just put electric cut-outs on it. That way it is quiet enough to keep the cops off my butt while in town.

3 1/2" or 4" exhaust was just so large, cumbersome and expensive, that it was just not practical. Besides, no matter what I tried, it robbed HP. And a lot more than 8 HP.

I run 3 1/2" to the dumps and then 3" on out the back. Much easier, cleaner, cheaper and no clearance issues. Besides, I can make it as loud as I want any time I want.

Good info fellas.

Dave, Thats what Im planning to do if I stick with the 3.5" collector run 3.5" pipe to the mufflers then after the mufflers when the gases have cooled sufficiently, step down to 3" over the rear end then another pair of 3" in/out mufflers at the rear of the car for further noise control as I have the space. I may also experiment with alum tubing and possible oval tubing and use electric cutouts to further reduce the noise if reqd.

Here's food for thought, I just confirmed with my dyno guy, the combo made 850HP at 6300rpm and 770TQ at 5300rpm with 2 1/8" Dyno headers with a 3.5" collector

Interesting.

Just to be clear; I run 3" after the cut-outs. With the cut-outs, the extra 1/2" exhaust pipe diameter just doesn't matter. I can crack open the cut-outs just a little and get the same results without being too loud if I want.

With cut-outs you can concentrate on the exhaust system's cost, fit, and sound. Instead of the quest for maximum flow causing all kinds of problems.

And did I say how much FUN cut-outs are? I will never have another muscle car without them.