What kind of gains in E.T. and speed would unhooking the exhaust pipes from the headers could I see at the track? I run TTI headers with a 3" collector into 2 1/4 pipes through Ultra Flows and out to the chrome tips. Also would header extensions be beneficial? It runs great with the setup, just wondering if it was worth the effort to unhook them. Motor is a 416 stroker. Thanks!! Greg

You will most likely go slower with open headers if you do not add collector length. I start at 12 inches and go longer til it slows down.

All you preverts can just let that go.


I learned this years ago when guys picked up with mufflers. They were adding collectors length. Most collectors are too short IMO.

I think you will pick up a lot !!! I would bet 4 tenths with that 21/4 pipe gone.maybe more.

2-3 tenths very likely. Maybe more. Adding a tailpipe to the collector would help also, but it sounds like you are just unbolting the exhaust, not removing it. Probably not enough room underneath to add tailpipes.

I had a 408 stroker running in the 11.20s with tti headers. I had 3 inch dual exhaust with 40 series flow masters iirc that dumped before the rear axle. Much less restrictive then yours. I gained 5 rwhp by unbolting it.

Agreed.

My Duster picked up 2-3 tenths (13.0 car) and my GTX (11 sec car) would pick up 4 with crappy flowmaster muffler system.

A friend of mine had a 383 satellite that ran 12.8 with 2-1/4 pipes, dropped .4 just unbolting the pipes, didn't even take them off.
Mick

It will probally pick up enough to make you wonder why it did that much I had a 440 motor in a 1969 Dart with Hooker fenderwell headers with 3.5 inch collectors running into 2.5 inch head pipes about 20 inche long running into a old set of 2.5 Turbo muffllers and then out with 2.5 inch side tail pipes that ended in front of the rear tires. That car ran a best 12.23 at 109.5 MPH with the exhaust system on at LACR 1/4 mie track, it ran 11.39 at 117.& MPH with it removed My next pump gas street car ran a best of 7.01 at 95.3 MPH in the 1/8 mile with a 3 inch system with 3x14 inch oval Magnaflows straight through mufflers, I removed that system, it went all the way to the back bumper, and the car picked up to 6.98 at 95.5 MPH
Bottom line is all of our cars don't react and get the exact same results with the same changes
Let us know your results please, more data to the data base

My guess is it will pick up WAY less than most here are saying. Less than a tenth.

On my old 3" w/ flowmaster 40's WAY less then a .10 second gain. Wasn't worth the hassle to unbolt them. Plus how it is on the street, is how I race it at the track

Bet you'd see bigger gains on a supercharged/turbocharged setups.

Next weekend is the Mopar race at Milan so I think I will unbolt it and see what it does and report back here. I am with you Darth that how it is on the street is how its raced but with more power the curiosity is killen me

3" into 2.25" is the problem area, I think 2 tenths.

Add a collector extension.. for a total length of 16"..
dump the exhaust and those muffs.. they have high back
pressure... you should pick up a couple of tenths anyways..
maybe more but you will need to re tune the carb

Depends mainly on how restrictive the system is and how optimized the A/R ratio is at WOT pulling through the load.

Over 30+ years I've seen >1/2 second on a super-restrictive system, and then I've seen only a couple hundreths, and depending on suspension and traction it may possibly/mainly show up only as MPH.

Going from a small but free flowing dual 2 1/4 to open headers I'd expect .08 to .2, tough to tell but you'll improve. May want to bring some jets +2 to +6 from where your at now.

My 360 makes 450-500hp on a good day. I have a 3" system to ultra flow mufflers and it goes out 2.5" tailpipes. It's all muffler shop bent stuff. I put some exhaust cutouts about 12" back and with them open it is .1 and 1mph faster.

When I went from flow masters to ultra flows it picked up 2mph roughly, I changed some other stuff also so it's hard to tell but they for sure helped. I also quit getting a sooty intake after I lost the flow masters

I say you will pick 3 tenths. Get that rollbar in big money!

I kinda have to outright laugh at some of these replies. 3 or 4 tenths is like 50 or 60 horsepower on this engine( or more). Just don't see it at all. That's like going from stock J heads to Eddie heads. I picked up 4 tenths doing that years ago on a 340 with boltons. Gaining the same by ditching exhaust.... Lol

2.25" AND flowmasters tells me he will see more than my .1 but .5 eh I dunno.

On my chasis dyno we see from 3hp to max 15-18 hp gain with cutouts open. depending on the placement of them sometimes it was a pay cut!!!

alot depends on the camshaft...lots of overlap hate exhaust.ive seen anywhere from 2tenths up to almost a full second on the same car same exhaust system just a cam swap.