I've read all the exhaust testing that Ted has done recently and am wondering if there are any results with straight duals vs. duals with an X pipe. I'm about to build out my exhaust system and am curious if it would benifit the design of my exhaust system.

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

Well, all the X pipe manufacturers claim they makle more power.  Do you believe them?

John - "The Hoosier Hurricane"

I don't believe them, necessarily. That's why I posed the question to see if anyone had actually measure an increase in torque/horsepower by installing one...



Has anyone had any luck with one?

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

Frank says they work. I have experience installing one but it's been in use with this engine since day one so I can't compare it.

If no one here knows, they are cheap enough to swap out and use your butt dyno.


Lawrenceville, GA

There is something other than a butt dyno?

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

There's several older threads on this, mostly in the Racing section, I run a (Jegs) X pipe on my F code. I cannot tell you that the X pipe is THE only answer, but I can state that the car runs the same ET and MPH with the X pipe, 2 1/2" Flowmasters and tailpipes, as it does with headers and collecters! To clarify, I pulled the full exhaust system, mufflers, tailpipes, and factory (cast iron) exhaust manifolds off the car. 75 lbs ?

    I replaced that with my early Hedmanns (which are not very good headers in todays world) and a pair of 30"x 2 1/2" collecters. The car ran exactly the same speed and ET either way. Makes me think the X pipe system makes more HP than the headers since it's pulling more weight to the same speed. I have not pursued this any further, since I run "Pure Stock" and the 2 1/2" system is legal, there's no reason to experiment further. 

Frank/Rebop

Bristol, In ( by Elkhart) 

Due to the imbalance of the firing orders from bank to bank on a V8, a crossover pipe will enhance lowend torque.  The closer the pipe is placed to the engine, the better.  X pipes are the ultimate in crossover pipe technology as the distance between the two exhaust pipes or tailpipes becomes minimal.  The Mustang mags have tested this to death and although I don’t recall the numbers, the crossover pipes always helps where the system must be run with a full set of pipes.

 

And here’s why the crossover pipes work.  When examining the firing orders of any V8 with a 90° crankshaft, you’ll find where two cylinders on each bank fire consecutively and then miss a beat.  The crossover pipe helps to balance out the surge in exhaust pressure in a tailpipe that is a result of cylinders on the same bank firing back to back.  That pressure surge ends up in the other pipe and eventually into the other muffler.

 

Ford and Mercurys started using crossover pipes in the early Sixties on the dual exhaust equipped cars if that’s any consolation.  For the race cars, 180° headers are available for some applications where clearance permits them and this allows the firing order to alternate between paired collectors in a defined manner.

 

Here’s another thread with some similar information.

http://www.y-blocksforever.com/forums/Topic44336-3-1.aspx

Lorena, Texas (South of Waco)

 

    To add to what Ted said here, and this is only an opinion, I think the fact that each cylinder exhausts into two mufflers instead of one, helps lower the maximum pressure spikes. This effectively lowers the backpressure each cylinder sees. I've read the same articles in different Hot rod magazines, in all cases there was a noticeable difference in low end to midrange torque. Top end, not so much. I suspect the advantage is exagerated in my case because the motor makes comparitively less torque until the blower spools up. i need everything I can get at launch. 

Frank/Rebop

Bristol, In ( by Elkhart) 

That makes sense, Frank. I think you can look at it as if the pipe from the header to the X is a collector and if the gas can exit through 2 mufflers, then the portion after the X will be much like exiting the tailpipe to atmosphere. So with the X you get less resistance and pressure balancing whereas with an H you only balance pressures.

Did you tune the carburetor or timing at all when going from the full exhaust to headers?


Lawrenceville, GA

Back in the early 80's we ran a set of true crossover headers on my scrub late model race car. They were a real pain in the ass to install. but they seemed to perform well. We didn't have access to a dyno back then, I bought them used from Neil Bonnet who swore they were good for twenty HP. I don't recall who made them.

Glen Henderson



Freedom is not Free

Letohatchee, AL