I am piecing together a new exhaust system for my 73. For the sake of routing the pipe I am considering placing the X-pipe under the differential similar to the way a stock exhaust system looks where the two pipes run very close together in that spot. My question is will that erase any performance gains which I would have gotten from the X-pipe by having it so far downstream?
My new system will have long tube headers and 2-1/2" pipes with mufflers at the rear as in a stock set up.

 

Hi,

Did you see this on youtube.

 

Put it where it fits best.

 

That video was great! Putting a X pipe or H pipe on the exhaust reminds me of the intake manifold discussions since on moderately modified motors, aftermarket manifolds, for the most part, add very little power, maybe 5-7 HP on a more aggressive modified motor, less on a mildly modified engine. If you are chasing every last HP/TG, then an X/H pipe for the dollars is worth it.

The real benefit is sound control from the X pipe, mostly. I have neither an X/H pipe on my built 355 L-82 with 2.5 inch duals, Monza turbo mufflers, and 1 7/8 long tube headers...I like the sound as is.

BUT I can tell you this about X pipes: I had the stock 2.5 inch duals with stock ford restrictive mufflers, Stock 4 cat H pipe, and very small OEM primary tubular ford shorty headers on my 1994 Mustang GT 5.0. The sound was less than pleasant. I switched one component at a time on the 5.0: First, magnaflow cat back muffler system, then BBK shorty 1 5/8 inch headers, and last, a maganflow X pipe with 4 high flow cats. The last installation of the X pipe completely transformed the sound of the 5.0 engine. The sound of the exhaust at all RPM's changed with it being much louder (good) at lower RPM's to a tuned, smoother, song at 3,500-6,000 RPM...it really is sweet, guys!

X pipe all the way for sound enhancement! I would skip the H pipe....

 

Packaging is always a problem with Corvettes. However, the farther forward you can put it (most guys put their X pipe right behind the transmission) will at least reduce the flow penalty of cylinders 8&4 and 5&7 that have to deal with the doubled instantaneous exhaust mass flow in the pipes.
I prefer an H-pipe, which can be installed farther forward (I have mine installed right at the header reducers). This exhaust mod is lightweight, makes a noticeable reduction in exhaust noise/drone, and often results in a slight free power increase. No downside to an H pipe.

 

Actually I just saw that video yesterday. They did recommend putting the X-pipe farther upstream for more benefit. I know it wont give me that much of a power gain but if I can reduce the drone at cruising speed its worth it.

 

AND it will give you a better sound
That would be enough for me :- )

 

I will be running Borla Pro xs mufflers I'm hoping for a nice sound.

 

I have my X-pipe right behind the transmission. I really like the sound it makes with the chambered mufflers. Much better than without the X.

It has an aggressive snarl or growl to it.

Mike

 

I placed my pipe here. Changed the tone a little. Idle is smoother now.

 

X pipe right behind the crossmember. Part of the Flowmaster crossmember back Force 2 kit.

 

I wouldn't put it under the diff. makes it very hard to jack up the entire rear of the car.

 

I put mine just a little forward of that right behind the crossmember. It also changed the exhaust tone to a little deeper sound at idle and got rid of some the raspiness at speed.

 

This is where I put mine in 2015 when I upgraded to SS.

 

I think both the H and X pipes only really provide a meaningful power benefit when your performance is limited by your exhaust. -If you went with a slightly undersized diameter for your HP level, the H pipe / X pipe should be more beneficial.


Regarding placement, Pipemax will calculate the theoretical "ideal" location for the crossover pipe, I think on my car it calculated it as "within 21 inches of the header collector" or something like that, but I'm doing this from memory.


Adam

 

dont get too wrapped up about it though put it where its convenient what a dyno may show youllnever feel with the weight of a car behind it.

 

This is a great example of a pass under cross member That way you are limited on the tedious routing required by a sorry stock pass through with the hole locations not lined up with header exhausts.

I personally have dual 3 inch with a 4 inch ovalled H pipe maybe 4 inches long. H pipes are more effective the shorter they are. H and X double the exhaust note frequency.

 

Vizard recommends an H pipe right at the collector. Given his engineering background and his extensive dyno experience I'm inclined to take his advice until I see data to the contrary.

 

This is great feedback guys. From what I'm reading here I'm probably gonna pt the cross over near the collectors. While I prefer X pipes I think the H pipe looks easier to fit. Sound is important to me though.

 

Its not a big difference, really
Better using none, you may like it, you can always add later if you want
My car sounded meaner with none at all but its so friggin loud at higher rpm decided toning down some of the high pitch rasp/crackle stuff was in order.
At lower rpm it sounds kind o f muted, not quieter just not as "pronounced" if that helps.
Alwasy fun experimenting...have heard (know how that goes) that the less bends in a system the better.