Thread: H pipe in exhaust

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Ok here's a question for you folks.

I'm putting a 283 +.060 over in my 40 Ford p/u.
Should I connect the left and right pipes with a "H" pipe/crossover pipe ?
I'm using cast iron/stock type exhaust manifolds. Complete exhaust system/pipes will have to be made to fit.
Whats the pro's cons of it if any. Seems like just more work to me but if it makes a difference then its worth the work.

thanks

gordy

Navy, an H-pipe will balance the sound pulses and improve your exhaust note along with some minor performance improvement but if you really want to optimize use an X-pipe between the two. The X-pipe forces the gasses from the two streams to intermingle, improving scavenging of exhaust from the cylinders by using the velocity pressure of the other cylinders to essentially "vacuum" the combustion chamber as the exhaust valve opens, and especially as it is past the top and starting to close. You get the best of everything with the X-pipe, improved sound plus improved performance. An old tech article spells out some specifics - Exhaust System Installation H-Pipe, X-Pipe,- Car Craft Magazine

You'll change the tone of the exhaust, but with those stock manifolds, the performance gains will be minimal. If you really want performance gains, you need long tube headders.

Navy, Firebird is right about maximizing performance, but if you're doing a custom exhaust you might as well take advantage of the knowledge of the flow dynamics so you don't have to change your pipes when you switch to a 383 stroker motor with headers in a few years

The reason an x pipe is an improment to exhaust flow is that because the firing orders of v8 engines are not symetrical side to side has a gap in the positive pulses on one side at same time as a lull in the oppsite side---the old racing flat 180* cranks solved this problem but created others---

as the exhaust pulse gets beyond the tunable range of the headers/collectors its just looking for a way out to the atmoshere----------so from the X to the end of the system---beyond mufflers/tail pipes------the exhaust can go down both pipes at a much steadier flow/pressure instead of being pulsed -lay out your firing order on a piece of graph paper and it will become clearer than what I have written-------
for example chev firing order

1 3 57
84 6 2

you can see the lull between 1 and 3 on the left as rt side has double of 8 and 4, 3 and 6 even side to side while then left side gets double of 5 and 7------I hope this heps make it a little clearer about the differances-----

Good Read !! Thanks rspears !

Originally Posted by rspears

Navy, an H-pipe will balance the sound pulses and improve your exhaust note along with some minor performance improvement but if you really want to optimize use an X-pipe between the two. The X-pipe forces the gasses from the two streams to intermingle, improving scavenging of exhaust from the cylinders by using the velocity pressure of the other cylinders to essentially "vacuum" the combustion chamber as the exhaust valve opens, and especially as it is past the top and starting to close. You get the best of everything with the X-pipe, improved sound plus improved performance. An old tech article spells out some specifics - Exhaust System Installation H-Pipe, X-Pipe,- Car Craft Magazine

Jerry: Thanks for your input, its guys like you that keep me doing things right the first time !

Originally Posted by jerry clayton

The reason an x pipe is an improment to exhaust flow is that because the firing orders of v8 engines are not symetrical side to side has a gap in the positive pulses on one side at same time as a lull in the oppsite side---the old racing flat 180* cranks solved this problem but created others---

as the exhaust pulse gets beyond the tunable range of the headers/collectors its just looking for a way out to the atmoshere----------so from the X to the end of the system---beyond mufflers/tail pipes------the exhaust can go down both pipes at a much steadier flow/pressure instead of being pulsed -lay out your firing order on a piece of graph paper and it will become clearer than what I have written-------
for example chev firing order

1 3 57
84 6 2

you can see the lull between 1 and 3 on the left as rt side has double of 8 and 4, 3 and 6 even side to side while then left side gets double of 5 and 7------I hope this heps make it a little clearer about the differances-----

As so well explained by both Jerry and Roger an H or preferably X pipe will both show an improvement in performance. Generally speaking however, that performance improvement is relatively minor and probably not enough to even be noticed in most driving situations (especially with a street driven motor under 300 cubic inches). The biggest difference you will likely see will be in the exhaust tone.

The one thing I would suggest if you use an H or X pipe is when you have your exhaust built is to pay close attention to the routing of the pipes. Often times if a transmission needs to be pulled or in some instances even a starter removed it may be necessary to drop the pipes. This can be a big PIA on a custom system made system where all the joints have been welded. If I’m running an H or X pipe, I often use a pair of ball and socket joints just before the mufflers so the whole pipe can be unbolted and removed for maintenance if needed.





Just my 2 cents.



.

Thats worth a whole lot more than 2 cents ! Thanks for the input.

Originally Posted by Mike P

As so well explained by both Jerry and Roger an H or preferably X pipe will both show an improvement in performance. Generally speaking however, that performance improvement is relatively minor and probably not enough to even be noticed in most driving situations (especially with a street driven motor under 300 cubic inches). The biggest difference you will likely see will be in the exhaust tone.

The one thing I would suggest if you use an H or X pipe is when you have your exhaust built is to pay close attention to the routing of the pipes. Often times if a transmission needs to be pulled or in some instances even a starter removed it may be necessary to drop the pipes. This can be a big PIA on a custom system made system where all the joints have been welded. If I’m running an H or X pipe, I often use a pair of ball and socket joints just before the mufflers so the whole pipe can be unbolted and removed for maintenance if needed.





Just my 2 cents.



.

Mike's right, Gordy. For "normal" driving you'll never see anything from either an H or X pipe other than maybe a smoother exhaust note. The scavenging is not going to kick in until you get up in the rpm range, when the engine's flowing at it's peak. I don't know if I'd worry with it much for a cruiser truck with a 283 unless you're planning on going to the drags bracket racing, or worrying over MPG to the second or third decimal place every time you fill your tank

Crikey!
You fellas never cease to amaze me!
There is such a wealth of knowledge on here that is patiently shared and explained clearly and succinctly.
I've learned a lot in the last five minutes from the information that has been posted.
Thank-you all from me too!

I guess its all going to come down to fit verse's function. Clearance is going to be tight. Thanks again everybody !

I've laid out several of these and the space really varies between the type of cars, however the one kinda rule of thumb is to look at the layout with the X portion right around the front u joint location----which of course is just at the rear of the trans tail shaft and then the split lets the drive shaft room -------------

FWIW... If you don't have room for the X but you find room for an H then do that as at a minimum it'll help the flow and it changes the sound for the better!

I'm with johnboy ,good read on the exhaust !