Exhaust H pipe location?
Thread Starter
Pro
Joined: May 2008
Posts: 582
Likes: 9
Exhaust H pipe location?
I had asked a question along this line on a different post about my exhaust build but I thought I would start a thread asking this one question.
What effect does the location of a H pipe have on engine performance and sound?
I know that the closer to the engine the better, but what about behind the transmission cross member?
What effect does the location of a H pipe have on engine performance and sound?
I know that the closer to the engine the better, but what about behind the transmission cross member?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
couldnt tell a difference on either H or not on any car Ive had.
X dumbs down the rasp some still no difference in performance I can tell.
Do whatever fits your budget and space. Rest is internet folklore
X dumbs down the rasp some still no difference in performance I can tell.
Do whatever fits your budget and space. Rest is internet folklore
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I had asked a question along this line on a different post about my exhaust build but I thought I would start a thread asking this one question.
What effect does the location of a H pipe have on engine performance and sound?
I know that the closer to the engine the better, but what about behind the transmission cross member?
What effect does the location of a H pipe have on engine performance and sound?
I know that the closer to the engine the better, but what about behind the transmission cross member?
Thread Starter
Pro
Joined: May 2008
Posts: 582
Likes: 9
You are correct, the closer you can get the crossover to the engine (or to the header collectors) the more efficient it will be. Space is a problem under Corvettes is why most guys put theirs behind the transmission crossmember. I had mine there for quite a while, and there was some reduction in exhaust noise, but it was minimal. On a lark I decided to try a crossover at the header reducers. Very noticeable change (reduction) in the exhaust harshness, and elimination of the drone frequently experienced at 1500 RPM. Very good noise reduction effect at that location. The downside is that the bellhousing and transmission make routing the crossover a PITA. I made it, but ground clearance is an issue at times.
Drifting
Joined: Jul 2009
Posts: 1,534
Likes: 14
From: Dallas-Fort Worth TX
I had the H-pipe placed a few inches behind the cross member. Really is the only place to install it. This way its also away from the trans pan. Per Flowmaster and I think Borla, x vs. h pipe, there is no advantage from one over the other, but they do recommend to have one vs. not have one at all. Ray Y has a very nice mandrel set up.
Thread Starter
Pro
Joined: May 2008
Posts: 582
Likes: 9
If you take a look at the link it has my exhaust build.
http://forums.corvetteforum.com/c3-t...st-system.html
I think I should have built the X pipe but because I have this section finished and also want to leave an area where I can add cats later if I have to(may be transferring to a different state) I am going to stick with the plan for the H pipe. Just really wanted it closer to the engine and not behind the transmission and am worried that if I do place it behind the transmission it will not work properly.
With the old smaller exhaust shop bent exhaust, I had added a H pipe that went under the transmission in front of the mount and it did make a big difference in sound. It was a lot quieter, less drone on the highway and a smoother sound. I had that system in for years before the H pipe was added and that was the only change at that time. I could not notice a difference in power but I was getting 1 to 2 MPH more in the quarter mile. I have read a few other post on here stating that the H pipe makes the exhaust deeper, but I did not experience that on either my Corvette or my 71 C-10.
With the hanger bracket and how the bends are on my exhaust now there is no way to run it under the transmission in front of the mount now.
I may be nuking this out.
http://forums.corvetteforum.com/c3-t...st-system.html
I think I should have built the X pipe but because I have this section finished and also want to leave an area where I can add cats later if I have to(may be transferring to a different state) I am going to stick with the plan for the H pipe. Just really wanted it closer to the engine and not behind the transmission and am worried that if I do place it behind the transmission it will not work properly.
With the old smaller exhaust shop bent exhaust, I had added a H pipe that went under the transmission in front of the mount and it did make a big difference in sound. It was a lot quieter, less drone on the highway and a smoother sound. I had that system in for years before the H pipe was added and that was the only change at that time. I could not notice a difference in power but I was getting 1 to 2 MPH more in the quarter mile. I have read a few other post on here stating that the H pipe makes the exhaust deeper, but I did not experience that on either my Corvette or my 71 C-10.
With the hanger bracket and how the bends are on my exhaust now there is no way to run it under the transmission in front of the mount now.
I may be nuking this out.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
I had asked a question along this line on a different post about my exhaust build but I thought I would start a thread asking this one question.
What effect does the location of a H pipe have on engine performance and sound?
I know that the closer to the engine the better, but what about behind the transmission cross member?
What effect does the location of a H pipe have on engine performance and sound?
I know that the closer to the engine the better, but what about behind the transmission cross member?
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Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
If you can find a book on header science another statement they make to get the most from an H pipe is to keep the length short and use the biggest size practical.
I took a piece of 4 inch tubing and ovaled it. My H pipe is about 1 .5 inches long and between the pipes where they come together under the differential
I took a piece of 4 inch tubing and ovaled it. My H pipe is about 1 .5 inches long and between the pipes where they come together under the differential
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Car Craft had a write up years ago and they suggested using a crayon. They said working from the rear, start touching the crayon every 10 inches on a hot exhaust and where it melts instantly is where the cross over should be placed.....
Idk but I have mine just past the trans cross member.
Idk but I have mine just past the trans cross member.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
If you can find a book on header science another statement they make to get the most from an H pipe is to keep the length short and use the biggest size practical.
I took a piece of 4 inch tubing and ovaled it. My H pipe is about 1 .5 inches long and between the pipes where they come together under the differential
I took a piece of 4 inch tubing and ovaled it. My H pipe is about 1 .5 inches long and between the pipes where they come together under the differential
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I welded a couple nipples onto the reducers and the crossover sections slip onto the nipples. I had to form the pipes into a D shape in the middle to fit into the area between the bellhousing and the transmission front face. The intersection of the two pieces is sealed with a peripheral cap and gasket material that also provides a couple layers of insulation between the pipes and the transmission case. The crossover can grow with the heat and allows the headers to be mechanically "unlinked" during the expansion. (I've since thought of another way to join the headers together to still allow for expansion but not have to carry the weight of flanges in the system. I'll probably build it when I get done with some other higher priority projects.)
Vizard says a crossover at this forward location is usually worth about five horsepower (some engines more, some less). Not enough to notice with my engine, but at about a 3 hp/lb easy modification, and the noticeable noise reduction, well worth the effort. The only downside is, as I mentioned earlier, the loss of a little ground clearance when driving over uneven surfaces.
Vizard says a crossover at this forward location is usually worth about five horsepower (some engines more, some less). Not enough to notice with my engine, but at about a 3 hp/lb easy modification, and the noticeable noise reduction, well worth the effort. The only downside is, as I mentioned earlier, the loss of a little ground clearance when driving over uneven surfaces.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I welded a couple nipples onto the reducers and the crossover sections slip onto the nipples. I had to form the pipes into a D shape in the middle to fit into the area between the bellhousing and the transmission front face. The intersection of the two pieces is sealed with a peripheral cap and gasket material that also provides a couple layers of insulation between the pipes and the transmission case. The crossover can grow with the heat and allows the headers to be mechanically "unlinked" during the expansion. (I've since thought of another way to join the headers together to still allow for expansion but not have to carry the weight of flanges in the system. I'll probably build it when I get done with some other higher priority projects.)
Vizard says a crossover at this forward location is usually worth about five horsepower (some engines more, some less). Not enough to notice with my engine, but at about a 3 hp/lb easy modification, and the noticeable noise reduction, well worth the effort. The only downside is, as I mentioned earlier, the loss of a little ground clearance when driving over uneven surfaces.
Vizard says a crossover at this forward location is usually worth about five horsepower (some engines more, some less). Not enough to notice with my engine, but at about a 3 hp/lb easy modification, and the noticeable noise reduction, well worth the effort. The only downside is, as I mentioned earlier, the loss of a little ground clearance when driving over uneven surfaces.
Most everything I am around in Historic racing has tranny and rear end coolers.
I keep the pipes away from my TKO 600. Wide away straight back with 3 inch pipes in a pass under modded cross member
Why does every body shoot for those two stock holes?
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I know that you have done the most beautiful flat bottom job. But heat is a major problem............... If you are really running a car in a lapping type environment.
Most everything I am around in Historic racing has tranny and rear end coolers.
I keep the pipes away from my TKO 600. Wide away straight back with 3 inch pipes in a pass under modded cross member
Why does every body shoot for those two stock holes?
Most everything I am around in Historic racing has tranny and rear end coolers.
I keep the pipes away from my TKO 600. Wide away straight back with 3 inch pipes in a pass under modded cross member
Why does every body shoot for those two stock holes?
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
2.5" SS system from Pypes. Had no choice between X or H, they only have the X. From what I saw from other posts, H is supposed to give u more of a muscle car sound vs X pipe. Whether true or not...I dont know.
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Thread Starter
Pro
Joined: May 2008
Posts: 582
Likes: 9
I spent a little bit of time looking at what I have and was even thinking about redoing my exhaust and going with the X pipe, but after looking at everything that has been posted and keeping in mind the $ to redo what I have already built I think I am going to build the H pipe directly behind the transmission cross member.
Thank you to everyone who have posted information and photos. I will post photos when complete.
Thank you to everyone who have posted information and photos. I will post photos when complete.