Exhaust question
Posting Guru
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From: Rossmoor at Seal Beach
One of the Y-Block engine builders did some back to back exhaust testing with some 1.625/1.75 stepped tube t-bird headers on a warm 312, nothing exotic about it, cam, aftermarket intake, mild port on the best stock head casting, stuff that is not outside of the scope of the average Joe. The test included different size pipes, mufflers, no mufflers, crossover, no crossover, different pipe lengths and the results are interesting.
The baseline test was with 2.25" pipes. The crossover setup used 2.25" pipes with a 2" crossover.
A gain was found with a crossover only when mufflers were not used.
With mufflers, it did have a higher hp and tq peak. Average hp remained the same but average tq was down 1 ftlb.
Without mufflers a the peaks jumped by 5hp and 3ftlb and the averages jumped by 3hp and 3ftlb.
This is only one test so I would not call it conclusive but it looks like it's a wash. The difference is so small that you probably will not notice it even without mufflers, and considering that the engine is modified, it's safe to assume that a stock engine will not gain as much.
From personal experience, my butt dyno didn't notice a power difference back when I had an H-pipe fitted but I did notice that the tone was a little more mellow.
Unfortunately, manifolds were not tested. We can assume what will happen but it would be interesting to see.
The baseline test was with 2.25" pipes. The crossover setup used 2.25" pipes with a 2" crossover.
A gain was found with a crossover only when mufflers were not used.
With mufflers, it did have a higher hp and tq peak. Average hp remained the same but average tq was down 1 ftlb.
Without mufflers a the peaks jumped by 5hp and 3ftlb and the averages jumped by 3hp and 3ftlb.
This is only one test so I would not call it conclusive but it looks like it's a wash. The difference is so small that you probably will not notice it even without mufflers, and considering that the engine is modified, it's safe to assume that a stock engine will not gain as much.
From personal experience, my butt dyno didn't notice a power difference back when I had an H-pipe fitted but I did notice that the tone was a little more mellow.
Unfortunately, manifolds were not tested. We can assume what will happen but it would be interesting to see.
Then there is the question of H-pipe Vs X-pipe... if you have a High perf Strip App go for it, but other then that , it really isn't worth the extra bucks.... Most of these give minimal gains, until you are at very high RPM... street apps, rarely hit High RPM's Better off to put the bucks in the headers, and pipes, and free flowing mufflers and have a pro set it up right!
Elder User
Joined: Jul 2004
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From: Fairbanks
When I went to put dual exhaust on my 77 with the 460 the shop I was going to talked me out of it. Instead we are running dual into the muffler and single out. Joe has been doing all my exhaust work for better than 20 years and stays abreast of what is happening in his field. Mine has a nice deep sound and flows great.
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Joined: Apr 2011
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From: Portland, Or
Only reason I even looked for header is because I have the infamous exhaust leak from my exhaust manifold and thought "if im going to deal with pulling them off then I may as well upgrade them." If not for that I would have saved the money for much more needed work on my truck. Whatever you choose is up to you and im sure everyone here would love to know what you decided on and how you like it.
Cargo Master
Joined: Apr 2003
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I've thought about removing the X and installing duals with no crossover to see if I feel a difference. The X is he only system I've used with the current engine.
An H or X really isn't that expensive if you get a good universal kit, some extra bends and make it yourself. My mandrel bent X setup cost less than the muffler shops wanted to run pipes without a crossover of any kind and would not be mandrel bent.
Posting Guru
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From: Rossmoor at Seal Beach
I was hoping he'd be able to test an X setup but it's not easy to set up with the dyno equipment in the way. I am running an X pipe. It sounds great, wicked with glass packs, but I really don't know if it's doing anything. You can find a lot of dynos with them online because of the popularity with Mustangs and they generally seem to work. I'd just prefer to see it from someone who I know personally and trust not to skew the results. I also have friends who do drag race with their street cars and every one of them who has raced before and after X pipe, where the style of exhaust was the only change, say their car was faster when the X pipe was used. I don't think either would be used for a high performance strip application. When have you seen a dragster with an H or X pipe?
I've thought about removing the X and installing duals with no crossover to see if I feel a difference. The X is he only system I've used with the current engine.
An H or X really isn't that expensive if you get a good universal kit, some extra bends and make it yourself. My mandrel bent X setup cost less than the muffler shops wanted to run pipes without a crossover of any kind and would not be mandrel bent.
I've thought about removing the X and installing duals with no crossover to see if I feel a difference. The X is he only system I've used with the current engine.
An H or X really isn't that expensive if you get a good universal kit, some extra bends and make it yourself. My mandrel bent X setup cost less than the muffler shops wanted to run pipes without a crossover of any kind and would not be mandrel bent.
I read a test that was posted on another site, between the X,H, and straight pipes,, the gains we only a few 10th's of a second in the quarter mile.. really not worth it unless you were drag racing regularly.... The other benefit was when circle racing at high RPM constantly I considered it, and may later on swap in an X pipe kit, as they are not that expensive, but they do lower the exhaust system to clear the drive train.
Cargo Master
Joined: Apr 2003
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The X does hang lower than the frame rails. If you're not lowered too much, you will not have an issue. I'm about 3" lower up front and stock in back. There's not a bump big enough, unless perhaps I jump a curb, that will scrape.
Posting Guru
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I run 2.5" all the way to the back and have an H pipe. The H pipe crosses just under the drive line. I also have the stock spare mounted. The tail pipes goes on each side of the spare and straight out the back. I have the truck lowered 3" all the way round. There is NO problem with clearance. I would have to set it on a huge bolder to cause a problem and since I don't 4 wheel with it ------.
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