johnj92131 Posted May 23, 2017 Share Posted May 23, 2017 Since you're in Mexico, how about a crank from one of the big VAM engines? now that you mention headers, are the renix era exhausts optimal or is there some extra power to be had there? because the exhaust pipes in my MJ are rather rusty and they gonna fall apart some time soon and i was planning that when the time comes, put a larger pipe, shorter one that exists just behind the drivers side door, no point in going all the way back of the truck, or maybe a vertical exahust, serves no purpose but looks cool... Just remember that bigger is not always better. Especially when it comes to exhaust! Link to comment Share on other sites More sharing options...
omega_rugal Posted May 23, 2017 Author Share Posted May 23, 2017 Just remember that bigger is not always better. Especially when it comes to exhaust! a little larger pipe won`t hurt, maybe porting the exhaust a bit, if there`s anythign left to be ported that is, while the header is down, why not... Link to comment Share on other sites More sharing options...
Eagle Posted May 25, 2017 Share Posted May 25, 2017 Just remember that bigger is not always better. Especially when it comes to exhaust! a little larger pipe won`t hurt, maybe porting the exhaust a bit, if there`s anythign left to be ported that is, while the header is down, why not... Don't be so sure. Remember, the OP said he's looking for torque, not high-end power. I've never done propane, so I don't know if it might be different from gasoline. I do know that when I had my original '88 Cherokee for a few years, it needed an exhaust. At the time my brother was manager of a Speedy muffler shop, and he talked me into doing a full 2-1/2" system with a turbo muffler. (Stock is 2-1/2" as far as the catalytic converter, 2-1/4" from the cat through the muffler and out the tailpipe.) It sounded nice -- but performance suffered, and gas mileage was between 2 and 4 MPG worse. That was the only time in my life when I actually looked forward to an exhaust system dying so I could justify replacing it with stock parts again. Link to comment Share on other sites More sharing options...
omega_rugal Posted May 25, 2017 Author Share Posted May 25, 2017 on a second though, a less restrictive exhaust would also decrease the dinamic compression at low revs, a bit which may explain your loss of mpgs, on an HO the valve overlap and scaveging effect is expected and also the decrease in dinamic compression.. more on the subject: according to strokers calculator, the OEM renix camshaft profile is the only one with advance/retard of -8, by moving this value to 0, DC raises, how much degrees of advance /retard gives you moving forward o backwards one tooth of the timing chain? Link to comment Share on other sites More sharing options...
cruiser54 Posted May 25, 2017 Share Posted May 25, 2017 Advancing the cam generally adds torque. Link to comment Share on other sites More sharing options...
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