Read a bunch of the info on the site about the Mav exhausts. Seems to be a consensus on 2 1/2" pipe dual exhaust with an X or an H pipe on a 302. Anyone care to chime in on: X or H pipe? Long tubes make a difference (already installed and not changing them lol)? There was something on here about smooth bent vs. crimped pipe, or something like that. Should I even ask the exhaust shop about that? 302 bored .30 over, long tubes, Thrush Turbo muffles (already own), Street use.... anything else to consider?
"X or H pipe?" Go with the one that produces the sound you like. There is no performance advantage between the two. "H" produces more of a classic muscle car sound. "X" sounds more modern. Both produce a 2-4 horsepower/torque increase. The "H" produces it at a lower RPM, the "X" at a higher RPM. No, they will not produce a 10-15hp increase. Long tube headers produce the maximum flow, but with minimum ground clearance. Mandrel-bent pipe is always better than crush-bent pipe. It's also a lot more expensive.
I dont know either way but I would definitely say go with the sound you like I went hooker long tubes with glass pack mufflers 3 1/2" pipe curved out in front of the tires on each side on my black comet my white gt has dual exhaust but I doesnt have either an x or h pipe just headman headers with 2 1/2" pipe leading to magnaflow mufflers then out the back
Thanks for the replies! Larry - That's some good info. Sounds like I'm looking for an H pipe. I don't hit the high RPMs too much, and enjoy a classic sound. Crush-bent it is then: On a budget. Junari - Side pipes are just a pipe dream for me right now (yup, I went there lol). Love them! But maybe later. How do you like the straight pipe? Sound, drone, the good, the bad? That would probably save me some dough.... The posts were so X or H, didn't even consider straight.
I like the sound and its not nearly as loud inside as I thought it would be without carpet. I havent go to drive it a long distance yet. I have to get the hangers fixed so theyre not banging around under the car but the initial sound is GREAT and the short distances Ive went with it sounds GREAT it has that loud but deep GRUMBLE sound going down the road. I think its going to be just quiet enough to call it street legal since its not all blaaaah its got a tone thanks to the glass packs
H pipes are also called balance tubes for a reason. There is no scavenging effect as you'd get with an x pipe setup. It would be plain wrong to assign potential horsepower gains to each design. This is because much is related to the rest of the exhausr systems overall design. Especially the mufflers restriction..more restrictive chambered designs.. or less restrictive straight thru cores. So, what can we learn from these basic rules? Well, larger 3" diameter header collectors mixed with slightly more restrictive chambered mufflers(flowmasters or whatever) would prefer an x pipe due to added scavenge requirements created from running too large a collector on only 306 cubic inches. Not only does the x pipe act as a balance tube to ease each mufflers burden as multiple firing occurs on the same cylinder bank.. but also has a secondary effect of improving scavenge and reducing backflow (reverse flow) during overlap. The bigger the cam and collector.. the better the x pipes overall result and high teens to twenty plus horses are not uncommon if it helps fix a few of the designs weaknesses. Or on the other side of the coin.. you may have a more optimally sized 2 1/2" collector but still combined with slightly restrictive mufflers. In this case, the smaller header collector would improve scavenging/reduce backflow during valve overlap and the bulk of the potential gains to be had would fall mostly towards a simple h pipe to help ease the mufflers flow saturation point. If you decide on crimp bent pipe.. move up to a full 2 1/2" system and be sure the mufflers match as well. If you can stand the extra noise.. straight through magnaflow style mufflers will also help power and efficiency too. It's also tough to package a well designed x pipe into tight areas which either forces the use of an h pipe instead.. or pushes the x pipe back further in the system where it is less effective at scavenging due to reduced Temps and poor transition angles.
My comments were based on dyno test data between H and X pipes. Neither provides any additional scavenging effect. Both equalize exhaust pressure between pipes. Each has its own sound.
Haha how loud is it? Too loud for a residential neighborhood wouldn't be great... I usually leave before sunrise. I'm gonna let groberts and larry duke it out for a minute. Some great info, but not sure what definitively to take away from it yet...
lol.. what's there to debate?.. nothing credible was even posted here. I mean no offense.. but shooting from the hip here when I say that simply jumping on random "this car" forums and polling random people which may not have much if any real world exhaust system design, build knowledge/experience, maybe even some kind of industry or professionally related credentials?.. regarding the physics going on inside an exhaust system is like watching every episode of your favorite cooking program and intently waiting for them to discuss bernoulli's principle as it relates to the venturi in your Holley carburetor. Probably not going to happen. My normal thinking on that matter is that if someone doesn't want to take the time to study and understand the actual physics involved here?.. just pick the answer that you like best and run with it. In my experience, most people don't know how to finely tune an engine in the first place.. much less how to retune it for a more optimized exhaust system, so some potential gains are usually lost in the upgrade process. Can't really modify and tune it very well.. if you don't understand it very well. Plus, the difference in increased power between an X and H is negligible on something milder like this anyways. Bigger problem for you here is actually fitting one into such a small area and all the "H vs X" goes right out the proverbial window when you're forced to use an H design anyways. Always some kind of trade off and squashing a poorly transitioned/angled X pipe design into tighter chassis's will also hurt potential gains to be had from the X's superior design as well. Plus H's are easier/cheaper to do and it sounds like what your after here is based more on economy than performance. Good luck with it.
Groberts, I think it's fair to say that your response was dismissive of me and my question, and in poor form. To preface something by saying "I mean no offense" doesn't counteract what it is you say. I'm not going sit here and argue with what I effectual consider a trollish answer. You didn't need to chime-in in the first place if you feel that asking questions on this forum is essentially worthless. Anyone else's input is greatly appreciated. Looks like it's between straight pipe and H pipe.
There is obviously much being lost on intent and in translation of what I was trying to get across. I was rushed in my response and not really into tippy toeing around to worry about peoples "feelings" in a technical discussion of the exhausts inner workings. IMO, information should either be factually based on the reality of the physics involved.. or it's simply not factual information.. however nicely worded it may be. And try and trust my intentions here, because if I was being dismissive I surely wouldn't have devoted about 10 minutes of my time to even try and help answer the original question. Nothing to gain other than the good natured feeling of helping others with things that I too once struggled with myself. Unfortunately, can't read smirks and body language so some mistake text on a forum with some sort of twisted "forum superiority complex". I layed it out on the platter for you, and with gracious intent I might add, simply because I have been helped forward by many great people in my entire car building life. Simply trying to pay it forward, was all. Good luck on the hunt. PS. also IMO, asking about the physical differences between and H and an X.. and then suddenly diluting it to straight vs H?.. tells my engine building brain that you do not care as much about performance as I had originally thought before entering this discussion. Had I realized that early on.. would never have replied and apparently offended anyone in the first place. Again.. good luck with it all.
"Nothing credible"? Hey, if you think you know more than major automotive publications who have performed real-world dyno-testing in a controlled environment, comparing the X-pipe to the H-pipe, then more power to you. Maybe those guys didn't "take the time to study". 99% of the people on this forum are not building state of-the-art race engines. They just want to enjoy driving their car and get better than stock performance (which is easy to do even without a degree Quantum Physics). Some things just don't need to be that complicated.
Well I for one don't pretend to know much more than what I learn on my own (little) or what I care to believe from hanging out with like minded buddies wrenching in the garage. I sometimes think we are a bunch of idiots but we have fun and actually are considerably faster than stock. I enjoy the Quantum Physics and have benefitted from taking the time to understand. It's all good and appreciated....
