Off road exhaust

Discussion in 'Road Racing' started by [email protected], Mar 8, 2014.

  1. Pete@FTR

    [email protected] Active Member Preferred Vendor

    Messages:
    815
    Likes Received:
    13
    Joined:
    Sep 18, 2012
    Location:
    Rocklin, CA
    Actually yeah I would like that haha. Been doing so much nerdy race tech reading lately
     
  2. Burninrock24

    Burninrock24 Active Member

    Messages:
    602
    Likes Received:
    46
    Joined:
    Mar 19, 2013
    Location:
    Minneapolis, MN
    Juicy info:

    "H-pipe technology, which does work, that it does equalize the pulses, but it doesn’t really help the scavenging effect so much because what happens is it will equalize it from side to side from a typical V-type engine, but it doesn’t exactly draw all the gases and force the pulses to work off of one another in the end to really improve exhaust flow. " - Source: http://www.onallcylinders.com/2012/08/14/video-exhaust-x-pipes-vs-h-pipes/

    This one has the x-pipe paired with a 3" catback, so it's not exactly an equal comparison, but at 300rwhp the difference between a 2.5" and 3" is negligible. A motor with that power can't produce the CFM to make a 2.5" a restrictive pipe. Here: http://www.carcraft.com/techarticles/exhaust_system_installation/

    Here is a video of a guy demonstrating the scavenging effect of the X pipe in his garage with an air compressor firing through one bank and showing the suction on the other bank. http://www.youtube.com/watch?v=yMyKv_P80eI

    Then books I own and that you should read! Lots of these are at your local library.

    Practical Gas Fow: Techniques for Low-Budget Performance Tuning by John Dalton http://www.amazon.com/Practical-Gas-Flow-John-Dalton/dp/1855205645

    Chassis Engineering by Herb Adams: http://www.amazon.com/Chassis-Engineering-Building-Performance-Handling/dp/1557880557

    How to Build Horsepower by David Vizard: http://www.amazon.com/David-Vizards-Build-Horsepower-Design/dp/1934709174

    How to Build Max-Performance 4.6 Liter Ford Engines by Sean Hyland: http://www.amazon.com/Build-Max-Performance-4-6-Liter-Ford-Engines/dp/1613250819

    How to Port and Flow Test Cylinder Heads by David Vizard: http://www.amazon.com/David-Vizards-Cylinder-Heads-Design/dp/1934709646

    Then this is literally the best free racing and quick reference suspension tuning guide you could ever want. So great. http://farnorthracing.com/autocross_secrets.html

    There is some really fun stuff we were researching with pipe organ tuning and it's auto applications. Where adjusting pipe length can help promote the fastest exhaust escape velocities at a certain RPM. Based on the frequencies of the cylinder firings and their relation to standing waves in pipe organs. I'll dig up some of that info if you want it!
     
  3. 96blak54

    96blak54 Legend

    Messages:
    7,575
    Likes Received:
    920
    Joined:
    Feb 21, 2011
    Location:
    Ky
    Throw the Sean hyland out because its lame out dated with no real explanation of exhaust scavenging tuning. Throw the David Vizard literature in the trash as he "was" just an opportunist taking advantage of young power hungry money paying minds in pursuit of knowledge that can be learned if they would wrench instead of "watching". Also full length exhaust scavenging is only desired for mid power street drivable torque. But I agree with you 100% on scavenging affects of full length exhaust.....lol. Lets not debate over this...lol
     
  4. Burninrock24

    Burninrock24 Active Member

    Messages:
    602
    Likes Received:
    46
    Joined:
    Mar 19, 2013
    Location:
    Minneapolis, MN
    I wasn't exactly saying all the books are good for explaining exhaust scavenging but just good to have in general. I've found Sean Hylands to be good for references, but yes some info is dated (like SVO parts lol). I still like Vizards, helps to explain good concepts. If you could point to certain sections of his work that is flat out wrong, I'd be more than willing to refute his tech. But for the most part I like his books. He does cover a lot of material that doesn't apply to these cars though.
     
  5. 96blak54

    96blak54 Legend

    Messages:
    7,575
    Likes Received:
    920
    Joined:
    Feb 21, 2011
    Location:
    Ky
    Ive seen a video of a show he did....shake head no no no. The books apparently must be better. ..your not the only one stating that to me. I will check out his work more thoroughly in his books. Maybe the video should have came second.
     
  6. hotmustang95

    hotmustang95 Active Member

    Messages:
    602
    Likes Received:
    2
    Joined:
    Apr 6, 2011
    Location:
    Boynton Beach FL
  7. wmfateam

    wmfateam Active Member

    Messages:
    725
    Likes Received:
    4
    Joined:
    Aug 23, 2013
    Location:
    Gilbert, AZ
  8. ElrodKTPQ_89

    ElrodKTPQ_89 Legend

    Messages:
    5,068
    Likes Received:
    127
    Joined:
    Aug 6, 2013
    Location:
    Crossett, AR
  9. B.mad

    B.mad Well-Known Member Preferred Vendor

    Messages:
    2,003
    Likes Received:
    5
    Joined:
    Mar 9, 2014
    Location:
    SoCal
    The difference in the mid pipes isnt much horsepower wise, what a couple of HP? you wont feel it. Go by what sounds better, thats what i did. But i have my exhaust going out the back. But one thing i would do regardless of exhaust is have it ceramic coated. not only does it look very very nice, it also helps with the scavenging. Same concept with the ceramic coated headers being better than non coated.
     
  10. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

    Messages:
    3,409
    Likes Received:
    22
    Joined:
    Jul 4, 2011
    Location:
    Orlando
    This really isn't necessary. Go look at the kits from Factory Five for the MkIV and Type 65 Coupes. 302 Ford V8's, independent exhausts - meaning no X/H pipe. Those cars run balls to the wall. I suspect the X/H pipe is probably more for efficiency (EPA) and/or to quiet things down.
     
  11. B.mad

    B.mad Well-Known Member Preferred Vendor

    Messages:
    2,003
    Likes Received:
    5
    Joined:
    Mar 9, 2014
    Location:
    SoCal

    yes you are right it is for EPA and quieter exhaust. And as far as running true duals vs crossover, it really depends on the who you ask. Drag cars run "true duals" and they go "balls to the walls", but they also have high horsepower applications, launch at 6000 RPM, and have a really high (numerically) gear ratio. For a street car, a crossover is a better benefit because itll give you back pressure and give you low end.

    The way i was told

    open headers=low end sacrifice for high end power
    crossover= low end power for high end sacrifice
    straight duals= i am thinking a combo of the both.
     
  12. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

    Messages:
    3,409
    Likes Received:
    22
    Joined:
    Jul 4, 2011
    Location:
    Orlando
    I hear you man. But I'm also saying there are a lot of guys running those Cobra kit cars on the street with everything from stock 302's to highly modified 302's - all with "true duals."

    So while your assessment above may be correct, I think on these cars it's probably not that noticeable. If you are talking about shorties vs long tubes, okay that makes more of an impact on low torque vs high rpm hp. And if you are talking about a single turbo, then a crossover is obviously required. But as far as the H/X pipe cross-over, so far downstream, I'm not sure it really makes a difference. I don't know from personal experience though, so I could be wrong.
     
  13. hotmustang95

    hotmustang95 Active Member

    Messages:
    602
    Likes Received:
    2
    Joined:
    Apr 6, 2011
    Location:
    Boynton Beach FL
    I'll just paste it here from another site I posted it on.


    I've always wanted to have that race car side exhaust on my car. I once thought about getting boom tubes, the ones Nascars use that are square. Problem was my full length subframe connectors would push that pipe down even further to the ground and would not look right. It needed to be tight up against the body. Other option would be to run it up inside the car. Lot of work and planning involved in that so it never got done, until today.

    I thought about it for months on how it should look and so I bought pieces here and there. The hardest part is doing all this in my driveway. Even though this was months of planning it took me about 24 hours of work to finish. I decided to run both exhaust pipes that are 2.5" into one 3.5". This would result in less time and money. Also remember this is a straight through type of system. The mufflers are Magnaflow race units that have no baffles. Pretty much straight pipes so there is no concern about restrictions. All the turns in the system were done with 90 degree mandrel bent pipe that I chopped up in any way I needed.

    The plate on the outside of the car is polished SS. The exhaust tip is also polished SS. The plate is held in place with SS rivets. I must mention that most of the system is welded together but I did set it up in a way that it can be taken apart easily for service to it or the car.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  14. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

    Messages:
    3,409
    Likes Received:
    22
    Joined:
    Jul 4, 2011
    Location:
    Orlando
    That's pretty sweet dude :) Good work.

    Edit: more work, and would cost more in parts, but thought I should mention it: if others want a side exit on each side, they could run smaller pipe up on each side and then turn it out right in front of the wheels, rather than "Y"-ing it into one pipe. I like what you did here.
     
  15. ElrodKTPQ_89

    ElrodKTPQ_89 Legend

    Messages:
    5,068
    Likes Received:
    127
    Joined:
    Aug 6, 2013
    Location:
    Crossett, AR
    That looks awesome man! Gotta love how those Magnapacks sound too!
     
  16. B.mad

    B.mad Well-Known Member Preferred Vendor

    Messages:
    2,003
    Likes Received:
    5
    Joined:
    Mar 9, 2014
    Location:
    SoCal

    Ya i agree, but that was just my take on it. Again i have no experience, and i know that when mufflers are dumped under the seats, there is obviously no cross over (which is similiar to the side exhaust), but again i have no experience, we both might be right..or wrong?? lol