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Custom Exhaust

Discussion in 'Performance' started by Dj1house, Jan 17, 2021.

  1. Dj1house

    Dj1house New Member

    I was playing around with the idea of taking my Sambar to an exhaust shop to have a full custom exhaust done. I have a few questions though. Since I have a KT6 with the EK23 2 cylinder, what diameter exhaust should it be? 2"? 2.5"? I assume it needs to have an expansion chamber like the stock one has, correct? Any advice is welcome.
     
  2. SDK1968

    SDK1968 Active Member

    not sure about that engine vs my K6A....

    but i ran 2" from the flange right behind the O2 sensor all the way out the back. it made a huge difference in how it ran.

    it is a little bit louder though. sounds like a side x side now.
     
  3. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    For a naturally aspirated engine, there is an equation to size the exhaust tubing based on the exhaust valve diameter and the max rpm the engine will run at. The exhaust tubing acts as a ram, and increases the actual airflow through the engine. Too large of tubing and you loose the ram effect, decreasing the scavenge, and hurting torque.

    On a supercharged or turbocharged engine, the exhaust need to be as large as possible to reduce back pressure, which will increase the scavenge.

    On my naturally aspirated Hijet, I am planning 1-1/4-inch tubing from the manifold back, and installing a tuneable exhaust tip, from SuperTrapp. Upside of that is that the SuperTrapp is a spark arrestor when I’m off road.
     
    Limestone likes this.
  4. Dj1house

    Dj1house New Member

    My EK23 is a N/A engine, so I'll try to work out what size I need for the exhaust. I was thinking about trying to get equal length headers to optimize the scavenging. But in the case of that big drum expansion chamber (if that's what it even is, I'm thinking in terms of 2 stroke here) can I just get rid of it? I wanted to remove the cat and just make it headers through to a muffler, but I don't know about that bug drum. Trying to free up some ponies here.
     
  5. Dj1house

    Dj1house New Member

    Looks like yours is a 660cc whereas mine is a 550, so 2" is probably too big for my little 2 cylinder. But you didn't change the exhaust manifold? And you're running no muffler?
     
  6. SDK1968

    SDK1968 Active Member

    If you are talking to me & not Jigs?

    correct. 2" straight pipe, no muffler... but i still ran it all the way to the back bumper. no worries about burning a valve or starting a fire.
     
  7. Dj1house

    Dj1house New Member

    I just took the Sambar to a reputable exhaust shop, said they could handle it. They said that they would be using 2" stainless from the manifold back and taking out the cat/muffler thing. I'm worried about it if the carburetor will have to then be tuned? And also there's 2 pipes running to the cat that would need to be addressed, one tube that runs to the air intake and one that is some sort emissions pipe. Not sure how the truck is going to perform after the modifications...
     
  8. SDK1968

    SDK1968 Active Member

    i didnt have a carb model on the exhaust change.... there were ZERO negatives on mine. EVERYTHING was better. low end, midrange, high end all good on torque(feel) all good on power.

    top end speed went up about 10kmh too. on my Zuki: it can breath in & now it can breath out.


    oh the only drawback is its a little louder.
     
  9. AeaRy

    AeaRy New Member

    I pulled off the manifold; welded 1-7/8 tubing directly to it and then used a motorcycle resonator/muffler welded to the tubing. Tip is right where the OE exhaust was (but facing out instead of back). It has definitely freed up some of the low-end torque and I have no problems getting her up to 60mph in a reasonable time now. This was after testing with straight piping which took away some of the upper end and was just flat out raucous.

    249858705_10158872312100939_3138253538444173682_n.jpeg
     
    Limestone likes this.
  10. SDK1968

    SDK1968 Active Member

    oh wow!! that is super short & actually looks pretty cool.

    mine is still ran all the way out the back.... might try something like this after the resonator rusts thru..
     
  11. AeaRy

    AeaRy New Member

    Thanks! To cover my crappy welding I always use VHT FlameProof satin black...doesn't look horrendous. Will eventually have to fab something new up though (after EFI conversion) to allow for a tiny-turbo setup
     
  12. Limestone

    Limestone Well-Known Member

    It does look good!
    I was wondering if it was far enough back to keep as much heat away from the Engine,
    so as not to cause Excessive Heat issues!
    Not trying to be a Debbie Downer,
    I like it!
    Limestone
     
  13. AeaRy

    AeaRy New Member

    Thanks Limestone. I drove her around (not timidly) for about 3 hours today and took a infrared thermometer to the "carbon fiber" shell of the exhaust and only registered around 150F (ambient temperature today was 80F). I don't think there is much of a heat issue with a motorcycle style exhaust like this one where 1) the actual outlets are angled down and out and 2) since they are designed to essentially run next to the motor in a free air environment as is. With the amount of compartment space freed up losing the OE muffler (as you can see), there is tons of room around the canister for airflow and natural cooling.
     
  14. Limestone

    Limestone Well-Known Member

    AeaRy,
    I like everything about it!
    Great Job!

    A lot of times I'll play "Devil's Advocate", if you will, and ask Questions,
    not only to educate myself, but Mainly for future reference, and others, to learn from,
    and many times asking for some who might view, but won't ask!

    These are great references for others down the road!
    Limestone
     
  15. AeaRy

    AeaRy New Member

    Of course! Working on the interior currently until some parts from yohohamamotors get delivered
     

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