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Thread: Half Exhuast

  1. #1
    Registered User red_dog007's Avatar
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    Default Half Exhuast

    Ok, so I am thinking 3.2.1 exhaust. Not really sure if I should do 6.1 exhaust.


    Though this is my idea.
    Buy the manifold and then have a custom pipe made. What I was thinking was having the exhaust cut of shortly after the transmission and have it point downwards. Somewhere between the end of the exhaust and manifold put in a cherry bomb or something to help with noise. Or even a slim jim muffler.


    Now, my concern is would this be too loud? I want quiet when around town with maybe a little throaty noise, but when I get on it I want it to sound good and loud, but not Honda loud.

    Then my second concern is if I have the exhaust cut off after the transmission pointing downwardish, am I going to have to worry about catching the road on fire or anything? I wouldn't have the end at a 90 degree angle, maybe something more like 45 to 60 degrees so exhaust won't be blowing directly on the street.

    *Held for my future Datsun*
    1997 Buick LeSabre 122,000 miles (My DD)
    2003 Mitsubishi Outlander 90,000 miles (Wife's DD)

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    Crumudgeon
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    Default

    What I was thinking was having the exhaust cut of shortly after the transmission and have it point downwards. Somewhere between the end of the exhaust and manifold put in a cherry bomb or something to help with noise.
    Dumb idea. it will be loud and stinky inside the car. I've had racers ask me to build exhausts just like this and every one has come back and at least had me run the exhaust out the back of the car or to the side just in front of the rear wheel.

  3. #3
    Registered User Oiluj's Avatar
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    On my 1972 240Z, the previous owner put a 2-1/2" single exhaust with a small, (10" long, 3" dia), cherry-bomb style resonator midway back. At the tail end it has an open split over/under angled tip at the back. (no muffler).

    The car sounded like a race car, but was unpleasantly load and attracted lots of attention. The first thing I plan to do when I get the car back together is to change the exhaust before a cop hears it and gives me a ticket!
    Julio
    1972 240Z (in-progress, 95% complete)
    CZC# 15388

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    Registered User red_dog007's Avatar
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    Yeah, that is what I figured. Would be too loud and stink up the cabin.


    Guess I will get full exhaust. Need to find some exhaust clips of the 3.2.1 and the 6.1 to see which I like better.

    *Held for my future Datsun*
    1997 Buick LeSabre 122,000 miles (My DD)
    2003 Mitsubishi Outlander 90,000 miles (Wife's DD)

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    Default

    FWIW, on my '83, I have a 3.2.1 header stock to the CAT, then just pipe out to the rear of the car. Didn't plan it that way, but when the old muffler tore off after getting caught on a curb (don't ask) I just added a strraight piece of exhaust pipe until such time as I replace the muffler.

    Im now having second thoughts about replacing the muffler at all. As it is now, at idle and low rpms, it sounds throaty, but not loud or harsh, and under hard acceleration it sounds ferrari-like, especially at the upper rpms. No bark, no resonance. When the time comes I think I'll run one piece of custom-bent stainless form the CAT back.
    1972 240Z Resto almost finished
    1983 280ZX This winter's project

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    Biafra for President e_racer1999's Avatar
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    I have some vid clips of my 6-1 with no exhaust. Youtube user corndogbatter
    Jason King
    6/72 240Z / HLS30 89646 (Yellow)
    1996 Infiniti I30 *I finally have all Nissans again!*
    1971 510 4door (wife's car)
    IZCC Member #14186

    Quote Originally Posted by xray View Post
    As unfortunate as it may be, if you want to vintage race, go Euro....If you want to race for real, stick with the Z!

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    Registered User red_dog007's Avatar
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    So you have the 6-1 manifold and that is it? Nothing else on the exhaust? That sounds freaking awesome! That is what I want right there! Maybe a touch quieter.

    Stock my engine sounds like that but much quieter. Maybe I will just get a manifold, and then get a shop to fit me up a pipe. If I fell like I need a muffler, I can just always go back to get one put on.

    *Held for my future Datsun*
    1997 Buick LeSabre 122,000 miles (My DD)
    2003 Mitsubishi Outlander 90,000 miles (Wife's DD)

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    Registered User FHPTOM's Avatar
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    I definitely agree with John Coffey. I had another racer talk me into cutting my exhaust back to the transmission for extra HP and save weight.

    It is really too loud which makes it hard to hear what the rest of the car is doing on the track.

    Now I need to get it redone taking it back out to the rear. $100 - $150 that could be spent elsewhere.

    Tom
    11/1974 260Z RLS30-066841
    Restored then gutted to race....

  9. #9
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    Quote Originally Posted by e_racer1999 View Post
    I have some vid clips of my 6-1 with no exhaust. Youtube user corndogbatter
    Jason, I noticed the safety shut off switch is working. Won't it shut off with the ignition switch?
    That's OK if you like it loud, but your neighbors might appreciate a token pre-muffler to cancel out some of the resonance. Guess it depends, how you plan to use the car and the tolerance level of the local constabulary.
    Last edited by geezer; 08-12-2008 at 04:11 PM.

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    Default

    I ran my Z with only the resonator on it for a few days for testing. under cruise it was really mellow. not too loud, and very deep, but step on the gas and it really opened up. I really didn't get exhaust fumes too badly, but maybe I've somehow been desensitized to them.
    Owner of:
    1978 280z HLS30-465974
    Current Progress:Tweaking, tuning, planning, waiting

  11. #11
    Registered User Walter Moore's Avatar
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    Quote Originally Posted by peterc View Post
    FWIW, on my '83, I have a 3.2.1 header stock to the CAT, then just pipe out to the rear of the car. Didn't plan it that way, but when the old muffler tore off after getting caught on a curb (don't ask) I just added a strraight piece of exhaust pipe until such time as I replace the muffler.

    Im now having second thoughts about replacing the muffler at all. As it is now, at idle and low rpms, it sounds throaty, but not loud or harsh, and under hard acceleration it sounds ferrari-like, especially at the upper rpms. No bark, no resonance. When the time comes I think I'll run one piece of custom-bent stainless form the CAT back.
    Actually, I have had several older GM products where the exhaust fell off just after the converter, and in most cases I was able to just drive them that way for years. The older converters did a pretty good job of silencing the exhaust noise without a muffler. Some newer converters however will be objectionably loud without a muffler. (The car companies must have made them less restrictive over the years...)

    But in my opinion you still need enough pipe to get the exhaust behind the passenger compartment, which on a Z means out the back.
    '71 240Z, Because any fool can drive fast in a straight line.

  12. #12
    Biafra for President e_racer1999's Avatar
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    Quote Originally Posted by geezer View Post
    Jason, I noticed the safety shut off switch is working. Won't it shut off with the ignition switch?
    That's OK if you like it loud, but your neighbors might appreciate a token pre-muffler to cancel out some of the resonance. Guess it depends, how you plan to use the car and the tolerance level of the local constabulary.
    Well, that was the first time staring it after 12 months of not running. I had relocated the batt to the back and did the IR alternator conversion. Messed up with the diode so it didn't shut off, hence the cutoff switch.

    I only ran it for a day without the full exhaust system (MSA 2.5" aluminized). The exhaust system through and through is the tits (6-1 w/ MSA 2.5")
    Jason King
    6/72 240Z / HLS30 89646 (Yellow)
    1996 Infiniti I30 *I finally have all Nissans again!*
    1971 510 4door (wife's car)
    IZCC Member #14186

    Quote Originally Posted by xray View Post
    As unfortunate as it may be, if you want to vintage race, go Euro....If you want to race for real, stick with the Z!

  13. #13
    Go Fast, Don't Crash 280~Master's Avatar
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    My ideal exhaust would be 6-1 header or an early series 1 exhaust manifold with 2 1/2 pipe on a turbo muffler. I would place an automatic cut-out just behind or equal with the tranny for those times I need the extra HP and sound. As of right now I have a stock exhaust manifold with 1 1/2 pipe and no muffler. Its loud at idle and crazy loud when getting on it. My 76 is labeled a non-catalytic car.
    John Thomas Bertrand
    Model: HLS30 STD CPE 2DR
    Color: 305 LIGHT BLUE
    Serial: HLS30-298085
    Engine: L28-081399
    Port of Entry: 34 JACKSONVILLE
    Method of Transport: TRUCK
    Dealer to whom delivered:
    Brown Datsun INC
    213 E Liberty ST
    Lyons, GA 30436


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