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Thread: Need exhaust manifolds

  1. #11
    Registered Member Chevy Chase's Avatar
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    Dave, Thanks for the recommendation. I like the description of them and the reviews. I will give them a try.

  2. #12
    Registered Member enigma57's Avatar
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    I like your exhaust sizing chart better than the one I have, Chevy Chase! Seems more plausible regarding pipe sizing in the 2.0" - 2-1/4" - 2-1/2" range based on my past experience. The pipe sizing you stated should work well for you. The exhaust gas will have cooled a bit by that point and 2-1/4" tailpipes should do the job.

    I was a pipefitter in a former life, so I look at designing a pipe system from a standpoint of flow versus friction losses in turns and offsets. Just make sure the inner core of your mufflers is a full 2-1/2" sizing and you should be fine. Even if you need to run 2-1/2" inlet and outlet and transition to 2-1/4" using a reducer fitting at the discharge end of your mufflers. I like the DynoMax Super Turbo muffler on the street because they flow better than other designs such as Flowmasters and are much quieter than Flowmasters. If you run a full sized H-type crossover (balance) pipe as well...... That will boost torque and quieten / smooth out the exhaust note a bit, as well.

    Regarding pipe sizing...... If you are running a modern overdrive transmission with lockup converter and rear gearing that pulls engine speed down to around 2,000 RPMs when cruising at 70 MPH...... Thinking of it from 'the engine is an air pump' perspective...... You probably won't need as large an exhaust system as the same size engine would if it were geared lower and spinning faster (and pumping a greater volume through the exhaust system).

    On the other hand, a larger system doesn't hurt anything and I have run a 2-1/2" single exhaust system and turbo muffler behind an otherwse stock 170 cu. in. '62 Dodge slant 6 engine and it ran great once uncorked (original system was only 1-3/4" diameter on those cars). My original exhaust manifold was cracked and I went to the wrecking yard and found one of the 225 manifolds with 2-1/4" outlet that MOPAR used in the early '70s to boost mileage during the 2nd Arab oil embargo. 2-1/2" exhaust tubing slips nicely over 2-1/4" so I kept about 3" of the 400 series stainless steel MOPAR exhaust stub when I pulled the manifold and had a muffler shop bend a 2-1/2" system for the car. Just slipped the new 2-1/2" tubing over the 2-1/4" stub about an inch and welded it on.

    Also ran a 2-1/4" single exhaust on a little 1600cc Toyota hemi 4-banger I souped up in the early '80s. Again, ran great. Not overly loud, nice exhaust note when I got down on it and no issues with excess back pressure even if I spun it up past 6,000 RPMs going through the gears (which I did quite often in those days).

    I was going to run that size system on my '57 (2-1/2" dual head pipes and 2-1/4" tailpipes) when I drop in the warmed over 292 inline 6 but as I have no tube benders here at home, I decided to scarf up some pre-bent tubing sections off e-bay and cut / fit / weld them to form my exhaust system. Found a really good deal on mandrel bent 2-1/2" tailpipes from Flowmaster, so will go ahead and use them even though 2-1/4" would 'just' do the job. Managed to snag some chambered exhaust intended for 'Vette side pipes so decided to cut the ends off on either side of the straight chambered sections and work them into the exhaust system under my '57 rather than run regular mufflers. If it turns out to be too loud, I'll add some resonators if need be. Or some deadhead J-pipe Helmholtz chambers (closed nodes).

    Regarding donut gaskets...... In the '70s I would pick up the 2" Ford versions (I believe they were for early to mid-'60s Ford FE (352 or 390) engines. These really were one of Ford's 'better ideas'. Unlike the standard asbestos (in those days) or graphite (now of days) donut gaskets...... Ford made theirs from a soft metal. And once you torqued them down, they wouldn't leak and they would last longer than the exhaust system. I don't know what soft metal they used, but it was a dark gray colour and reminded me of a soft babbit material. Worked great on 2" Chevy ramshorn manifolds. But Ford never made them in a larger size for 2-1/2" donuts, so had to use what was available when stepping up to 2-1/2" ramshorns or for Chevy big block applications. If I had the stuff here to do it, I'd make some 2-1/2" donut gaskets from either a soft babbit or deadsoft copper for 2-1/2" donuts and they'd last practically forever.

    Happy Motoring,

    Harry
    'G-d Bless The U.S.A.'...... Lee Greenwood......

    http://www.youtube.com/watch?v=U_5aoptI5j0

    Staff Sergeant Roy Benavidez......

    https://www.youtube.com/watch?v=i3nncd4sxaM&t=466s

  3. #13
    Registered Member enigma57's Avatar
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    Quote Originally Posted by Dave the Wave View Post
    look into "remflex", i swear by them.
    Remflex is a good brand, Dave. I will be running their #2034 one-piece intake / exhaust gasket on the 292 inline 6 I'm building for my '57 sedan.

    Happy Motoring,

    Harry
    'G-d Bless The U.S.A.'...... Lee Greenwood......

    http://www.youtube.com/watch?v=U_5aoptI5j0

    Staff Sergeant Roy Benavidez......

    https://www.youtube.com/watch?v=i3nncd4sxaM&t=466s

  4. #14
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    there`s a happy medium to be found for exhaust gas flow. an old timer, a few years back told me, to small diameter will cause to much back pressure, less flow, as we all know. however, he said to big will cause the gasses to just move to slow, therefor the pipe actually sucks up the heat of the exhaust, actually slowing down the exiting gases. don`t hold me to it, but i read about sizing somewhere a few years back. I THINK it was on flow master`s site.

  5. #15
    Registered Member BamaNomad's Avatar
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    The smaller the exhaust pipes, the faster the exhaust gas has to flow thru the pipes, and vice versa! If your pipes are too large, the exhaust doesn't do the 'scavenging' action that is desired and you will lose torque! Larger pipes are good for HIGH RPM HORSEPOWER, but pipes on the smaller side are good for low rpm TORQUE. Obviuosly the actual diameters desired are a function of several variables, including CID, expected rpm of operation, etc... Personally if I'm installing headers, I like to keep the primary diameters on the lower side (1-5/8" for small blocks), maybe a bit larger (1-3/4?) for big blocks, although I don't drive big blocks! As the exhaust cools between leaving the engine and exiting out the tail pipes the exhaust gases cool and compress a little requiring smaller tubes for exit.

  6. #16
    Registered Member busterwivell's Avatar
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    I didn't see this posting earlier, or I'd have posted my experience. I bought the Sanderson block huggers early on. When it came time to install on my 350, I couldn't clear my 605 box. Speedway 2 and a half ram's horns did. Been on for 15K miles so far without a problem.

  7. #17
    Registered Member Chevy Chase's Avatar
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    Quote Originally Posted by busterwivell View Post
    I didn't see this posting earlier, or I'd have posted my experience. I bought the Sanderson block huggers early on. When it came time to install on my 350, I couldn't clear my 605 box. Speedway 2 and a half ram's horns did. Been on for 15K miles so far without a problem.
    Does your engine have original-style front engine mounts or aftermarket side mounts? Also, are the rams horns both center dump? The previous owner of my 57 installed a driver's side engine mount and used the original front engine mounts. My guess as to why there is no side engine mount on the passenger side is the headers would not clear it. The PO also installed a cross member for the TH350.

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