Lotus Elan

Exhaust Sizing

PostPost by: Tmac897 » Sun May 19, 2024 6:22 pm

If I ever do get this engine running, I’m going to need an exhaust system. My engine is .040 over, with a hotter street cam. Although this is a new head, valve train, and cams, it’s still intended to be a street car, so I doubt I’m going to be revving the engine over the standard 6500; but I sized it at 7000 RPMs using one of the online calculators. (Actually a couple of them). The projected size of the pipe is 1.6 inches, so less than the standard 1 5/8” exhaust. The headers I have are 1 1/4” and the 2x1 collector is 1 5/8”.

Is there still benefit in considering a 2” exhaust, or would that be overkill?

Tony
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PostPost by: bitsobrits » Sun May 19, 2024 7:30 pm

Tony,

I would vote that 2" is serious overkill for a "warmed over" street engine. 1 3/4" would be the max size I would consider for your application. I run a 1720cc TC with fully ported head and high lift/short duration cams, and race spec header and have a 2" center pipe and muffler. And I really don't think the 2" is necessary for even my set up.
Steve

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Elan S3 1967 FHC pre airflow

Formerly:
Elan S1 1964
Elan S3 1966 FHC pre airflow
Elan S3 1967 FHC airflow
Elan S4 1969 FHC
Europa S2 1970
Esprit S2 1979
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PostPost by: h20hamelan » Sun May 19, 2024 10:09 pm

the problem in N.A. is pipes, and muffler supply
there really is not anything below 2 inch

if you find something, let us know please.
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PostPost by: gjz30075 » Sun May 19, 2024 10:58 pm

bitsobrits wrote:Tony,

I would vote that 2" is serious overkill for a "warmed over" street engine. 1 3/4" would be the max size I would consider for your application. I run a 1720cc TC with fully ported head and high lift/short duration cams, and race spec header and have a 2" center pipe and muffler. And I really don't think the 2" is necessary for even my set up.


This is my setup also and you're probably right but it sure sounds good.
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PostPost by: Lotus54 » Mon May 20, 2024 4:10 am

I bought this Stainless for mine- worked well. Except I measured from existing head pipes- and the replacement I got was a bit shorter. So I had to weld on a few inches. Getting it just a bit longer would be better.
I also had to cut and angle and weld to give the proper routing.

https://www.summitracing.com/parts/STW-1-6SS-5


(I also welded on an O2 sensor bung, and have an A/F meter in the car. Sure makes setting Webers a LOT easier).
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PostPost by: Tmac897 » Mon May 20, 2024 11:34 am

Lotus54 wrote:I bought this Stainless for mine- worked well. Except I measured from existing head pipes- and the replacement I got was a bit shorter. So I had to weld on a few inches. Getting it just a bit longer would be better.
I also had to cut and angle and weld to give the proper routing.

https://www.summitracing.com/parts/STW-1-6SS-5


(I also welded on an O2 sensor bung, and have an A/F meter in the car. Sure makes setting Webers a LOT easier).


Thanks for the info!
Tony
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