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Exhaust sizes for L20?


phatdave

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I'm thinking seriously about doing my own exhaust...even though Mike Klotz pretty much tells me I will kill myself with bending ,standing,stooping.... :D

 

Thanks Mike........But if I go ahead with it, what would be optimal size from my header to my big ass RACTIVE ss muffler? The collector on the header is 2 1/2". Muffler shops say I will lose some bottom end torque and gain hiway efficency(sp).

 

I'm thinking 2" would probably be OKAY!?

 

Any input here?

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Mike , my Canuck brother.....I have a stainless RACTIVE brand muffler, that is Huge. 2 1/2 " inlet with a end pipe on it.

 

I have a buddy with a Geo Metro with a straight pipe and no muffler. We put the Ractive on it and it sounded SWEET. I am going with it. It is like 36" inches long and has a diameter of probably 10" . HUGE.

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Mike , my Canuck brother.....I have a stainless RACTIVE brand muffler, that is Huge. 2 1/2 " inlet with a end pipe on it.

 

I have a buddy with a Geo Metro with a straight pipe and no muffler. We put the Ractive on it and it sounded SWEET. I am going with it. It is like 36" inches long and has a diameter of probably 10" . HUGE.

 

o00000000oh super Dave!

 

Back pressure issues aside, a larger diameter pipe has a larger surface area. A larger area will radiate heat and cool the exhaust gasses. A cooler exhaust gas will take up less room. A cooler gas is under less pressure to expand so any restriction has less effect on it. Ideally the muffler should be as far to the rear as possible to allow the exhaust to cool and shrink before entering it.

 

A muffler attached to the manifold with a long pipe to the rear would be much more restrictive than the same pipe with the muffler at the very back end.

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On my Ratsun I was given a Super44 FlowMaster with 2.5" inlet and outlet and ran 2.5" exhaust the hole way off of stock manifold. Sounded killer! Best sounding vehicle I have owned. Ran even better! Did not notice any low-end losss:fu: Maybe a little too loud 4 an old guy like you tho:D:lol::eek::blink:

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Mike....I have...as you probably know....have a header, and the Ractive I talked about.

 

 

So there will be a fairly straight run of exhaust pipe teminating at the back of the truck with the Ractive Muff. I said Muff:D

 

So what is your take on pipe? 2 1/2 to big? I guess I will lose stop light to stop light toque, but I'm not out to race it, just get to work and maybe to the yearly Datsun get-to-gethers.

 

I would rather have hiway power and it seems that bigger pipe would do that.

 

 

I'm sure ther is some math formula that could be used ,but math makes my head hurt. I would rather go on conventional wisdom, if there is indeed such a thing as that here on Ratsun.

 

When I get it running I will take a road trip to the great white north and say hey...and of course have some puotine and a molson.....later my Canuck buddy.

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I have a 2" with an L20b on one 'goon and a 2.5" with a Z22e on the other 'goon. Both have resonators and mufflers attached. The 2" is about as loud and as big as I'd want to go with a L20b. The 2.5" is too big for the Z22e, a 2.25" would work better and be quieter, but, probably no better than a 2". Gotta wear earplugs for anything over a 15 minute drive or I get a huge headache.

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just do like i do and run a 2.5" down pipe off the end of the header an call it good... hahaha, no but really i reccomend a flex pipe, i broke my exhaust pipe like 4-5 inchs from the back of the header.. :( i think what they did was a little dog leg with 2.5 to 2.25 to 2" every few inchs kinda like a cone type thing .. guess they had to doit to easily work to a 2" instead of goin from 2.5 to 2.. an ya i got 2" from there back.. an a "Turbo" muffler.. some cheap crap thing makes my truck all quiet.. sounds decent tho

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that a tube bender swages the pipe diameter down when it makes bends - the effective diameter of the pipe through the bend area will be at least 1/4" smaller than the pipe before bending, so a straight 2.25" pipe will be reduced to 2" or smaller through the bend area.

 

The only way to avoid the reduction in size is to weld the whole system up from mandrel-bent bends in the same size as the main sections of straight tubing............

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On my Ratsun I was given a Super44 FlowMaster with 2.5" inlet and outlet and ran 2.5" exhaust the hole way off of stock manifold. Sounded killer! Best sounding vehicle I have owned. Ran even better! Did not notice any low-end losss:fu: Maybe a little too loud 4 an old guy like you tho:D:lol::eek::blink:

 

 

To loud for an old guy like me? DOUG Iv'e been a rock and roll guitar player for years. I can hardly even hear anymore....I can however hear when some 30 Y.O. broad whispers in my ear " Yours is BIGGER than DatDougs...his is kinda tiney." :fu:

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