Better exhaust for 90 gtz

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90_Black_GTZ
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Better exhaust for 90 gtz

Postby 90_Black_GTZ » Wed Feb 13, 2002 2:24 pm

I'm looking to maybe improve my exhaust on my 90 GTZ, but I'm not sure of my options.  The part numbers and systems that are suggested on the main page seem to not be there.  Can I get some up-to-date suggestions from people?  Maybe even suggestions on how to get it done, like could I do it in stages?  Cost at each stage?  

TIA


90 Black GTZ (I am the original owner since May 5, 1990)
187,000 miles

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Better exhaust for 90 gtz

Postby Guest » Wed Feb 13, 2002 2:44 pm

At Meineke, I paid $300 for 2.25" catback with a new cat.  With complete downpipe, it'd probably be $400 total.



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rweatherford
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Better exhaust for 90 gtz

Postby rweatherford » Thu Feb 14, 2002 8:15 am

Quote (Dante93GTZ @ Feb. 13 2002,2:44)
At Meineke, I paid $300 for 2.25" catback with a new cat.  With complete downpipe, it'd probably be $400 total.

Dante are you still running the stock 93 HO exhaust manifold and downpipe?


Rex Weatherford
92 Beretta GTZ Quad4 Turbo / 5-speed (sold)
Best 1/4 ET =  13.523 @ 105.16 mph

07 Mazda 5 Black on Black (it's slow)


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90BerettaGTZ
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Better exhaust for 90 gtz

Postby 90BerettaGTZ » Thu Feb 14, 2002 9:19 am

2.25 bah!

go 2.5" or youre wasting you time and money. dont worry about loss of torque down low. you dont lose any. actually get an increase near 3,000 rpm. again..go 2.5". theres no negative impact plus you have room later on to modify further.



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90_Black_GTZ
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Better exhaust for 90 gtz

Postby 90_Black_GTZ » Thu Feb 14, 2002 3:31 pm

Stock muffler from Meineke ?

Also, what kind of gains did you see from the cat back mod?


90 Black GTZ (I am the original owner since May 5, 1990)
187,000 miles

Guest

Better exhaust for 90 gtz

Postby Guest » Sat Feb 16, 2002 3:28 pm

Go with a full mandrel bent 2 1/4 in exhaust w/ a dynomax ultra flow muffler this should be your best bet for performance.



Guest

Better exhaust for 90 gtz

Postby Guest » Sat Feb 16, 2002 9:35 pm

Quote (rweatherford @ Feb. 13 2002,09:15)
Quote (Dante93GTZ @ Feb. 13 2002,2:44)
At Meineke, I paid $300 for 2.25" catback with a new cat.  With complete downpipe, it'd probably be $400 total.

Dante are you still running the stock 93 HO exhaust manifold and downpipe?

Nope - A ported 91-92 manifold with 2.5" downpipe... ;)



Guest

Better exhaust for 90 gtz

Postby Guest » Sat Feb 16, 2002 9:36 pm

Quote (90_Black_GTZ @ Feb. 13 2002,4:31)
Stock muffler from Meineke ?

Also, what kind of gains did you see from the cat back mod?

Meineke just reattached my stock muffler to the new piping...

I noticed a lot better sound and high rpm acceleration.



Guest

Better exhaust for 90 gtz

Postby Guest » Sun Feb 17, 2002 12:06 pm

Quote (LJones @ Feb. 16 2002,3:28)
Go with a full mandrel bent 2 1/4 in exhaust w/ a dynomax ultra flow muffler this should be your best bet for performance.

I concur 100%, although just about any straight thorugh muffler will work well.......and for those of you who want a little less noise, you can get a perforated core glass pack like a thrush or cherry bomb, and put that in upstream as a resonator. 2.5in exhaust piping is really not necessary unless you have headwork, cams etc., AND a throttle body that is larger than the stock 56-57mm. Remember.........if the engine is only breathing in through 60mm or less, then there is NO reason to go larger on the exhaust size (2.5in = 63.5mm).



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Better exhaust for 90 gtz

Postby Guest » Sun Feb 17, 2002 12:53 pm

Quote (BIGBULS @ Feb. 17 2002,12:06)
Remember.........if the engine is only breathing in through 60mm or less, then there is NO reason to go larger on the exhaust size (2.5in = 63.5mm).

I don't know about that... there's not just the air from the intake going through the exhaust pipes, there's also hydrocarbons from the combusted fuel

opening up the exhaust more than the intake can have benefits.  it depends on the particular engine because there are a lot of factors involved.



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rweatherford
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Better exhaust for 90 gtz

Postby rweatherford » Sun Feb 17, 2002 9:28 pm

Quote (BIGBULS @ Feb. 17 2002,12:06)
Quote (LJones @ Feb. 16 2002,3:28)
Go with a full mandrel bent 2 1/4 in exhaust w/ a dynomax ultra flow muffler this should be your best bet for performance.

I concur 100%, although just about any straight thorugh muffler will work well.......and for those of you who want a little less noise, you can get a perforated core glass pack like a thrush or cherry bomb, and put that in upstream as a resonator. 2.5in exhaust piping is really not necessary unless you have headwork, cams etc., AND a throttle body that is larger than the stock 56-57mm. Remember.........if the engine is only breathing in through 60mm or less, then there is NO reason to go larger on the exhaust size (2.5in = 63.5mm).

Don't forget the little temperature change....  which changes volume.

If I did my quick and dirty PVNRT calculation correctly when the air goes in it expands 3 times it's volume when it comes out...

Probably good idea to have a little larger exhaust.


Rex Weatherford
92 Beretta GTZ Quad4 Turbo / 5-speed (sold)
Best 1/4 ET =  13.523 @ 105.16 mph

07 Mazda 5 Black on Black (it's slow)


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Better exhaust for 90 gtz

Postby Guest » Sun Feb 17, 2002 11:18 pm

This stands to reason, but why is it that EVERY stock car I can think of has a larger TB than exhaust diameter. For instance, my Grand Prix has a 67mm TB, but only a 2.25 inch exhaust (57.15mm). Same with my SE-R...60mm TB, 50mm exhaust. Also my friend's Probe GT...60mm TB, 2in exhaust (50.8mm). Makes me think...hmmmmmmmmmm. Anybody well enough schooled in engineering to figure this one out?? I just know that the guideline for engines between 2.0L and 2.5L displacement is for a 2.25in mandrel bent exhaust......so says Mike Kojima, a contributing writer for Sport Compact Car, and a Nissan engineer in his own right. Obviously, this is for engines that can breathe, but since the larger 2.8/3.1L V6's dont pull very well up top, they don't generate the exhaust gas velocity to need larger (say 2.5in) piping than the GTZ's.



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rweatherford
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Better exhaust for 90 gtz

Postby rweatherford » Mon Feb 18, 2002 8:36 am

Quote (BIGBULS @ Feb. 17 2002,11:18)
This stands to reason, but why is it that EVERY stock car I can think of has a larger TB than exhaust diameter. For instance, my Grand Prix has a 67mm TB, but only a 2.25 inch exhaust (57.15mm). Same with my SE-R...60mm TB, 50mm exhaust. Also my friend's Probe GT...60mm TB, 2in exhaust (50.8mm). Makes me think...hmmmmmmmmmm. Anybody well enough schooled in engineering to figure this one out?? I just know that the guideline for engines between 2.0L and 2.5L displacement is for a 2.25in mandrel bent exhaust......so says Mike Kojima, a contributing writer for Sport Compact Car, and a Nissan engineer in his own right. Obviously, this is for engines that can breathe, but since the larger 2.8/3.1L V6's dont pull very well up top, they don't generate the exhaust gas velocity to need larger (say 2.5in) piping than the GTZ's.

I'd say it's the same reason as the intake valves being larger.  You want NO restriction on the intake side because the air has to be "pushed" into the cylinder by atmospheric pressure.  But the exhaust CAN be pushed out without loosing any real power.


Rex Weatherford
92 Beretta GTZ Quad4 Turbo / 5-speed (sold)
Best 1/4 ET =  13.523 @ 105.16 mph

07 Mazda 5 Black on Black (it's slow)



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