2.5 vs 3 inch downpipe again?
Thread Starter
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Joined: Nov 2004
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From: St. Louis
Originally Posted by Zeus
Doh!
The laws of physics seem to be bent or broken every day in the automotive world... not because they are wrong... it's that you NEVER, EVER have all the variables. So on paper guys, the argument for going somewhat smaller than 3" looks real good, however, when you go out in the rain, the ink tends to bleed and run a bit. I've argued this 'til I'm blue in the face. When I was back on Honda-Tech in the Type R days, someone contacted one of the engineers at Garrett or Turbonetics (I think it was the former, but my mind isn't as sharp as it used to be) and was told in lengthly detail why they would usually be better served running a full 3" on a turbocharged 1.8 liter. So run what you will, but those with the most experience are going to tell you that 3" is just fine.
Don't forget that there is almost always a difference between what works out on paper, and what works out on the road... no matter how minimal it is.
The laws of physics seem to be bent or broken every day in the automotive world... not because they are wrong... it's that you NEVER, EVER have all the variables. So on paper guys, the argument for going somewhat smaller than 3" looks real good, however, when you go out in the rain, the ink tends to bleed and run a bit. I've argued this 'til I'm blue in the face. When I was back on Honda-Tech in the Type R days, someone contacted one of the engineers at Garrett or Turbonetics (I think it was the former, but my mind isn't as sharp as it used to be) and was told in lengthly detail why they would usually be better served running a full 3" on a turbocharged 1.8 liter. So run what you will, but those with the most experience are going to tell you that 3" is just fine.
Don't forget that there is almost always a difference between what works out on paper, and what works out on the road... no matter how minimal it is.
The slip fit design has been changed. We only use two slip fit joints now. Any and all problems you have read about have been fixed, I gaurantee it.
We also have this on sale right now if you mention you saw this, any combination of our system, cat or catless, magnaflow or or muffler and shipped to you for only $750.
David Buschur
www.buschurracing.com
We also have this on sale right now if you mention you saw this, any combination of our system, cat or catless, magnaflow or or muffler and shipped to you for only $750.
David Buschur
www.buschurracing.com
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Joined: Mar 2005
Posts: 9
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From: Portland
Originally Posted by wingless
I don't think you guy's have searched....
To keep the exhaust velocity up you need to go from smaller diameter to larger diameter as the exhaust gas cools and expands.
Asuming a 3" cat back, the folowing is true:
The exit hole of the stock o2 housing is 2.5" and the stock cat is 2.5".
If you keep these two items (or add 2.5" hi-flow cat or 2.5"delete), a 2.5" dp. will flow better than a 3" dp.
Keeping the stock o2 and jumping to 3"dp. with a 3" hi-flow or delete will out flow the above set up.
The most power will come from a 3" o2> 3" dp>3" hi-flo/delete.
If this is incorrect please speak up, as this is what I have read from the discussions on this board.
To keep the exhaust velocity up you need to go from smaller diameter to larger diameter as the exhaust gas cools and expands.
Asuming a 3" cat back, the folowing is true:
The exit hole of the stock o2 housing is 2.5" and the stock cat is 2.5".
If you keep these two items (or add 2.5" hi-flow cat or 2.5"delete), a 2.5" dp. will flow better than a 3" dp.
Keeping the stock o2 and jumping to 3"dp. with a 3" hi-flow or delete will out flow the above set up.
The most power will come from a 3" o2> 3" dp>3" hi-flo/delete.
If this is incorrect please speak up, as this is what I have read from the discussions on this board.
THANK YOU! I have been looking for this answer.
If you are staying with stock cat, it wouldn't make sense to do a 3" downpipe. And another thing, you ever notice that many of the Japanese companies don't make 3" downpipes. In fact why doesn't HKS, a top company, make a 3" downpipe? Ever think about that?
Think about this, just because a Japanese company doesn't make a part doesn't mean they are doing the right thing. What, the Japanese tuners are smarter than the US tuners? haha
The Japanese have had "their" cars there since, well since the first Japanese car was built. The USA started racing and tuning the same cars around the early 1990's. We now have the fastest imports in the world here. That means you need a 3" downipe
David Buschur
www.buschurracing.com
The Japanese have had "their" cars there since, well since the first Japanese car was built. The USA started racing and tuning the same cars around the early 1990's. We now have the fastest imports in the world here. That means you need a 3" downipe
David Buschur
www.buschurracing.com
Originally Posted by davidbuschur
Think about this, just because a Japanese company doesn't make a part doesn't mean they are doing the right thing. What, the Japanese tuners are smarter than the US tuners? haha
The Japanese have had "their" cars there since, well since the first Japanese car was built. The USA started racing and tuning the same cars around the early 1990's. We now have the fastest imports in the world here. That means you need a 3" downipe
David Buschur
www.buschurracing.com
The Japanese have had "their" cars there since, well since the first Japanese car was built. The USA started racing and tuning the same cars around the early 1990's. We now have the fastest imports in the world here. That means you need a 3" downipe
David Buschur
www.buschurracing.com
Evolving Member
Joined: Sep 2004
Posts: 319
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From: DesPlaines/Niles IL
umm i think its stupid to compare Japanese and US tuning cuz they have completely different preferences...
For one, Japanese like to go zig zag while Americans like to go on a straight line...
For one, Japanese like to go zig zag while Americans like to go on a straight line...
Originally Posted by davidbuschur
Originally Posted by davidbuschur
Originally Posted by davidbuschur
Think about this, just because a Japanese company doesn't make a part doesn't mean they are doing the right thing. What, the Japanese tuners are smarter than the US tuners? haha
The Japanese have had "their" cars there since, well since the first Japanese car was built. The USA started racing and tuning the same cars around the early 1990's. We now have the fastest imports in the world here. That means you need a 3" downipe
David Buschur
www.buschurracing.com
The Japanese have had "their" cars there since, well since the first Japanese car was built. The USA started racing and tuning the same cars around the early 1990's. We now have the fastest imports in the world here. That means you need a 3" downipe
David Buschur
www.buschurracing.com
3 inch Downpipe, 3 inch hi-flo Cat, 3 inch Cat-back. Period
