So I want a 3 Inch Downpipe... where do i go?
#22
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A well built 3" DP MIGHT be worthwhile but NOT, and I repeat, NOT a full 3". And it seems that because it is a waste of time, there isn't a well built one available.
#25
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Turbochargers change the equation a bit more than slightly...first off, you have a huge restriction in the exhaust directly after the primaries...a naturally aspirated car doesn't have that. This basically means exhuast gas velocity and pulse tuning are a moot point, unlike in a naturally-aspirated car. You no longer have defined pulses because they've all be chopped up and thrown into one big gas plume by the turbine.
Why do you think a turbocharged car spools better when it's running merely a downpipe and no cat-back? Funny thing is, after the primaries are properly collected on an N/A car's header, you actually want the pipe to open up as much as possible there as well (assuming smooth transition). Say your N/A car's header primaries collected into 2.5"...a smooth, short transition from 2.5" - 4" into open air would make more horsepower at no expense in torque compared with a full 2.5" cat-back. Same goes for the exhaust dia. post turbocharger.
Here's something for you to chew on since, basically, the burden of proof rests on you, as you're going against all modern thought on the topic: since a turbocharger relies on a pressure differential across the turbine to spool and produce boost, explain to us why you wouldn't want the largest diameter possible exiting the turbine?
Why do you think a turbocharged car spools better when it's running merely a downpipe and no cat-back? Funny thing is, after the primaries are properly collected on an N/A car's header, you actually want the pipe to open up as much as possible there as well (assuming smooth transition). Say your N/A car's header primaries collected into 2.5"...a smooth, short transition from 2.5" - 4" into open air would make more horsepower at no expense in torque compared with a full 2.5" cat-back. Same goes for the exhaust dia. post turbocharger.
Here's something for you to chew on since, basically, the burden of proof rests on you, as you're going against all modern thought on the topic: since a turbocharger relies on a pressure differential across the turbine to spool and produce boost, explain to us why you wouldn't want the largest diameter possible exiting the turbine?
#28
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t25... you really are off base. A turbo is happiest with NO piping at all, just something to smooth exit gases and the open air make it happiest.
I run a full 3" DP on my 1.6L civic... and will be running a full 3" on my 1.6L miata. Its an easy size to get piping in and it has proven gains over smaller piping.
If I could fit 4"+... I would use it.
I run a full 3" DP on my 1.6L civic... and will be running a full 3" on my 1.6L miata. Its an easy size to get piping in and it has proven gains over smaller piping.
If I could fit 4"+... I would use it.
#34
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I dont know what you guys are saying... I have a bunch of friends that have had evo's,sti's,GTI's all with big downpipes. You lose lowend but top end pays off for it. One of my buddies was running a GTI 1.8T with a gt30R and a 3 inch turboback. Car ran amazingly. I remember he made my 350z look like it was stopped on the freeway.
#36
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You would certainly lose low-end if you want from a log- or short-runner tubular manifold to a super long-runner manifold (like this: http://www.turbotechnologyinc.com/pr.../e&e/e&e02.jpg ), on the same engine, with the same turbo with the same downpipe size.
Post turbine, however, you want the larger MF'n diameter you can get.
Post turbine, however, you want the larger MF'n diameter you can get.
#40
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http://www.bellengineering.net/Pages...peupgrade.html
Read it. I am happy to stand corrected on several of your points. Dragsters are not road cars, don't use them to back you up cause they are so different they aren't comparable. And if they use 4", what makes you think that a pissy little 1.6 needs 3" :gay:
Like I said, I stand corrected on some things and have learned a lot in this thread, and also laughed at a lot of comments. Don't put me down because of **** you have read on forums. ********* like us post on forums, what makes what we say right? I'd trust Begi though, they research.
Read it. I am happy to stand corrected on several of your points. Dragsters are not road cars, don't use them to back you up cause they are so different they aren't comparable. And if they use 4", what makes you think that a pissy little 1.6 needs 3" :gay:
Like I said, I stand corrected on some things and have learned a lot in this thread, and also laughed at a lot of comments. Don't put me down because of **** you have read on forums. ********* like us post on forums, what makes what we say right? I'd trust Begi though, they research.
Engines do not like exhaust gas back pressure. Getting the exhaust gasses smoothly out of the system with a minimum of back pressure is therefore crucial to producing power. Turbocharged engines like it even less. Yet, it is very clear that just “bigger” is not the answer to “better.” We are stuck with convertors and mufflers, but there are other areas that can hurt power just as bad if not handled properly. Specifically, “handling” is the treatment of the gasses passing through the turbine and those vented through the integral wastegate.
The problems to solve are:
~Matching flow intersections to smooth changes
~Expanding flow area based on aerodynamically correct expansion rates
Avoidance of dumping the exhaust gas into a sudden cavern such as “the middle of Grand Canyon.”
The problems to solve are:
~Matching flow intersections to smooth changes
~Expanding flow area based on aerodynamically correct expansion rates
Avoidance of dumping the exhaust gas into a sudden cavern such as “the middle of Grand Canyon.”