Single Turbo RX-7's Questions about all aspects of single turbo setups.

Anyone run an Open Exhaust (Open at the downpipe) ?

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Old Nov 30, 2005 | 11:24 PM
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Cool Anyone run an Open Exhaust (Open at the downpipe) ?

I'm going to run a 90' tube from the bottom of my downpipe to behind the front wheel.

Yes, I know it will be loud, stinky, annoying and spit out lots of fire but......... I'm trying to make some big power and I'm willing to do whatever it takes.

Anyhow, just seeing if anyone has done this and how were their results?

Last edited by LUPE; Nov 30, 2005 at 11:32 PM.
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Old Dec 1, 2005 | 06:29 AM
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Nobody?
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Old Dec 1, 2005 | 06:35 AM
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I did when i first had my car together. cosmo re, T04s 3' dp etc etc

VERY VERY LOUD, sounds badass though
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Old Dec 1, 2005 | 07:16 AM
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Go drive around for 15 minutes with just your downpipe...the answer will be clear to you.
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Old Dec 1, 2005 | 07:28 AM
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Originally Posted by Jack
Go drive around for 15 minutes with just your downpipe...the answer will be clear to you.
Noise won't bother me. I didn't ask for opinions about the noise. I asked for opinions on performance.
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Old Dec 1, 2005 | 10:09 AM
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I logged a few wot throttle runs with the exhaust open after the midpipe. I also looged runs with the exhaust fuully connected within minutes of the open exhaust runs. I was attempting to determine how restrictive the RacingBeat Dual Tip exhaust was. From recollection, the spool was about 1 psi more around 3,5xx rpms and the EGTS were approximately 50 degrees F cooler.
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Old Dec 1, 2005 | 02:40 PM
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Well, I have my wastegate plumbed into my downpipe. I'm going to dump that into the atmosphere and run my exhaust open behind my front wheel.

I should gain some HP around 30-32 psi
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Old Dec 1, 2005 | 02:58 PM
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I used a turndown, a 90 that aimed down and a little to the side after the downpipe in the mid 90's but there wasn't a substantial gain and I went back to normal 3" back with straight through mufflers. Keep in mind this was with worked stock turbos so the back pressure in the exhaust was not really the limiting factor as the housing design itself was the bottleneck. If everything else is plumbed right then it should provide a benefit but also you should consider that making a 90 degree bend to come out by your front wheel is going to cause extra back pressure, possibly more than just running a full tube all the way to the back of the car without substantial directional changes.

Kevin T. Wyum

edit: I'm assuming you meant it would exit near the front of the door and not the wheel well as that would require 150+ degrees of bends and be a complete waste of time. Fabricate a new header and downpipe to aim the exhaust housing toward the wheel well to get the benefit you're hoping for and see in other drag and race only cars.

Last edited by Kevin T. Wyum; Dec 1, 2005 at 03:04 PM.
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Old Dec 1, 2005 | 03:02 PM
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Originally Posted by Kevin T. Wyum
I used a turndown, a 90 the aimed down and a little to the side after the downpipe in the mid 90's but there wasn't a substantial gain and I went back to normal 3" back with straight through mufflers. Keep in mind this was with worked stock turbos so the back pressure in the exhaust was not really the limiting factor as the housing design itself was the bottleneck. If everything else is plumbed right then it should provide a benefit but also you should consider that making a 90 degree bend to come out by your front wheel is going to cause extra back pressure, possibly more than just running a full tube all the way to the back of the car without substantial directional changes.

Kevin T. Wyum
Well, I wasn't planning on making a complete 90 degree turn. Probably put some angle so it came out in front of the door.......

Like this.......

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Old Dec 1, 2005 | 03:06 PM
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Ignore my edit after seeing this. A dump like that would be good assuming you're doing your own downpipe. I assume this guys setup is a nice gentle bend coming right off the back of the turbine housing
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Old Dec 1, 2005 | 03:09 PM
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Originally Posted by Kevin T. Wyum
Ignore my edit after seeing this. A dump like that would be good assuming you're doing your own downpipe. I assume this guys setup is a nice gentle bend coming right off the back of the turbine housing
Right, the downpipe will be modified for a nice gradual bend.
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Old Dec 1, 2005 | 04:26 PM
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never on my seven.... but i've been down pipe only for about 6 months now on my 11 sec turbo civic and have noticed a big diff in boost response and thrtl response and also picked up
1.5mph and .4sec in the 1/4! but..... i kno you said it didnt matter to you but the noise thing is
pretty bad plus the whole inhale of exhaust in the lungs thing sucks too. but its pretty cool
because you can here your turbo spool so much better!
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Old Dec 1, 2005 | 05:36 PM
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Hey, Don't really have any experience to share but I have always thought the way nascar does them is neat. I think a rectangular tube would look so much better. Just thought you might enjoy!
Attached Thumbnails Anyone run an Open Exhaust (Open at the downpipe) ?-muffler-nascar.jpg  
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Old Dec 2, 2005 | 06:30 AM
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I'm just going to run mine to the side of the car, see how much stuff I can catch on fire.
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Old Dec 2, 2005 | 12:25 PM
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Originally Posted by LUPE
I'm just going to run mine to the side of the car, see how much stuff I can catch on fire.
i wanna watch. ive got bags of leaves. you should sell tickets
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Old Jan 21, 2006 | 08:17 PM
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Well, I opened the exhaust today.

The exhaust exits in front of the passenger door. My god, it's loud and blows fire like crazy.
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Old Jan 21, 2006 | 08:48 PM
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im briging a video camera for that ****.
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Old Jan 21, 2006 | 09:08 PM
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Originally Posted by johnrxt2
im briging a video camera for that ****.
Yeah, I wish I had mine tonight.......
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Old Jan 21, 2006 | 09:21 PM
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i got off work friday night and all day sunday, ill prob tape pulls from all of the cars dynoed that sat. especially the af61 cars, r they on the list for sat or sunday?
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Old Jan 21, 2006 | 09:40 PM
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Originally Posted by johnrxt2
i got off work friday night and all day sunday, ill prob tape pulls from all of the cars dynoed that sat. especially the af61 cars, r they on the list for sat or sunday?
one is saturday and one is sunday
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Old Jan 21, 2006 | 11:59 PM
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Hey Lupe, talk to Dave Gibson from Speed Machine Performance. I know that for the last half of the season their team Falken FD ran with DP only. They did some retuning and he would probably have some good info for you.

About the upcoming dynos for the AF61 cars, how many of them will be FC's?? I'm dieing to see more dyno sheets for that turbo!!!!!!!

Zach
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Old Jan 22, 2006 | 12:18 AM
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Originally Posted by BoostedRex
Hey Lupe, talk to Dave Gibson from Speed Machine Performance. I know that for the last half of the season their team Falken FD ran with DP only. They did some retuning and he would probably have some good info for you.

About the upcoming dynos for the AF61 cars, how many of them will be FC's?? I'm dieing to see more dyno sheets for that turbo!!!!!!!

Zach
Only 3rd gens with the Af61R turbo will be dyno-ing this time.

The last fc/af61r with a stock cat made 420@13-14 psi...
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Old Jan 22, 2006 | 12:50 AM
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I remember hearing about that one. I didn't see the sheet for it though. Do you have it handy? I'm curious as to what the curves looked like. And how soon will the sheets from this weekend get posted up?

Zach
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Old Jan 22, 2006 | 02:25 AM
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Originally Posted by BoostedRex
I remember hearing about that one. I didn't see the sheet for it though. Do you have it handy? I'm curious as to what the curves looked like. And how soon will the sheets from this weekend get posted up?

Zach
Sheets from two different dyno's were posted. Do a search.
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Old Jan 22, 2006 | 03:19 AM
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Sorry, I'm a little busy rebuilding a couple of 7's. It's easier if someone could PM or email it to me.

Zach
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