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Running no exhaust at all?

Old 09-14-09, 12:45 AM
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Running no exhaust at all?

I just got a 1988 N/A, and I am going to gut the thing and just quarter mile it and have a fun little N/A. But this is my first rotary vehicle and i was kinda curious on the exhaust back pressure and power gains and losses. Its not gonna be street legal so im not worried about emissions and police bothering me for sound ordinace. So my question it if I remove the exhaust right at the first collecter and run a side pipe out the side or back, is it bad for the rotory or does it lose power due to no back pressure, or both?
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Old 09-14-09, 07:09 AM
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It will be loud - too loud. As in bleeding ears loud. Forget the street - I run a RacingBeat header, resonate midpipe and a Corksport single cat-back on my track car and I don't come near passing sound levels at the *track*.

You need a muffler - and one that will stand up to the very high exhaust temps that a rotary puts out. A glass pack or cherry bomb just ain't gonna cut it.

Do a search on this forum for exhaust discussions - depending on where you collect the two exhaust streams together, you can lose or gain low end torque (which you desperately need on this car).

Good luck,

-b
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Old 09-14-09, 11:38 AM
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try it, an unmuffled rotary is like the loudest sound possible.

minimum you'll need a muffler of some kind, and it'll need to go at least in front of the rear wheel.

i'd suggest against the corksport as that is louder than just having a piece of pipe
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Old 09-14-09, 11:58 AM
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The funny thing I noticed is that glasspacks don't seem to get any louder once the packing burns out.

My exhaust is a header, funky collector into a 2.5" $27 Thrush glasspack, some 2.5" pipe, and then a 2.5" Dynomax stainless shell rear muffler. Oh and a 1 7/8" reducer in the exhaust tip, which doesn't restrict power believe it or not. The tip is worth as much muffling as one of the mufflers, so essentially it's a three muffler system.

And it's still too loud for me to drive comfortably. But it gets better fuel economy than the VW so it's the car I prefer to use...
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Old 09-14-09, 12:14 PM
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rb race headers and thats it just run it like that
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Old 09-14-09, 01:06 PM
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As long as you don't live anywhere in the same state as me, go right ahead, it won't hurt the motor.

Your ears on the other hand....
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Old 09-14-09, 09:48 PM
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Yeah. I just got a car running on labor day with just an open RB header. Drove it down the street, came back and said I wouldn't drive that car again till I got exhaust. I literaly felt like my ears were going to bleed. It is that loud.
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Old 09-15-09, 02:12 AM
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well thanks alot for the info guys I was just making just I was not going to damage the rotor or anything, but I did take the exhaust off and took it for a spin and I did notice a power gain but got off of it and took right back home, all I gotta say is WOW I need to learn to read lips now haha. But hey im having problems with my brakes now you guys should look at my brake post.
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Old 09-15-09, 04:09 PM
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From your description in other threads you definitely have air in the line (or a failing master cylinder, but I doubt that sine you just changed the pads)

Don't listen to the autozone guy.

bleeder valve closed, pump the brakes 3-4 times, with a hose connected to the valve, crack it open while your helper has pressure on the pedal. Once you crack the valve open, the pedal will sink to the floor, don't move the pedal. Once fluid stops, close the valve, release the pedal, and repeat steps until no air bubbles are visible in the line output. Do all 4, and you should be back to a full hard pedal.

inspect your brake hoses, make sure none of them look like they're swelling from the pressure, in which case, bad line.

If you do all of this and you've still got nothing, and you have no visible leaks around any of the calipers, then you have a dead master cylinder and it's time to replace that. Bench bleed that before installing, and then bleed all 4 lines just as you did before.
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Old 09-15-09, 05:05 PM
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Thumbs up

Originally Posted by silkworm View Post
as long as you don't live anywhere in the same state as me, go right ahead, it won't hurt the motor.

Your ears on the other hand....
hahahaha
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Old 10-13-09, 06:19 PM
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Sorry to bring back a month old thread, but nobody mentioned this point: Since you're running a series 4, your 5th and 6th ports are actuated by backpressure. When you took off your old exhaust to try your open header, you should have seen a rubber line going from one of the catalytic converters to your engine. This is the backpressure line for the secondary ports. If you didn't run an open header, you would need to rig up a different form of opening the ports with an rpm activated automatic switch or just plain wire them open. If you wired them open, you would suffer a loss of torque at the lower end of the tachometer.
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Old 10-23-09, 10:54 PM
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Read Racing Beat writeups on exhaust. You need some length.
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Old 10-30-09, 11:35 AM
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length improves "exhaust scavenging" Julian is correct but if yout just going for the wow factor plumb it right through the hood I had that in mind, just wear ear plugs.
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