WGT exhaust

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Arnie_O
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Re: WGT exhaust

Post by Arnie_O » Sat Aug 10, 2019 6:20 pm

Sorry Guys
Neil collected his car this afternoon after some extensive work needed to sort a lot of little issues left fronte last shop.
With the excitement we missed the video, plus his motor is still being run in.
We have another one to fit soon so please bear with us.
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Hobbawobba (Sun Aug 11, 2019 7:32 am)
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Re: WGT exhaust

Post by Hobbawobba » Sun Aug 11, 2019 7:34 am

Understandable! Haha. I always forget to take pics/vids in the moment :lol:

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kenwhiteside
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Re: WGT exhaust

Post by kenwhiteside » Sun Aug 11, 2019 8:26 am

Picked up one of the old racing beat power pulse PR spec mufflers to replace the leaking stainless steel exhaust ones that's on the car. This is the larger 2.5ish inch inside diameter one rather than the standard 2 inch one.

Browsing the forum a number of people seem to be running 2.5inch systems with only one resonator on NAs. I would have thought this setup would be fairly loud and droney. Mine is turbo so should be inherently quieter.

Any direct experiences of a 2.5 inch single box system on a turbo?

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gt_james
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Re: WGT exhaust

Post by gt_james » Mon Aug 12, 2019 9:43 am

2.5 sounds small on a turbo. My NA has a 3" exhaust. Turbo rotaries really like to breathe.

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Re: WGT exhaust

Post by kenwhiteside » Mon Aug 12, 2019 12:19 pm

Its 2" at the moment feeding into the factory pipe at less than 2" over the diff so 2.5" will be a good increase in diameter. Remember the elfords are only 165hp stock. 3" is probably a better size for a 13b producing north of 300hp but I am nowhere near that. Less restriction is of course probably better for performance however I dont what excessively noisy hence the question is anyone has run a single back box only system. Saw a post on AusRotary of a guy running a 12a turbo with a single back box system that was around 95dB (high idle test) so not too crazy.

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Re: WGT exhaust

Post by Hobbawobba » Mon Aug 12, 2019 2:41 pm

I agree with the 3" being pretty big for an NA unless pushing the limits. My researched a couple years ago showed 2.25 to 2.5 on a fairly decent streeter is fine. I had a 2.25 on my 12a

Those Racing Beat mufflers are supposed to be fairly quiet aren't they? I'd say give 2.5" a go. Could always add in a resonator/muffler before the diff if its loud? Your car was nice and quiet at Beaulieu. Turned around and you were right there :o :lol:

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Re: WGT exhaust

Post by gt_james » Mon Aug 12, 2019 5:23 pm

IIRC, Racing beat recommend 2.25-2.5" on a stock NA 12A, 2.5" for street port, 2.75-3" for bridge/PP. They recommended at least 2.5" on a 6 port 13B, 2.75" is harder to get so I went up to 3".

My NA 13B 6port is a long primary with 2 2" pipes to back over the axle with a big pre silencer in each primary, then the tail section into a 3" with a big back box, made to be as quiet as possible for trackday noise limits but not cause backpressure, its 99dB at 5000revs.

My NA 12A bridgeport is similar but with 2.5" rearsection, hotdog res in each primary and a smaller back box, that is 108dB at 4500rpm.

The key to getting a rotary quiet is not piping size, its silencing type and material. Even on a turbo if you want the car quiet you will need at least one big presilencer, and a good back box. Remember rotary engines are really tough on exhausts and put a lot of heat and pressure into the system.

I did a lot of research and essentially you will want to use thick wall tubing, make the silencer outer can as large as possible (my presilencers are 4", you could go bigger and oval on a turbo single pipe system, and my back box is 8" round!). Baffles tend to blow out, and packing material in burgess type silencers needs to be stainless wool or ideally lava rock core, then quality E glass woven matt, and still expect to repack.

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