Ultralite exhaust options?

[rnr]

I was at Laguna Seca for a sound check yesterday and got an incredible 109 dB reading. It was actually so loud that rather than the usual 3 lap sound check the flagger furiously waved me down before I could complete a full lap. Now the sound limit for Laguna is 92 dB (most other tracks are in the 102-103 range) and since that is my closest track I really would like to run there.

 

I've spoken to the Hushpower folks about getting an exhaust to quieten it down but we dont really know if their solutions will actually do enough. One option would be to get their exhaust (~$200) and pre drill it for super traps. That way if I ever blow sound I can always put the traps in and hopefully pass sound.

 

I also spoke to Phase 9 which is a local muffler fabricator used by a lot of Porsche guys and they suggested going for a 2 step solution. Use a single muffler for daily use that brings you down to the ~100 dB and then use a quick release second muffler on a u-bend pipe to quieten it down to the 92 dB limit. I actually saw a Caterham using this exact setup at Laguna and while its not elegant it does certainly work.

 

What are other people using for mufflers on their Ultralites and are there any other options that I've missed?

 

BTW I am running what I beleive is the stock muffler - pic below:

 

http://farm3.static.flickr.com/2793/4313274614_e1f7dd2caa.jpg

[Mondo]

Will be watching to see what you come up with.... kind of hard to swap out though as most of us have O2 sensors just past the collector. Plus I'm kind of partial to my new exhaust shield;)

[rnr]

Will be watching to see what you come up with.... kind of hard to swap out though as most of us have O2 sensors just past the collector. Plus I'm kind of partial to my new exhaust shield;)

 

Couldn't you put the O2 sensors in the new exhaust?

 

The U-bend solution could also work with an existing exhaust/heatshield as well. You can see the dual muffler Caterham I was talking about at http://gotbluemilk.com/web100215b/56/imagepages/image41.html

 

Incidentally one of the previous owners of my car has actually taken it to Laguna and I even have a picture of it from a GGLC track day. Though I also have a picture of the Caterham above at the same event without its second muffler so maybe is was a higher sound day and/or the sound guy had the day off.

 

http://farm1.static.flickr.com/35/103720832_cf11109f9b.jpg

[Mondo]

Never seen that before... clever

[TheDingo8MyBaby]

Have you looked at running it behind the RR wheel and out the back? You should be able to throw a cancellation muffler on there in addition to the absorbtion syle you currently have.

Edited February 26, 2010 by TheDingo8MyBaby

[rnr]

Have you looked at running it behind the RR wheel and out the back? You should be able to throw a cancellation muffler on there in addition to the absorbtion syle you currently have.

 

Something like a second muffler in series on the side with the exhaust tube exiting out the back? Interesting idea - I'll have to see if there is enough clearance under the chassis to route an exhaust tube without impacting the suspension or the gas tank.

[11Budlite]

Something similar to what Caterham offers that mounts another silencer across the back could work. This one even has a dump valve: https://www.caterhamparts.co.uk/product_info.php?products_id=3959&osCsid=df947a3707ae579ee213c93e730770ba

 

Or one of the monster Raceco silencers: http://www.raceco.com/silencers.html

[BMW RACER]

109 Is very loud! The SCCA limit for racecars is 103. At Laguna the sound station used to be on drivers right coming out of turn 5. So, you might try running the exhaust under the back axle and then putting a 90 degree bend that points it out to the left.

Good luck with this, Laguna is tough on sound. All the richy riches that moved next to the racetrack don't want you disturbing their wine (whine?) and cheese parties

[khamai]

Rahul,

If you can get to the rear of the car it will give you more options and the ability to point the tailpipe to the left (away from the sound station). I think you can find enough clearance along the right side of the tub, notch the inside of the rear wing, then go under the diff and under the tank (you may need to shield the tank).

 

Cheers,

Kiyoshi

[rnr]

Keep the ideas coming. I just eyeballed the car and I dont think that there is enough room to go around to the back of the car. The rear wheels completely fill the wheel arches which mans going through the fender wont work. Also with the roughly 4 inches of ground clearance I cant go under the frame either. Will put out some measuring tape and look more carefully tonight.

 

I just spoke to the guy at Quiet Horsepower (http://www.quiethorsepower.com) and he suggested either using 2 Phase 10 exhausts in series (pic 1) or a Phase 9 in concert with a phase 10 (pic 2). He builds exhausts for a lot of 911s and Formula Atlantic cars so he should be able to get it under sound but it sure will be an odd looking setup

 

http://farm5.static.flickr.com/4021/4389805733_def52968a6.jpg

 

http://www.quiethorsepower.com/images/side_914-6.jpg

[BMW RACER]

At the leist point it down.

[rnr]

Also spoke to Burns Stainless and they recommended going to a 2.5 inch (current setup is 3 inch) version of their 2 stage exhaust.

 

http://www.burnsstainless.com/sm-250-450-17-2s.aspx

 

3 inch version @ http://www.burnsstainless.com/sm-300-625-17-2s.aspx

 

they are also going to get back to me with a quote on a 24 inch long 2-stage version

 

 

P.S. I'm posting all this info both as a reminder to myself and as an online diary of the various options so that the next person out there has some idea of what else is out there. Don't yell at me for over posting

[DeanG]

You could run in straight up like a semi does. It would look redneck funny.

[rnr]

You could run in straight up like a semi does. It would look redneck funny.

 

I actually did consider it - problem is that a passenger could easily burn themselves on the tip. I'm very interested in the Hushpower Cool Shell setup which claims to keep the can temp down to 200F. Lets see - as of now I'mm just collecting my options so that I can hopefully decide next week. I have a Lotus Club track day back at Laguna on Mar 23rd and I'd really like to take the Se7en.

[khamai]

rnr,

You could have built the roll-cage with 3" exhaust tubing!!!! Chapman would have been proud!

 

Kiyoshi

[Mondo]

For some reason, the pics of my heatshield will not post (click my name and check my photo album). I bought some heat material to go between the muffler and shield from here (not cheap) and it works great, just warm to the touch (and that's regular paint, not for heat):

 

http://www.koolmat.com/heatmast.shtml

[rnr]

You could have built the roll-cage with 3" exhaust tubing!!!! Chapman would have been proud!

 

Lemons racing actually has an explicit rule against using muffler tubing for roll cages

 

 

I bought some heat material to go between the muffler and shield from here (not cheap) and it works great, just warm to the touch (and that's regular paint, not for heat):

That's very cool - is there an airgap to the heat shield material and if so how much?

[Mondo]

No real air gap between the muffler/heat shield material/cover... bit of a gap where the cover narrows down up front. Tried to keep the cover as small and close the the exhaust as possible. We don't have a ceramic coating place in town so painted it to match car instead of exhaust. Might look better/cleaner if cover matched exhaust system.

[rnr]

No real air gap between the muffler/heat shield material/cover... bit of a gap where the cover narrows down up front. Tried to keep the cover as small and close the the exhaust as possible. We don't have a ceramic coating place in town so painted it to match car instead of exhaust. Might look better/cleaner if cover matched exhaust system.

 

So it basically comes as a rectangular grometted sheet of metal with the heat shield material under it or do you have to make the cover yourself? Right now I'm leaning towards the phase 9/phase 10 solution but those will require an heat shield that I can cut and form to the appropriate shape

[Mondo]

I bought that insulation material to cover half the diameter of the muffler... it's expensive as it cost "per square inch"! I had the shield made. It's a pretty thick metal, not real light.

It was more complicated than it looks (at least to me) as it's 3 different size half pipe pieces welded/grinded together (without warping)... plus welding on some mounting tabs with threaded holes to the muffler (have to grind off ceramic coating to weld). I think we put some tabs on the inside of the cover to match the grommet holes on the insulation to keep in place. Luckily I got a price before the fabricator got started because I know he spent way more time than the hourly price I paid.

Like a lot things, it's often more complicated to look simple.