Yeah, get Bose involved. That actually makes sense.

 

I have the LRD Pro 4 full system on my Raptor. It gives a good power gain. I have had it sound checked twice and it had a 98 and 99 db level.

 

So now things are getting interesting. How to let air move, presure, yet reduce amplitude.
As note previously, sound absorbing material, baffling, and restriction (as in end caps) are
the traditional methods. Doesn't wave canceling not only involve reflecting the wave back
to the source, but reflecting back the presure as well?

It's been way too long since I took my physics courses, but it seems like a new approach
to an old problem is needed. Anyway, I agree that if the industry doesn't solve the problem
first, the government will, and they never do anything simple or straight forward!

That's the biggest reason I sold my 2-strokes (actually I still have my dirt bike) and took
to the plunge into the newer 4-strokes. Might as well do it for my reasons before the
government makes me do it for theirs.

 

There is probably something to do with the pressure pulse being reflected back as well, which is undesireable. But like a helicopter you hear coming, it's just air pulses not engine noise, so the "thumper" air pulses of the 4 stroke need to be cancelled. But I still believe there is a way that some computer nerd could figure out to "break" the sound wave as it moves through a canister without the somewhat archaic notion of just making the exit hole smaller.

I can see some guy with sound waves printed on his computer screen and an advanced cad system playing theory games with this. How about some college kid making his thesis on this and getting rich off it?

I'm way too stupid, I'm just a dumb lumber salesman. [img]i/expressions/face-icon-small-cool.gif[/img]

 

The yoshi pipe IS loud, and i didnt think it gave the Z i rode much more performance. I havent ridden a stock Z, but compared to my 450r (even stock), it didnt seem to give it much performance at all, but it could have, and i may just be too used to the 450r...

 

Riddle me this, Batman -
A single cylinder in a corvette engine has around the same displacement, compression and power output as a slightly modified Raptor engine. With both engines at full throttle at 5000rpm, why is a piped Raptor engine, at 1/8 the size of the Vette engine, MUCH louder?

There would be a lot more air flowing through the Vette exhaust system, so it can't just be airflow that makes an engine loud.

Also, my '71 Camaro has a v8 that is louder than both of the above, even though each cylinder is making less power than either the Vette or the Raptor.

I think a huge part of the sound equasion comes from the cam overlap and duration. Without changing anything else, put a "big" cam in a small block and put a "small" cam in the same engine and it will be much louder with the "big" cam. Once quad engines start making use of EFI, we will be able to run smaller, quieter cams with free flowing exhausts and make as much power as we do now.

My suggesion - don't try to make ATVs quieter by changing the exhaust, make them quieter by switching to EFI and smaller cams with less overlap and duration.

Just a thought. Does it sound reasonable?

RR1

 

I put the FMF Q pipe on my girlfriends yfz 450 i got her and jetted it 168 w/ a k&n. With the inner end peice in its not that loud at all and it helped it out. the triple combo works great together. but i took the inner "pea shooter" out and it gave it a healthy sounding growl..little less back pressure as well. Its definitely louder w/o it in ..but its a good pipe for the money

 

What about the CT pipe?....They require discs but they claim that bringing it from 16 discs (maximum h.p.) down to 8 discs (to quiet it down) still produces more horsepower than any pipe on the market.

 

That's a good point. I would say off the top of my head that the Corvette cylinder pulse travels a long ways through and exhaust system compared to the Raptor, and during that time is cooled thus slowing it down, and also "mixed" with a bunch of other pulses. In fact in header theory the pulse hits the collector open area and creates a negative pulse or low pressure occurance which then scavenges exhaust out of the next cylinder that opens, and so there's a bunch of things going on in there that must affect these sound waves and pulses.

Thinking out loud here, the Raptor blows a ton of air out the exhaust compared to the car. Short pipe in comparison as well as the other factors listed above, that aside I wonder what the actual cylinder pressure in the Raptor is compared to the car? I would surmise the Raptor cam has small amounts of overlap to build higher pressures. But your are very correct in my opinion that the EFI system "tames down" these cams and probably would result in some sound improvement.