motorcycle muffler a problem?

[georgeramos]

Based on the car running well I am not too concerned but research has shown me that the PO had a Supertrapp muffler designed for dirt bikes on the car. Could this be detrimental to the engine and or its performance? i dont necessarily want to spend bucks on a new muffler if I dont have to...

Thanks

George

[bradartigue]

New rear mufflers are $80 and you won't have to explain why you're over the age of 16 and have a Supertrapp.

[Texasbull]

My first car was a VW baja beatle with open engine cowl and headers flowing into a motorcycle muffler, never noticed any issues with it. Most dirt bike mufflers are very free-flowing, so they're really not much different than Thrusters or similar mufflers. If ya like the way it sounds on your car, leave it!

[grittracing]

not that i now much about this subject but my thoughts would be, if your getting a muffler for a dirt bike made for 2 cyl. and than you want to use it on a 4 cyl. i would say you might have to much back pressure. bannanna in the tail pipe not good. my thoughts

[maytag]

First, let's be sure it's a motorcycle muffler. SuperTrapp made mufflers for cars for many, many years. And they look just like the mufflers they made for bikes: stackable-plates for supposed tunability. And in my opinion, they sounded just as bad on cars as they did on bikes.

As for motorcycle mufflers on cars: think of it as a restriction just like your carb is a restriction. Whatever amount of flow your carbs are able to produce, your muffler should be able to handle the same.

I considered using motorcycle mufflers for a while, partly because I have so many at my place, left over from the super-bike racing days. One thing to consider is that most modern 4-cylinder motorcycles are turning at twice the RPM's as our TC motors. So I was looking at it this way:

if my 2-cyl Ducati was using (2) 43mm carbs, and turning 11k rpm, then the same exhaust system should be able to exhaust a motor using (4) 40mm carbs turning at 6k rpm.
my arbitrary and rudimentary math looks like this in my head:
43mmx11,000rpm=473,000x2cyl=946,000
40mmx6000rpm=240,000x4cyl=960,000

now, take a truly modern-tech bike, like the new Yamaha R1 and do the same math:
47mmx12,500rpm=587,500x4cyl=2,350,000

another way to do the same basic calculations would be simply displacement of the motor multiplied by rpm: 2000cc x 6krpm=12k, versus 1000cc x 12krpm=12k.

and LAST way to look at it reasonably: HP. IF a muffler is on a bike producing 175hp, then it should flow plenty for a motor producing 125hp.

obviously these are very rudimentary and rough ideas of how much flow you can expect. But remember that the muffler can be used to help tune HP as well. Some back-pressure can be a good thing for the lower-end of your rpm range. of course, that can come at the expense of breathing at the upper range.

[Ken]

I bought a Supertrap SC muffler from Summit racing it is an automobile application model muffler, it has not given any problem it’s a SC Elete2211, only eleven inches long so it is a little loud and I use all the baffles.
http://www.supertrapp.com/product_secti ... p?CatID=30

[georgeramos]

I mentioned the dirt bike thing because the only (current) product Supertrapp makes that looks anything like it is their "universal" dirt bike muffler. I inquired on the Supertrapp forum and they said thats what it looked like too them too...

Brad, what $80 muffler would you recommend for a good throaty sound? this one is a bit high frequency (some say ricey I think) for my taste. Since the PO bought it used I dont even know if the (replaceable) core is any good. Im considering buying a new core which is also close to $80!

thanks all

George

[bradartigue]

I mentioned the dirt bike thing because the only (current) product Supertrapp makes that looks anything like it is their "universal" dirt bike muffler. I inquired on the Supertrapp forum and they said thats what it looked like too them too...

Brad, what $80 muffler would you recommend for a good throaty sound? this one is a bit high frequency (some say ricey I think) for my taste. Since the PO bought it used I dont even know if the (replaceable) core is any good. Im considering buying a new core which is also close to $80!

thanks all

George

I think the stock muffler sounds pretty damn throaty. FIATs actually sound good with stock equipment, but most people have never heard a car with the stock stuff actually working. Keep in mind that twin-tip ANSA is no more than a regular muffler with two pipes (and it is a piece of crap, by the way, rusts like mad) and even when other "performance" options were available they did little to improve performance and a lot to increase noise.

Stock muffler = $89
Center pipe = $100
Catalyst = garbage can unless you need it in your state