Do mufflers affect performance?

[skav]

I'm curious to see what everybody thinks. I have baffles in my tips, but it's a bit loud without the Gibson slip ons. The slip ons quiet it down a lot, but makes me wonder if they rob any HP.

Has anybody ran back to back, on and off?

 

[prosthogod]

I'm going to guess, yes. Haven't done the test but more backpressure should lead to loss in HP

 

[Tom Brown]

With a normally aspirated engine, a little back pressure can improve performance and efficiency.

 

[Motor Boater]

Funny thing, I was at Teagues shop a few years ago talking with someone about the new CARB compliance stuff. They had one engine that had gone through the program at the time and they said oddly enough with the additon of Catalytic convertors the engine actually made more horsepower then it had previously.

 

[prosthogod]

If they made horsepower then everyone would put them on (builders). If they made horsepower, it would be a cheap upgrade for HP

 

[RiverDave]

Depends on the muffler system.. Some of them have negligable losses.. Others you can lose about 500 RPM (again negligable in my mind)

 

[rivermobster]

do they affect performance? absolutely.

HOW do they affect it is the millon dollar question. Every application is different. You would have to dyno YOUR paticular set-up, to know how it would be affected.

No one can tell you for sure.

 

[skav]

I definitely like the way it sounds better wo the muffs, but it gets a little obnoxious towing the kids on the tube and wake board all day.

The Gibsons seem pretty free flowing, but I'm sure they create BP.


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[kevnmcd]

I have a pair of the Gibson Bullet mufflers. I never did a comparison in the same day/conditions but if I lost any performance, it was pretty negligible. Of course, I am only running a mild 509 (525hp) and am on the bottom range for that muffler.

 

[prosthogod]

This question interests me because I got a tounge lashing by the refuge cop for no mufflers and I just met Ron Gibson and he said he would get me a smokin deal. I had Gibson bullets on my other boat and they definitly quieted things down and seemed to loose some HP. If the manufacturers claim in ads that they don't, is it BS or did someone do some testing. Granted there are a lot of different applications out there , but some simple testing could be done on various packages that an extrapolation could be inferred. Quiet is nice but loss of HP isn't.

 

[pronstar]

Mufflers won't gain HP, but you can get negligible loss from a well-designed setup.

Backpressure is never good for it's own sake.

But too much flow can cause the exhaust temp and velocity to decrease, which decreases the scavenging effect. So if you go from "too large" primaries, to smaller "right sized" primaries, you'll gain power but not from the addition of backpressure.

It's not really backpressure that you want...you want a properly-sized exhaust system.

 

[harlanorrin]

Back in the days when we raced at the L B Marine Stadium several times a year, a test session was run. After the results were in with drag hydros, circle flats and G N boats, most were same or faster. There were magazine test results published.
HARLAN ORRIN

 

[RiverDave]

do they affect performance? absolutely.

HOW do they affect it is the millon dollar question. Every application is different. You would have to dyno YOUR paticular set-up, to know how it would be affected.

No one can tell you for sure.

When the noise nazi laws 1st started going big time 4 - 5 years ago there were all kinds of tests done on basic merc packages with all the different mufflers.. Some lost 500 RPM (not much) others didn't lose anything. Never heard of any of the new systems actually gaining power.

Out of all of them I always thought the fat boy tips by Rex looked the best.. There is a problem on his website with the power silencers so they aren't displaying or I'd post a picture.

Gibson's are also bad ass.. They have versions for up to 425 HP and bullets for larger HP motors.

This question interests me because I got a tounge lashing by the refuge cop for no mufflers and I just met Ron Gibson and he said he would get me a smokin deal. I had Gibson bullets on my other boat and they definitly quieted things down and seemed to loose some HP. If the manufacturers claim in ads that they don't, is it BS or did someone do some testing. Granted there are a lot of different applications out there , but some simple testing could be done on various packages that an extrapolation could be inferred. Quiet is nice but loss of HP isn't.

Gibson runs power curves on his MTI.. Now the bullets.. If there was no HP loss, one would think he would run the bullets..

Mufflers won't gain HP, but you can get negligible loss from a well-designed setup.

Backpressure is never good for it's own sake.

But too much flow can cause the exhaust temp and velocity to decrease, which decreases the scavenging effect. So if you go from "too large" primaries, to smaller "right sized" primaries, you'll gain power but not from the addition of backpressure.

It's not really backpressure that you want...you want a properly-sized exhaust system.

Properly sized and "tuned" exhaust system.

RD

 

[shippingguy]

When they did do those tests like Dave said there was actually one company that claimed "better performance" with their set up. Well needless to say they gave me a set for free and I ran them on my 27 Shadow with a 525 and lets just say they came off 10 minutes later! Those were ZOOMERS!:thumbsdown Now with my current 27 Shadow with Teague 800 I run nothing!

 

[rivermobster]

When the noise nazi laws 1st started going big time 4 - 5 years ago there were all kinds of tests done on basic merc packages with all the different mufflers.. Some lost 500 RPM (not much) others didn't lose anything. Never heard of any of the new systems actually gaining power.


Properly sized and "tuned" exhaust system.

RD

Without trying to give ya the Tom Brown explantion, here are the basics of it...

When the exh valve opens, it sends a "pluse" through the exh. If the exh system is designed correctly, that "pulse" will help pull in the fresh intake mixture (create a vacume), durring valve overlap and help pull the exh gas out behind it as well. Its called exhaust scavaging.

However the system is designed, with or without a muffler, it needs to be designed to provide the proper amount of scavaging.

On my Harley...

I got 10hp less, than i would have got if i would have used a 2 into 1 exh. The 2 into 1 is much more quiet as well, cause it has very nice mufflers built in. But I had to go 2 into 2, open pipes, no mufflers (poor scavaging).

There is no "one size fits all" example. Every system is different.

 

[reliable1]

I have a 525 in my boat with the gibson slip ons, I to was curious so I tested with and without back to back with the exact same mph results. The only difference in my case was the noise.

 

[The Doctor]

It's all a matter of volumetric efficiency and each engine combination has "unique" characteristics so there's no blanket way to say any form of mufflers will produce better or worse for performance on the average engine. Until you run each combination on a dynamometer with and without every muffling device in identical test parameters, it's a crap shoot and, at my age, I think I've heard all this crap before.

It's absolutely true that some engines perform better in sections of the power band with reasonable amounts of back pressure. Perfectly tuned headers on certain applications will occasionally benefit from certain muffling devices in areas of the power band but no blanket statement about muffling devices will ring true with every scenario IMHO.

 

[Riverbound]

I run the Gibson bullets on our stoker (stock 500hp/CMI e-tops) With them on I do see a 200rpm loss on the top end other than that the boat runs the same with or without them on. the boat is much louder with them off and borderline annoying IMO. knuckleheads/JBG also run them on their stoker with the quad rotor motor and I dont think they see any difference with or without them.

 

[blackbart]

all mufflers create some sort of power loss
and catalytic converters same thing unless u have sound cancleing
mufflers,, or the shuttle would have never made it to orbit

or no 4 sceoned 1/4 mile just my thaughts:hmm

 

[skav]

What if you went from a 4" open to a 4 1/2" muffed? Would that still create more back pressure?

 

[Crazyhippy]

The "Rotary mufflers" that are so prevalent in the ski race world seem to improve Horsepower dramatically.


Something something Tapatalk

 

[skav]

The "Rotary mufflers" that are so prevalent in the ski race world seem to improve Horsepower dramatically.


Something something Tapatalk

??? Pictures?

 

[Faceaz]

Gibson runs power curves on his MTI.. Now the bullets.. If there was no HP loss, one would think he would run the bullets..


RD

Don't know anything about the mufflers, but I do know in general Gibson has his motors detuned, by a couple hundred hp each - if I remember correctly. I don't think he's too worried about a slight power loss between the two.

 

[Outdrive1]

Ive had three boats with Imco Gatling mufflers, haven't noticed a difference with or without them hp wise. The Ilmors are car engine quiet with them at idle, I didnt like the sound so I don't run them.

 

[Crazyhippy]

??? Pictures?

 

[Outdrive1]

Lol

 

[Crazyhippy]

Lol

What? They're quiet...:skull

 

[Sleeper CP]

That's a rotary muf all right.

S CP

 

[rivermobster]

What if you went from a 4" open to a 4 1/2" muffed? Would that still create more back pressure?

back pressure is irelevent.

how the pulse is effected is all that matters.

adding back pressure is nothing more than changing the way the exh pulse leaves the engine! most manufactures today do not tune for performace, they tune for emisssions. its impossible to know how any mods may or may not change the exh tuning. no one can give you an answer.

but i can tell you this...

on a 4cycle engine, increasing the exh tube size, is Almost always not a good thing.

I tried to google a few things for ya, but nothing really good came up. Below is a pretty decent article about how intake and exh. theory work.

Also remember, and engine is just an air pump! Once you change the flow of air through it, you effect its fuel flow needs. And, once you change how the air comes out of the engine, you affect how the air flow goes into the engine as well.

Simple right??


http://en.wikipedia.org/wiki/Manifold_(automotive)#Exhaust_Scavenging

 

[GR8WHITE]

When the noise nazi laws 1st started going big time 4 - 5 years ago there were all kinds of tests done on basic merc packages with all the different mufflers.. Some lost 500 RPM (not much) others didn't lose anything. Never heard of any of the new systems actually gaining power.

Out of all of them I always thought the fat boy tips by Rex looked the best.. There is a problem on his website with the power silencers so they aren't displaying or I'd post a picture.

Dave when I bought my shockwave the previous owner already installed the rex marine power silencers. Is this what you were referring to? I never got to hear or feel the boat with regular tips on the 454 magnum. I am curious to how much they actually kill the sound because my boat is actually pretty quiet.

 

[djunkie]

500 rpm loss sounds like a whole lot to me.

 

[RiverDave]

When the noise nazi laws 1st started going big time 4 - 5 years ago there were all kinds of tests done on basic merc packages with all the different mufflers.. Some lost 500 RPM (not much) others didn't lose anything. Never heard of any of the new systems actually gaining power.

Out of all of them I always thought the fat boy tips by Rex looked the best.. There is a problem on his website with the power silencers so they aren't displaying or I'd post a picture.

Dave when I bought my shockwave the previous owner already installed the rex marine power silencers. Is this what you were referring to? I never got to hear or feel the boat with regular tips on the 454 magnum. I am curious to how much they actually kill the sound because my boat is actually pretty quiet.

Those are the ones I was referring too..



Oh and Joe, ya got most of it, but you're missin something..

RD

 

[GR8WHITE]

How much do the power silencers actually quiet the exhaust?

 

[djunkie]

I got these on my boat. Not sure what kind they are but the boat is still pretty loud with them. Wonder how much, if any, power I'm losing with them.

 

[RiverDave]

How much do the power silencers actually quiet the exhaust?

Rex is on here, I'm sure he can answer that.

RD

 

[GR8WHITE]

Rex is on here, I'm sure he can answer that.

RD

Paging Rexone, come in Rexone.:champagne:

 

[POWERCATDON]

I have been running Northstars since the test at lake elsinore several years back. I have had one stay open after a run and broke one of the internal springs. they are still working great. not to sure on the loss of power or RPM. but i increased the boost on the blower and if need be i can hit the button with my foot and activate the bottles. I sure miss the old sound. But know i can hear the music when crusin. Boat is fast enough for this old man.

 

[skav]

Ha. Gotcha.

 

[skav]

These are the tips it had before the Gibson bullets. It sounded good, but was very loud towing the kids.

These didn't look removable, so I left them in with the bullets.

 

[skav]

I just talked to Gary (GT) and he told me to take the bullets off cause they are too restrictive for my motor. He told me that he'd build me some Gatling tails.

Anybody want some basically brand new 4 1/2" gibson bullets?


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[charlyox]

Do they look like these? This is what I put on back in '05 when all the noise crackdown was going on. At Havasu they had a decibel meter where you launched to check if you were "legal". I put these on and they much deeper tone. I didn't notice any power loss.

 

[skav]

Do they look like these? This is what I put on back in '05 when all the noise crackdown was going on. At Havasu they had a decibel meter where you launched to check if you were "legal". I put these on and they much deeper tone. I didn't notice any power loss.

Yep. That's what they look like. Probably about 14" long.

 

[rivermobster]

Oh and Joe, ya got most of it, but you're missin something..

RD

Im not missing anything, I'm just not going all Tom Brown on this subject!

There is TONS of info on exhaust tuning. Novels have been written on this subject! I'm just tryin to give the OP the idea that no one can answer his questions. You would need a dyno with an a/f meter to give an acurate answer. Too many variables here.

 

[RLJ676]

I have straight dry exhaust that exit above the rubrail/swim platform....needless to say I'm veeeeeery loud for a single HP500. I tried some of the slip in mufflers that are good for up to 500 hp. It made it much more civil sounding, but I lost a great deal of power (6-7 mph, broken tach prevents me from knowing rpm....). That is until I started it up one day and blew one out!

 

[RCDave]

Rex is on here, I'm sure he can answer that.

RD

I had those Rex Marine muffler tips installed on my Shockwave. It quieted it down significantly. They are excellent quality and IMO the best looking on the market. They replaced the tips that came stock on my boat. I did loose 1-2 mph and about 100-150 rpm on my 496HO.

 

[fed4life]

When bought my Cobra the Rex Marine Power Silencers were already on the boat. In talking with the previous owner they were installed when the boat was ordered in 2005. I have contemplated taking them off just for the simple fact that i wanted to hear more rumble but in the end i decided not to. There a pain in the ass to take off and honestly, i really like the beefy look of them, especially when there all polished up. I couldnt tell you if they rob any HP or not but i know my boat does a solid 70 gps and thats good enough. I also like the fact that at idle i can still hear the engine rumble but its not to loud that i cant hear it over the stereo.

 

[CoolCruzin]

Was going to take out mine when I got the boat new.Never did .
Nice to hear the stereo .Loud gets old at the end of the day.

 

[Outdrive1]

I just talked to Gary (GT) and he told me to take the bullets off cause they are too restrictive for my motor. He told me that he'd build me some Gatling tails.

Anybody want some basically brand new 4 1/2" gibson bullets?


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Gatling tails look like stock tips. For a muffler its a great looking system .

 

[Guest]

My boat had mufflers on it.......for 1 hour. They were promptly replaced with a pair of Rex Marine Signature Superflapper tips.....Anyone want to buy a 1 hour old set of Eddie Marine Muffler Tips?