Baffles vs. no Baffles

[freshmaker]

Any thoughts on baffles? I recently put the Cobra Streetrod pipes on and ran them without baffles for a few miles. Loved the sound! I then put the baffles in and it's kind of lame. I'm considering some Big City Thunder baffles but need the cash for other mods for now.

[Mr.Sinister]

What did you think of performance wise ? I run staight pipes no baffles . I have considered some small baffles for a little backpressure . I would lose a little in the sound department but gain a little in performance . Also at the end of a 30+ minute ride I would not have any hearing loss .

[navillustoo]

QUOTE=Mr.Sinister]What did you think of performance wise ? I run staight pipes no baffles . I have considered some small baffles for a little backpressure . I would lose a little in the sound department but gain a little in performance . Also at the end of a 30+ minute ride I would not have any hearing loss .[/QUOTE]

Sin,
I've seen you and a few others refer to a performance gain by introducing a "little back pressure" into their exhaust systems. I can't sit by and not comment on this misconception! I don't know who started or where this idea of back pressure being a performance gain came from, but that is very wrong! Why people may think they have gained performance from introducing back pressure into the exhaust is because the back pressure moves the torque curve lower in the RPM range of the engine. It lowers the RPM at which the peak torque occurs, which also lowers the peak horsepower that is made by the engine. Ultimately, you are lowering the engine's performance! It may feel like the engine picks up power off the line because of the lower torque peak, but it will kill the top end. The best performing exhaust system is one that is straight through, no restrictions! The way many exhaust manufacturers keep the torque peak at a lower RPM is by building stepped head pipes. These start out at a smaller diameter than what is normally used(mostly 1-5/8") and then they're stepped up to successively larger pipes. What this does is keep the hot gases flowing at a greater volocity in the smaller pipes, then as the gases cool down and expand, the pipes get bigger to maintain that high volocity of flow. Keeping the flow of exhaust gas volocity high is key to a good performing engine. The best exhaust system period, is a 2 into 1 system. These use the alternating flow from the pipes to scavenge the other pipe of exhaust gas, that is why there is such a large gain of power with a V8 engine when you install headers in lieu of the cast iron exhaust manifolds that the car makers use.
I hope this helps to clear up the misconception that many seem to have concerning back pressure! Back pressure is NOT a good or necessary thing! If you want more low end acceleration and to make the most horsepower your engine is capable of, the bets way is unbaffled pipes and a lower gear ratio. That's how drag racers do it!

Brian

[Menace]

Any thoughts on baffles? I recently put the Cobra Streetrod pipes on and ran them without baffles for a few miles. Loved the sound! I then put the baffles in and it's kind of lame. I'm considering some Big City Thunder baffles but need the cash for other mods for now.

I went with the big city thunder monsters. I would not compare these to baffles becuase there is almost 0 restriction, but the sound was much meaner than baffles.

[RustyJake]

Thanks for the lesson Brian. I always enjoy reading the information you provide. I'm sure when it's mentioned about gaining power, is exactly what you indicated, the 'feel' of the power in the lower RPM which is related to introducing some back pressure. Having torque at a higher RPM may not be an advantage with the v-twin??
Isn't a little back pressure good for the engine? (valves). Or is that something that's a misconception as well? Figured this was a good opportunity to ask about some of these seeing we're on the subject.

[navillustoo]

Thanks for the lesson Brian. I always enjoy reading the information you provide. I'm sure when it's mentioned about gaining power, is exactly what you indicated, the 'feel' of the power in the lower RPM which is related to introducing some back pressure. Having torque at a higher RPM may not be an advantage with the v-twin??
You're definitely right about that Glenn, a V-twin engine, especially those with single crank pins, are not designed for or able to produce at high RPMs. Even though you can feel the difference in the seat of your pants, we're only talking about the torque peak moving up a couple hundred RPM. It wouldn't take much of a gear change to take advantage of this increased torque.
Isn't a little back pressure good for the engine? (valves). Or is that something that's a misconception as well? Figured this was a good opportunity to ask about some of these seeing we're on the subject.
I've never heard this one! I don't know how back pressure could be good for the valves. There are two things I know about taking care of your valves. One, don't run the engine too lean or you will burn valves, and two, don't run too short of an exhaust pipe or you will burn exhaust valves. I believe that back pressure being good for an engine is as big a misconception as it being a performance gain. Automotive engineers use the back pressure, created from having to silence their engines to meet federal requirements, to their advantage. They use it to lower the torque peak, which will get the vehicle moving sooner and with less fuel consumption. Of course these values are so minute as to be immeasureable, but that's what they'll claim!
The bottom line is if you want to make as much horsepower and torque as you possibly can with any engine, you want to reduce or eliminate back pressure altogether. Unbaffled pipes are the only way to do this.

Brian[

[SuperCharged666]

I herd that if you put straight pipes on your bike you have to rejet the carbs? Anybody know why?

[freshmaker]

To tell you the truth, I noticed no performace gain or loss. What I did notice the sound... LOVE IT. I guess I'll just continue to run without.

[navillustoo]

I herd that if you put straight pipes on your bike you have to rejet the carbs? Anybody know why?
SC,
The why is that the straight pipes allow the engine to breathe more freely. With more air flowing through the engine, you'll need more fuel to maintain a proper Air/Fuel ratio. If straight pipes are added without rejetting, the engine will be too lean and you'll run the risk of doing internal damage to the engine. Not to mention the fact that you'll not realize the performance gain you're looking for by adding the straight pipes.

Brian

[ickmak]

My Eyes hurt now:smart: , Thanks for the info

[Mr.Sinister]

Nav , Thank You ! That clears up alot . New ??????????? Gearing . Sprocket with less teeth or more for off the line ? Any ideas on how many teeth ? I don't need to go to 80+mph . 0-75 faster would be more useful .

[navillustoo]

Nav , Thank You ! That clears up alot . New ??????????? Gearing . Sprocket with less teeth or more for off the line ? Any ideas on how many teeth ? I don't need to go to 80+mph . 0-75 faster would be more useful .

Sin,
For quicker off the line acceleration, you would need a sprocket with more teeth. This will cause the engine to turn more RPMs at highway speeds, which alot of people complain about. You'd probably want to use a Dyna ignition box as well, to allow a higher rev limiter setting(I'm guessing the 750's have a rev-limiter like the 1100's do, I've never hit the rev-limiter on our 750's though!) This will allow you to take advantage of the extra horsepower you're making, instead of cutting off before peak power is realized. This ignition is part of the performance up-grade that http://www.designedperformance.com sells for the 750's.
As far as how many more teeth, I don't really know, but if I had to guess, I would say only a couple more than the stock 41 tooth sprocket. I'd be inclined to try the engine mods you have with the stock sprocket and see how that works, I have never seen any 42 to 44 tooth sprockets for the 750's. Most folks seem to want more top end and opt for the 37 or 39 tooth sprockets.

Brian

[Mr.Sinister]

I rarely get over 70 . Not because I cant .Because all my ridding is around town . If 70 was my top speed I would be ok with that so long as I got there really fuckin fast . I have only done 100+mph twice on my bike . Both times in the first 2 months I had it . I don't have to be able to pop wheelies . But I would like that kind of grunt . :happy: Thanks again .

[fegs]

I've never heard this one! I don't know how back pressure could be good for the valves. There are two things I know about taking care of your valves. One, don't run the engine too lean or you will burn valves, and two, don't run too short of an exhaust pipe or you will burn exhaust valves. I believe that back pressure being good for an engine is as big a misconception as it being a performance gain. Automotive engineers use the back pressure, created from having to silence their engines to meet federal requirements, to their advantage. They use it to lower the torque peak, which will get the vehicle moving sooner and with less fuel consumption. Of course these values are so minute as to be immeasureable, but that's what they'll claim!
The bottom line is if you want to make as much horsepower and torque as you possibly can with any engine, you want to reduce or eliminate back pressure altogether. Unbaffled pipes are the only way to do this.

Brian[

Well, from an engineering point of view, back pressure is "good" depending on what you are biulding. On our rotary engines, it works well as it allows for better fuel mixure and overall gas (hc, co and nox) from the exhaust. Also, hp improvement is not solely based on exhaust, consider intake air, temperature, ms of fuel (fuel injected of course), timing, valve opening and duration, etc. It s all relative to what you are building and final goal of the engine, design ,etc.....

[snakeeyes]

QUOTE=Mr.Sinister]What did you think of performance wise ? I run staight pipes no baffles . I have considered some small baffles for a little backpressure . I would lose a little in the sound department but gain a little in performance . Also at the end of a 30+ minute ride I would not have any hearing loss .
Sin,
I've seen you and a few others refer to a performance gain by introducing a "little back pressure" into their exhaust systems. I can't sit by and not comment on this misconception! I don't know who started or where this idea of back pressure being a performance gain came from, but that is very wrong! Why people may think they have gained performance from introducing back pressure into the exhaust is because the back pressure moves the torque curve lower in the RPM range of the engine. It lowers the RPM at which the peak torque occurs, which also lowers the peak horsepower that is made by the engine. Ultimately, you are lowering the engine's performance! It may feel like the engine picks up power off the line because of the lower torque peak, but it will kill the top end. The best performing exhaust system is one that is straight through, no restrictions! The way many exhaust manufacturers keep the torque peak at a lower RPM is by building stepped head pipes. These start out at a smaller diameter than what is normally used(mostly 1-5/8") and then they're stepped up to successively larger pipes. What this does is keep the hot gases flowing at a greater volocity in the smaller pipes, then as the gases cool down and expand, the pipes get bigger to maintain that high volocity of flow. Keeping the flow of exhaust gas volocity high is key to a good performing engine. The best exhaust system period, is a 2 into 1 system. These use the alternating flow from the pipes to scavenge the other pipe of exhaust gas, that is why there is such a large gain of power with a V8 engine when you install headers in lieu of the cast iron exhaust manifolds that the car makers use.
I hope this helps to clear up the misconception that many seem to have concerning back pressure! Back pressure is NOT a good or necessary thing! If you want more low end acceleration and to make the most horsepower your engine is capable of, the bets way is unbaffled pipes and a lower gear ratio. That's how drag racers do it!

Brian[/quote]

navillustoo, I dug this thread up from the grave. You seem pretty confidant in talking about how straight pipes are better than baffled pipes. I dont disagree, as everyone in this forum has been telling me how it's a "scientific fact" that baffles and back pressure increase your HP, and that running un-baffled pipes is bad and loses HP.

I just installed cobra drag pipes not too long ago and love them without baffles. The baffles in sounded like shit and too muffled for me. I didnt notice a difference though between the two as far as power or performance. I came on here asking a few questions about my unbaffled cobras and people freaked out telling me I'm loosing power, messing up my engine etc etc.

you seem like you know what your talking about and your insight made me feel better about running no baffles now. Everyone was trying to tell me how I should either put my cobra baffles back in or buy BCT baffles, which I dont think are bad, I just like what I have now. no baffles. Thanks.

[Fuzzzy]

hmmm high RPMs well lets see umm thinking . Oh i got it the more rpms the lower the Hp . just google it . If rpms go up you loose hp . pretty simple i think .

[mcvierh]

it's not about the back pressure FreeSpirit....people just don't know how to say it right and for a lack of a better term call it back-pressure....it's the scavenging phenomena their all talking about.....do a search using the key word "phenomena"..I've posted on it so many times I'm not doing it anymore, well maybe not this week.

[Fuzzzy]

it's not about the back pressure FreeSpirit....people just don't know how to say it right and for a lack of a better term call it back-pressure....it's the scavenging phenomena their all talking about.....do a search using the key word "phenomena"..I've posted on it so many times I'm not doing it anymore, well maybe not this week.

The best way to prove baffles or not is put two 750s side by side and take off like a bat out of hell . my bet is on the one with baffles . Think a while back i seen on here about how fast will ss750 go. Well not sure but i think you said well over 100 mph alot did not agree that yours went that fast well im here to tell you i beleave cause ive had mine well over 100. thanks to you. and your post. and if im not wrong hp power is speed not rpms.

[mcvierh]

The best way to prove baffles or not is put two 750s side by side and take off like a bat out of hell . my bet is on the one with baffles . Think a while back i seen on here about how fast will ss750 go. Well not sure but i think you said well over 100 mph alot did not agree that yours went that fast well im here to tell you i beleave cause ive had mine well over 100. thanks to you. and your post. and if im not wrong hp power is speed not rpms.

Mine clocked 126.6, that was WOT............

[Fuzzzy]

Dont where 126 is had mine just a hair passed the temp light. Ive got a dyna 3000 hooked up to mine tho.

[Fuzzzy]

oh for got WT..........

[HitCat44]

Just plain pitiful, this "sumped up" thread is a classic example of reading the truth but it doesn't fit his situation so he digs up past misconceptions to make him feel better and justified in closed eyed bliss.
Believe it, Baffle it, or don't. Your choice. But, enough with the incessant and tiresome self-justifications.
+10 to McV and his dead-on knowledge and experience in this, and other such, issues. :thumbsup:
My Pipes are baffled but my brain is thankfully not. (Wife disagrees :sad: )

[Bastard1962]

Bringing this post back from the dead....

cut my pipes and exhaust off my 86 shadow. bought can opener baffles despite what i've heard about their sound. they were $6. few questions...

whether back pressure is good for hp or not isn't my concern. I just want to know how bad the backfiring and popping, especially when quickly decelerating in gear, is and if the baffles are the answer.

I haven't installed the baffles yet cause i love the sound of my pipes minus the occasional backfire and popping. i bought 4''ers and am wondering if takin 2'' off of them will help keep that disrupting the neighborhood sound!?



***edit this sums up the entire discussion..


Sin,
I've seen you and a few others refer to a performance gain by introducing a "little back pressure" into their exhaust systems. I can't sit by and not comment on this misconception! I don't know who started or where this idea of back pressure being a performance gain came from, but that is very wrong! Why people may think they have gained performance from introducing back pressure into the exhaust is because the back pressure moves the torque curve lower in the RPM range of the engine. It lowers the RPM at which the peak torque occurs, which also lowers the peak horsepower that is made by the engine. Ultimately, you are lowering the engine's performance! It may feel like the engine picks up power off the line because of the lower torque peak, but it will kill the top end. The best performing exhaust system is one that is straight through, no restrictions! The way many exhaust manufacturers keep the torque peak at a lower RPM is by building stepped head pipes. These start out at a smaller diameter than what is normally used(mostly 1-5/8") and then they're stepped up to successively larger pipes. What this does is keep the hot gases flowing at a greater volocity in the smaller pipes, then as the gases cool down and expand, the pipes get bigger to maintain that high volocity of flow. Keeping the flow of exhaust gas volocity high is key to a good performing engine. The best exhaust system period, is a 2 into 1 system. These use the alternating flow from the pipes to scavenge the other pipe of exhaust gas, that is why there is such a large gain of power with a V8 engine when you install headers in lieu of the cast iron exhaust manifolds that the car makers use.
I hope this helps to clear up the misconception that many seem to have concerning back pressure! Back pressure is NOT a good or necessary thing! If you want more low end acceleration and to make the most horsepower your engine is capable of, the bets way is unbaffled pipes and a lower gear ratio. That's how drag racers do it!

Brian

navillustoo, I dug this thread up from the grave. You seem pretty confidant in talking about how straight pipes are better than baffled pipes. I dont disagree, as everyone in this forum has been telling me how it's a "scientific fact" that baffles and back pressure increase your HP, and that running un-baffled pipes is bad and loses HP.

I just installed cobra drag pipes not too long ago and love them without baffles. The baffles in sounded like shit and too muffled for me. I didnt notice a difference though between the two as far as power or performance. I came on here asking a few questions about my unbaffled cobras and people freaked out telling me I'm loosing power, messing up my engine etc etc.

you seem like you know what your talking about and your insight made me feel better about running no baffles now. Everyone was trying to tell me how I should either put my cobra baffles back in or buy BCT baffles, which I dont think are bad, I just like what I have now. no baffles. Thanks.[/QUOTE]

[crimsonblooded]

Bastard.. how bout an intro in the intro thread... with pics of this invisible bike you speak of... no pics=no bike

[HitCat44]

:no: :no: :no: :no: :no: :no: :no: :no:

[Bastard1962]

check the edit

[JayT]

INTRO! Why help? where the bike? who are you?

[Bastard1962]

edited post! because i'm dumb! broke, no camera or computer, so no pics! im your long lost little sister with a beard.

[HitCat44]

check the edit

I did, Still Horseshit. :thumbsdow

CHECK THIS.... :flipa:

Ya making UpState look bad Forrest. Quit it and get with the program Yooz Fuck :thumbsup:

[Bastard1962]

I did, Still Horseshit. :thumbsdow

CHECK THIS.... :flipa:

Ya making UpState look bad Forrest. Quit it and get with the program Yooz Fuck :thumbsup:


It's obvious that whether I install the baffles or not is entirely my decision. My question about the can openers reducing the popping still stands as well as my question of making them shorter.

[HitCat44]

baffles or not is entirely my decision

AB-SO-FUCKIN-LUTELY
Likewise, So is the ISSUE. And, So is OUR choice on whether or not to assist...
Enjoy!

[Bastard1962]

i'd say my post was pretty ambiguous and worth some clarification.

[BaldEagle]

Ah, a noob who is proud of himself. :baby: :blushing:

[gb6049]

No baffles -

* sounds good, check
* looks good, check
* runs good, check

Thats all I need to know, got torque cones myself. Pipes are getting a nice copper patine to em.

[mcvierh]

Hey you Bastard do you really wanna lose that popping?, then why the fuck don't you just adjust you A/F mixture screws since you now running lean as all get out. Click that thing to the right and just type in "air fuel adjustment"-->http://www.shadowriders.net/forums/tren_z/misc/tren_z_header_search.gif (http://www.shadowriders.net/forums/search.php) Oh yeah I almost forgot, Fuck Off, and Welcome to The Dark Side of The Shadow World.