Torque difference w/ baffles : V-Twin Forum: Harley Davidson Forums

larose481 · 04-07-2009, 04:12 PM

I have an 06' Night Train with a set of the staggered bs without baffles and love the way it sounds. My question is, I was wondering if anyone has any real torque number differences between w/ or w/out the baffles. I am installing a set of Andrews 26's next week and will have to have it dyno tuned and was wondering if it is a huge difference with the baffles as I would prefer to leave them out and if I was to take them with me to the dyno and the map is way different between the two then I will get boned on the dyno price as they have a set price for a custom map and if I start changing things that will effect the map I am sure to pay for it. Other than the pipes, PCIII, and S/E air cleaner it is a stock 88". Thanks.

dynarule · 04-07-2009, 04:37 PM

Without the baff's you will loose on the low to mid but scream on the top, you need back pressure to gain torque. If you put them in (and i highly recomend you do) you will see an increase in your torque for sure,and it will still be plenty loud as i too have these same pipes.

Dave63 · 04-07-2009, 04:42 PM

Quote:

Originally Posted by dynarule

Without the baff's you will loose on the low to mid but scream on the top, you need back pressure to gain torque. If you put them in (and i highly recomend you do) you will see an increase in your torque for sure,and it will still be plenty loud as i too have these same pipes.

You need exhaust velocity for torque, which increases scavaging and improves performance.

dynarule · 04-07-2009, 04:43 PM

Quote:

Originally Posted by Dave63

You need exhaust velocity for torque, which increases scavaging and improves performance.

I think you may be wrong here!

Dave63 · 04-07-2009, 04:46 PM

Quote:

Originally Posted by dynarule

I think you may be wrong here!

Please look it up so I can spare myself of explaining it again....

If engines needed backpressure to make torque, then dragsters wouldn't do 100 mph.

Or read:

http://www.thumpertalk.com/forum/sho...d.php?t=659727

http://my.prostreetonline.com/forums...php?t-1639.htm

dynarule · 04-07-2009, 04:52 PM

No Baffs = Top End!
Baffs = Low End!

dynarule · 04-07-2009, 04:57 PM

You might want to re read your own links. Why do you think they put those baffs in at the very end of the pipe? Speed up maybe? Put the restriction at the end and wa la.

Dave63 · 04-07-2009, 05:10 PM

Quote:

Originally Posted by dynarule

You might want to re read your own links. Why do you think they put those baffs in at the very end of the pipe? Speed up maybe? Put the restriction at the end and wa la.

Yeah.... that's why torque cones are installed at the heads.

This is Engines-101...simple stuff. Same reason 2-1 pipes generally make more torque and HPs then 2-2 pipes. Exhaust veloicity.

laserp · 04-07-2009, 05:13 PM

I'm no expert, but I believe the concept is to manage exhaust velocity. Without a baffle, it can be too high, torque dip. The baffle meters the exhaust velocity to where it needs to be, it,s not the back pressure that does it, it's tuning your exhaust pipe for your specific build. I've read opinions on this topic from the experts here and they all frown at the idea that it's back pressure your after.

dynarule · 04-07-2009, 05:14 PM

Quote:

Originally Posted by Dave63

Yeah.... that's why torque cones are installed at the heads.

Please go to tech school or something. This is Engines-101...simple stuff.

Trying to get the performance of baffs with the sound of drag pipes.
I think you may need to go to tech school. Engines 101. You may learn something today. LOL

Dave63 · 04-07-2009, 05:16 PM

OK....I'll do that.

You can get the sound of drag pipes with no baffles by simply reducing pipe diameter, and increasing exhaust flow/velocity AND increasing torque at the same time.

No baffles.

Why do you think 1-3/4" pipe is best on HDs?

Using the term "Back pressure" for a system based on optimum exhaust flow, velocity and scavenging tells me volumes about your knowledge of how engines work.

dynarule · 04-07-2009, 05:22 PM

Too bad you live in PA, I would buy you a beer and have a good ol time. Speaking of beer!!!!!! its beer thirty.

Dave63 · 04-07-2009, 05:24 PM

Quote:

Originally Posted by dynarule

Too bad you live in PA, I would buy you a beer and have a good ol time. Speaking of beer!!!!!! its beer thirty.

It's ALWAYS beer-thirty....

Back pressure is part of the equasion, but not the most important one.

Faast Ed · 04-07-2009, 05:27 PM

Quote:

If engines needed backpressure to make torque, then dragsters wouldn't do 100 mph.

Pretty sure he was talkin' about low-end torque. If dragsters were cruising around the country, up and down mountains, I think they'd change thier exhaust profiles.

larose481 · 04-07-2009, 06:57 PM

Thanks for all the responses so far and how fast. What are we talking as far as a loss between the two? Is it minor but enough to feel the difference or is it a large amount? I put the baffles in it tonight and it is ok but I still like it better without. Just trying to see if it is a major killer and should run them. I am sure there is an improvement with the baffles as I have looked as much as I could find but wondering how bad it is without. Maybe the best thing for me to do before I tear it apart is reload a map w/ baffles and go try it and see what it rides like. I would still like to see if anyone has done any dynoing both ways or a little better idea. Thanks again for the responses as this is my first post and glad to see you respond.