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Discussion Starter #1 (Edited)
The attached doc explains the Pro Pipe baffle mod more clearly. The dyno is not mine but a mild build, one with the standard baffle and the modfied baffle with dyno tune on the same day. Notice the big boost in torque on the low end. 95 tq @ 2500 rpm - 100 tq @ 3000 rpm

 

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And just what mod was done?
 

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How does this mod effect the TQ curve differently than simply banding up one or two rows of holes on the baffle as some here suggest to essentially accomplish the same thing?
This mod isn't as simple to do but it is pretty easy if it's more effective, I would use it. My problem is that I don't have a dyno to play with different options and no competent tuner so....
I will be installing a TVII closed loop system soon and will use one of these mods to try to get rid of that low end dip I get from my propipe.
So any of you dyno/exhaust expert types wanna chime in on this? I know alot of peeps here have propipe and would like to use the best mod.

Hey Chas, I see you are in Flagataff, isn't that 7000 feet? Was that dyno done up there? pretty impressive if it was and with MM/EFI too! Do you know what the engine mods were?
 

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Discussion Starter #5 (Edited)
Any doubts

Any doubting Thomasa's block off the first row of holes on your baffle and show us a dyno chart of the before and after. Blocking the holes is an old trick and restricts the flow a bit. This might or might not be the best for your particuliar build.

The mod I did is tunable on the dyno or seat of the pants. The first one I modified didn't do much. I had 4 holes and the washer was 2" from the baffle. I drilled more holes and turned the bolt out until there was 1/2" left on the engine side.

I test rode the Deuce with 3.15 gearing and 17" rear wheel at 7,000ft alt. The shift from 1st to 2nd spun the rear tire. At 1100 ft in Phoenix a roll on in 1st (make sure the bike is pointed straight ahead) and it will lay a strip 10-12ft.

I later added some fuel with my laptop at 80 to WOT from 4000 to 6200 rpm which helped the top end lean condition caused by the mod.

Next week I will dyno with the Pro Pipe mod and then with a new tune with the D&D Fat Cat which arrived yesterday. I will post the three charts, Pro Pipe no mod, Pro Pipe mod and D&D Fat Cat.
 

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Cool, I happen to have an extra baffle for my propipe so I am gonna do one your way and one with a row or two of holes banded. Won't have a dyno print out sept for the one in the seat of my pants, that might not be very pretty.....

Any reason you can't weld the washer to the bolt other than loosing the tuning option of different sized washers?
 

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chas2379 said:
The attached doc explains the Pro Pipe baffle mod more clearly. The dyno is not mine but a mild build, one with the standard baffle and the modfied baffle with dyno tune on the same day. Notice the big boost in torque on the low end. 95 tq @ 2500 rpm - 100 tq @ 3000 rpm

Chas...
With your modified baffle, what did you do about the fiberglass? I rode 1000 miles high speed to and from Daytona a few weeks ago with a brand new PPHS and half of the fiberglass is blown/burnt out of it. Do you keep your glass repacked or just remove it and cover some holes?
 

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If you want to keep your fiberglass, you gotta put a strip of aluminum window screen around the outside and underneath. The screen that comes underneath the fiberglass deteriorates and when it does your fiberglass blows out soon afterwards. Hold the screen in place with some safety wire.
 

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Chas,
please do me a favor and cut and paste so i can see your mods, i am not able to open your file. Really want to see what you have done. Did you notice any diff in sound with mods? performance sounds like impressive change. What gave you the idea to do this?
 

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Discussion Starter #10 (Edited)
tyler1300 said:
Chas,
please do me a favor and cut and paste so i can see your mods, i am not able to open your file. Really want to see what you have done. Did you notice any diff in sound with mods? performance sounds like impressive change. What gave you the idea to do this?
The total bolt length is 4" . I drilled nine, not the 4 shown, 7/16" holes in the end of baffle with one in the center for the bolt.


I welded one lock nut on the end of the baffle. I put a 1 5/8" washer on the bolt and use a nut to hold the washer next to the bolt head. I then inserted the bolt from the back of the baffle through lock nut that was welded to the baffle. The bolt extends through the baffle a total of 1/2" including the nut.

This is a starting point for your tune. Your bike should be dyno tuned and the bolt with the washer can be adjusted in or out with a socket and extension

The end of the stock street baffle is closed and has no holes. The washer is not welded but held with the nut. This way you can change the size of the washer. Some builds might need a larger washer. You won't really know for sure until you have it on the dyno.

 

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Discussion Starter #11
Geezerdog said:
Chas...
With your modified baffle, what did you do about the fiberglass? I rode 1000 miles high speed to and from Daytona a few weeks ago with a brand new PPHS and half of the fiberglass is blown/burnt out of it. Do you keep your glass repacked or just remove it and cover some holes?
I just wrapped copper wire around fiberglass. Probably doesn't hold the glass as good as screen.
 

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Thanks for taking the time to shaare this info. A couple of questions. Why do you think this works? Is this just adjusting the back pressure? Why the need for the additional holes drilled in the end of the baffle? I have tried to use screen under and over packing around the length of the baffle but it never lasts. Do you think extending a "washer" perhaps 1/2" larger than the edge of the end of the baffle< secured with the welded nut would act as a deflecter and prevent the direct flow of the exhaust from tearing apart the wrap. I could still drill the 4 or 6 holes through the washer.
Besides back pressure improvement i really want to make this pipe quieter for touring. You seems to have some insight into the physics here, any suggestions on quieting this down without destroying the performance would be really appreciated.
 

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tyler1300 said:
Thanks for taking the time to shaare this info. A couple of questions. Why do you think this works? Is this just adjusting the back pressure? Why the need for the additional holes drilled in the end of the baffle? I have tried to use screen under and over packing around the length of the baffle but it never lasts. Do you think extending a "washer" perhaps 1/2" larger than the edge of the end of the baffle< secured with the welded nut would act as a deflecter and prevent the direct flow of the exhaust from tearing apart the wrap. I could still drill the 4 or 6 holes through the washer.
Besides back pressure improvement i really want to make this pipe quieter for touring. You seems to have some insight into the physics here, any suggestions on quieting this down without destroying the performance would be really appreciated.
I haven't had any trouble with the wrap. It's still in my current exhaust after 2 years. Before the first dyno run with the Pro-Pipe, I drilled some extra holes in it. Then we ran it like that, then used a hose clamp to tune it. I ended up welding two of the holes closed to get the most torque. It runs great now! NO dips in the torque curve below 5200 rpm. :)
 

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why did u drill the holes in the first place? What do u feel was the net effect of drilling the holes.

I sometimes wonder that if it was that simple to improve this pipe why didn't/ doesn't V&H di it. They must have a dedicated department of engineers devoted to computed simulations of air flow turbulance/ laminar flow and back pressure. Designed with the aid of stratigically designed sensors to measure these various factors. After all they are in a competition for performance with other major players in the after market exhaust industry. If drilling 2-4 holes would dramatically improve the product i can't believe they wouldn't do it. What the trade off--i mean free torgue waiting to be had?

Perhaps your wrap was not torn up as mine was BECAUSE you drilled a few holes thus changing the flow dynamics inside the exhaust can.

Chas, thanks again
Steve
 

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tyler1300 said:
I sometimes wonder that if it was that simple to improve this pipe why didn't/ doesn't V&H di it. They must have a dedicated department of engineers devoted to computed simulations of air flow turbulance/ laminar flow and back pressure. Designed with the aid of stratigically designed sensors to measure these various factors. After all they are in a competition for performance with other major players in the after market exhaust industry. If drilling 2-4 holes would dramatically improve the product i can't believe they wouldn't do it. What the trade off--i mean free torgue waiting to be had?
Chas, thanks again
Steve
They don't do it because they made the pipe for EVERYONE, not just one type of build. Thats why they sell competition baffles too. It's a good starting point for home tuners.
 

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Geezer-Glide said:
They don't do it because they made the pipe for EVERYONE, not just one type of build. Thats why they sell competition baffles too. It's a good starting point for home tuners.
Exactly! No two bikes are the same, unless they are bone stock. They make the pipes to perform in an acceptable manner for a stock machine or one with the usual minor mods like new air cleaner and most bolt-in cams. If you want to use them on a more heavily modified bike, they you usually have to fine-tune them to get the best performance. This applies to just about any exhaust system except the cheap ones without removable baffles.

I have easy (and cheap) access to a dyno, so I don't mind experimenting. I knew from past experience that an engine set up like mine needs a bit more flow to get the most torque down in the lower rpm range where I want it. That's why I predrilled it before I dyno-tuned it. The Pro-Pipe baffle is very simple in design and easy to tune by either drilling, welding, or adding hose clamps. I've actually had to weld a couple holes shut on a few bikes I've built to get the most torque where the customer wanted it.
 

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ToddM said:
Exactly! No two bikes are the same, unless they are bone stock. They make the pipes to perform in an acceptable manner for a stock machine or one with the usual minor mods like new air cleaner and most bolt-in cams. If you want to use them on a more heavily modified bike, they you usually have to fine-tune them to get the best performance. This applies to just about any exhaust system except the cheap ones without removable baffles.

I have easy (and cheap) access to a dyno, so I don't mind experimenting. I knew from past experience that an engine set up like mine needs a bit more flow to get the most torque down in the lower rpm range where I want it. That's why I predrilled it before I dyno-tuned it. The Pro-Pipe baffle is very simple in design and easy to tune by either drilling, welding, or adding hose clamps. I've actually had to weld a couple holes shut on a few bikes I've built to get the most torque where the customer wanted it.
Todd,

Didn't realize you had such experience with these. Any thoughts on direction to take for my 98", 585, CV44 build? Right now, I've got the std baffle, blown-out fiberglass, no dips and it actualy runs pretty strong. I'm just a little lean right now and installing a new a/c - so I'll get leaner... so I'll combine a little exhaust tuning while on the dyno.

Was thinking of playing with hose clamps on a row or two . Any thoughts on which direction would be a good start - your washer/screw combo, hose clamps or??


GC
 

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FXDRYDR said:
Todd,

Didn't realize you had such experience with these. Any thoughts on direction to take for my 98", 585, CV44 build? Right now, I've got the std baffle, blown-out fiberglass, no dips and it actualy runs pretty strong. I'm just a little lean right now and installing a new a/c - so I'll get leaner... so I'll combine a little exhaust tuning while on the dyno.

Was thinking of playing with hose clamps on a row or two . Any thoughts on which direction would be a good start - your washer/screw combo, hose clamps or??GC
Actually, Chas2379's idea about using the bolt and washer sounds pretty good. It would be a lot easier to tune. I'll have to try it sometime.

If you decide to do it my way, this is my usual procedure:

Make a few runs with the pipe in stock form.

Due to your engine size, I'd start by drilling maybe four 5/8" holes holes around the outside of the baffle between the other holes and try to space them as equally as possible. That will enable you to use a hose clamp to close them off as needed. Then fire it up and adjust the mixture for best AFR and compare the results with the first runs.

If your torque is going in the right direction, try another hole. Add one at a time until it stops improving. If it starts dropping, slightly covering a row of holes. Keep covering more and more until you get it where you want it. This will take some time, so hopefully the guy who owns the dyno doesn't charge an arm and a leg. Anyone charging over $75/hour is ripping you off, IMHO. Most stealerships will charge more than that... but that's expected of them. :(
 

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Todd,
it's interesting that in your last post you talk about drilling additional holes on the side of the baffle but in your diagram you drill the holes on the end of the baffle. Why the difference?

I followed your directions for drilling the end of the baffle and also used the bolt with washer. Seat of the pants results were extremely positive. Definitely feels like it's "breathing" easier. Even idles a bit smoother. Pulls beautifully to my new "Rev Extended" 6,500rpm redline. I'm not sure but the pipe seems to have a different improved lower tone. Not so much thwak, thwak. More rhinehart sounding. Even though i think the pipe is loud the lower tone makes it less irritating.

I did one additional thing which you make think is strange,but what the heck. I mentioned earlier that my baffle wrap < not the piece on the very end> keeps getting blown off despite screens etc. So i placed a oil filer remover, you know the thing you put a ratchet into over the end of the baffle and ran the bolt up through that. It fit very snug & coveered up one row of holes. I drilled the four holes through that then into the end of the baffle. This provides about a 1/4 overhang that I'm hoping will cause the blast of exhaust gas to not slam directly into the leading enge of the wrap.

Bottom line, thanks for your suggestions and followups on this topic, FYI I'm running Andrews 37, pwr command, big sucker w/ the PPHS.
Take care
Steve
 

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tyler1300 said:
Todd,
it's interesting that in your last post you talk about drilling additional holes on the side of the baffle but in your diagram you drill the holes on the end of the baffle. Why the difference?Take care
Steve
Steve, if you look again at that post with the diagram, you will see that it was not posted by me. It was from chas2379. I prefer to drill around the outside the the baffle which makes it easier to fine-tune with the hose clamp. Straight-through airflow isn't desired in this type of system, or V&H would have put their holes in the end of the baffle rather than around it's circumference. Chas2379 partially compensates for his holes in the end by using the washer to inturrupt the airflow slightly.

About your solution with the wrap, it sounds like it will work ok. I still haven't had any problem losing the wrap in my baffle, at least not yet. I did try removing it when doing the dyno testing and didn't notice any significant difference in performance. The increase in sound level was minimal too. The difference was well within the margin of error of the dyno, so it may not have had any effect at all. If mine ever blows out, I'll just leave it that way. It's not worth messing with for just a couple HP or ft.lbs., since there are a lot of variables that can cause that kind of change during a normal run. Besides, I don't bother with dyno shootout. Numbers are just for bragging anyway, IMHO. As long as it's running good for me on the street, who cares about actual numbers? I just use them as a reference to see if any changes I make are having any effect at all. If I don't see a change of at least 4, then I don't consider it effective.
 
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