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single pipe w/c triple?

FTXMOTORSPORTS

Well-known member
Premium Member
Who out there has had any success with building single pipe/manifold combo's for big polaris w/c triples (1050-1350cc)? 70 stroke. Its definitely a bit of a black science and there is very little written about the process mathmatically or otherwise so I'm curious to hear what any of you may have tried-good or bad!Will be testing our own ideas in the upcoming months also. Oh, before I get all the "you're wasting your time" stuff, a pipe per cylinder is out of the question completely-could be a fun exercise I think!
Put yer thinking caps on kids....

curt
 
single twc

wouldnt the single pipe take some work out of turboing it? yes your going to lose base power from the single, but the turbo gain would put you well above tripple pipes right? might even prove people wrong with it in the raw chassis. raw 1200 twc
 
either

either way that set up opens more opportunities for chassis placement. i am not well informed on turbos anyway, just seems that it would be easy that way
 
nitro

make it look like a nitro exhaust out the back. figure out reverse well your at it, maby an 809 ratax ignition? good luck
 
thats what we need! A single pipe to bring the tq up on the WC motors, they really lack in that department!!! JK curt!!


Would be kinda neat to see how they would run with a correctly setup single! And it would really open up the list of sleds to stuff these awesome powerplants into!!!
 
Curt is that the reason for the single,so it could be put in a different chassis?
 
Curt... it has been done, and I know how to do it. I will trade you the info for a full set of Zbroz, 09' front conversion.... tunnel extension, carbon fiber boards... and let see what else I can come up with.... :D
 
Curt is that the reason for the single,so it could be put in a different chassis?

We are tinkering more with the 1 litre mod hydroplane, have found the limits of what can be done with the 1200 wet pipe.Are into a hull this season that will handle the power safely(phew!) and are currently developing a dry single pipe/manifold combo to go with the new top end layout we've schemed up to make even more power. Just so no one thinks I am looking to steal secrets...this is NOT for a turbo, not even for a sled so the power characteristics we are building are completely different and we are forced to use a single expansion chamber. Have talked with most of the big name and old school single pipe guys(sled and pwc) and there is definitely a lack of mathmatical process to this, was just curious if some of you had found any short cuts in development. Heres what I already know-the manifold length/design is key and with the cylinder spacing of a polaris w/c its pretty much impossible to build the "perfect" manifold.(for a wide useable powerband any way!) We've settled on a manifold design that we are fabbing currently. I've worked up a tuned length based on what we learned last season testing several "production" single pipes from various applications that will be the starting point of the pipe. I'm taking a few ideas from a friend in the pwc industry also and working them into the equation. We are also going to play with a couple mods on the wet pipe as well but are pretty limited due to the double walled areas of that pipe.
I'm curious to try and manipulate the chamber find the sweet spot that works along with the signals from two open exhaust ports and get it all to work in harmony in this application. also have exhaust valves on the new motor to add another tool to the bag.balance tubes,water injection etc-so much cool stuff to tinker with!
Alot of what we've learned over the years about building a pipe per cylinder doesn't apply here-thats what makes it most interesting to us.

So how about it, any input?

curt
 
I grabbed my copy of Gordon Blair's "Design & Simulation of 2-stroke Engines" as soon as I saw this.......guess what??? Nothing about triples so far, only 2 into 1 and 1 pipe per cyl calculations.

I'll keep reading.
 
We are tinkering more with the 1 litre mod hydroplane, have found the limits of what can be done with the 1200 wet pipe.Are into a hull this season that will handle the power safely(phew!) and are currently developing a dry single pipe/manifold combo to go with the new top end layout we've schemed up to make even more power. Just so no one thinks I am looking to steal secrets...this is NOT for a turbo, not even for a sled so the power characteristics we are building are completely different and we are forced to use a single expansion chamber. Have talked with most of the big name and old school single pipe guys(sled and pwc) and there is definitely a lack of mathmatical process to this, was just curious if some of you had found any short cuts in development. Heres what I already know-the manifold length/design is key and with the cylinder spacing of a polaris w/c its pretty much impossible to build the "perfect" manifold.(for a wide useable powerband any way!) We've settled on a manifold design that we are fabbing currently. I've worked up a tuned length based on what we learned last season testing several "production" single pipes from various applications that will be the starting point of the pipe. I'm taking a few ideas from a friend in the pwc industry also and working them into the equation. We are also going to play with a couple mods on the wet pipe as well but are pretty limited due to the double walled areas of that pipe.
I'm curious to try and manipulate the chamber find the sweet spot that works along with the signals from two open exhaust ports and get it all to work in harmony in this application. also have exhaust valves on the new motor to add another tool to the bag.balance tubes,water injection etc-so much cool stuff to tinker with!
Alot of what we've learned over the years about building a pipe per cylinder doesn't apply here-thats what makes it most interesting to us.

So how about it, any input?

curt
Sounds like you have the manifold worked out - my understanding of the problem is then the chamber design and size?

It's definitely an un-discovered science for sure. Years ago Bob Hannah (late 70's AMA Multi-national champ) would tune his motocross bike pipes with a ballpein hammer. Used to lap the track and then tap a little on the expansion chamber and dent it, another lap, more denting.. on and on until he got it to the powerband where he liked it.

Might be something similar required here with one of the production pipes you were using? Not necessarily in the crude fashion Bob used but what about two of the same pipes - cut one shorter and one longer and then try them out? Might be more a case of trial and error?

NSC
 
Motocross Action Magazine had an article about that (^^^^) years ago. If you dented the pipe in just the right spot, there was definitely a hp gain.

So there's you're best tech tip so far......smack it with a hammer until it works!! HAHA!!

Sounds like good, solid info to me!!
 
Yep, Houle was one of a bunch of great conversations I've had with pipe builders in the sled and watercraft industries.May build a trombone pipe with a slip fit at the belly to quickly alter tuned length-thats the easy part! I'm more curious to see or learn how much effect the diverging and converging cone angles will have in this application...manifold is looking good so far!

curt
 
Yep, Houle was one of a bunch of great conversations I've had with pipe builders in the sled and watercraft industries.May build a trombone pipe with a slip fit at the belly to quickly alter tuned length-thats the easy part! I'm more curious to see or learn how much effect the diverging and converging cone angles will have in this application...manifold is looking good so far!

curt

Steve was big into the 900's and 1050's in the mid/late 90's doing ALOT for that motor in the watercraft stuff. Running singles and tripples, wet and dry setups. My buddy ran their boat and won the IJSBA world finals in havasu AZ on a hotseat preped boat!
 
Curt have you talked to Lowell Horning by chance? He has been playing the game for a long time and does sleds and watercraft projects. He has a lot a info in his head. Been a while since I talked to him and I heard he moved to Havasu, but this is the last number I had for him in Montana. 406-375-0801

www.2-stroke-porting.com


Oh Yeah. I can't wait to get my new hood I bought from you today. Should look good. Thanks again.

Dave Halverson
 
Hadn't thought about Lowell...haven't talked with him in two seasons or more...thanks for the reminder Dave, will holler at him monday and see if he's around!
Your hood is boxed and will be on its way monday!

curt
 
This is what Curt is working on!
CURTBOAT.jpg


HOOKUP.jpg
 
you might want to call mike at cpi racing he has built many pipes for 2 strokes and has a ton of knowlege of what you are looking for.
 
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