ATTN: 3CYL snowmoblie guys!

[wing nut]

hey guys,

i got a little project goin on and im thinkin of using a tuned pipe or "expansion chamber" i was wondering how much the tuned pipes for the 3cylinder snowmobiles. and also if the snowmobile motors are alot different from outboards?? also how much would a pretty good snowmoblie pipe go for?

thanks,
scott

[Daytona19]

Watch ebay, I got a SLP set for my 3 cyl Polaris for 150.00. Thats a steal compared to new.

[Raceman]

".................and also if the snowmobile motors are alot different from outboards??"

Yeah, snowmobiles motors are used by Yankees three months out of the year and outboards are used by all the normal boyz down south year round.:D :D

[pyro]

2 questions regarding the expansion chambers:

How much gains do they provide for a 3 cyl sled motor?

Can I somehow fit a set under the hood of my '98 XLT classic?

Right now, the 3 exhaust dumps merge together and go into one chamber.

[wing nut]

Originally posted by Raceman
".................and also if the snowmobile motors are alot different from outboards??"

Yeah, snowmobiles motors are used by Yankees three months out of the year and outboards are used by all the normal boyz down south year round.:D :D

damn guess i cant use them then:rolleyes: lol

ok now since there pretty much the same as outboard 3cyl motors. can anyone give me an idea what they look like for the snowmobiles? im looking for something that will make some serious HP! i can make one but it would take forever so i figure using a snowmobile pipe will save some time, and be better then just a straight pipe.

thanks,
scott

[Capt.Insane-o]

Finding a set of pipes that match the bore/stroke aspect of your motor and the rpm/powerband range. Simply using any old pipe set up will probably yeild dissapointing results.

[moore]

Hi ,
You can check out pipes at
www.denniskirk.com under the
snowmobile / exhaust section , don't know
what youv'e got but it look's like triples are in the $700 range for say a late model
Polaris .
ttyl
Dean.

[wing nut]

Originally posted by moore
Hi ,
You can check out pipes at
www.denniskirk.com under the
snowmobile / exhaust section , don't know
what youv'e got but it look's like triples are in the $700 range for say a late model
Polaris .
ttyl
Dean.

ive got a 49CI 1985 3cyl 70hp evinrude lol

scott

[sho305]

I don't know how much you know, but the pipe has to be tuned for the specific motor. There are formulas to help if you can find them out. More or less the sound pulse hits the cones to pull the gases out of the exhaust port, then ram them back in before the piston closes the port. The length of the pipe, the head of the pipe, and the diameters all affect what rpm(s) it works at and how hard it pushes. It times that reflection to work at certain rpms. I would guess the porting will be different also as OBs don't use them. The problem is the pipe works on a rpm band...so it does not work and takes power away at other rpms. Unless you figure out a way to change that. They tend to work better with one pipe per cylinder. There is also the problem of cooling it on a boat.

[wing nut]

Originally posted by sho305
I don't know how much you know, but the pipe has to be tuned for the specific motor. There are formulas to help if you can find them out. More or less the sound pulse hits the cones to pull the gases out of the exhaust port, then ram them back in before the piston closes the port. The length of the pipe, the head of the pipe, and the diameters all affect what rpm(s) it works at and how hard it pushes. It times that reflection to work at certain rpms. I would guess the porting will be different also as OBs don't use them. The problem is the pipe works on a rpm band...so it does not work and takes power away at other rpms. Unless you figure out a way to change that. They tend to work better with one pipe per cylinder. There is also the problem of cooling it on a boat.

why do the little 2 and 3 cyl. hydro boats use them?? im talkin about a pipe that will only help on TOP end. it would also be more helpful the just having a straigh pipe out he side of the motor.

scott

[sho305]

Not sure I'm 100% on this as I have not messed with it in a while. I think the megaphone, or the pipe that gets larger and ends, causes the exhaust pulse to help suck out the cylinder gases. Then more can flow from the transfer ports. The size would be made to help at wot rpms usually. This pipe has less effect I think, than a sled pipe type. So likely it still has enough power to get on plane with the light hull at under the rpms that pipe works at.

The sled pipe will suck the gases out the exhaust port to help new mixture get in, plus then reflect back to ram it back in some. So the motor will be ported knowing this, and fresh fuel mix will go out into the pipe and be rammed back in the cylinder at the last moment. Tuned right it will work very well to supercharge the cylinder, but it runs on the sound wave speed that is constant where rpms are not. So the size will dictate the rpms it works at, like an organ pipe tuned to a frequency. I'm guessing if you could get one to work some, then disable it at low rpms it might work. I'm not sure how much/if you would have to change the porting. I'm just guessing here. I think it would work, but nobody has hassled with it because you can port it and do other mods to get power without the pipe.

[wing nut]

i see what your sayin now, so you think its better just to leave a 3 into 1 straigh pipe out the side of the motor then? (yea i know its gonna be loud) i dont have a heavy hull, ill be running in the bays so i dont care about how loud it is, and all i wana do is go fast.

scott

[sho305]

For my .02, I would start with a single pipe 3-to-1. Make it mild so it don't kill the bottom end too bad, and tune for top rpm or just below. See what happens. Triple pipes would be nice, but a single works fine on a sled, and sure would be easier to try this with. If I did it, I would run the pipe down the back of the mid some, so it blasted at the water. It will be loud. Up to you on that. I saw one with 6 pipes out the back and up in the air, never heard how it ran. Had support brackets holding them up, looked wild. If you could figure out how to restrict the pipe at low rpm properly, that would be the trick. The pwc's spray water in the pipe to slow the sound wave, and get it to work better at lower rpms.

[moore]

Hi ,
Well i guessed I missed an important point ! It's snow season here and all the mountain machines are being tuned up for the winter , this fellow seems to be the guy to call for chambers for H2 and H1 Kawasaki Triples so he might be able to help you out
http://kawasakitriplesworldwide.com/tom%20pipes/tomcats%20pipes.htm
this site has pipe software if you want to really get into it ,
http://www.tsrsoftware.com/index_2.html
ttyl
Dean.

[Daytona19]

Pipes can make a huge gain in 3 cyl sleds. Your XLT is a good example and with SLP pipes you will gain in the 40 hp more catagory. The only thing is with your sled you have small carbs on the model and they will limit you for fuel flow. You sled was designed to be a good all around sled with out the fuel comsumption problems of the XLT special, or Ultra sp or Storm. I think you have 32 mm carbs on that and for real performance gains 38mm would be nice at a minimum. DONT put DG pipes on they are a waist of time and just make noise. Thers another issue check regulations in your area, hefty fines were handed out to overly loud sled here in our area. SLP makes a quiet set with HP gians your looking for. One other thing you should really consider is putting on a cluth kit. I seen HUGE gains by this also, lets say 4 or 5 sleds lengths in 300 ft was a good average with an EPI pro clutch kit. These are needed in my opnion even if you have pipes because all the hp in the world doesnt do any good if you dont have that power to the ground. While pipes help the HP you need traction on that sled and the clutch is the main componet for that. If you do one do the other and your friens will truly be impressed if not you will be juat another in the crowd...http://www.startinglineproducts.com/Polaris_Catalog/index_exh.html

[pyro]

Thanks Daytona! I've considered doing some clutch work to it. The nice thing about the stock clutch is that the belt lasts FOREVER! It gets going pretty quick, but it doesn't lift the skis when you hit it. This engine takes a second to spool up, it doesn't have the instant RPMs that my friend's XC 700 has. Top end is 90 mph GPS on ice.

Soon, I will be upgrading the shocks and springs so I can ride 2-up without bottoming out. I have a "Seat Jack" 2-up seat bolted to the back of it.

I don't want to lose low end, and I don't want it to be louder. Right now, it sounds like a Ford Escort when it's idling. Doesn't wake up the neighbors!

[ken medendorp]

The Crank shop and HOT TO GO are a nother couple good place's to go for pipes for POLARIS snowmobile's.
On my big bore storm I use Hot TO Go pipes and use the stock exhaust silencer can.Not that noisy also when I go riding with my freind that has a stock skidoo formula z 670 I use a half of a gallon of gas less then he does when we fill up and mine is a 900cc .
I have another freind with a 680 ultra he pic up 30hp from a set of crank shop pipes

[David_L6]

Don't waste your money.

Expansion chambers are better suited to applications that have transmissions. They are designed for a specific bore, stroke, port timing combination. (No telling what other parameters are considered.)


The hydroplanes you are thinking of weigh ~500 pounds (or less) - boat, motor, and driver.
Most of the guys racing hydros with the 3 cyl OMC do NOT run expansion chambers. There are a couple of exceptions, but look a the differences in what they are doing and what you are doing. Some of those guys have to use water injection just to get on plane. Once on plane the injection is turned off. Those motors don't vary RPMs as much as is necessary in a non-racing application. You could end up with a motor that won't even stay running at anything other than wide open.

A plain, straight pipe out the side will probably actually hurt your power. The stock exhaust side plate is used by more than a few hydro racers. They just don't have a mid-section to dump into.

The hydros that are using chambers are the alky burners that are racing motors that were designed for racing and turn twice as many RPMs as what your motor will turn. They have to slide the pipes on those motors to change the tuning to accelerate out of the turns and have top end power also. Those boats weigh even less than the gas burners with the OMC 3 cyl. They weigh somewhere ~ 400 pounds.

There are currently 3 organizations in the U.S. running hydros that have a class for the 3 cyl OMC.
Dave Mason won the 2002 APBA and AOF Nationals and does not use chambers. Dave also went to the 2002 NBRA Nationals and was beaten by another boat that does not use expansion chambers - Ralph Cook. I don't know who won the 2003 APBA Nationals, but the 2003 AOF and NBRA Nationals were won by Ralph Cook. Ralph also won the runabout class at every Nationals he's been to the last 2 or 3 years and set 1 mile course records in both hydro and runabout in 2002 and upped his own record in runabout in 2003.


One last thing to think about: The APBA Formula E hydro kilo record is 104+ mph. It was set by a 3 cyl OMC that did not use expansion chambers.

[Daytona19]

Pyro a few things if it were my sled I would do, BUT dont tell your friends. First the Clutch, personally The Erlandson Pro kit ( EPI ) was very reliable and I had the same belt for two or three years on my Polaris Ultra, The air box can be modified by removing the air horns to allow more air, they are the rubber type horns that fit on the inside of the box and can be pulled out. Another thing is traction. The RRSR or rear sissor stops limit how far the suspension can collasp, I moved mine back an inch to two inches by drilling a location for them in the suspension rail back from original hole and still using the the blocks from the factory to change how much weight transfer you want. For drag racing all the way back and in the lowest postion was best for me a 190 pounds but in trails left in the hole I drilled but the block turned to its highest setting was good. The 38 mm carrbs from a xlt special will really work too and give much more top end, it may take away from low end BUT the other things I recommend will give you low end back. Your stock carbs are good to about 60 mph and then fall flat you need nore fuel/air for top end. I would think a good set of combustion chambers would be good to , Mine ran really clean and bumped the compression which helped alot, Mine were SLP also to match my pipes. The pipes were a big HP ad on and jetting was required but with the quiet set from SLP I was never bothered but DNR and had alot of gains from them. RUN IT RICH if you put pipes and tweek from there. Also you can tighten the limit straps on your suspension at the front but turning the lock nuts and this will cange the angl of your track and allow more free movement with less drag. ALSO you can drop on gear on the top and gisn huge holeshot with the loss of about 3 to 5 mph on top. I did all of this on my Ultra SP and it was a rocket and was geared to about 97 mph at best BUT hang on. Very few sleds unless highly modified could walk it and up until last year no new sled from the box in 300 ft would be within 2 or 3 sled lengths. Which for a 1996 Ultra wasnt bad, I 500 ft the big sleds such as 800 class would give it a run but they should they were 800's. These tips will help and if you do them in order as listed you will be impressed each time you try something new, I bet with the clutch alone your friend on the 700 wont believe the difference as long as you both are studded or not studded. Good luck.

[wing nut]

Originally posted by David_L6

A plain, straight pipe out the side will probably actually hurt your power. The stock exhaust side plate is used by more than a few hydro racers. They just don't have a mid-section to dump into.




what do you mean they dont have a midsection to dump into?? other then a 3 into 1 pipe out the side of the motor how would you free up the exaust ALOT? im going to be putting a massive amount of air into the motor byt use of really really huge carbaretors but i need a way to get the exaust out of the motor quicker. i have a little offshore kinda snout on the midsection, but i dont think its going to be enough. what about a megaphone kinda thing like that 6cyl looper in the gallery?

scott

[David_L6]

Scott,

sasbenson has built record setting 3 cyl OMC motors for the hydro and runabout racers. He builds a couple of kinds (maybe more) of exhaust systems for those motors - including expansion chambers.

Place a post and ask him if he can build you something that will work with the other mods you are doing. I'd list what you have done already in the post also.

What do you mean by
really huge carbs? i.e. what do they measure? A motor can be over carbed...


The race motors that use a stock side plate have an elbow (pipe 90) rigged on the bottom some way. I've never looked that close. They don't have a midsection like a stocker. Piece of plate top (powerhead mount) and bottom (lower unit mount) with a tube that the drive shaft runs through connecting the 2 plates and holding it all together. Naturally there's a little more to it than that, but not much.

The factory racing version of the 3 cyl OMC ran the exhaust through a mid section. I'd try mods to the mid before going to some kind of open pipe.

[WARLOCK]

PULL THOSE CARBS OFF, PUT 38MM'S, BORE THEM TO 39.5MM. PUT A SET OF AEEN TRIPLE PIPES ON. CLUTCH IT AND I THINK YOU'LL BE SUPRISED. TRIPLE PIPES ON MY ULTRA GAINED ME 31HP. ALSO, THEY'RE NOT TOO LOUD EITHER. LATER, DAVE

[sho305]

These guys can tell you how to make your sled run good. Personaly I liked the milder pipes, more of a semi trail pipe. Sleds all clutched up and big pipes ride poorly on the trail but roast on a lake. I like to trail ride sometimes, depends on what you do. The more power a pipe makes, the less it makes at another rpm so your clutch must be setup to run at that rpm only. A milder pipe will still have some range to the powerband yet more power than the stock pipe. That makes it more responsive and better midrange along with a top end gain. The DG pipes were known to show a great hp number on a dyno at top rpm, and nothing else, maybe they still do that. I had good luck with the psi pipes on yamis I ran. Your sled will be more fun to ride but you may not be the fastest guy on the lake.

On the other hand, that is the reason pipes don't work on a boat. You have no clutch and must run what, maybe 3000 to 7000 rpm range to get the boat to run well. Plus pipes are big and hot and hard to put someplace on a OB motor. A sled will go to top rpm in seconds and stay there until top speed, max hp all the way 0-100+/-mph. I think if you had a light boat and got a mild pipe, and only cared about top speed...you may be able to disable the pipe to get on plane and then you should get a good power gain on the mid and top rpms. Maybe a prop that breaks loose a lot.

I thought that pipes would rule once too, but the OB makers have done a good job to make the motors deliver at the large rpm range they need to. Also a wild pipe can make so much power it would blow up anyway under the high marine loads. I bet pwc pipes are fairly mild too. I think it can work on the right mild setup though. Check out bmw's new motors...they are all variable with no throttle at all. The intake size and variable valve lift control output of the motor completely. At idle the valves barely open. Aside from the large size of a pipe, it could be made to be variable somehow. They can spend for hardware to control it at bmw. Its just that you can do the usual mods to OBs and get power without the pipe hassle, but I would try it for fun if I had that type of rig and time. A pipe alone will make large power gains with few other mods.

Remember you need to tune your motor for the rpm range you want to run, be it pipes or carb size or porting...to get the best power at the rpms you will need to use. Too big or small will hurt you. The sum of the whole package is what will matter.