Twin pipes on an Indy 500?? - Snowmobile Forum: Your #1 Snowmobile Forum

GreenerPolaris · 04-18-2012, 09:51 AM

Wanted to weld up a twin pipe set up on my buddies sled to gain some HP but didn't know what problems I would run into besides maybe jetting ? Can't afford a tuned set up so was curious if anyone had attempted this before and not sure what I would use for twin cans. It's a 91 Indy 500 aftermarket clutch and aftermarket air box.

**BC_Dan** · 04-18-2012, 10:56 AM

You should understand the relationship of the size of the pipe and the distance from the piston to the restriction in the pipe before starting. If your measurements are off, you won't gain a lot of performance. If they are WAY off, you may actually cause a lean condition that will either give you fits in tuning trying to find the proper jetting or burn holes in the piston.

The shape and length of the pipe is critical in performance. When the piston is at bottom dead center, both intake and exhaust porting into the cylinder are open. The exhaust rushes out, carrying some of the fresh intake charge with it. However, the pressure wave created by the combustion process hits the restriction in the pipe and rebounds back toward the piston and at the exact necessary moment, shoves the unburned air/fuel mix back into the cylinder to be burned. The pipe is tuned to a hot exhaust; it's assumed that you want the most power when the engine is hot. The pressure wave that is created travels at the speed of sound, which changes with temperature. There's quite a bit of science and math involved; it could get expensive until you get it right.

Google "designing 2-stroke exhaust" and you will find a bunch of info, including software that will help you with the necessary calculations.

I would work on clutching and figuring out ways to reduce weight to make the sled more responsive. JMHO...

joshkidner · 04-18-2012, 03:39 PM

wow BC_Dan your quite smart :P if what he says is true about it getting expensive, i would keep looking for the pipes on craigslist or ebay. you could get them for under 150 dollars. PSI and SLP are prob more likely to be found being they seem to be the most popular.

white lightning · 04-19-2012, 10:52 AM

Its better to stick with an aftermarket pipe brands that is designed for the sled. WL.

gpa21 · 04-22-2012, 07:27 PM

Quote:

Originally Posted by BC_Dan

I would work on clutching and figuring out ways to reduce weight to make the sled more responsive. JMHO...

Would you suggest the same thing for a '93 XLT SP? Was thinking about changing mine to triple pipes. But what you said in the rest of your comment is all greek to me.
Thanks.

**BC_Dan** · 04-22-2012, 08:09 PM

You can probably find triple pipes out there on ebay or craigslist for the xlt, not many twins for the 500. You can even find new triple pipes from Aaen Performance - High Performance products for Snowmobiles and Polaris ATV's but they are almost 800 bucks!

The triple pipes and the xlt engine usually meant a very short life for the engine. To get the power out of the triple/triples, you really have to spin 'em fast, which decreases life of the engine by a bunch. The HP increase is supposed to be 20 hp, which is pretty substantial.

93Wildcat700 · 04-23-2012, 10:50 AM

^^^what Dan said is correct. I have seen a few of the xlt's on tipple pipes. They don't last long without crank work and updated bearings. Even than my relatively stock 600 Polaris edge was beating them all day so prob not worth the effort.

I had plenty of fun on a single piped purple xlt i babysat a few times. LOL. they aren't bad in stock form.. Its just not a racer by any means.

They kind of sound ridiculous with pipes anyway, like some weird freaked out trumpet. LOL. They sound funny.

As with any sled, unless you are just tinkering for fun stay away from heavy modding. My first few years of working on sleds i learned a TON just from doing regular maintenance and Reducing weight/Making sure everything is working 100% at its optimum.

If i had your XLT i would be looking at Plastic skis, making sure all your clutching is clean and fresh/new springs/bushings/belt.. Drive bearings... Right there is 500 bucks. there is plenty to do on older sleds without getting carried away.

Not trying to steer you away from it but twins on a Indy 500 is kind of overboard. With so many things being made for those sleds i would find a nice singe pipe/can known to make some good hp.

white lightning · 04-23-2012, 11:23 AM

Not so much about the updated bearings on the XLTs to extended the crank life - its the oil that isnt getting to the bearings was the biggest problem. I agree with BC DAN to the point, but once you get the oil passage drilled out in the crankcase, turn up the oil injector a little and use GOOD oil, will prolong the crank life on the triple pipes high revving XLT engines. WL

gpa21 · 04-23-2012, 02:29 PM

Thanks for the info guys, i a ppreciate it. Being this sled is a "93 with only about 1400 miles on it, I think i will just stick with doing some clutch work, I know it has decent top end, I am just kinda looking to get a little bit more off the line.

**BC_Dan** · 04-23-2012, 03:14 PM

Just going through the clutches (maybe putting in new springs) will probably give you some pretty good benefit. That's not horrible for expense and gives you something to do over the summer

XCRacer440 · 05-07-2012, 09:36 PM

Had a set of SLP twins on a I500. It didn't make a noticeable difference, even with clutching and jetting. Also had a DG single and it didn't provide any big noticeable gains.

kenvb · 12-30-2012, 07:07 PM

had a 95 XLT SKS , I added a DG can to the exhaust, saved some pounds,and sounded awesome, did some full throttle runs,check sparkplug color. no issues, but I add oil to the gas and run premium.this XLT ran great that way .sold to young fellow who runs the crap outtta it and he loves it