Sled: Polaris

Anybody have some dyno numbers they have on the difference between PSI 600 pipes (cone built) and Aaen or Decker 650 pipes on 650 w/02 cylinders (1990 RXL engine with 38mm Mikunis)?  I know this is old equipment, but I thought I would give it a try.  Thanks.

I'm not sure about the 600 figures but, I think you would get 100 hp with some porting. As for the Aaen or Deckers, I think you can get 25-28 hp on a stock 650 engine and if you want to go crazy with it, you can get 165-170. HTG got 165 on mine on their dyno and since I have bored the engine out since then, it's been estimated that with fresh pistons/rings, it's up at 170 with 190 lbs. cranking compression.

Good Luck with yours.

Rob. C/O Oneshot Racing!!

RACE HARD BUT HAVE FUN TOO.

Thanks for the reply, Rob.  I figured there was at least one guy who still likes to talk about the old iron here. I was just wondering if I'm leaving some hp on the table using the cone-type 600 pipes as opposed to going with "650" Pipes on my 650 (1990 '02 cylinders).  The Aaen pipes are the same for the 600 and 650's (same P/N) so I am assuming the old style "600" PSI (quiet "stockblaster" style) are pretty much the same as the "later-model" stampes "650" PSI stockblasters on a 650.  I was hoping someone had done a few pulls using 600 pipes instead of 650 pipes just for comparison.  I have a set of Aaen 650's (stamped pipes) that I am going to dyno alongside the 600 PSI section pipes for comparison and for few giggles...

Your 650 sounds like it can get the job done.  Are you running HTG's?  What rpms do you run with them?  What other pipes did you run on your 650?  Did acceleration match dyno numbers when run in the field (good pipe as opposed to just a "dyno bomb?)  What were your thoughts on power, noise levels, and durability?

Tony

 I recently ran accros an old pipe shoot out review and have it on my PC at home.

Send me an email and I'll send you details

rtb2@comcast.net 

I also have a set of 650 PSI pipes in the garage looking for a new home if you're interested?

That's  great Roger, I'll send you a pm.

Tony

Hey Tony:

Like I said, I haven't done much at all with any 600 pipes. The ones on my 650 were made by Jaws I think. Anyways, they were on the Sled when I bought it and they work so good, I honestly haven't bothered trying anything else.

The Sleds engine was built by HTG. Porting included a lot of metal removed from around the transfer ports and some but not a lot of porting done on both the exhaust and intake sides of the cylinders. The Cyls. were o-ringed and the heads were shaved until the squish was almost non-existant. Cranking comp is 185-190 lbs with new Pistons and rings. It shifts out at 9,800 rpms and was engaging at 7,200 when I first bought it off the Guy who had HTG build the motor. The Pipes came with the motor from HTG and are perfect for 500-660 ft drags. They are loud but very efficient. The motor itself is very strong and durable ( right now it needs new set of Wiseco 60 thou over Prolites as there are at least 100 or more passes on the Prolites I put in quite a while ago). Comp is down to 165lbs. so she is due for a fresh top end.

The Crank was done by Litner & Bush and it's runout even today is still Perfect. The Carbs were bored to 39.5 mms and work really sweet off the line. It had Storm clutching on it when I bought her but, it has Polaris Stock units now with very little difference in Performance other than a slight drop in Overdrive shiftout on the secondary.

The fellow I bought it from who makes his living as a Mechanic, did all the Front and Rear Suspension alignment himself as well as improvising a Custom made Suspension limiter so the skis don't come off the Ice any more than a ft or two depending on Ice Conditions. (it is adjustable of course). The Front suspension has been tied down as has the rear skid so that there is 2 inches of travel in the rear and about 1 inch in the front.

The Track is a Camoplast Speed Unit and has 350 Woodys 1" Chizels and Picks. It has a homemade Slider Luber which I made myself and a few other goodies that I won't mention right now. Maybe in Person eh?

You can see the Sled/motor on "Off-road Snowmobile Online" under Readers Sleds if you are interested.

Anything else like clutch specs etc. are Classified!!

The former Owner won Cosdras 96/97 Improved Stock 700 Class Championship so the little Beast has some History and has been published in other Magazines as well such as "Hot Sled" and "Snogoer".

Hope you are lucky with whatever you choose to do.

Ciao, Rob

C/O Oneshot Racing!!

RACE HARD BUT HAVE FUN TOO!!

If i remeber right, i think Decker pipes were the most desirable for the old 650's because they made the most power. They were all fairly close hp wise though, and all of them worked pretty good. I too used to have a 650 improver, and it ran very well and was alot of fun to race. I surprised alot of guys with that thing, and beat alot of sleds that i really shouldn't have because of hp differences. Brings back some good memories.

Yeah Buddy, I've had a lot of fun with mine too. I especially remember the Outlaw Event where we won every Improved Class except Open (I didn't enter thinking I'd get my clock cleaned/ turned out the Guy who won came in 4th in our 900 Imp Stk. class final with a T-cat..oh well) and there were a few heavy hitters there. I really like the Guy who scoffed at our "Old" Indy at the starting line and said we were wasting our time. Strangely enough, he was nowhere to be seen after we beat him by 10 lengths!

Later, Rob.

My lilttle bro has a set of 600 triple PSI pipes.  They are hydroformed.  They have an attachment welded right to them to screw a EGT right in.  They have built in silencers that dump straight into a single can.  Today we were playing around out in the shop and I threw them pipes on my 440 Rupp.  Strangely they made my sled idle 1000 Rpms higher !!!  They also seemed really snappy on the stand !!!!  I mean really snappy !!!! Has anyone else ran into this where a set of pipes make a sled idle alot higher ???  I may need to go up one size on the pilot jet for these pipes if I find out that they work good on the dyno.  Any suggestions ?????

I also ran deckers on my 650 because I heard they made the most power.

Well guys,

 Here's an update on the thread.

I got back from the dyno and it didn't go so well. I had planned on dynoing the engine with the PSI 600 pipes, a set of Aaen 650s and then a set of Decker 650's.  That was the plan, anyway...  

The '90 RXL engine (38 mm Miukunis) with 600 PSI cone pipes pulled about 103 hp. (106 corrected hp) at 8800 rpm on the the first two pulls. Halfway through the 3rd pull with the 600 PSI pipes, the dyno came unglued (spit out the dyno shaft and tried to rip the entire water brake from its cradle- good thing the sled wasa tied down as it tried to go for a ride also).  Yikes.   The hp numbers were dismal (I had expected a few more hp, even with the 600 pipes), but I felt especially bad about the guy's dyno as it had served him well for many years. 

 Typically, I have seen stock 1988-89 650 cylinders make about 110 hp with the 650 PSIs and Aaens, whereas the Deckers pull high 1-teens.  The stock 91 and newer RXL/Indy cylinders normally pull high 1-teens and the Deckers mid 120's on stock cylinders.

So anyway, I pull the sled off the dyno, take it home, and pull the 600 PSI pipes to put the Deckers on to test on the snow instead.  What I find is a bunch (I mean a lot) of aluminum in the PTO exhaust pipe.  Yup, broken intake skirt.  Then I go and try to fit the Decker pipes in the chassis (it's a Polaris Centurion with a  1978 RXL hood) and there is no way they will fit without hacking up the hood. Oh, well.  I had also thought the Deckers would be what I wanted to use as all dyno testing I have seen pick the Deckers as highest hp for stock or slightly modded 650s.  I still have the Aaens to try for fitment as I am pretty sure they will pull more than the PSI 600 pipes.  If they don't fit, they are also going along with the Deckers and it will have to be 106 hp and that's it.

 Ok, here's my question, are the 90 RXL cylinders any different from the 91 and newer RXLs/Indys?  I thought they were the same, but testing done by DynoTech showed airflow in the 160s cfm range for a stoc