Polaris rmk 858 rk tek on the dyno

[FinRmk]

Hello and greetings from finland

So I bought a 858 big bore kit from rk tek and got it on the dyno on wednesday.
I got a power commander 5 to set the fueling and the guy who adjusted the fueling has over 20 years of experience of fuel adjusting.
When I ordered the kit I was told it would bring about 30hp to my sled.
I've watched many many dyno charts from the stock 800 polaris engine and the results have been from 140 to 145 hp. So you would think that the 858 would produce over 170hp.
Unfortunatly here is the dyno chart

So the result : 160.2hp
Im disapointed on that very much..
yesterday we dynoed a 800 rmk with SLP Stage 3 kit and the result: 169.3hp
So you do the math..was it worth it to get a 858 big bore and get big power?? I don't think so...

 

[Sunvang]

How long have you rode with this? I hear they got to have some time on them before they get to their full potenial.


Sent from my iPhone using Tapatalk

 

[FinRmk]

The engine has about 150 miles on it.

 

[snowmobiler]

30 hp out of 58 cc's would be cool.

 

[N.A84]

Those numbers looks realistic, slp stage 3 delivered about the same amount of hp here in norway if i remember correctly.

 

[Jkinzer]

crazy the difference between a dyno chart and on the mountain experience with side by side comparisons... have installed multiple SLP stage 4 kits and quite a few 858's over the last few years and a properly clutched 858 will out run an slp stage 4 with ease on the mountain... the 858 is quicker, pulls harder, and pulls much longer on top before falling off which it doesnt really do at all when properly set up

 

[Jkinzer]

my phone wouldn't show me the dyno sheet earlier, just got to see it and at 8000 rpm you are leaving A LOT on the table with the 858 kit... your fueling must be way too rich or running an aftermarket exhaust with the wrong back pressure. these kits need to be ran at 8450-8500 rpm for optimum performance and the difference from 8000-8450/8500 is HUGE

 

[N.A84]

Lol my screen is so bad, doesnt the sheet say 8500 or so? Cant belive they stopped at 8000..?

 

[tdorval]

Looks like they ran it over 8 but hard to tell.

 

[Sheetmetalfab]

It appears to run to 8500.

 

[FinRmk]

It sure was reving 8500 on the the dyno. It starts to lose hp after about 8350 rpm.
And the fueling is set by very professional tuner and exhaust is stock.

 

[kanedog]

In true snowmobile aftermarket form-"we haven't heard of any issues with our xxx kit. You are the first one."

"Yea, I'm prolly the first one to put it on a dyno and call you out on your lies. I need my money back now. You lied. Thank you very much."

 

[Jaynelson]

Most engine mods on a Pro seem like a waste of time....might as well just put the money toward a turbo kit, at least you know it'll make good power.

 

[N.A84]

^^^what he said

 

[Jkinzer]

that chart is very hard to read... on my screen it looks like it stops at 8000rpm, i have installed many of these kits for customers and have been riding one personally for the last 2 seasons and we have all been nothing but impressed with them

 

[FinRmk]

858 dyno:

slp stage 3:

there you go..

 

[icr]

that chart is very hard to read... on my screen it looks like it stops at 8000rpm, i have installed many of these kits for customers and have been riding one personally for the last 2 seasons and we have all been nothing but impressed with them

What elevation do you ride at?

 

[Jkinzer]

What elevation do you ride at?

5-9k feet with a few customers riding theirs at 10-12k

 

[Jkinzer]

858 dyno:

slp stage 3:

there you go..

the power difference from 8000 to 8500 is huge, looking at that chart their must be an issue somewhere because our 858's do not fall off at 8000rpm like that shows, have heard of lower elevation guys having better luck with aftermarket reeds

 

[kanedog]

Where's your uncorrected/unmanipulated dyno sheet?