800 Cylinder Shim?

[B2]

As a happy subscriber to DTR, I was intrigued by their testing of aftermarket pipes for the Pro 800, as well as the results of changing the ports by adding the cylinder shim and cutting the head to match. What is everyones opinion of this? It seems like cheap horsepower, but what is the trade off? Why would Polaris leave so much on the table if this did not sacrifice some serious reliability? It will be interesting to see how much of the hp gain was just advanced timing, as DTR stated they will test a stocker with advanced timing and no shim. It seems the pipes did not provide much of a gain, but the shim and timing with a pipe can get this motor close to 170 hp. Thanks for the input.

 

[2XM3]

You answered your own question....they don't want motors to have ANY issues more hp = more stress = more problems for polaris and if you touch anything goodby engine warrenty, (see 800 iq threads) Sled runs GREAT for maybe 95% of all riders with 140 whatever hp, and so far knock wood not many issues. You want more , its your baby. FYI mine got moded 2nd week I had it...lol

 

[allblowdup]

DTR dynoed the sled at 151 hp and did the pipe /shim /timing mods from there. After 3 yrs of having reliability issues they r not taking any chances with the 2011 800. They have cut the BMEP down in any way they could. The new fule injection system seems to work flawlesly so I don't think that they needed to but they are not taking any chances. Going by what DTR said they did not run into deto even with all the mods done. On the Dragons this was not possible. I would have no issues installing these mods on my pro. Getting warranty may be another thing though and that would have to be your own decision . Same as it has been for ever.

Nice to see that they found out were the power went though.

 

[rmk685]

The engine they tested was an 800 R. If my memory serves me correct, I think I remember reading somewhere awhile ago that the timing is slightly different between the flatland sled and the rmk's. I could be wrong as I am gettting old. Could someone confirm this, as it would make a difference with the shim/timing mod?

By the way if youre not a dtr member, I would highly recommend it as Jim does countless hours of honest testing for folks like us.

 

[FTXMOTORSPORTS]

IMO porting is the better answer...head can remain untoutched(if you like) and the port deficiencies are addressed independantly instead of just raising them all a pre determined amount. The transfers need far different changes than the main and aux. exhaust ports. With an engine that has shown skirt piston skirt support issues already, it seems counter productive to raise the cylinder and take away more of the support?
One benefit with raising the cyl. on this engine is that the extended length of the transfers(after raising) does help with volume issues that the 800 suffers from but again, there are better ways to accomplish this through a GOOD port job and still retain all of the piston skirt support the design can offer.

My .02 fellas

Curt

 

[number9t]

what shops have figured out the porting on new 800? I agree porting is the way to go, but its takes alot of expensive r&d that gets passed on to the customer, and rightfully so.

 

[FTXMOTORSPORTS]

When it comes to porting, this isn't a "new" 800-internal flow paths are the same as the "old" IQ 800. The difference is now, we have a timing curve that benefits from a little advancing(the IQ typically would deto with an advance key), a wheezy low compression head and a fuel delivery system that is much better managed. Proper porting compliments stock components a little and compliments well designed aftermarket components a bunch! it all has to work together.
Cylinder porting for all of the CFI twins and most other current engines is available at our shop (Fastrax/ Union Bay Racing) along with heads, timing keys, intake, exhaust and Power commander support. Call for details!

Curt

 

[mountainhorse]

B2:Why would Polaris leave so much on the table...

EPA...meeting Regs AND as said above.

 

[RKT]

A good port job always makes power.. The problem is that this new engine may need to exercise its warranty and the porting voids it in a big hurry...

 

[IceCap]

RKT you were posting a lot more at the beginning of the season with your discoveries on how to get more power out of the new 2 CFI 800 engine.

So what have you found so far? It seems a bit quite lately?

 

[RKT]

RKT you were posting a lot more at the beginning of the season with your discoveries on how to get more power out of the new 2 CFI 800 engine.

So what have you found so far? It seems a bit quite lately?

Still working on it.. Ours has been plagued with "anomalies" after 700 miles and last week, we MAY have just gotten all these "anomalies" remedied.. Will know tomorrow.. Hard to develop products when the sled is acting up.

We do have a VERY good mountain Team Tied set up .. WORKS EXCELLENT!

Still plenty of snow yet... testing continues, as usual..

The shim kit is a great idea.. but the added crankcase volume at the higher elevations, may prove to be a negative (we need tighter crankcase volumes at the higher alts) But it may have to be used..
My goal is to try and extract as much power as we can without having to remove the cylinder

Hopefully it happens

Kelsey

 

[AndrettiDog]

A good port job always makes power.. The problem is that this new engine may need to exercise its warranty and the porting voids it in a big hurry...

Doesn't the shim and timing key do the same (void the warranty)?

The shim kit is a great idea.. but the added crankcase volume at the higher elevations, may prove to be a negative (we need tighter crankcase volumes at the higher alts) But it may have to be used..
My goal is to try and extract as much power as we can without having to remove the cylinder

Would you elaborate (because I don't know)? Why is volume in the crankcase a bad thing?

Good thread...

 

[FTXMOTORSPORTS]

Hey Kelsey, we have found that at the 85mm bore, these babies are already on the tight side below 8000' would you agree in your testing? our experiements with bigger bores and a pipe per cylinder really made it apparent in our development work. Drop the bore to 81mm, even on the same stroke(70) and velocities went through the roof, engine loosened up and was happy to run elevated(over rev) rpm etc...

We found that by increasing the volume through proper transfer porting was a huge benefit all through the curve but still occasionally to pull a bit of compression and increase stinger dia to have a nice loose happy engine on top end for long wfo pulls under high load. (again, under 8000'). We saw far less issues in this respect with customers running over 8000' altitudes consistently.

Bugito, think about case volume like this: if its to small for the requirement of the engine, it is a "restriction" so to speak. If volume is to large, it effects cylinder filling speeds and overall velocity....kind of like it causes "lag" for a lack of a better term.

a smaller volume will produce stronger/quicker air flow paths which greatly help engine response and rpm building, problem is, if its to small, it won't support sustained top end airflow and will "choke" the engine.
There is much more to this than that but that is an easy way to comprehend the issue!

Look at 1200psi's billet bad boy cfi bottom end-why do you think he went with watercraft spacing between cylinders? to fit separated cylinders for sure, but also, much better case volume to support monster airflow up top and make some H.P.!

 

[RKT]

Hey Kelsey, we have found that at the 85mm bore, these babies are already on the tight side below 8000' would you agree in your testing? our experiements with bigger bores and a pipe per cylinder really made it apparent in our development work. Drop the bore to 81mm, even on the same stroke(70) and velocities went through the roof, engine loosened up and was happy to run elevated(over rev) rpm etc...

We found that by increasing the volume through proper transfer porting was a huge benefit all through the curve but still occasionally to pull a bit of compression and increase stinger dia to have a nice loose happy engine on top end for long wfo pulls under high load. (again, under 8000'). We saw far less issues in this respect with customers running over 8000' altitudes consistently.

Bugito, think about case volume like this: if its to small for the requirement of the engine, it is a "restriction" so to speak. If volume is to large, it effects cylinder filling speeds and overall velocity....kind of like it causes "lag" for a lack of a better term.

a smaller volume will produce stronger/quicker air flow paths which greatly help engine response and rpm building, problem is, if its to small, it won't support sustained top end airflow and will "choke" the engine.
There is much more to this than that but that is an easy way to comprehend the issue!

Look at 1200psi's billet bad boy cfi bottom end-why do you think he went with watercraft spacing between cylinders? to fit separated cylinders for sure, but also, much better case volume to support monster airflow up top and make some H.P.!

FTX... No doubt a PROPER port job and head change will bring that engine to life. My concern is in the reliability of the engine (still not 100% confident in its longevity).. Most have a 2 or 4 year warranty on the sled and do not want to negate this warranty.
So, we are trying to find power with simple bolt ons and such.. We are having luck with this but still looking for more ponies...
It may very well be that without removing the jug and getting busy with it.. it will never get to the power level desired.. But we are trying to exhaust all the possibilites before addressing the real issue (porting)

I think a very custom and specific single pipe is what this engine needs, unfortunately, this pipe is not available YET.. So, when that shows, we may be off and running...until then.. we just keep plugging away at it.. But all these sea level tests really tell us very little as to what this engine requires at the higher elevations..

Kelsey

 

[FTXMOTORSPORTS]

AAAAH yes, the age old issue of warranty VS performance. Its a tough bridge to cross for a lot of people for sure. Its a good thing modern sleds work fairly well as is with a little tweakin'!

I like where your heads at on the pipe...keep me in the loop

Curt