XP Airbox: stay or go?

DaveB · Oct 16, 2009

Talking with Capt. Jack this morning (Extreme Machines, Sylvan Lake) and we got to BS'in about my power problems last year. He said he's had SEVERAL come through his door acting exactly the same....big bores and stockers. The symptoms he described were exactly what I was dealing with last year...big bore ran fine, seemed okaaaaaayyyy, but never really pulled over 8000 and never outran a stocker. What he ended up doing was jetting down...then down some more....then down to 380's (!!!) and then the thing started to run! This is at 2800' elev. So he re-jetted back up to 480's (stock) and pulled the lower airbox off the carbs. PRESTO! Off the rev limiter! Add weight or 2 clicker positions right now. SO they went to pods. Since doing this to several sleds, the owners haven't been happier. Maybe Danno will chime in here in case I'm missing anything.

Which brings me to the question: anyone else remove the airbox and get gains? Losses? What's the poop here?

Anylizer · Oct 16, 2009

If that is truly the case????? it kinda sounds like the DPM wasn't functioning properly? Just asking???? seems like alot of jet change!

A.

Cheynespub · Oct 16, 2009

I am looking at getting the XP and this would be really nice to know.

winter brew · Oct 16, 2009

I know a couple guys that have gone to pods....neither noticed gains and their sleds still run with those with the airbox. History would tell us to keep the stock intake for the mountains for the cooler intake, but if you can get air to the pods it may work good for you. Let us know what you try. :beer;

Insaneboltrounder/sjohns · Oct 16, 2009

Dynojet testing showed a 1 hp gain when you yanked the box. 280s??? You try 1st.... ill wait to hear how yours worked

DaveB · Oct 16, 2009

Insaneboltrounder/sjohns said:
Dynojet testing showed a 1 hp gain when you yanked the box. 280s??? You try 1st.... ill wait to hear how yours worked

Read again Elvis....380's.

freerider · Oct 16, 2009

I run air filters on my 08 800 Summit with some other motor mods, not a big bore though. I cut my factory box off about 3/4 to make an air scoop to the filters. I noticed a big difference in power, and had to jet up 3 sizes from what the manufacture of my pistons and head had for a stock air box. I think it is a must do.

Insaneboltrounder/sjohns · Oct 16, 2009

DaveB said:
Read again Elvis....380's.

My bad.... prob go like heck for a lil while

MontanaPowder · Oct 18, 2009

More Air

Dave, Greg at Jaws told me I needed more air with my twin pipes on 860. I said I allready have two flowrites in top box to vent behind windshield, he says top box will do nothing, needs to be lower box.

I cut out top left traingle of lower box. Install 3/4 inch weatherstrip around opening. Now cut out same area on your left side panel and put prefilter. Pulling fresh air for about five bucks.

IMO
The motor is a pump.

The following help pump more,

Big Bore(correct porting)
Twin Pipes(correct timing so pump is happy out and in)Motor happier per stroke. Likes more rpm
RPM (rev limiter to 9000) runs freely to 8700+ now
AIR

I had following done to ecm so above not effected

Rev Limiter
Remove water over temp
Remove knock sensor
Timing

Hope this helps, I do not know if others are running twins on the 880 but do know the 860 allready strong finds another dimension as I rode all season and then added twins at end for last three rides and testing.

WatchThis!!! · Oct 18, 2009

Montana, how does your sled run over a single? Is there much tuning/tinkering?

MARCUSO · Oct 18, 2009

Hey Dave, not sure if this means much to ya... LOL
Joel mentioned to me that he found a 3 HP gain from pulling the airbox on a stock dyno test.

shoppingcart111 · Oct 18, 2009

Does putting flowrites in the lower box basically infront of the carb mouth affect anything with jetting or mixture? Since they are after the sensor in the top box I was wondering if it would mess things up. I was having a problem lsat year with bogging and not pulling full rpms on climbs, which hasen't been resolved from the dealer yet.

mctrailboss · Oct 18, 2009

I put the timbersled kit on my sled and dropped the main jets 2 sizes. problem solved. every xp I rode with last year had this problem in the powder and a few guys have went this route and we all love it. I have no dyno results to back this up but it definately seems snappier, and no more bogging.

MontanaPowder · Oct 18, 2009

Twins and photo of air box mod for Dave

WatchThis!!! said:
Montana, how does your sled run over a single? Is there much tuning/tinkering?

There is as always a very big difference between single and twins.

Tinkering is my passion so not an issue here. You do need to tune a bit to get best results per my post above, ecm needs mod for a mod sled.

portgrinder · Oct 18, 2009

MARCUSO said:
Hey Dave, not sure if this means much to ya... LOL
Joel mentioned to me that he found a 3 HP gain from pulling the airbox on a stock dyno test.

Don't listen to me...I have no clue!

Doing the bb on my '06 back a few years ago, had it all dialed in on the dyno, put the airbox back on and BAM down 10hp. After some airbox work and some jetting we got it back to normal.

Just realize that freeing up airflow leans you down big time. Less draw on the float bowls and ALSO your signal line to the dpm.

There is some restriction in the airboxes, far more important is doing plug checks and making sure you're where you need to be on the main jet.

I'm sure the chowder heads in quebec are more concerned with the sound performance of an airbox than how much power it makes. They have to be.

Dakota Drifter · Oct 18, 2009

Has the ski doo dpm update fixed anyones rpm issues or made their sled run better ?

turboal · Oct 18, 2009

seeing that the effected units display an over rich condition there is enough evidence to say that one of the 4 sensors is out of range .
just a likely hood the air density sensor is out of spec .
this sensor is located in the mpem and is least likely to have been tested .
requires testing on the two mpem pins designated in the shop manual .
there is a chart that follows the resistance that it should be at any elevation.
380;s is exactly what we run when we disable the dpm system .

doo has historically been 10 sizes rich on the dpm set up .

other item to note on big bores is look at the air box in the content of it is supposed to flow 155hp at sea level .
bb makeing 165 to 170 singles at elevations over 5000ft are only moveing 145hp worth of air.

twin piped 860 moves 185hp worth of air and at elevation over 5000ft it is makeing 165 hp air volume movement .
the twin application needs an improvement to air delivered to the system

doo offers the race dept optional intake in there 2010 catalogue this year , saw it in there the other day .

Dave , i must ask if the instrument cluster has ever been changed on your sled ?

the fueling of the motor relys on 7 maps in the mpem
each map has its unique relationship to what readings it is recieving from the
water temp sensor
throttle position sensor
rpm
air temp sensor
atmospheric pressure sensor
all have a test but the least likely tested is the atmospheric sensor
also to note the instrument cluster handles all information and has no test that says it is ill and not working correctly .

previous engine designed you could take your buddies dpem and tether and check your sled out to see if the brain had issues .
on the xp you have to swap the brain , the tether , and the instrument cluster , stands to reason it could have issues that effect the strength of the signal the brain recievs from the 4 sensors and effect running .

numerous owners expressed the similiar scenariio you have experienced and were stock units .
hope some of this is help full

DaveB · Oct 18, 2009

Always helpful Al! makes sense.

cdnsleddog · Oct 19, 2009

Dave, if you are still having problems with your machine this year your welcome to try the ECM and cluster out of mine. PM me if needed

DaveB · Oct 19, 2009

cdnsleddog said:
Dave, if you are still having problems with your machine this year your welcome to try the ECM and cluster out of mine. PM me if needed

Cool...hopefully I won't need to...but thanks. This thread is just "hypothetical" after talking to Danno last week. I'm hoping my sled is sorted out. I found out some smart guy made a nice clean custom bracket to hold the front of his sled jack....and now he can't get his airbox off...hahahaha....I'm such a dolt sometimes. Easy fix though....

XP Airbox: stay or go?

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