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Discussion Starter #1
Just thought I'd give my opinion of all the work I've done to my xp & what I'd do differently if I was to do it again! Lets start with what I've done, I bought a used air-air kit that came with 9-1 cp pistons and lots of other parts, pretty good deal, then I decided lets do it right the first time & fire ringed the cylinder, cnc ported the head, valve springs, cams and arp head studs thinking this should rip & hold together! Well got it all together fired up running pig rich at idle can't lean it out any more so test drive time it's a dog out of the hole but pretty cool on boost , clutching issue so I get my clutching pretty good for 6k feet altitude seems pretty good just suprised at how much boost lag I've got! Then I went up camping @ 9k feet on the woods & it just seems like this thing is laboring unless on boost, so not much fun to drive! So long story short if I had to do it again I think I'd do a low boost kit or just not do all the internal eng work through a set of valve springs at it and keep the boost at ten or lower!
 

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We tend to be our own worse enemies... If some is good more is better... NOT...

Also less expensive isn't always the best bang for your buck...

You have to keep in mind what you plan on doing (riding) with your ride... Don't build a full blown engine and think your going to use it as a daily driver... IT'S NOT GOING TO HAPPEN...

Been there done that...
 

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Just a thought. When I bought my kit they recommended 9.5-1 pistons not 9-1's to help with turbo lag. Just kind of thinking outloud but uping your comp ratio may help with drivability. Might be something to talk to Rayce about.
 

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I had the same thought! Who said anything about Rayce? LOL
I just letting you know who told me this so you knew who to talk to about it. That being said mine has very little lag at 9.5. You might be able to run 10 or so at that elevation. Again just thinking outloud.
 

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Discussion Starter #6
I had the same thought! Who said anything about Rayce? LOL
I just letting you know who told me this so you knew who to talk to about it. That being said mine has very little lag at 9.5. You might be able to run 10 or so at that elevation. Again just thinking outloud.
Those are good thoughts! I've been running 12 psi on 91, but with the low cp theres a lit of lag for sure! I guess glamis will be the tell all, fill her full of 110 and go for 16 psi! I should pdobably go but a 570 for CO!
 

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....This is exactly why i left my motor stock!....I know polaris built a stout engine in the prostar and some VERY credible sources say the motor internals will handle double its stock output with proper care in tuning and good fuel. I followed these leads and run my motor on 9psi using E85....it has stock throttle response down low and still manages a 4 second 0-60mph time....I took it on a 60mile ride this past weekend and put it through every possible situation you could encounter in my riding area from loose rocks to sugar sand....highway tarmac and 2 feet of water....even sitting in traffic at some points!....we didnt miss a beat and even had fuel to spare when we got home....in all i am really pleased with my setup and would recommend to anyone looking to get the most from their 900 XP.....

 

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Just thought I'd give my opinion of all the work I've done to my xp & what I'd do differently if I was to do it again! Lets start with what I've done, I bought a used air-air kit that came with 9-1 cp pistons and lots of other parts, pretty good deal, then I decided lets do it right the first time & fire ringed the cylinder, cnc ported the head, valve springs, cams and arp head studs thinking this should rip & hold together! Well got it all together fired up running pig rich at idle can't lean it out any more so test drive time it's a dog out of the hole but pretty cool on boost , clutching issue so I get my clutching pretty good for 6k feet altitude seems pretty good just suprised at how much boost lag I've got! Then I went up camping @ 9k feet on the woods & it just seems like this thing is laboring unless on boost, so not much fun to drive! So long story short if I had to do it again I think I'd do a low boost kit or just not do all the internal eng work through a set of valve springs at it and keep the boost at ten or lower!
Are you still fat on the bottom? Your low end performance will be crap if so. What's keeping you from leaning out more? Did you replace the injectors with aftermarket? What's the shortest pulse they can do? Maybe your fuel controller needs to be remapped or replaced with one that can handle this?

Not sure what cam you're running, but you might want to go back to something less aggresive as well? Something that gains some low end torque in place for high rpm HP.

I don't think you've went the wrong direction, you just haven't reach the end yet. :ride:

Just some thoughts,
Brian
 

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interesting thread,
i have come to the conclusion turbo is not for me,
and i certainly don,t want to carry a pit mechanic in my pocket, where ever i,m ridingto constantly make adjustments with varying altitudes,
up here in the rockies
good luck quirly
 

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Discussion Starter #11
Just thought I'd give my opinion of all the work I've done to my xp & what I'd do differently if I was to do it again! Lets start with what I've done, I bought a used air-air kit that came with 9-1 cp pistons and lots of other parts, pretty good deal, then I decided lets do it right the first time & fire ringed the cylinder, cnc ported the head, valve springs, cams and arp head studs thinking this should rip & hold together! Well got it all together fired up running pig rich at idle can't lean it out any more so test drive time it's a dog out of the hole but pretty cool on boost , clutching issue so I get my clutching pretty good for 6k feet altitude seems pretty good just suprised at how much boost lag I've got! Then I went up camping @ 9k feet on the woods & it just seems like this thing is laboring unless on boost, so not much fun to drive! So long story short if I had to do it again I think I'd do a low boost kit or just not do all the internal eng work through a set of valve springs at it and keep the boost at ten or lower!
Are you still fat on the bottom? Your low end performance will be crap if so. What's keeping you from leaning out more? Did you replace the injectors with aftermarket? What's the shortest pulse they can do? Maybe your fuel controller needs to be remapped or replaced with one that can handle this?

Not sure what cam you're running, but you might want to go back to something less aggresive as well? Something that gains some low end torque in place for high rpm HP.

I don't think you've went the wrong direction, you just haven't reach the end yet. :ride:

Just some thoughts,
Brian
Its more fat at an idle! When I started it was fat all over so I ended up taking my fuel controller all the way lean at all aspects & I've slowly been tuning it in! I thnk the biggest thing I'm fighting is the low cr & my alltitude! I'm still hoping for big things in Glamis! Swingarm had mentioned I might have an exhaust leak causing my fat condition, I'm 99.9% sure I don't, but when I've got some time I'm going to go through the exhaust system & double check! Thanks for your positive thoughts & encouragement!
 

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Discussion Starter #12
interesting thread,
i have come to the conclusion turbo is not for me,
and i certainly don,t want to carry a pit mechanic in my pocket, where ever i,m ridingto constantly make adjustments with varying altitudes,
up here in the rockies
good luck quirly
Chris, I'm not against the turbo by any means, I just think at the altitude we ride closer to the stock cr my be a little more user friendly! I agree though I really don't want to spend more time wrenching then riding!!!
 

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Discussion Starter #13
Sorry Brian, I'm running stock injectors with 2 extra injectors for fuel under boost!
 
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At those altitudes I'd say you are on the money..the lower compression is hurting the power before boost builds..it's also prolonging boost building. I haven't researched the XP kit too much but I wonder if a smaller turbo might be better in your case..so it will spool faster..or and maybe an Aerocharger...can't believe I just said that lol.
As said Rayce told me if I go too low on. The CR I wouldnt be happy with the N/A cruise power.
 

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Sorry Brian, I'm running stock injectors with 2 extra injectors for fuel under boost!
That's raising a red flag then. If the extra injectors don't kick in until boosting, then too rich with stock injectors is showing there is another issue. I don't know anything about your fuel controller, but it might need to be remapped. Is your idle rough as well? You might also check your IAC. BTW, what's your A/F at idle?
 

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May also want to take a look at your fuel pressure to if you haven't already. I'm in the process of installing an adjustable fuel pressure regulator because I was building to much pressure.
 

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Discussion Starter #17
A/f at idle is 10.8-11.2, it usually fires up and dies thenafter that it will start just fine, right after start up the af will go to around 14-14.5 for a few seconds then go fat! At first we thought I had my timing chain tentioner to tight so I backed it off and that helped a bit so I'm consisering putting my factory tentioner in and seeing what that does! Thanks for all the ideas guys!
 

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check for boost leaks in the charge side of the system. also if the wastegate is not closing all the way, it will take much longer to build boost. the closed tension on the wastgate should be pretty tight.
 

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Mine was running fat at less than boost after I installed the bigger fuel pump so I installed a rising rate fuel pressure regulator. Set for 39 psi at zero boost, with the boost line disconnected, it would pull the pressure back to 35 psi at idle and increase it as the boost came up. worked great for partial throttle running. I'm planning to install a fuel pressure sending unit and gauge so I can see where it is going as boost increases. (actually its another pretty lighted thing to look at while I'm driving)
After I installed the turbo I started to see why people sold a lot of rzrs after going with a turbo. there'
s always one more thing to do. This next week I am installing a bypass full flow thermostat housing in order to not only add cooling (hopefully) but to use the bpass line to cool the bearing housing on the trubo. The outlet of the coolant line coming from the turbo will run through a bed mounted B&M remote fluid cooler (with a 7 inch fan and shroud) and back into the radiator hose going to the radiator. I don't think it will add any power but it should add to the life of the turbo. I'll post pics as soon as its all together.
After that I am installing the third injector to bring it up to 12-13 psi and that's where I plan to leave it.

AS with yours, my little 800 has some issues with turbo lag off the bottom. Once you are about 10 feet out, it pulls like a bull. I'm not complaining at all. I love the turbo but if this weren't so much entertainment learning about turbos on this thing, I would probably look at an XP and leave it stock.


Ok, probably wouldn't leave it stock but the cycle would at least start over again. :rofl3::rofl3:
 

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A/f at idle is 10.8-11.2, it usually fires up and dies thenafter that it will start just fine, right after start up the af will go to around 14-14.5 for a few seconds then go fat! At first we thought I had my timing chain tentioner to tight so I backed it off and that helped a bit so I'm consisering putting my factory tentioner in and seeing what that does! Thanks for all the ideas guys!
If it's fluctuating, it may be your IAC valve or the hose has kinked, cracked, etc.
 
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