Obviously you can get 10+hp per pound of boost on a turbo, and it seems close to 8hp per pound on a supercharger. It seams as if though mcx gets more hp out of their setup than most turbo brands on pump 91 octane for some reason. If I was to change my mind from going with the MCX, and to go with a S/C from MPI use low compression gasket, timing changes, PCV, ignition module, autotune, better BOV, head studs, larger fuel pump etc. how many pounds safely could I run on a 2012 Apex in pump gas? I know on my nytro I pushed it 13-13.5lbs using a similar setup. Thinking this route being I do 90% groomed trail, and 10% two tracks only. Almost no off trail, but an occasional potato field. I know I won't get as much boost out of a charger as a turbo, and the mpg seem to be about 3mpg worse from what I hear, but the price difference is way to big to not go charger again. IMO....Didn't know if the newer Apex could handle the same pounds I was running in my Nytro safely with this setup? I heard one guy on here say the pistons on the new apex are not as strong as the old apex? Allen had my nytro @13- 13.5lbs on a stage one so wondering what to expect out of the Apex? From what I have been reading I am capped at about 12lbs on the stage one Apex. Is this the max?
Also on the flip side if I didn't add the head shim I am reading on here that the highest boost you can go at 91 octane is 8lbs correct? So 8lbs max without a shim, and 12lbs with a shim, or is there a tad more in the blower and engine you can push it to safely on a 2012?
Thanks for your help as usual guys... Thinking POSSIBLE summer project here.
Also on the flip side if I didn't add the head shim I am reading on here that the highest boost you can go at 91 octane is 8lbs correct? So 8lbs max without a shim, and 12lbs with a shim, or is there a tad more in the blower and engine you can push it to safely on a 2012?
Thanks for your help as usual guys... Thinking POSSIBLE summer project here.
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Riceburner
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I am running 15.5 PSI max on my MCX kit on 91 octane. No issues other than a little to much power for the trail. The engine is fine after 5,000 km. Don't forget your Ape has a Deto Sensor .
The guys who replaced pistons on 2011 & newer were running 19 lbs ish sometimes on race fuel & racing them year round.
MCX makes more than 10 hp /lb of boost. very efficient.
MPI SC makes about 10 hp per lb of boost but you need to subtract 10 hp ish from the total to run the blower. [ Check MPI's website for RX 1 Dyno charts.]
You can get 12 psi from a MPI Stage 1 at sea level. In theory that is about it. My old RX 1 showed 14 & is very strong but that seemed high to me.
MPG is about 1.5 mpg worse not 3 mpg. If you are hard on the throttle it is even less.
8 psi W/O shim is correct. 1/1 pullys should give you that.
There appears to be a tad more in the blower at sea level than 12 psi from what I have seen but the blower is not that fond of it and the charge temps get hotter than some like.
Your engine will handle it no problem
If I boost another Apex it will be on a stock motor running 8 PSI with an MPI Super Charger.
I love my Turbo and it has a lot of advantages over the Blower but I want that instantaneous trail power next time & I'm willing to give up some top end, Fuel mileage etc for it.
Go for it. The price is right & the MPI kit is awesome. I owned one & helped build another
Perfect! Thank you for the answer. The only reason I was thinking 8 lbs over 12lbs, is if I sold the sled later I could pull the system off easier. Selling the charger separate from the sled. The low compression, and larger pump make it more time consuming, or expensive to separate the two at a later date...... Thanks again
kinger
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I agree with this, we are all power hungry and the MCX is top on the dyno but man actually driving my 10-11 psi SC on the trails, it actually scares me which I have a pretty high tolerance for. So as much as I want to say I want 300hp it doesn't matter this sled is too fast. Also I raced a AC 1100T this winter on the 275hp setting and beat him. I always said you can never have enough power but I am so happy with my snappy 250hp beast I wouldn't change a thing.
I'm assuming I had the same traction issues you had in the past kinger on my last boosted sled. I had a nytro with a supercharger setup @248hp, on a 128" track. Blast to ride in the corners, and mid range was awesome. All because of track spin. It was riding one of those dirt cars in the corners lol. #*$&@ end rotating , and power sliding till the track caught. But being you couldn't enjoy the take off it wasn't a great drag sled unless you did a rolling 30 mph pull on the lake or rail bed. So the scare factor was not there like yours is now. That is why I have the same concern here. Thinking of trying to find a nytro 144 skid, and picking it four down the middle. Being right now I have a 128" Apex model. Still need to corner in the tight and Twisties against those damn ski doo's, And the guys on here seem to rave about the 144 tip up for best of both worlds. It would be the only way to increase the scare factor without going to a stage two upgrade 
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kinger
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Yes I would say my 151" was the same difference as going from stock to boosted. It's that dramatic. If you go 144 that would help so much. I will say it appears length is better then width. Mine is a skinny 13.5" but with 151 not able to wheelie as much there is a lot of of track on the ground vs a wider 144 and popping a wheelie. I don't have ANY handling issues. I was worried sick about ruining the sled in the corners but I don't even notice it which is why I went with the 13.5". Go long buddy!!
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Cool! Thanks agin for the help Bud
auto2665
Extreme
8 lbs or 12 lbs? Do you really think it will make a difference when riding in the tight twisted trails like you say you like to ride? Save your money and swallow your pride. You'll keep up with just about anyone you meet up with, with 8 or 12. Why worry about running higher octane fuel for 4-5 hp? what a waste! Just to say you have 15lbs? I think your sled will be much more trailable at 8lbs and plenty fast enough. Just saying..... I think MPI can remap your ECU and retard timing so you can run a little more boost at Sea level with 92 octane
Riceburner
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My Turbo Apex has a 144 Nytro skid. It works well..
With the MCX Turbo you have stud clearance issues you will not have on the MPI SC kit.
I'm a trail rider so I put on a 1" Hacksaw with 1.17" Megabytes in a 4-2 pattern studded outside which is a great trail combo. I have just enough stud clearance with an extra 1/4" added to the tunnel protectors.
If I do a SC Apex, it will be a 128 stretched to 136, Ripsaw running 1.45 Megabytes with an extra 1/4" of tunnel protection in a 4-2 pattern for 32 scratch lines. This is what we run on the SC RX 1 and it hooks up awesome at launch.
I would recommend that combo for you. A lot cheaper for you to do & it works great.
With the MCX Turbo you have stud clearance issues you will not have on the MPI SC kit.
I'm a trail rider so I put on a 1" Hacksaw with 1.17" Megabytes in a 4-2 pattern studded outside which is a great trail combo. I have just enough stud clearance with an extra 1/4" added to the tunnel protectors.
If I do a SC Apex, it will be a 128 stretched to 136, Ripsaw running 1.45 Megabytes with an extra 1/4" of tunnel protection in a 4-2 pattern for 32 scratch lines. This is what we run on the SC RX 1 and it hooks up awesome at launch.
I would recommend that combo for you. A lot cheaper for you to do & it works great.
Great Idea rice. Appreciate the info that is proven.
@ auto there is no re flash for the newer apex. I've had sleds with 2lbs, sleds with 10lbs, sleds up to 14.5 on the trail. The main two questions were being both only use premium pump gas were. 8 or 12lbs on a shorty apex? Second if I go 12 does the apex allow me to go up a tad more while I'm already paying for the dyno, and adjustment time another pound or two like the nytro's allowed me to in the past?
@ auto there is no re flash for the newer apex. I've had sleds with 2lbs, sleds with 10lbs, sleds up to 14.5 on the trail. The main two questions were being both only use premium pump gas were. 8 or 12lbs on a shorty apex? Second if I go 12 does the apex allow me to go up a tad more while I'm already paying for the dyno, and adjustment time another pound or two like the nytro's allowed me to in the past?
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Riceburner
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My recommendation on a 128" track is 7-8psi. Stock motor, no head shim.
Yes the engine will handle 14.5 psi no problem with a head shim or low compression pistons.
I remembered since my last post I had to drop the tunnel protectors 1/4" as well as add 1/4" to the protectors themselves if you go with the 144 skid & the MCX Turbo. You also need to bolt the skid through the bottom hole in the rear bracket instead of the top one. Fabricating the two forward tunnel protector mounts on the left side is required as well, as the under tunnel snow to air intercooler on the MCX prevents using the stock brackets.
kinger
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I think the 128" is to short for any boost level. I am just dumbfounded the difference in mine. I wouldn't go less then 144 ever. JMO
attak 06
Veteran
Hi. I'm installing a used stage 1 on my 2011 XTX. I'm at sea level and there are 24-24 pulleys. With those pulleys, what boost can I expect on pump gas. 91 octane here in Newfoundland. Was thinking about using octane booster. Was also wondering if I needs a head shim to run this combination? Installing soon..
I would contact ulmer,or mpi. Pulleys can get you in a range, but you can fine tune with your bov.
I went with riceburners idea. 7-8lbs, no shim with a 136 track. Upgraded my suspension. Also a bit. Should be an awesome ride.....
I went with riceburners idea. 7-8lbs, no shim with a 136 track. Upgraded my suspension. Also a bit. Should be an awesome ride.....
kinger
VIP Member
I'm so excited to get scared again! Every year I forget until that first good hard run...then I poop myself and remember to respect the beast and then I'm good for the rest of the season haha
