Essarex
Pro
I finally got the chance to try out my summer project; my 06 MPI Apex. It is a stage 1, with pulleys designed to produce 9-10psi, but, with an HSK blow off valve that vents to about 7-8psi. With stock compression, 7-8 is all that I dare on 93 octane. This setup builds boost very quickly but bleeds it off for pump gas safety on the top end.
I guessed at the clutch calibration and nailed it. I’m using Polaris 10-74 weights, stock sacked out primary spring, stock sacked out secondary spring, with a Shockwave progressive helix, wound almost all the way in (close to a 53/47 I think). It is about perfect for a groomed trail on a typical 15 degree F day.
No overheating, no track ratcheting (stock introvert drivers), good fueling with the GEMS, basically a gas and go weekend of riding.
I geared the sled up from 24/38 to 26/38, so the speedometer is closer to reality that stock.
When I first ran my stock Apex with the stock ripsaw, it did about 115 on a snowy trail. After going to the 128 cobra, I only saw 109 in like conditions. Now, with the supercharger, same cobra, and new gearing, I hit 120 easily. I’m sure it would have pulled at least 5 more, but it is damn easy to run out of trail with so much pull. I haven’t done the calculation; it would be nice to know how much closer the real speed is to the indicated speed.
40 – 115 takes about as much time as it did stock 40 – 80. The throttle response is almost too abrupt; accidently bump it mid corner and you are in the trees. Stock (high) compression with 7psi is amazing.
I got 11mpg on one tank, following a new rider most of the day, not exceeding about 60 for most of the tank. Funny thing is that the A/F ratio runs very rich, 9-10:1 at that 50-60 range. During the second tank, I rode it with another group that carried more speed all day, closer to 80-90 on average, and that tank produced about 10mpg. Interestingly, the A/F runs closer to normal at that range, about 13:1. At full throttle it runs a perfect 12.5:1 or so.
I wish there were a way to get 13:1 everywhere except at WOT, where it needs to be 12:5:1. That 10:1 at 50mph is what gives these superchargers a bad reputation for fuel economy.
Anyway, it was a long wait all season given this BS weather, but at the end it was truly a satisfying experience. Can’t wait until the next trip!
I guessed at the clutch calibration and nailed it. I’m using Polaris 10-74 weights, stock sacked out primary spring, stock sacked out secondary spring, with a Shockwave progressive helix, wound almost all the way in (close to a 53/47 I think). It is about perfect for a groomed trail on a typical 15 degree F day.
No overheating, no track ratcheting (stock introvert drivers), good fueling with the GEMS, basically a gas and go weekend of riding.
I geared the sled up from 24/38 to 26/38, so the speedometer is closer to reality that stock.
When I first ran my stock Apex with the stock ripsaw, it did about 115 on a snowy trail. After going to the 128 cobra, I only saw 109 in like conditions. Now, with the supercharger, same cobra, and new gearing, I hit 120 easily. I’m sure it would have pulled at least 5 more, but it is damn easy to run out of trail with so much pull. I haven’t done the calculation; it would be nice to know how much closer the real speed is to the indicated speed.
40 – 115 takes about as much time as it did stock 40 – 80. The throttle response is almost too abrupt; accidently bump it mid corner and you are in the trees. Stock (high) compression with 7psi is amazing.
I got 11mpg on one tank, following a new rider most of the day, not exceeding about 60 for most of the tank. Funny thing is that the A/F ratio runs very rich, 9-10:1 at that 50-60 range. During the second tank, I rode it with another group that carried more speed all day, closer to 80-90 on average, and that tank produced about 10mpg. Interestingly, the A/F runs closer to normal at that range, about 13:1. At full throttle it runs a perfect 12.5:1 or so.
I wish there were a way to get 13:1 everywhere except at WOT, where it needs to be 12:5:1. That 10:1 at 50mph is what gives these superchargers a bad reputation for fuel economy.
Anyway, it was a long wait all season given this BS weather, but at the end it was truly a satisfying experience. Can’t wait until the next trip!
triple777
Newbie
i agree with you on everything took mine out for the first time last week in the black hills all good ran on 91 plus octane boost same fuel mileage as stock ltx and i played in the trees alot more this thing rocks just wish i could open her up boost rules
kinger
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Yep agreed with you on all counts. I do run 10-11 psi on a shimmed engine and get about the same mpg. The fueling is a issue (rich in mid range) but with good clutching I still get about the same mpg as you with 40hp more.
Once these babies are set up just gas and go for the year, pull maint in the off season. I love it!
I know turbos are better at some things but this thing is stupid reliable and like you said you have to be careful in the trails, the hp is instant.
Once these babies are set up just gas and go for the year, pull maint in the off season. I love it!
I know turbos are better at some things but this thing is stupid reliable and like you said you have to be careful in the trails, the hp is instant.
stephenpen
Expert
What pulleys are you running ?
Essarex
Pro
24/26
