MPI stage 1 blower, boost/pulley/rpm--EFI sled

[KnappAttack]

Working on MPI stage 1, wondering what boost you guys are seeing with what pulleys, at what RPM on an average day in the trails in the winter, on your boost guage. I'm going to run engine at 10500 to 10800 on the EFI. Any info is much appreciated. Thanks, Mike Knapp#17

 

[HAMMER]

 

[KnappAttack]

I'm thinking about starting with a 24 on engine and 26 on blower. At around 10800 I would think that would put it around 10 lbs at 1000 above sea level. Does this sound reasonable? Anyone?

 

[monker]

sounds about right. I think the RXs have a 26 tooth bottom and 22 top, but this was running about 1000 less rpms.

 

[HAMMER]

I was seeing around 7lbs @ 10,800 @ 6000ft with 1:1 pulleys (24/24)... Compensated +0.5lb per 1000ft that would be around 10lbs at sea level... Compensated -0.5lb again for your altitude of 1000ft above sea level would be approximately 9.5lbs... So I wouldn’t under drive it, I would go with at least a 1:1 (24/24) since your looking for 10lbs @ 10,800 @ 1000ft.

10,800 x 1 x 12.67 = 136,836

That's right in the heart of the compressor map, 71% efficiency, good as it gets with that unit.

 

[Srxspec]

Just what I've seen on RX-1 & Apex at 1350 ft elevation where our shop is located.

 

[TurboJamie]

Im running the 1:1 ratio spinning right around 11,000 making the 10 psi of boost on my pro comp gauge at 1000' elevation.

 

[KnappAttack]

Thats the feedback I'm looking for. Thanks Guys!!!
A 24 engine, 26 blower should put it in the 7.5psi range then at about 10,800-10,900. Should be a good number for trail riding 300 mi days on 91-92 pump octane then.

 

[TurboJamie]

Thats the feedback I'm looking for. Thanks Guys!!!
A 24 engine, 26 blower should put it in the 7.5psi range then at about 10,800-10,900. Should be a good number for trail riding 300 mi days on 91-92 pump octane then.

I would agree that sounds pretty good to me. Thats where I started out but as we all know that extra lb of pressure is sure fun!