Read this: Info on 4-tec motors, injectors,rrfpr's, etc.

[Mark S]

Attached is some info based on research done and information learned while recently trying to figure out why I was running lean with the addition of a Rude sc'r and rrfpr over the Rotax stage 3 kit I had previously. It was too cold today to go out and test, so I figured I would type this up and perhaps could help some others with similar questions.

Mark

[Shibby1485]

Mark... outstanding!!

absolute tremendous contribution to the forum, well done, VERY informative

i like your apprroach and how you do things. dont just slap something on your ski without fully understanding how it affects each running condition of the motor and how it works and plays a role in performance.

thanks!!!

[RX951]

wow, I love technical information. that was very straight forward !
Thanks for the reading ! is this a sticky candidate ?

[aha]

That was a great write up Mark! The math kinda went over my head but I get the idea. Based on the formula you put in the doc I am wondering if someone can build a HP calc in excel... any math/excel wizzes around? haha

I agree with you regarding monitor whats going on with your motor... I am doing a few upgrades and am not even planning on cranking the motor up without an AFR guage and boost gauge hooked up. Going to add a fuel pressure gauge to that list now

Thanks again for the great info!.

[Green Hulk]

Mark, thank you very much for taking the time to type that all up and share it with us.

This is a must read for anyone modifiying their skis.

I'm going to stick this one to the top for a while.

Thank you very much!

[Muddy River]

Mark is the real deal! THe first person I knew of that had a stageIII boat back in 05 with a 100 hours on it! He is definately a genuine guy! Good Job Mark! Very informative and your right about we need to monitor our engines more closely!

[daverxp4]

Mark, thank you very much for taking the time to type that all up and share it with us.

This is a must read for anyone modifiying their skis.

I'm going to stick this one to the top for a while.

Thank you very much!

how about puting it in the how to section faq there are alot of these we shouldadd to that section

[WFO]

95-100% duty cycle at 8100-8200 ?

[Mark S]

That was a great write up Mark! The math kinda went over my head but I get the idea. Based on the formula you put in the doc I am wondering if someone can build a HP calc in excel... any math/excel wizzes around? haha

I agree with you regarding monitor whats going on with your motor... I am doing a few upgrades and am not even planning on cranking the motor up without an AFR guage and boost gauge hooked up. Going to add a fuel pressure gauge to that list now

Thanks again for the great info!.

Here you go.
Mark

[aha]

Thanks for the calc Mark!!

[RXP & RXT]

That is so cool!! That means that I was making 285hp when I was testing my turbo rxt (see my turbo rxt thread)

[RXPT400]

Great post....

[SeanCucf]

Wow.......just wow.

[engineermike]

I, for one, can vouch for the fact that the stock ecu will command a 100% duty cycle. Most stock ecu's won't for fear of overheating the injector coil. Anyway, I've found that it's a funciton of boost, not rpm. I was able to get 100% DC at 7700 rpm or less at higher boost levels.

Mike

[stickem]

Heres some quick conversions also

• Conversions
• 500cc per minute is approximately equal to 49lbs per hour which is equal to approximately 100hp.
• lbs/hour = cc per minute / 10.5
• lbs per hour = HP / 2.04
• cc per minute = lbs per hour x 10.5
• cc per minute = HP x 5
• HP = cc per minute / 5
• HP = lbs per hour x 2.04