RXP-X - Does this suggest a boost leak?

[Jarrett]

I went out this morning to my normal testing spot hoping to get some higher RPMs and higher top speeds in the cooler air. I got a little more top speed, but my RPMs weren't as high as I thought they would be for the difference in air temp from my last baseline run. The humidity was double my last run, but the air temps were almost 30 degrees cooler. Everything else was pretty much the same. I got 1.1 more MPH out of it, but I was expecting quite a bit more RPMs. Does the lack of RPMs with the air temp difference suggest a boost leak somewhere?

Date: 8/19/09 | 8/29/09
Elevation: 530 | 530
Air Temps: 99 | 70
H2O Temp: 89 | 84
Humidity: 35% | 70%
Fuel Level: 2bars | 2bars
Peak RPMs: 8020 | 8060-8080
Peak Speed: 71.8 | 72.9

I did change the oil between these runs. I guess an overfill is an option, but I think it was overfilled before. Bear in mind I slow the ski down about 1.5 - 2 MPH just due to my weight. A regular sized rider would have been pulling out 74.5 - 75 MPH out of the ski this morning, so I'm not as concerned as much with top speed as I am with RPM.

[tempest.runner]

Your rpm's seem normal to me. I usually average 8040 and peak at 8100.

[richrxp]

I think everything is ok.

The same thing happened last week to me,had thought of higher rpm,s but just wasn't happening.

Don,t forget the watertemperature plays a big role in this,its a combination off everything,i think the watertemperature is still a bit high causing loss off rpm,s ,how many hours on the ski?

I am asking because your supercharger clutch may have a lower slip then before.

This also will cause some performance drops.

But alltogether i think your fine,don't worry about it!

[Jarrett]

The ski only has 12 hours on it.

Probably should have mentioned it has mods on it:

4" Fizzle intake
Worx Grate
Ride plate holes filled
Reverse bucket mod
Stock Solas 15/22R w/nose cone in

[MPower]

Looks like a normal gain to me Jarret. Temps were cooler but the air was way thicker. Now wait for a day that is 70 deg and 20% humidity with 70 deg water and you will see well over 8100 RPM

[troyheb]

The ski only has 12 hours on it.

Probably should have mentioned it has mods on it:

4" Fizzle intake
Worx Grate
Ride plate holes filled
Reverse bucket mod
Stock Solas 15/22R w/nose cone in

I have a RXTX with basically same mods, my RPMs run about the same as yours.

[Jarrett]

Cool, thanks guys. Now I'm thinking how to get this thing to 75 MPH with me on it while improving the hole shot

[MPower]

Cool, thanks guys. Now I'm thinking how to get this thing to 75 MPH with me on it while improving the hole shot

Send your prop to Erik!!! Thought you were going to do that? Stop dickin around

[Jarrett]

Yeah I definitely need to Been dragging my feet on it. Considering sending the throttle body out to be worked on as well. Might do all of that this week.

[speedskixp]

Cool, thanks guys. Now I'm thinking how to get this thing to 75 MPH with me on it while improving the hole shot

Yeah, the humidity is holding it back a little.. You should be able to get it to 75 with you on it fairly easy. If all else fails add a upgraded sc wheel. Holeshot may be a little harder as weight really effects that more than top speed. I'm not a small guy myself and it ussualy costs me the hole shot when I race. Even after swapping boats with the opponent.