Thread: Am I done with mods?
02-03-2008, 08:41 PM #1
- Join Date
- Sep 2007
- Myrtle Beach, SC
Am I done with mods?
Here's what I've done to my 02 GTX NA (NOT supercharged!) 4tec.
new seadoo oem impeller and wear ring
filled ride plate and intake grate holes
blocked up the opas fins
Took the ski out today as the high was about 67F here in Myrtle Beach. I left the back seat off so the intake air would be as close to ambient temp as possible. It would run 56-57 mph on my Garmin 72 gps in areas where the water was relatively calm. With 2 bars of fuel left I shifted my weight as far back as I could with my feet still in the foot wells and saw 57.9 mph a couple times but it wouldn't stay there very long. When it's showing 56+ on the Garmin the analog tach on the GTX is pointing about a pointer width past the 7500 rpm mark. So I'm guessing it's turning about 7600 rpms. From what I've read the ECU on the NA 4 tecs will limit RPM's to around 7650 right? Question: Since I'm running about 7600 rpm now and more speed requires more rpms, but the ECU won't allow rpms (and thus speed) to increase, is the any point to doing any more mods (such as intake air, exhaust, grate, wedge)? IOW let's say I install a 2 deg pump wedge which lifts up the nose resulting in less drag. The rpm's will come up due to the lower hull drag (maybe 100 rpms for a 1mph increase?), but if that's enough to put it on the limiter then I'm not going to see the speed gain right? Also if I'm on the limiter will it lean out the mix and cause the exhaust temp to rise melting the manifold end bell?
Last question: How are some people seeing 60mph on a NA GTX when the rev limiter in the ECU won't allow the ski to do more than 58 mph tops?
02-03-2008, 08:52 PM #2
- Join Date
- Nov 2007
- Odessa, TX
If your ski is hitting the rev limiter the easist solution is to add 1mm too the prop. That adds speed and lowers RPM in very small steps.
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