Thread: advice on lost rpm please
06-03-2007, 11:01 AM #1
advice on lost rpm please
guy i was testing today and lost some rom due to summer heat
was spinning my 14/23 @7190..
summer heat has me down to 7160..
removed riva cone filter last night as i now found my hull leak as i knew i was down on rpm and thought it may help a little running a open end air box (stock)..
speed is still good with stock tabs on @ 76.4 three bars of fuel dispite small rpm loss...
am i right in aiming for 7250 rpm range,
wanted a set of ross sonic booms as reported these will give me 100 rpm but still worried about sea water injestion due to wave jumping even though the hull leak is fixed..
will keep an eye on ammont of water i get in hull from now to see if there a go for me..
have a 3 degree keyway but its not fitted as i worry about advancing the timing but understand that will give me more rpm..
how much rpm will i gain from key??
can anyone surgest some rpm gain for me to get me closer to 7250 rpm
fitted.. vf 11 reeds
150 stock cut heads
open air box+ fairing cut open and flexi tube aimed at box.
syphon builge removed
tell tale removed
bearing cone on oil mix
e.f.i set @ 184.108.40.206 seems good but no expert
85mm nozzle fitted, 87mm on shelf..
anyone got any advice please...or should i go 14/22...
thanks in advance as always ... paul
06-03-2007, 11:17 AM #2
- Join Date
- Apr 2006
- South MS
Your turning good numbers and are probably right where you should be.
The keyway gave my boat 50-60rpms (.5mph) and a bit of acceleration. The engine will be fine at 150lbs and advanced timing if you run premium fuel.
With your mods +keyway, I ran my efi controller on #2 on the top end screw, it would drop about 30rpms there. On a radar run, I would drop it to #1 pick up 30rpms and keep an eye on the tach.
Are you running a 2 layer head gasket? You could drop it to one layer.
Gut the inside of the air box too.
Have you done a back to back test with the 87mm nozzle?
06-03-2007, 03:24 PM #3
thanks ron, thought my numbers needed to be higher so will try the 87mm and see what the #'s come out at..
sorry ment to say air box is gutted from arrestors,was thinking of cutting the front out of the lid but keeping it on to stop any stray salt spray,what do you think..
06-03-2007, 10:44 PM #4
Thats not so bad for rpms in the heat IMO.
I picked up 50 from the key, and better accelleration.
Try the 87mm with everything removed.
06-04-2007, 02:16 AM #5
when you say try the 87mm with all removed.. (air box lid)or (ride naked for better aerodynamics)
pulled tabs agian yesterday, never ever ever again,the wind picked the chop up some out at sea, and saw my life flash infront of me as she tryed to spit me off near 75 ish...
i think my ski is pretty much maxed out now....
thinking of sending lowell my cylinders for porting, am i better off sending the zero hour new ones or the mint 100 hour ones,whats you thoughts???
Last edited by Hydrotherapy; 06-04-2007 at 04:35 AM.
06-04-2007, 09:15 AM #6
06-04-2007, 03:39 PM #7
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