Thread: pipe target rpm's
08-23-2007, 01:41 PM #1
pipe target rpm's
What's the sweet spot on the stock gp or raider pipe? I know on the gpr's it's around 7150.
08-23-2007, 02:19 PM #2
08-23-2007, 02:36 PM #3
I should have know to look there
So it looks like 6800. Interesting.
08-23-2007, 02:42 PM #4
I turn 6970-6990 in the heat and 7010 in 70 degree weather. I don't see a benefit in spinning a single pipe above the factory rev limit of 7050 unless the RPM's need to be that high to take advantage of the porting. There seems to be different target RPM's for different porting.
08-24-2007, 10:16 AM #5
I would think that the pipe would effect how fast you can send a return wave of exaust to stuff the fresh charge back in the cylinder. Thus this rateing is only the effective range of how far the pipe will take you, not the desired rpm of the motor.
In other words the pipe is only good till 6800 after that the return wave curve falls off.
The more rpm you can turn, the faster you will be as long as you have enough prop pitch. And you are not overturning the prop past its usefull pitch.imo
08-24-2007, 10:50 AM #6
On a lot of the GPs that where here in Fl would run them about 7050 with just a few mods. Excellent torque and top end. One of the tricks was to use a Raider or 99 GP stinger.
The ported single pipe ski that I had with MSD had no problems running 7500 with the 12 vein pump so I think the pipe is more flexible then first thought.
Those 65U motors used a plugging type of signal to keep gasses in the cylinder verses sonic wave in the stinger. Ross Liberty from Factory Pipe wrote a huge article on it and was in a couple of the PWC rags at that time. Being 120 degrees out it is very hard to use a sonic bounce in the exhaust chamber due to one wave canceling the other. Tha exaust manifold itself somehow plugged the other cylinders at the correct time.
08-27-2007, 01:45 PM #7
I remember our conversation about this Duke. I searched for the article, but came up empty. 7500 rpm's with a 12 veinThat must be why your arms are stretched
Jdog, What are you basing the 6800 figure on?
I am trying to figure out weather or not to bring the pitch up on my GP. It's hitting 7200 now,and am just curious if I should pitch up to drop the revs but get the speed up. I am running a xo prop now, but have a J and a nujet 6.0 at my disposal. .
08-27-2007, 02:51 PM #8
You could try a 15.5/18.5 YD SC XI or a 13/19 YD SC I or even a
YD CD 13/19 I think I would try the YD SC XI (x prop) just to compare.
08-27-2007, 04:30 PM #9
mike- you are doing the same thing i am so let me help-a 14/20 is too much prop-been there and done it-either go to a 13/19 i prop or depitched 14/20 to 13/19 or stay right where you are-the 14/20 will drop you too low and lug the motor and you will lose speed and rpm's- mark
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