Can't get rpm's up?? A TUFF! one here.
06-15-2007, 10:21 AM
#11
Charter Member
check float level on the carbs while in the water??? may be right on the dyno but the boat does set different in the water....
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-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
06-17-2007, 04:31 PM
#13
Registered
Thread Starter
Seems like everyone lost interest here! BUT, I found the answer finally.
Nothing was wrong with the engines, timing, floats, etc.....
changed props to a 23" from a 26" and WOW!! 80MPH @ 5100rpm!! These will sping to 6000 real easy so I don't know what the top is going to be. Seems my lower unit gear ratio must be different from a 1.50 which is normal.
Any math whiz out there to figure out the lower unit gear ratio??
1.50 upper , unknown lower unit+ 5100rpm@80mph (GPS)- 23" pitch prop???????
Nothing was wrong with the engines, timing, floats, etc.....
changed props to a 23" from a 26" and WOW!! 80MPH @ 5100rpm!! These will sping to 6000 real easy so I don't know what the top is going to be. Seems my lower unit gear ratio must be different from a 1.50 which is normal.
Any math whiz out there to figure out the lower unit gear ratio??
1.50 upper , unknown lower unit+ 5100rpm@80mph (GPS)- 23" pitch prop???????
06-17-2007, 09:38 PM
#14
Registered
Check out this link:
http://www.go-fast.com/Prop_Slip_Calculator.htm
It seems like you have 1.36 gears, but your slip is only 3% at 5100rpm with a 23" prop. Typical slip would be in the 10% range, your tach might be off.
bl
http://www.go-fast.com/Prop_Slip_Calculator.htm
It seems like you have 1.36 gears, but your slip is only 3% at 5100rpm with a 23" prop. Typical slip would be in the 10% range, your tach might be off.
bl
06-17-2007, 10:20 PM
#15
Registered
Thread Starter
That is about what I figured the ratio was.... but the uppers are SUPPOSED to be 1.50's!! Could the lower ratio be different than the "standard" 1.50 for lowers?? That could explain the low slip figure. 3% is next to impossible, but then @ 80 mph I am watching more things than the tach! Maybe I was 100 or 200 rpm off... it is a dual tach with marks every 500 rpm, not 100's. Still, I feel go about the 80mph figure to start with another possible 800 safe rpm to go.
Here is the boat- soon to be called " WILDFIRE".
The last picture is as purchased from "Too Old" aka Trick today.
Here is the boat- soon to be called " WILDFIRE".
The last picture is as purchased from "Too Old" aka Trick today.
Last edited by blown formula; 06-17-2007 at 10:29 PM. Reason: add a picture
06-18-2007, 08:04 AM
#16
Registered
you could put it in gear, rotate the crank , and confirm your gear ratio by counting or measuring the prop rotation.
maybe rotate 5 or ten revs on the engine to get accurate prop rotation, maybe use starter with coil wire pulled?
then you would know
my drives are 1.36 with speed at 72 at 5000 rpm
true 24 pitch (merc racing labbed props)
Ramb
maybe rotate 5 or ten revs on the engine to get accurate prop rotation, maybe use starter with coil wire pulled?
then you would know
my drives are 1.36 with speed at 72 at 5000 rpm
true 24 pitch (merc racing labbed props)
Ramb
06-18-2007, 09:01 AM
#17
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Join Date: Jun 2003
Location: Oklahoma
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That is about what I figured the ratio was.... but the uppers are SUPPOSED to be 1.50's!! Could the lower ratio be different than the "standard" 1.50 for lowers?? That could explain the low slip figure. 3% is next to impossible, but then @ 80 mph I am watching more things than the tach! Maybe I was 100 or 200 rpm off... it is a dual tach with marks every 500 rpm, not 100's. Still, I feel go about the 80mph figure to start with another possible 800 safe rpm to go.
Here is the boat- soon to be called " WILDFIRE".
The last picture is as purchased from "Too Old" aka Trick today.
Here is the boat- soon to be called " WILDFIRE".
The last picture is as purchased from "Too Old" aka Trick today.
do you mind sending me your painters contact info, I'm wanting to paint mine this winter-- starting to check around now.
thanks in advance!
06-18-2007, 09:44 AM
#18
Registered
Thread Starter
I think your ratio info is so close I do not need to check my ratio. We match almost perfectly......
My painter was in Tulsa, Okla....... "STREET DREAMS". They did pretty good work but don't normally do larger things like a boat, usually custom cars..... It took them 18 months!! I had to stay on their asses all the time to work on it.
The Dash grafics & pinstriping were done by AWESOME ARTWORKS Collin Cauley 918-342-3703 he does airbrush graphics, cad graphics, etc. Good guy & works fast too.
He can probably recommend a good painter too you or he may do it himself, who know?? Painters can be a strange lot.....
My painter was in Tulsa, Okla....... "STREET DREAMS". They did pretty good work but don't normally do larger things like a boat, usually custom cars..... It took them 18 months!! I had to stay on their asses all the time to work on it.
The Dash grafics & pinstriping were done by AWESOME ARTWORKS Collin Cauley 918-342-3703 he does airbrush graphics, cad graphics, etc. Good guy & works fast too.
He can probably recommend a good painter too you or he may do it himself, who know?? Painters can be a strange lot.....
