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View Full Version : Used to run over a 100mph



Infamous
09-11-2007, 07:55 PM
I recently had my drive rebuilt and since then I can only get 84-85mph on the rev limiter @ 5600-5700rpm. :mad: I do not what gears were in it before I had it rebuilt. Any thoughts? I think a different ratio was used like 1.5s and I probably had 1.36's:idea: Don't know. I am currently running a labbed 30 that would not see the rev limiter and the boat would run 104 on a good day and hit a hundred consistantly anytime else.

topless
09-11-2007, 08:05 PM
I think the main question here is can you spin out in the reeds ?

Infamous
09-11-2007, 08:14 PM
Maybe if I take some lessons:D

Run_em_Hard
09-11-2007, 08:20 PM
What RPM's were you seeing before your had it rebuilt?

Infamous
09-11-2007, 08:29 PM
What RPM's were you seeing before your had it rebuilt?
Around 5400-5500 in the heat

OCMerrill
09-11-2007, 09:10 PM
It seems to me if your seeing more RPM and less speed and nothing else has changed outside of the drive....Ex: same prop.
Then the gearing in the drive has changed. So I agree with you that it appears possible the wrong gears were installed during the rebuild process. Both those ratios are very popular.
Is this speed GPS verified?

acatitude
09-11-2007, 09:26 PM
or you have a crack in your prop and are spinning higher rpms, but getting less mph. check it first

C-2
09-11-2007, 10:02 PM
Brian, try this link and play with your numbers - according to what I put in -
1.36 @ 30 pitch, 5500, 10% slip has you at 104
1.51 @ 30 pitch, 5700, 10% slip has you at 96
Seems you're still 10mph off?
------------
On a happier note, the wetbacks who bought Pete's house have it up for sale (fire sale, that is).
http://www.go-fast.com/Prop_Slip_Calculator.htm

Run_em_Hard
09-11-2007, 11:14 PM
Sounds to me like you might be thinking right. Call up whoever di your build and talk to them. Find out what gears they put in it and if they have your old ones.

brianthomas
09-12-2007, 03:55 AM
A 200 rpm drop will not cost you 20 mph though. There is something else wrong here.

hava life
09-12-2007, 03:26 PM
brianthomas A 200 rpm drop will not cost you 20 mph though. There is something else wrong here
You mean 200 RPM increase:)
Maybe the wifey had someone slow down the rocket because she wants you to get a bigger boat:D

AZJD
09-12-2007, 03:32 PM
I recently had my drive rebuilt and since then I can only get 84-85mph on the rev limiter @ 5600-5700rpm. :mad: I do not what gears were in it before I had it rebuilt. Any thoughts? I think a different ratio was used like 1.5s and I probably had 1.36's:idea: Don't know. I am currently running a labbed 30 that would not see the rev limiter and the boat would run 104 on a good day and hit a hundred consistantly anytime else.
Stupid question, but is this on GPS?

Jetaholic
09-12-2007, 03:35 PM
I think the main question here is can you spin out in the reeds ?
He used to be able to, but I think when they rebuilt the drive they installed over transom headers and he lost 5 mph :D

Infamous
09-12-2007, 05:35 PM
Stupid question, but is this on GPS?
No I had my buddy pace me in a helicopter:D j/k yes it is on gps

Infamous
09-12-2007, 05:42 PM
Talked to the shop. yes the wrong ratio was put in. I have 2 choices. 1)play with some bigger props or 2) put 1.36's back in. They will eat the cost. I think I will toy with the props see if I get some better #'s. If not I will have them change the gears.

Infamous
09-12-2007, 05:47 PM
Brian, try this link and play with your numbers - according to what I put in -
1.36 @ 30 pitch, 5500, 10% slip has you at 104
1.51 @ 30 pitch, 5700, 10% slip has you at 96
Seems you're still 10mph off?
------------
On a happier note, the wetbacks who bought Pete's house have it up for sale (fire sale, that is).
http://www.go-fast.com/Prop_Slip_Calculator.htm
Which Pete. Not old man Pete?