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Topic: The formula for MPH< Next Oldest | Next Newest >
TuchopMale Offline
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Post Icon Posted: April 23 2005,9:55 am Post # 1 see this member send this member a private message  quote this post in reply
I got this site the other day. Prop slip is usually no lower than 9%. 13% to 16% is prob more realistic. Parental Advisory: This could hurt your feelings if you have never GPSd your ride.

http://www.rbbi.com/folders/prop/propcalc.htm

:banghead  :banghead  :laugh  :laugh
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Post Icon Posted: April 23 2005,6:09 pm Post # 2 see this member send this member a private message  quote this post in reply
Waaaayyy to tech 4 me...my GPS does good enough... :good
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Post Icon Posted: April 23 2005,9:35 pm Post # 3 see this member send this member a private message  quote this post in reply
I seen that before and it don't make sense at all, I put in my combination when I ran 106 and this deal says 75, something's wrong with that deal!.. :rolleyes  :stupid
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TuchopMale Offline
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Post Icon Posted: April 26 2005,7:54 pm Post # 4 see this member send this member a private message  quote this post in reply
GFR,
I am not familiar w/ v-drives is there a gear or is it strt 1:1 drive ratio.
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Post Icon Posted: April 27 2005,8:45 am Post # 5 see this member send this member a private message  quote this post in reply
Quote (Tuchop @ April 23 2005,9:55 am)
Parental Advisory: This could hurt your feelings if you have never GPSd your ride.
:banghead  :banghead  :laugh  :laugh

That's pretty funny. :rotflmao  Thank God I was pretty conservative on my estimates for the 13 years I owned my boat before I GPS'ed it. :D





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Post Icon Posted: April 27 2005,8:47 am Post # 6 see this member send this member a private message  quote this post in reply
Tuchop, this is a pretty cool avatar BTW. :cool



I'm going to put it in the random pic place on my main site. :good





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TuchopMale Offline
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Post Icon Posted: April 27 2005,3:11 pm Post # 7 see this member send this member a private message  quote this post in reply
Quote (Havasu Doug @ April 27 2005,8:47 am)
Tuchop, this is a pretty cool avatar BTW. :cool



I'm going to put it in the random pic place on my main site. :good

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Post Icon Posted: April 27 2005,4:52 pm Post # 8 see this member send this member a private message  quote this post in reply
Quote (Tuchop @ April 26 2005,7:54 pm)
GFR,
I am not familiar w/ v-drives is there a gear or is it strt 1:1 drive ratio.

Vdrives can be just about any ratio, they have interchangeable gears to give you the final drive you wantor need.

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Post Icon Posted: April 27 2005,6:36 pm Post # 9 see this member send this member a private message  quote this post in reply
Speed = $$$$$$$$$$$$$$.  :D

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Post Icon Posted: April 30 2005,9:44 pm Post # 10 see this member send this member a private message  quote this post in reply
Dont know if you guys have seen this or not but, its the same thing for jets.

http://www.liquidaddiction.net/images/dragnjet/Jpc2.xlt
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Post Icon Posted: May 03 2005,6:08 am Post # 11 see this member send this member a private message  quote this post in reply
Quote (Tuchop @ April 26 2005,8:54 pm)
GFR,
I am not familiar w/ v-drives is there a gear or is it strt 1:1 drive ratio.

You can get 1:1 all the way to 2.00 to meet your horsepower and prop combo!..I'm running 18's now but I should use 15's with this POS motor I have now!. :rolleyes  :laugh
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Post Icon Posted: May 03 2005,4:36 pm Post # 12 see this member send this member a private message  quote this post in reply
Quote (GoFastRacer @ May 03 2005,7:08 am)
Quote (Tuchop @ April 26 2005,8:54 pm)
GFR,
I am not familiar w/ v-drives is there a gear or is it strt 1:1 drive ratio.

You can get 1:1 all the way to 2.00 to meet your horsepower and prop combo!..I'm running 18's now but I should use 15's with this POS motor I have now!. :rolleyes  :laugh

15's? It seems to me that even that POS motor as you call it is building enough HP and torque to pull 18's.What size and pitch prop are you running?I'm running 18's and need to go to 22's with my new motor.

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Post Icon Posted: May 03 2005,4:54 pm Post # 13 see this member send this member a private message  quote this post in reply
I thought you said it was fast enough :p

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Post Icon Posted: May 03 2005,5:50 pm Post # 14 see this member send this member a private message  quote this post in reply
I'll bet that calculator is for 3 blade props.And all the speed calculators I have seen also ask prop diameter.I know that that one is not right.I'm getting 650+ HP and turning 18's with a 11-1/2 x 15 prop at 7000 and I know I'm going faster than 76 MPH

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Post Icon Posted: May 03 2005,5:59 pm Post # 15 see this member send this member a private message  quote this post in reply
Quote (AZKC @ May 03 2005,5:54 pm)
I thought you said it was fast enough :p

I don't remember saying it was fast enough,but as usual with roller cams they tend to quit building torque in the 6500 to 7000 range and with the 22's I can keep it in the power band.RPM's are great but torque is what helps acceleration and lift and with a heavy hull like a Mandella I need it.WE had it on the GPS this weekend for the first time and was 93 MPH.With the 22's I feel 100 is very attainable.I'm also going to try some different prop pitches and profiles to see if I can get rid of the looseness,It's a little squirly on acceleration but not when it reaches speed.

Fords All The Way
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Post Icon Posted: May 03 2005,6:38 pm Post # 16 see this member send this member a private message  quote this post in reply
:drink
I went out and bought a GPS. I think that program is close for me but, I damn sure wouldn't complain if it GPSd better. A couple more weeks and I'll check it out :D  :D
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Post Icon Posted: May 03 2005,6:44 pm Post # 17 see this member send this member a private message  quote this post in reply
Quote (AzMandella @ May 03 2005,5:59 pm)
Quote (AZKC @ May 03 2005,5:54 pm)
I thought you said it was fast enough :p

I don't remember saying it was fast enough,but as usual with roller cams they tend to quit building torque in the 6500 to 7000 range and with the 22's I can keep it in the power band.RPM's are great but torque is what helps acceleration and lift and with a heavy hull like a Mandella I need it.WE had it on the GPS this weekend for the first time and was 93 MPH.With the 22's I feel 100 is very attainable.I'm also going to try some different prop pitches and profiles to see if I can get rid of the looseness,It's a little squirly on acceleration but not when it reaches speed.

AZmandella,
Does 93mph have ur undivided attention or what?? Does that thing ever feel like its gonna go over on its lid?? I have only been up to about 70 give or take a lie.  :rotflmao  :rotflmao
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Post Icon Posted: May 04 2005,5:50 am Post # 18 see this member send this member a private message  quote this post in reply
Quote (AzMandella @ May 03 2005,5:36 pm)
Quote (GoFastRacer @ May 03 2005,7:08 am)
Quote (Tuchop @ April 26 2005,8:54 pm)
GFR,
I am not familiar w/ v-drives is there a gear or is it strt 1:1 drive ratio.

You can get 1:1 all the way to 2.00 to meet your horsepower and prop combo!..I'm running 18's now but I should use 15's with this POS motor I have now!. :rolleyes  :laugh

15's? It seems to me that even that POS motor as you call it is building enough HP and torque to pull 18's.What size and pitch prop are you running?I'm running 18's and need to go to 22's with my new motor.

Nope it ain't pulling the gears, I'm only turning 6400, actually 12's would be more ideal. That motor needs a set of pistons to bring up the compression, my other motor(440) pulled 7500 with the 18', with 11 1/2x14 prop!.
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GoFastRacerMale Offline
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Post Icon Posted: May 04 2005,6:00 am Post # 19 see this member send this member a private message  quote this post in reply
Quote (AzMandella @ May 03 2005,6:50 pm)
I'll bet that calculator is for 3 blade props.And all the speed calculators I have seen also ask prop diameter.I know that that one is not right.I'm getting 650+ HP and turning 18's with a 11-1/2 x 15 prop at 7000 and I know I'm going faster than 76 MPH

Depending on prop slip with that combination you were going 93.8 with 20% slip!.
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Post Icon Posted: May 04 2005,10:24 am Post # 20 see this member send this member a private message  quote this post in reply
Quote (Tuchop @ May 03 2005,7:44 pm)
Quote (AzMandella @ May 03 2005,5:59 pm)
Quote (AZKC @ May 03 2005,5:54 pm)
I thought you said it was fast enough :p

I don't remember saying it was fast enough,but as usual with roller cams they tend to quit building torque in the 6500 to 7000 range and with the 22's I can keep it in the power band.RPM's are great but torque is what helps acceleration and lift and with a heavy hull like a Mandella I need it.WE had it on the GPS this weekend for the first time and was 93 MPH.With the 22's I feel 100 is very attainable.I'm also going to try some different prop pitches and profiles to see if I can get rid of the looseness,It's a little squirly on acceleration but not when it reaches speed.

AZmandella,
Does 93mph have ur undivided attention or what?? Does that thing ever feel like its gonna go over on its lid?? I have only been up to about 70 give or take a lie.  :rotflmao  :rotflmao

Anytime your going 80+ in a boat it has your undivided attention.It doesn't feel like it's going to go over on it's lid but it is a little loose side to side on acceleration.Once it reaches top speed it sets better.

Fords All The Way
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AzMandellaMale Offline
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Post Icon Posted: May 04 2005,10:35 am Post # 21 see this member send this member a private message  quote this post in reply
Quote (GoFastRacer @ May 04 2005,7:00 am)
Quote (AzMandella @ May 03 2005,6:50 pm)
I'll bet that calculator is for 3 blade props.And all the speed calculators I have seen also ask prop diameter.I know that that one is not right.I'm getting 650+ HP and turning 18's with a 11-1/2 x 15 prop at 7000 and I know I'm going faster than 76 MPH

Depending on prop slip with that combination you were going 93.8 with 20% slip!.

Well I have never put too much faith in speed calculators.With my old motor that put out a little over 450 HP and turned 5800 RPM's with the same prop and gears the speed calc. said the boat was faster than any speed I could get on the GPS.I would think I have less slip than 20% but the GPS said 93.You know they can be off a few miles + or -.I also can't run it with the plate completely flat,way tooooo much lift so by running 3 clicks or more on my finishline handle I'm sure I'm creating some drag.That's why I'm going to try some different profile props to find one that gives a little less bow lift and more foreward push.

Fords All The Way
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GoFastRacerMale Offline
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Post Icon Posted: May 04 2005,1:46 pm Post # 22 see this member send this member a private message  quote this post in reply
I have an Excel file that really works good and is very accurate!.. :good
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GoFastRacerMale Offline
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Post Icon Posted: May 04 2005,1:49 pm Post # 23 see this member send this member a private message  quote this post in reply
Quote (AzMandella @ May 04 2005,11:24 am)
It doesn't feel like it's going to go over on it's lid but it is a little loose side to side on acceleration.Once it reaches top speed it sets better.

Not mine, you don't even hardly have to hang on to the wheel on acceleration!. :)
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22 replies since April 23 2005,9:55 am < Next Oldest | Next Newest >

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