Thunderstruck hits 90 mph
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Thunder,
Im am running 30 B-1 4 blades and stock B-1 drives. I am turning the 30 at 59-6000. I want to try a set of 32 B-1. I am going to try and get out this wknd and run some numbers with the gps to get a accurate speed calculation. The last time I tried, I was only able to hold WOT for about 5-10 sec and didnt have time to really do any trimming or tab adjustments. I have been trying to take it easy on the drives so they dont let loose on me. I was considering the nose cone idea, but I had heard from a few people that they would not give me any results. I also have the LWP and the notched transom.
Im am running 30 B-1 4 blades and stock B-1 drives. I am turning the 30 at 59-6000. I want to try a set of 32 B-1. I am going to try and get out this wknd and run some numbers with the gps to get a accurate speed calculation. The last time I tried, I was only able to hold WOT for about 5-10 sec and didnt have time to really do any trimming or tab adjustments. I have been trying to take it easy on the drives so they dont let loose on me. I was considering the nose cone idea, but I had heard from a few people that they would not give me any results. I also have the LWP and the notched transom.
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Sure will. Im glad the cones help you out, sounds like they are working great for you. I my try them, but not until I get everything dialed in first.I would also like to try a set of 32's. From the info ( dyno sheet )that I have gathered so far is that from 5900-6000 rpm, the motors are making only 5 hp more. We built this motors to peak at 6000 rpm. with the 30's I can run them up to the 5900-5950 mark. I would rather run these motors at 5800 to give me a 200 rpm cushion in case I come out of the water, plus you are not going to see any mph gain by running them the 200 more rpm if you are only making 5 more hp. If I run the 32's, that should drop me down to the 5600 mark and then do some labbing to them to bring them back up to the 5800 mark. I am not sure what gain in mph I would get from going up to the 32 from the 30. I am estimating a possible 2 -3 mph gain. I will defenitly post some numbers after this wknd.
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My problem was little difference in speed between 28 and 30 pitch props and lab vs. no lab made no difference which it should. I was running 86 mph at 5550 rpm with 30 bravo I's and other props which is 15% slip. Nose cones brought me to 5450 rpm at 91 mph with labbed 30's which is 8.8% slip. Big difference. (I went out by myself w/ 1/4 tank gas, light chop and got another 1 mph after I posted the original 90 speed.)
Tom
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My problem was little difference in speed between 28 and 30 pitch props and lab vs. no lab made no difference which it should. I was running 86 mph at 5550 rpm with 30 bravo I's and other props which is 15% slip. Nose cones brought me to 5450 rpm at 91 mph with labbed 30's which is 8.8% slip. Big difference. (I went out by myself w/ 1/4 tank gas, light chop and got another 1 mph after I posted the original 90 speed.)
Tom
Tom
Sounds like the nose cones really helped you out. When my motors were stock, I was running about 82-84 mph at 5200 with 28. After the rebuild, I gained about 200 hp per motor and gained 6-8 mph at 6000 rpm with the 30's with best speed of 92 mph (about 9.0% slip). I didnt have alot of hrs on the motors then. Now that I have about 45-50 hrs,I will really see what it can do.I know I should be able to spin the 32 with no problem and possible 34's. If I could hit 100 with the 32 and nose cones, I would be really happy.
Last edited by Madkat; 06-07-2007 at 03:42 AM.
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Sounds like the nose cones really helped you out. When my motors were stock, I was running about 82-84 mph at 5200 with 28. After the rebuild, I gained about 200 hp per motor and gained 6-8 mph at 6000 rpm with the 30's with best speed of 92 mph (about 9.0% slip). I didnt have alot of hrs on the motors then. Now that I have about 45-50 hrs,I will really see what it can do.I know I should be able to spin the 32 with no problem and possible 34's. If I could hit 100 with the 32 and nose cones, I would be really happy.
Check out:
http://www.go-fast.com/Prop_Slip_Calculator.htm
Tom
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Hey Madkat, what port are you running out of? And if you're on the west side of Michigan, how good are your mufflers? ![Smilie](/forums/images/smilies/smile.gif)
Also, what type of notch are we talking about here on these 32's? Mine's a 1997 with no noticeable notch on the back end of the boat. I just haven't seen many around in Michigan to know the difference.
![Smilie](/forums/images/smilies/smile.gif)
Also, what type of notch are we talking about here on these 32's? Mine's a 1997 with no noticeable notch on the back end of the boat. I just haven't seen many around in Michigan to know the difference.
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Check your slip numbers. I got 16% slip for you assuming 1.5:1 gear ratio using 30"-1 = 29" for the prop in the calc per Throttleup's (Julie and Matt) recommendation. It's worse if you use 30" for the prop and 1.36 gears.
Check out:
http://www.go-fast.com/Prop_Slip_Calculator.htm
Tom
Check out:
http://www.go-fast.com/Prop_Slip_Calculator.htm
Tom
I will trust you if you say there is 16% slip. I tried at least 10 times putting in the dats and I get nothing. Never been good at using that calculater. Once I see what she does, maybe you can punch in the numbers and see what my slip is
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Hey Madkat, what port are you running out of? And if you're on the west side of Michigan, how good are your mufflers? ![Smilie](/forums/images/smilies/smile.gif)
Also, what type of notch are we talking about here on these 32's? Mine's a 1997 with no noticeable notch on the back end of the boat. I just haven't seen many around in Michigan to know the difference.
![Smilie](/forums/images/smilies/smile.gif)
Also, what type of notch are we talking about here on these 32's? Mine's a 1997 with no noticeable notch on the back end of the boat. I just haven't seen many around in Michigan to know the difference.
I run out of Lake Erie and St Clair. The mech. that did my motors lives over in Marne Mi. We were getting yelled at when we took it for a test drive last year over your way. On our side of the state, they dont say a word to me. I have never been pulled over for excessive noise. ( Yet). What is your email address. I just noticed that our membership is up and I cant post any pics.
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The formula is:
Slip = (1-actual speed/theoretical speed) x 100%
Theoretical Speed = rpm x pitch/1056/gear ratio
Or in your case:
Theo. Speed = 6000 X 29 /1056/1.5 = 109.9 mph
Slip = (1-92/109.9) X 100% = 16.3%
If you get your slip down to 10% with cones or whatever, your speed at 6K with 30's will be 109.9 X (1-.1) = 99 BABY!!!
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No problem, let me know whatever you need but, if the website doesn't work for you:
The formula is:
Slip = (1-actual speed/theoretical speed) x 100%
Theoretical Speed = rpm x pitch/1056/gear ratio
Or in your case:
Theo. Speed = 6000 X 29 /1056/1.5 = 109.9 mph
Slip = (1-92/109.9) X 100% = 16.3%
If you get your slip down to 10% with cones or whatever, your speed at 6K with 30's will be 109.9 X (1-.1) = 99 BABY!!!
The formula is:
Slip = (1-actual speed/theoretical speed) x 100%
Theoretical Speed = rpm x pitch/1056/gear ratio
Or in your case:
Theo. Speed = 6000 X 29 /1056/1.5 = 109.9 mph
Slip = (1-92/109.9) X 100% = 16.3%
If you get your slip down to 10% with cones or whatever, your speed at 6K with 30's will be 109.9 X (1-.1) = 99 BABY!!!
Makes alot more sense now. i will let you know on monday.