INCOGNITO- Prop Questions for 26' Cat
#1
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From: PA and MD
Incognito your email is not responding. I will post it here.
You wrote me; 'JUST SPLASHED MY 26' CAT AND IT RAN 108 MPH WITH 800HP BUT WAS ON THE REV LIMITER AT 6000RPM AND USING A BRAVO 30" PROP AND IMCO EXTREME 1.36 DRIVE. IT TOOK A LITTLE WHILE TO GET ON PLANE OTHER THAN THAT EVERYTHING WAS GOOD. I DON'T WANT TO BE ON THE REV LIMITER, DO YOU HAVE ANY SUGGESTIONS'.
You are running into that delicate area of high X, slip, getting on plane. It's not too bad where you are at now but like you said bumping the rev limiter in not good. Do you know your HP and TQ peaks of your engine? Going to a 32" braveo prop will lower your rpm by about 400 but might make the getting on plane issue a little more difficult and you all ready have a high slip of 13.5%- high for a cat. You might try a 1" spacer and the 30" which will load the prop a little more and drop the rpm and improve your slip number and might even pick up some speed. And then try the 32". By improving your slip to 10% the 30" will go 112.5mph.
Here's what I would do:
1- retest what you have and note the speed at every 500rpm and characteristics ie. planning, steering, rear end looseness if any.
2- Buy a out of the box 32" Bravo prop about $500 from Teaque and others and retest as above.
3- Buy a 1" drive spacer and install and retest the 30" and 32" as above.
You will have 4 combinations and will know which is right from the results. You can allways fine tune by labbing but save that for last. Besides you will have a leftover prop and maybe spacer which can be sold to recover some of the cost. You might ever keep the 2 props and put a spare prop mount in the boat so you have one for light and speed and the other for loaded and mid range punch.
You are so close now but I would spend the extra grand to get that last bit. Good Luck, Marty.
Anyone chime in with any other suggestions.
You wrote me; 'JUST SPLASHED MY 26' CAT AND IT RAN 108 MPH WITH 800HP BUT WAS ON THE REV LIMITER AT 6000RPM AND USING A BRAVO 30" PROP AND IMCO EXTREME 1.36 DRIVE. IT TOOK A LITTLE WHILE TO GET ON PLANE OTHER THAN THAT EVERYTHING WAS GOOD. I DON'T WANT TO BE ON THE REV LIMITER, DO YOU HAVE ANY SUGGESTIONS'.
You are running into that delicate area of high X, slip, getting on plane. It's not too bad where you are at now but like you said bumping the rev limiter in not good. Do you know your HP and TQ peaks of your engine? Going to a 32" braveo prop will lower your rpm by about 400 but might make the getting on plane issue a little more difficult and you all ready have a high slip of 13.5%- high for a cat. You might try a 1" spacer and the 30" which will load the prop a little more and drop the rpm and improve your slip number and might even pick up some speed. And then try the 32". By improving your slip to 10% the 30" will go 112.5mph.
Here's what I would do:
1- retest what you have and note the speed at every 500rpm and characteristics ie. planning, steering, rear end looseness if any.
2- Buy a out of the box 32" Bravo prop about $500 from Teaque and others and retest as above.
3- Buy a 1" drive spacer and install and retest the 30" and 32" as above.
You will have 4 combinations and will know which is right from the results. You can allways fine tune by labbing but save that for last. Besides you will have a leftover prop and maybe spacer which can be sold to recover some of the cost. You might ever keep the 2 props and put a spare prop mount in the boat so you have one for light and speed and the other for loaded and mid range punch.
You are so close now but I would spend the extra grand to get that last bit. Good Luck, Marty.
Anyone chime in with any other suggestions.
#2
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Joined: Feb 2002
Posts: 1,296
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From: LaPorte IN.
Keep in mind the weather is cool now and that good air is probably worth 100-200 extra RPM, and maybe even more. In the dead of summer the 30 may be just the ticket. Maybe you could simply raise your rev limit to 6200 and you will be good to go all the time. Sounds like an awsome ride. Tell us about the motor and all of the goodies. It is fun to see what combos are working well in other racers boats.
#3
I'm in the same "boat" just a little slower- details in the eliminator forum.
I installed a 2" shorty and XZ upper, then a 1/2" spacer and i'm pretty sure the x is happy, on the rev limiter now at 94.1 80 gallons and spring 60-70 temps with my merc labbed 28. Just bought a merc labbed 30 which will be here soon for testing. The 28 may be a better top end summer prop and would likely stay off the limiter (5450) but I suspect the 30 will give me best cruise, acceptable summer top end etc. it sure loosens up in this range- it just may pull the 30 and for what a prop costs it's worth chasing a few extra digits.
I second CM- it's worth the minimal investment for final dial in, I picked up 6.2 mph so far and I'm pretty sure there's more in there! Good luck!
I installed a 2" shorty and XZ upper, then a 1/2" spacer and i'm pretty sure the x is happy, on the rev limiter now at 94.1 80 gallons and spring 60-70 temps with my merc labbed 28. Just bought a merc labbed 30 which will be here soon for testing. The 28 may be a better top end summer prop and would likely stay off the limiter (5450) but I suspect the 30 will give me best cruise, acceptable summer top end etc. it sure loosens up in this range- it just may pull the 30 and for what a prop costs it's worth chasing a few extra digits.
I second CM- it's worth the minimal investment for final dial in, I picked up 6.2 mph so far and I'm pretty sure there's more in there! Good luck!
#5
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YEA BUDDY IM HERE JUST READ YOUR RESPONSE THANKS FOR YOUR INPUT --I E-MAILED YA-EARLIER--SORRY IF IT TAKES ME A WHILE TO REPLY SOMETIMES BUT I WORK ON THE COMPUTER SO AS SOON AS I TAKE CARE OF BUSINESS-I SNEEK IN AND READ AND REPLY--I GOT ME THAT 32 AND TRYING IT THIS WEEKEND-WEATHER PERMITTING(NOT TEMP BUT RAIN AND WIND)HOPEFULLY ILL BRING DOWN MY RPM AND RAISE MY MPH..PLANING IS IMPORTANT BUT NOT REALLY MY ULTIMATE GOAL,BESIDES YOU COULD LEAVE ON ME BUT IM COMING TO GET YA UP TOP-THIS AINT A DRAG RACE BABY ITS A MARATHON...AGAIN THANKS FOR ALL YOUR HELP..
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