Drive heartburn
#11
Platinum Member
Platinum Member
Re: Drive heartburn
Originally Posted by Panther
Hmmm, I'm turning a 32 Bravo 1 to 5000 rpm with a full load of fuel and 5300 with 1/4 - 1/2 tank of fuel.
I wonder if a 30" pitch would be better at 5300 full tank and 5600 1/2 tank?
The Valvetrain is set up to run 5200 - 5600, we spun them to 5800 on the dyno. I'd loose cruise speed but if the drive lasts longer than so be it.
I wonder if a 30" pitch would be better at 5300 full tank and 5600 1/2 tank?
The Valvetrain is set up to run 5200 - 5600, we spun them to 5800 on the dyno. I'd loose cruise speed but if the drive lasts longer than so be it.
#12
Registered
Thread Starter
Re: Drive heartburn
Originally Posted by articfriends
Max machine worx gets my vote. I just broke a drive 1 week ago,lower gears started chipping teeth away,ruined most the bearings thru out drive,60 hours on drive since it was freshened-(30hours w/750hp-30 hours w/950 hp). The upper xr gears still looked good,no broken or twisted shafts this time. Drive breakage is going to happen at 800 plus hp if your running any kind of bravo derivative,its just getting it to last a reasonable amount of time. Is there a reason your running a 34/35 pitch prop at only 4900rpm's?If you torque load the drive hard down low like that it will break quicker.If your any where near Michigan mr gadgets can build you a good drive using max parts or any combination of parts you want. I was at hardy pond this weekend, both races I got in were against velocitys like yours,1 had a mph on me ,the other walked away,pretty fast hulls ,Smitty
I was only playing with props with the 34. The stock 32 buries the bow and I don't get the top end at all, I also have a 30 lab finished to 31 it rocks but I can get 6200 to 6400 with it. I think with a new XR,etc. with 1.36 that is my prop of choice.
#13
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Thread Starter
Re: Drive heartburn
Originally Posted by Panther
Hmmm, I'm turning a 32 Bravo 1 to 5000 rpm with a full load of fuel and 5300 with 1/4 - 1/2 tank of fuel.
I wonder if a 30" pitch would be better at 5300 full tank and 5600 1/2 tank?
The Valvetrain is set up to run 5200 - 5600, we spun them to 5800 on the dyno. I'd loose cruise speed but if the drive lasts longer than so be it.
I wonder if a 30" pitch would be better at 5300 full tank and 5600 1/2 tank?
The Valvetrain is set up to run 5200 - 5600, we spun them to 5800 on the dyno. I'd loose cruise speed but if the drive lasts longer than so be it.
#14
Platinum Member
Platinum Member
Re: Drive heartburn
Originally Posted by RBeyer
My 30 lab finished to 31 runs 6200 to 6400. My thought is that my next drive selection be a 1.36 and my 31 will be the prop of choice. The 32 buries the bow and I don't get the WOT speed I should be.
#15
Re: Drive heartburn
Originally Posted by Panther
Hmmm, I'm turning a 32 Bravo 1 to 5000 rpm with a full load of fuel and 5300 with 1/4 - 1/2 tank of fuel.
I wonder if a 30" pitch would be better at 5300 full tank and 5600 1/2 tank?
The Valvetrain is set up to run 5200 - 5600, we spun them to 5800 on the dyno. I'd loose cruise speed but if the drive lasts longer than so be it.
I wonder if a 30" pitch would be better at 5300 full tank and 5600 1/2 tank?
The Valvetrain is set up to run 5200 - 5600, we spun them to 5800 on the dyno. I'd loose cruise speed but if the drive lasts longer than so be it.
#16
Geronimo36
Gold Member
Re: Drive heartburn
Originally Posted by articfriends
I'm of the opinion that when you "torque load" a drive it tortures the drive AND your motor.It sounds like we have very similar setups,my motor (procharged 540) made 944hp/880ft lbs tq at 5600,907hp/917ft lbs tq at 5200 and tq peaked on most dyno runs around 960 ft lbs at 4600. In my single engine baja 272 v w/std length outdrive i can pull a 30 pitch labbed merc prop to 5800-5900 rpm's,with a non-labbed 32 i lost a couple mph on top and pulled to 5200-5300 and boat acted evil,it wanted to bow steer,motor sounded like it was on a extended dyno pull. It cruised at same speed at 3500 that it normally does at 4000rpm's BUT i was showing 2-3 psi of boost to cruise at 4000rpm's where throttle isn't normally open far enough to show boost w/30 pitch at that rpm.If you lug your motor hard too far below hp peak then it increases your chances of detonation and strains your drive. I ran a 32 labbed this weekend,cruised nice on the midrange,took considerably longer to wind out above 5000 rpm's though but motor could pull it to 5600,I don't know where your hp and tq peaks are but you might want to try a 32 labbed also,Smitty
Originally Posted by mr_velocity
Billy has a spare set of non-labbed 30s sitting in his shop. Stop by and see him and give them a try. Just make sure you get a L & R since there are 3.
I think a labbed 32 may be the ticket though!
#17
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Join Date: Feb 2002
Location: Lake Michigan
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Re: Drive heartburn
Read the "Tech" artical in this months Powerboat Mag...The one with the Tiger and #6's.
Getting the rpms up will save the drive.
I would go either XR or Teague Platinum...don't waste your time and money on the IMCO's.
Getting the rpms up will save the drive.
I would go either XR or Teague Platinum...don't waste your time and money on the IMCO's.
#18
Geronimo36
Gold Member
Re: Drive heartburn
I'm also of the opinion that the IMCO lower case causes the props to "bite" way to much while under way, making re-entry that much harder on the drive. Any thoughts?
#19
Re: Drive heartburn
Originally Posted by Panther
I'm also of the opinion that the IMCO lower case causes the props to "bite" way to much while under way, making re-entry that much harder on the drive. Any thoughts?
#20
Charter Member #601
Charter Member
Re: Drive heartburn
The 1:36 lower gears are more money to replace when you do wear them 0ut. And you will. Most are going with the 1:5 unless they run out of prop. Just did a drive and swapped to 1:36 to keep the 32" prop. He added 200hp (966hp to 1150hp) and didnt want to change the prop.. worked out well..
The Velocity I did, was like yours with a blower, he runs 90+ I believe, not sure what prop, but 1:5 gears..
A well setup XR will go a long way for you, driven with respect.
If you would like to discuss setup and options on an XR.. give me a call before 9pm, would love to talk.
Dick
616-335-8446
The Velocity I did, was like yours with a blower, he runs 90+ I believe, not sure what prop, but 1:5 gears..
A well setup XR will go a long way for you, driven with respect.
If you would like to discuss setup and options on an XR.. give me a call before 9pm, would love to talk.
Dick
616-335-8446
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