Hey guys I am new to all this v-drive stuff but I am loving every bit about it!! My questions for someone is-- I have a 74 Sanger Flatbottom with a BBC 496 with 1.22 gears. I am being told that with all the torque my motor has is that I should put more gear into my box. How much gear would you try to start with?
And why I say sacrifice horsepower is because i am looking at putting a new cam shaft that will raise my torque even more and lower my horsepower.
Any advice would be appreciated.
Thanks
Mr T on the boards has a brother that has a white sanger flat bottom. He also runs a big block chevy in his with 22% gears. Now if you ask him he will tell you it turns 7500 rpm at 120 but ..... thats really another story in itself.
What rpm are you turning? What prop? More info on the motor? What do you want to do with it?
I am running a 11.25x16 meikens prop. brodix alum heads, tunnel ram, two holley 750's, lunatti roller cam-.312,.320,.722,.722---the boat only pulls to 5500 rpm and it is running 84 mph. I am looking a either putting gears to slow my rpm's of the motor alittle bit and spin the prop faster, or changing out the prop?? The cam in the motor now for what i can figure off of desk top dyno isnt even in the power band of the cam until 7500 rpm, and tops out at 5500 rpm on the torque. So that is why i thought about putting a cam that will be more torque and less horsepower on the top end.
I am wanting to go as fast as this boat will go without supercharging it. I just feel that the boat has alot more potential.
Thanks for any input
Go to an 18 gear... less pitch. Get your motor in the top rpm range.
Might even go to a 15% gear.
yes that would be true to drop gears and let the motor come up into the power band of the horsepower, but what i have been told about boats, and correct me if i am wrong but horsepower dont mean s**t, its all about torque, so that is why i have been thinking about a cam that will drop my total horsepower by 24 horses, but i will gain about 150 ftlbs of torque, and then having to spin my motor at a less rpm to be safter in the internal parts??
Thanks for the input.
yes that would be true to drop gears and let the motor come up into the power band of the horsepower, but what i have been told about boats, and correct me if i am wrong but horsepower dont mean s**t, its all about torque, so that is why i have been thinking about a cam that will drop my total horsepower by 24 horses, but i will gain about 150 ftlbs of torque, and then having to spin my motor at a less rpm to be safter in the internal parts??
Thanks for the input.
Like K-Flat said, Put some 18's in it and go and run it, See what it dose, may suprise ya. And it will give you more info. to work with. It's good to have some comparisons to work with before ya make engine changes. And even if it dose spin up to 7000 or 7200 If it's put together half way decent it shouldn't make change. You probably won't be running it wide-open for 5 miles at a time like the S.S. Boats do. :idea:
I would drop to 18% gears.Your basicaly running a 454 not a stroker motor that is creating gobs of torque.I run a stroked 514 with 18% and a 11-1/2 x 15 and turning 7000 rpm,but now that I have the stroker motor I am putting the 22% gears in because she tops out too quick.Besides with the parts you have said you have that motor should run at least in th 6500-7000 range with no problem if it was assembled properly.And if you still don't see 6500 after the gear change try dropping the pitch or shaving the diameter of the prop till it does rev.
Garucci,
Nice avatar, c'mon.
A smaller gear will wake that deal up. Most lake races are over in the first 200'.
If I were running your deal here is what I would want.
-Out of the hole your motor should spin up to at least 6500. Let the prop. burn(spin). this allows you to get into the power of the motor. Think of it as slipping the clutch in a car. The gear size will allow the motor to get close to achieving this. Prop diameter will control how much slip you get.
-Prop. hook. After the burn & the boat starts to roll over. You should not drop below lets say 5500 rpm. This is where the torque comes into play. If the rpm drops to much goto a smaller gear. Not enough maybe a lttle more pitch or diameter on the prop.
-Top end pull. If you want the top end speed. You need to use you tunnel ram. If you get your out of the hole combo & prop. hook combo to work your top end should be pretty much set. somewhere between 7000-7500 rpms.
Now. This is a conservative set up. If you want to got big. out of the hole 8000 rpm, burn 7000 rpm. top end 8000 rpm.
The big dog race teams are doing over 9000 out of the hole.
This is how I would start. There many that will tell you different. Just my opiniun.
Morg
Mr T on the boards has a brother that has a white sanger flat bottom. He also runs a big block chevy in his with 22% gears. Now if you ask him he will tell you it turns 7500 rpm at 120
i seen that boat, it be bad ass,,,,maybee 117m but it aint goieng 120
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