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CH3 belt drive and gearbox weights!


Well-known member
I'm gonna post some pic's in a bit of a gearbox on a scale and a belt drive hub. It's just the main hub, no case, no lower pulley, no lower bearing and shaft, no belt and no flywheel! I just happend to have one of each appart in the shop today and want to wiegh them.
Here is a pic and weight of just a CH3 hub.

I did that about a year ago and I can't find the thread. I will weigh this one before I put it on the Caddy I'm guessing the Caddy with the belt drive will weigh around 760lbs!
I thought that a belt drive was about double of a gear box and just the top of the belt is almost the same as a complete gear box
Bob Burnside":14ttsawa said:
Do you think 60# really makes that much different in a boat that's 18x8?
hell yea more beer :lol: my water waker blue lightning belt drive 57 pounds and damn tough , small block only so far
The weight doesn't really matter with big heavy boats but man the ratio sure does. I have a 500 Caddy torque monster with a belt drive that can't swing anywhere near the prop that a small block 347 cubic inch motor can swing with a 2.68 gearbox! The boats are completly differant one is a dump truck that can hual a load and the other is a Corvette that is a blast to drive it all depends on what you want! They are completly differant boats!
Engine# 1
A 347 cid engine making 425 ft lbs of torque times 2.68 reduction equals
1139 ft lbs torque.

500 caddy making 575 ft lbs of torque times 2 to 1 equals 1150 ft lbs of torque.

Engine #1 --347cid, swinging the optimum sized superwide to optimum rpm.

Engine # 2 --caddy, swinging the optimim powerplus, or a k-series, or a stumppuller to optimum RPM.

The caddy wins by a couple hundred foot pounds of thrust.
First I must mention my 500HP motor makes 452 ft pounds of torque at the same RPM I like a 2.68 to turn a superwide. Also my 550HP motor makes 504 ft pounds of torque that kinda changes things a lot I have had three customers switch from a 500 Caddy to a LS2 all three stated they prefer the LS motor. Mostly because it jumps up on a plane much quicker and the boat floats and handles much better! I did notice according to your calculations the Caddy you said only made 11 ft pounds more thrust! You left out this, lets say the Caddy boat weighs 2,000 pounds and makes 1150ft pounds of torque like you stated that comes to 1.7 pound of weight to 1 pound of thrust!. Now the same exact set up with a LS2 will be 262 lbs lighter so take 1,738 lbs dived by your 1,139 and you have only 1.5 pounds of weight per pound of thrust. So the LS motor will have more thrust per weight then a Caddy! Not to mention the boat will float and handle better. Their both great motors and have areas the shine at! I actualy own a Caddy boat!
I weighed my disassembled CH3 on our UPS scales at work this is what I got.

Upper Unit----60lbs

Lower Unit with bearing----23 lbs

Main Housing-------42lbs

All bolts and belt----7lbs

I did not say anything about your LS motors. I suspect your LS motors are some kind of sweet!!!!!!!

What I am saying is this. In my opinion, A 347 cid engine will not thrust with a 500 cid caddy. Ain't gonna happen.

A really slow turning, flat pitched, wide blade will not match the thrust numbers created by a 500 cid caddy with a 2 to 1 reduction and a properly sized powerplus, or a k-series, or a stump puller.

The 500 caddy will out thrust the 347 cid engine by a vast amount. I felt like I was being conservative with the 200 pounds of thrust. I truly suspect the caddy will out thrust the slow spinning flat setup by as much as 500 pounds of thrust.

One thing I did notice is that you are not using the 347 cid engine and 504 ft lbs of torque in the same sentence.

There is no substitute for cubic inches. .
I build many different combinations. I'm building one now that I believe will make 600ft pounds of torque with. It's all apples and oranges and what the owner want's his boat to do best!

Will you adapt your tested and tuned fuel injection system to my SE-100 intake?

Winter is coming and I truly hope to go into spring sporting your injection--
Hey! :lol: If someone really wanted to get testy they would say what is the point of posting weights of a portion of the drive if you don't include every other part that is necessary to run? (Caddy weight, still don't have a number from you WT! Just teasing) :lol: Thank's MB. :lol: :lol:
I guess I want to hear what the dump truck with the belt Caddy (ratio?) does against the LS 2.68 on the same barge! :lol:
I do not think the Caddy/ LS comparison is fair. Give them both the same drive ratio and see who wins. 650lbs x 2.68 = 1742lbs @ 3800engine RPM