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I called to inquire. GEEEZ, they're already down one gearFOOT, looks like they're goin.....fast.

Ok, so I compared a 2 cylinder small gearcase, nitro gearcase and big 70hp gearcase and other parts today.

To make a drive shaft for the nitro, you would need a 2 cylinder drive shaft, a 70hp long shaft cut and welded in 2 places to make it the same.

The gear case housing is the same for the 2 cylinder and the nitro. Some of the 2 cylinders came with the same bearing carriers, some had a different style forward bearing carrier. The water pumps are different but the large gear case has the same water pump as the nitro from what I could see.

Last I talked to Seaway, they had quite a few sets of pinion and forward gears for $440 or so. Then just turn the teeth off the reverse gear and use it as a spacer. 2 cylinder gear cases can be found for next to nothing sometimes especially if the gears are munched and there are lots of longshaft large gear case driveshafts around for whatever spline you need for the power head you're using so it shouldn't be hard to make a nitro lower unit if one can not be found.

I haven't tried this yet but I will be soon. I'll post how I make out.

Kevin, thanks for the report. When you looked at the pinion and gear set of the 2 cylinder case [which has a lower ratio to the nitro], did they look like they could handle the torque from the 3 cylinder? If so then a T racer could just do the drive shaft and use the case as is. They would need to run a 25 pitch to make up for the ratio difference. I know Cam
Morley tried it and said the pinion couldn't handle it. BUT, that problem is common with a lot of the Japan motors even with their stock power head. Racers heat treat the gears and pinion and that solved the problem. They even do prop shafts for the same reason. Good option and worth trying.

I can see how the pinion might not hold up as well since the different ratio means a smaller pinion gear and less area meshing at a time. I guess I should try one and see. I do have a 25 pitch prop. The gears are already pretty hard. I'm not sure if much else would help them for treatments.

I got an e-mail correcting me about heat treating. They don't heat treat them, they cryo the parts putting them in liquid nitrogen. Cost is $25. to $50. The same person says there is a german fellow in Vaughan that makes gears. Boy that really narrows it down!

[quote="Andrew4ce"]

To give you an idea of how much a gear case does for ya...

Kilo records.
88 mph SST45
94 mph SST60
104 mph FEH (SST60 based motor with quickie on a hydro)

5 mile/3 lap records (average speed)
69 mph SST45
72 mph SST60
87 mph FEH

Andrew, one motor that is even more interesting
THE SE OMC 49 cubic inch STINGER which is the base motor for most FEH motors not the SST 60 [56 cubic inch]
This motor is a bone STOCK sold at the dealer motor with a club foot nitro case no nose cone.
The Kilo record is 90 plus mile, I think 91 mph. Not to bad for a 49 cubic inch fishing motor.

We prop shaft dynoed both the Yamaha 70CES and a 1976 Stinger.
The Yamaha was rated at 70 hp. It dynod 70 hp at 6400 rpm EXACTLY as per the spec sheet from Japan.
The Stinger was rated at 75 hp at the crank. It dynod 78 hp at the prop. I think it too max'd out at 6300 or 6400 as well.
The Yamaha is close to a copy of the Stinger. The Yamaha has more off the dock and mid range, but the Stinger has a bit more top end.
There is a kilo run that still does not make sense. The 70CES Yamaha at 102 mph. That one has to be bad timers.

Ah ok, I thought the FEH was the 56, I don't pay much attention to mod stuff. That's even more impressive at 104 mph then.

What does a stock 70 yamaha make? The two motors are VERY different...or better yet what does it make at 7000rpm?

I love watching them run. I am more impressed with their speed on the race course. They must get close to the 100 mph of the course. That is the big difference. The OPC tunnels for example SST60 weigh 850 lbs. They run 80 mph of the course compared to 94 in the kilo. The FEH is likely 100 of the course. Plus their heads are inches above the water. I sure hope THE GUN and CORY race FEH this year. Great for the fans and even better for us race nuts.

About the same as this guy