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Old 03-04-2023, 03:39 PM   #29 (permalink)
Isaac Zachary
High Altitude Hybrid
Join Date: Dec 2020
Location: Gunnison, CO
Posts: 1,665

Avalon - '13 Toyota Avalon HV
90 day: 40.45 mpg (US)

Prius - '06 Toyota Prius
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Originally Posted by Solarpowered View Post
Well I figured an engine builder would get into the weeds some. And would know all the little tricks the layperson wouldn't, when it comes to the engine itself. He said lower rotational mass isn't worth enough to go chasing it down, and to focus efforts elsewhere. Because you'd spend $3,500 or more just the gain 0.3% fuel economy. Not even a full 1%

Still be fun for me to try if money was no object, but that ain't the case so yeah I'll just do what he says.
That's what I was trying to say. Rotational mass is a certain percent of total mass, and it's only a loss every time you brake (because using a bit more fuel to spin it up isn't a loss as it's stored energy that can let your vehicle either coast longer or help it up a hill). But braking is only a certain percentage of your driving. So say rotational inertial mass is 20% of total inertial mass, and you reduce it 5%, but you are braking and losing 30% of your energy throug braking, then even at those extremes you'd be gaining only 0.3% efficiency... Not great really.

You're better off slowing down earlier, as you get the same effect.

Originally Posted by freebeard View Post
This comports with John Karcey, the OG Mileage Motor builder. He went with a stock flywheel and 50lb Jaguar crankshaft pulley. On my build, I just added a Gene Berg 8lb pulley and a Type IV oil cooler in the stock location.

It's been sitting on the bench for years. Now that I'm past my EV conversion phase, I think it will go in the Superbeetle instead of rebuilding the stock (130,000 mile) motor.
I put a Type IV cooler on mine, but even by drilling and blocking passage ways so I could install an oil thermsostat, it still ran too cool.

I also put on a generic brand (Bugpack??) weighted crankshaft pulley. It ran very smoothly, but I'm not sure if the weighted crankshaft was all that necessary. ??
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