Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - How much power does it take to spin a 1.0l geo engine?

Stubby79 · 01-29-2013, 03:34 PM

The inertia of the engine spinning down would not gain you much, maybe a few hundred wats for a couple of seconds. However, being able to gear down to regen brake through the motor could gain you a fair bit (probably only limited to how long you have before you have to engage the "real" brakes and up to the programming of your controller). There'd be tens of thousands of watts pumped back in to your batteries that way.

However, having it connected directly to the engine would enable you to get a small bit of regen while at idle(at the cost of extra fuel), so between that and regen braking, your battereies would have a good chance of staying topped up in stop and go traffic. That's if you don't just have the engine shut off when you are idling. That adds another dimension to the question of efficiency: would it be worth sucking off power at idle at the cost of a bit of extra gas? or would you only do that if the batteries got low and stick to charging them before every trip?

I have figured a way to do it that doesn't involve driving the engine yet has the engine drive the motor any time it's running. The issue with it is, due to lack of space along the input shaft on the trans, you'd have to remove the clutch (or at least the throw out bearing and the clutch fork) and it would also force the engine to grind to a halt when you come to a stop. Any time you're moving, it wouldn't be a problem, but when you get below idle speeds in any given gear, it'd have to shut off. You could idle in neutral, but you'd have to shut it off to get it into gear without the clutch.

I was poking around the forum and notice the bit about accessing the 5th gear shaft off the side of the transmission. This might be an option, perhaps having the motor coupled with a CVT so that you actually have the torque necessary to move the car, but you would lose any ability to regen while the car idles and you'd not be running through the gears, so your electric motor will be doing speeds completely different from your engine...and finally you'd have drive line losses through the use of a V belt that you could get around if you were directly coupled to the engine.

All that means I'm still thinking of/leaning towards the idea of running it through the crankshaft. Now if the gas engine ran through the CVT and the electric through the trans, that combination would be more fuel efficient. That isn't happening unless the geo engine blows up beyond the point of repair (and I replace it with, say, a 10hp single cylinder engine running off of propane or something).

01-29-2013, 03:34 PM	#8 (permalink)
Stubby79 Master EcoModder Join Date: Sep 2012 Location: Victoria, BC Posts: 1,747 Firefly EV - '98 Pontiac Firefly EV 90 day: 107.65 mpg (US) Little Boy Blue - '05 Toyota Echo 90 day: 33.35 mpg (US) BlueZ - '19 Nissan 370Z Sport 90 day: 17.19 mpg (US) Thanks: 75 Thanked 577 Times in 426 Posts	The inertia of the engine spinning down would not gain you much, maybe a few hundred wats for a couple of seconds. However, being able to gear down to regen brake through the motor could gain you a fair bit (probably only limited to how long you have before you have to engage the "real" brakes and up to the programming of your controller). There'd be tens of thousands of watts pumped back in to your batteries that way. However, having it connected directly to the engine would enable you to get a small bit of regen while at idle(at the cost of extra fuel), so between that and regen braking, your battereies would have a good chance of staying topped up in stop and go traffic. That's if you don't just have the engine shut off when you are idling. That adds another dimension to the question of efficiency: would it be worth sucking off power at idle at the cost of a bit of extra gas? or would you only do that if the batteries got low and stick to charging them before every trip? I have figured a way to do it that doesn't involve driving the engine yet has the engine drive the motor any time it's running. The issue with it is, due to lack of space along the input shaft on the trans, you'd have to remove the clutch (or at least the throw out bearing and the clutch fork) and it would also force the engine to grind to a halt when you come to a stop. Any time you're moving, it wouldn't be a problem, but when you get below idle speeds in any given gear, it'd have to shut off. You could idle in neutral, but you'd have to shut it off to get it into gear without the clutch. I was poking around the forum and notice the bit about accessing the 5th gear shaft off the side of the transmission. This might be an option, perhaps having the motor coupled with a CVT so that you actually have the torque necessary to move the car, but you would lose any ability to regen while the car idles and you'd not be running through the gears, so your electric motor will be doing speeds completely different from your engine...and finally you'd have drive line losses through the use of a V belt that you could get around if you were directly coupled to the engine. All that means I'm still thinking of/leaning towards the idea of running it through the crankshaft. Now if the gas engine ran through the CVT and the electric through the trans, that combination would be more fuel efficient. That isn't happening unless the geo engine blows up beyond the point of repair (and I replace it with, say, a 10hp single cylinder engine running off of propane or something).