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Post by racket on Mar 13, 2024 23:58:22 GMT -5
Does your vehicle have a normal rear wheel drive differential ??
If it does , then a motorcycle chain redux between the freepowers gearbox and diff input will work
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Post by firegremlin on Mar 14, 2024 0:31:56 GMT -5
On advantage is that you could still drive the car home after the turbine failed. And that will occur. I only need to finish the lap, a small traction motor with a small battery is enough. Less than 20 pounds' worth of lifepo4 cells will get you back to the pits at reasonable speeds, even at Thunderhill. There was a legit Jet Electrica running in several races. A ton and a half driving on 23hp. They did 170 laps at CMP in a ~15 hour event, doing several laps at a time. Hot-swap "recharge" using an engine hoist to swap pallets of marine lead-acid cells, it was quite a sight. Moral of the story, you don't need a lot of electric power to go around a track in a budget endurance race. |
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Post by firegremlin on Mar 14, 2024 13:04:55 GMT -5
Does your vehicle have a normal rear wheel drive differential ?? If it does , then a motorcycle chain redux between the freepowers gearbox and diff input will work Stock, it has a north-south transaxle. Axles are unobtainium but wheel bearing hubs are bolt-in; I can adapt any modern-ish diff/axle/bearing combo without too much effort. www.greencarreports.com/news/1091265_always-wanted-a-harley-davidson-powered-prius-youre-in-luck - I got to drive that car in Sonoma. The builder solved his chain drive conundrum by mounting a Prius differential carrier in a small frame, welding sheet metal over holes, and filling it with a little bit of gear oil through a port he added. Bearings were just plain grease. Driven sprocket was mounted where the ring gear used to be. Stock Prius axles. It worked great and never gave us grief (unlike the sad, sad clutch pack). Chains/belts do permit quick gear ratio changes, and are more forgiving to minor misalignment or slack, so it'd be an option for sure. |
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Post by firegremlin on Mar 14, 2024 13:07:49 GMT -5
On the other hand, another famous Lemons build, an MR2 with a 5-cylinder radial, shredded a massive chain in just one lap. Short chains are hard, they need active oiling/cooling and a way to deal with shock loads.
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Post by racket on Mar 14, 2024 15:50:23 GMT -5
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Post by firegremlin on Mar 26, 2024 12:11:19 GMT -5
Update - I've been busy redoing my roof, just got the time to take apart the gearbox. For posterity - here are the gear counts:
22 teeth on the turbine output shaft gear
107 teeth on the gearbox input gear (torque converter)
17 teeth on the gearbox output shaft gear
106 teeth on the crankshaft gear (usually not sold with the turbine/gearbox combo, you have to get it separately).
That gives a primary reduction ratio of 4.86, and a secondary reduction ratio of 6.24.
If you drive normal small car wheels directly with the secondary, you'll hit a top speed of ~113mph at 50000rpm. This is workable.
Primary gears are only 14mm wide, with ~4.5mm pitch.
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richardm
Senior Member
Joined: June 2022
Posts: 411
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Post by richardm on Mar 26, 2024 14:27:00 GMT -5
That top speed of 113 mph at 50 K rpm assumes that your free turbine has enough torque . If you're talking about the DD15 turbo compound system it only adds about 50 hp to the main engine.
Not sure about getting a car at 113 mph on 50 hp..
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Post by racket on Mar 26, 2024 16:47:04 GMT -5
It is possible to modify the wheel by clipping the outlet side and opening up the flow area , in its original state the blade angles are rather "tight" to extract every last bit of energy from the gas deflection . Checkout lower half of this page jetandturbineowners.proboards.com/thread/1331/100shp-bike With the wheel clipped its possible to double the potential output and increase rpm to ~60K . |
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Post by firegremlin on Mar 27, 2024 18:35:55 GMT -5
Not sure about getting a car at 113 mph on 50 hp.. The car has the frontal area of a large hamster, but yes, 90-95mph is more likely to be the absolute max speed at that power level. Chain/belt drive might be the way to go here, with an ~8:1 ratio. |
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Post by firegremlin on Mar 27, 2024 18:42:13 GMT -5
It is possible to modify the wheel by clipping the outlet side and opening up the flow area , in its original state the blade angles are rather "tight" to extract every last bit of energy from the gas deflection . Checkout lower half of this page jetandturbineowners.proboards.com/thread/1331/100shp-bike With the wheel clipped its possible to double the potential output and increase rpm to ~60K . Would that affect low RPM performance/efficiency? I'm not really looking for 100HP here, that would burn through fuel way too fast, I think. |
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Post by racket on Mar 27, 2024 19:50:46 GMT -5
Nope because you'd be running a larger gas producer , but fuel burn will be more because you'd have the opportunity to use more power for higher speeds ................ain't no free lunches :-(
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