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Old 06-11-2008, 07:27 PM   #1 (permalink)

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Default Diesel Engine Project

Hey guys, I have a few technical questions I need some help with.

My brother and I are exploring the use of an "unconventional" power plant in an R16. In order to figure out if it will perform to our desired standard we need to figure out how to determine what gear ratio we need.

We will be using a CVT adapted to a fly wheel. So my question is this:
How can I determine what gear ratio I need in my RPM box, from knowing the RPM's the engine puts out?

Also, wouldn't I need to know the flywheel diameter/circumference?

Furthermore, whats the possible gear ratio spectrum for an RPM Gear Box?
(1-1;?-1).

I know this might not make much sense, but please bear with me.

Thanks.
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Old 06-11-2008, 08:01 PM   #2 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

That's not too unconventional. The rpm comes in 4:1 to about 11:1 I believe. Depending on your powerplant, and a cvt, you'd probably run from a 7:1 to a 8:1. A little math using the rpm, tire height, and top speed will be able to yeild a ratio.
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Old 06-11-2008, 08:08 PM   #3 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

The power plant is whats unconventional. Its has a lower RPM's What kind of ratio would I need for a lower RPM turning engine, to still have it go fast?

31" tires.
80-90MPH max speed.
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Old 06-11-2008, 08:15 PM   #4 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

How many RPM's does a Burro do?

What is it? so secretive!
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Old 06-11-2008, 08:19 PM   #5 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

Must be diesel.

Burro,thats a good one.
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Old 06-11-2008, 08:53 PM   #6 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

Kubota I think, pretty low rpm....
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Old 06-12-2008, 01:14 AM   #7 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

Bullnerd hit it.
I want to see if a TDI 1.6L 4 cylinder or a 1.4L 3 cylinder would work.
They put out great numbers, and they could even be fueled with Bio mixes.
VW has some that put out 170hp/260tq@5200-5800RPM, depending on the model.
They use twin turbos and a bunch of places will do custom mapping, and tuning mods.
Problem is most of the newer stuff is in europe, I talked to a guy a VW-USA Motor sport division, they have a flete of clean burning TDI race jetta's but they are for internal R&D and promotion, and that you cant get them over here for retail cause of a bunch of legal restrictions. He told me about the Taureg they are going to be running in the Baja 1000 he was saying that they get about 35 average MPG, that it hauls arse, and is clean running. He says that he hopes that winning the race will help get more TDI' in to the US market, he also mentioned that they dont have crate engine packages because VW didnt feel that there was a market that would make the investment worth it. He told me to get in touch with VW Mexico or Canada, cause they do diesels, so I seriously want to explore donig a turbo diesel, just didnt want anyone to laugh at me
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Old 06-12-2008, 01:18 AM   #8 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

Quote:
Originally Posted by Gene View Post
How many RPM's does a Burro do?

What is it? so secretive!
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Old 06-12-2008, 05:31 AM   #9 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

Here is a CVT gearing chart I made a while back but have refined a bit since then. Basically fill in the max engine RPM, CVT ratios, and sprocket sizes. If you are using the RPM box you can just make up sprocket sizes until you get the overall reduction you want. I already set up a sheet in it for the TDI engine using the numbers you posted above. I had to put it in a zip file since apparently we can't post Excel files anymore.
Attached Files
File Type: zip CVT_reduction.zip (3.2 KB, 18 views)
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Old 06-12-2008, 01:33 PM   #10 (permalink)

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Default Re: Engine RPM/RPM Gear Box Ratio?

Give Neil at ATV a call (623) 516-8640 and ask what they use in the Tazcars. The Eco-Tech engines only spin to about 5500. With the torque you'll have available I would imagine that a 6:1 would work great.
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