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Old 07-27-2009, 01:04 PM   #1
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Default Questions about Nitro Engines

Hello all,

1) How are the number of ports in an engine determined? From what I have read, the sleeve seems to be the determining factor. Can I literally take the sleeve out and immediately know the number of ports?
2) What affect does increasing or decreasing the the number of ports in an engine have on the performance?
3) I have an outside idea of what gear ratio is with real world cars, but have no idea what it is for RC cars. Don't all nitro engines have one gear?
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Old 07-27-2009, 01:26 PM   #2
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1. Pull the sleeve, count the holes in it.

2.In my limited experience:
More ports = Higher Rpm, more topend, usually thirtsty. 7-9 port.

Less ports = 3-4 port. More torque, better fuel economy. A few engine types have found a way to use 4 port mills and still get plenty of topend. (ex:NR+4,Vspec.)

3. I like turtles.
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Old 07-27-2009, 01:27 PM   #3
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double click, slow connectrion
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Old 07-27-2009, 01:46 PM   #4
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Quote:
Originally Posted by Garet Jax View Post
Hello all,

1) How are the number of ports in an engine determined? From what I have read, the sleeve seems to be the determining factor. Can I literally take the sleeve out and immediately know the number of ports?
2) What affect does increasing or decreasing the the number of ports in an engine have on the performance?
3) I have an outside idea of what gear ratio is with real world cars, but have no idea what it is for RC cars. Don't all nitro engines have one gear?
1. Yes you can except one port is for exaust and it dont count, so if it has 8 holes its a 7 port

2. Like stated above, but there is more to it than that. the shape of the ports affects timing, and location of the ports affects the engine as well.

3. by saying "one gear" you mean one speed? they have a gear on the clutch bell and a center diff gear. you can change the amount of teeth on either and change your gear ratio.
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Old 07-27-2009, 01:57 PM   #5
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3. by saying "one gear" you mean one speed? they have a gear on the clutch bell and a center diff gear. you can change the amount of teeth on either and change your gear ratio.
It is a little hard to ask a question when you don't really understand what you don't know.

Let me try this slightly differently. I believe that a 13T clutch bell is for use with a 13mm crankshaft, while a 14t clutch bell is for use with a 14mm crankshaft, 15t for 15mm and so on.

Clearly the notches on a clutch bell have to mesh with the notches on the center diff. Do 13t clutch bells only mesh with certain centre diffs, while 14t only mesh with different centre diffs or does the combination of 13t/14t/15t clutch bells with various center diffs make-up the gear ratio for the car?
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Old 07-27-2009, 02:32 PM   #6
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the shaft diameter has nothing to do with the tooth count (ie...a 13t clutch bell will fit the same crank as a 15t clutchbell ect...) the only thing different would be the roll out on the clutchbell witch means the smaller tooth count will take less time to make one full revolution than a bell with more teeth witch translates into less top end and more bottom. you said u have an understanding of gear ratios on a full size car so to see this on that plain, take a look at a ring and pinion set from a 3.08\1 and compare it to a 4.11\1...
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Old 07-27-2009, 03:12 PM   #7
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Quote:
Originally Posted by Garet Jax
3) I have an outside idea of what gear ratio is with real world cars, but have no idea what it is for RC cars. Don't all nitro engines have one gear?
Quote:
Originally Posted by hustler777 View Post
you said u have an understanding of gear ratios on a full size car so to see this on that plain, take a look at a ring and pinion set from a 3.08\1 and compare it to a 4.11\1...
I guess I should rephrase that - I thought I had an outside understanding of what gear ratios are for real cars. What's scarry though is that I know more about that than I do about gear ratios for RC cars.

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Old 07-27-2009, 04:36 PM   #8
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Each kit model has a selection of clutch bells.

For example an Associated RC8 comes with a 16 tooth bell. A 15 and 17 are optional. The Associated bells fit associated cars, Losi fit Losi, X-ray fit X-ray.

Generally the 15 would be for shortrt tracks, and the 17 for higher speeds. I allways run the same diff gear.

The buggy engines all have nearly the same cranks.

The clutch,flywheel,pinion gear, clutch bearings, bolt, shims, nut, etc., make up the clutch/pinion gear assembly. They come with the car kit, and work specifically for that car.

The engines are mostly universal.
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Old 07-27-2009, 05:31 PM   #9
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Default Another question....

Hi, thought I'd get in on this question thread.....
What other plugs would work in the Losi 454 engine? (other than the one that comes with it)
Thanks.
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