.21 engine

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jeff baham

Well-Known Member
Joined
Aug 10, 2002
Messages
1,257
ok im a 25+ boat racer but all the engine ive ran was 45 and 67 and a once 90 ,all cmbs, well now im turning to rc car drag racing with the 21 buggy , well my question to you is " on the rotor which side gives torque and which give rpms. opening or closeing
 
The answer is not simply black and white as you ask it. You could loose torque by cutting either side and not gain any rpm.

Sometimes cutting the open side will gain torque, but it could also lose torque. Sometimes cutting the close side will gain rpm at the cost of low end torque.

Most often, there are additional mods that need to be made before the additional open or close time becomes a benefit.
 
ok im a 25+ boat racer but all the engine ive ran was 45 and 67 and a once 90 ,all cmbs, well now im turning to rc car drag racing with the 21 buggy , well my question to you is " on the rotor which side gives torque and which give rpms. opening or closeing
Hi Jeff,

Applying to boat engines too.

The engines sold today are very well designed and if you need more out of your .21 contact someone who modifies them. The reason is I know you what to do it yourself as most of us would. Start by Paying someone for their mods to your second engine. This way you can get into the thick of things right away. Recommending that you buy two engines leaving one stock for a baseline. Then run modified one to find out just how much more Torque, RPM & HP it has more than the stock one.

NOTE: Transit Time is what you want to be looking for the quicker the better and faster you will go.

Let's say you have two of the same .21 engines eng #1 each making a max of 4 HP @ 40,000 rpm. Now what I am talking about is Transit Time. TT is the measured acceleration time of the engine to accelerate from point A to point B rpm! The key here is less time between A&B engines making the same max 4 HP, the quicker engine #2 will accelerate the vehicle verified by quicker ET. An easy way to measure TT using an engine Dyno. Wish I owned a Dyno for our engines

Let us know how you do.

Good luck,

Mike
 
Last edited by a moderator:
ok im a 25+ boat racer but all the engine ive ran was 45 and 67 and a once 90 ,all cmbs, well now im turning to rc car drag racing with the 21 buggy , well my question to you is " on the rotor which side gives torque and which give rpms. opening or closeing
Hi Jeff,

Applying to boat engines too.

The engines sold today are very well designed and if you need more out of your .21 contact someone who modifies them. The reason is I know you what to do it yourself as most of us would. Start by Paying someone for their mods to your second engine. This way you can get into the thick of things right away. Recommending that you buy two engines leaving one stock for a baseline. Then run modified one to find out just how much more Torque, RPM & HP it has more than the stock one.

NOTE: Transit Time is what you want to be looking for the quicker the better and faster you will go.

Let's say you have two of the same .21 engines eng #1 each making a max of 4 HP @ 40,000 rpm. Now what I am talking about is Transit Time. TT is the measured acceleration time of the engine to accelerate from point A to point B rpm! The key here is less time between A&B engines making the same max 4 HP, the quicker engine #2 will accelerate the vehicle verified by quicker ET. An easy way to measure TT using an engine Dyno. Wish I owned a Dyno for our engines

Let us know how you do.

Good luck,

Mike
I added some more information
 
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