stupid question

[darkslayor24]

ok this sounds dumb i know, but with nitro engines there are .12, .15, .18 and so on..now the dumb question, were is that measured and in wat unit is it measured in??? also 2.5 and such wat unit is that measured in?

 

[olds97_lss]

Well, it depends.
.12, .15, .18, .21, .28, .30 = cubic inch (ci)
2.5 = cubic centimeter (cc)

The most used:
Generally considered small block:
1.97cc (possibly 2.0) = .12ci (many 1/10 race engines and older 1/10 RTR engines)
2.5cc = .15ci (traxxas 2.5, 2.5R, OS 15 CV and many others)
3.0cc = .18ci (HPI 3.0, OS 18TM/TZ)

Considered "mid-block" (big block power/capacity in a small block crank case):
3.3cc = .20ci (traxxas 3.3, probably other .20's, just don't know them)
3.4cc = .21ci (OS21TM and others)
4.27cc=.26ci (Picco 26 Maxx and others for the t-maxx/revo)

Generally a true big block crank case:
3.4cc = .21ci (many big block 21 race and RTR engines)
4.1cc = .25ci (HPI 25)
4.27cc=.26ci (losi/dynamite 427, M26, M26SS)
4.6cc = .28ci (many big block 28's)
4.9cc = .30ci

You will notice that there are a few engines with "big block" capacity, but are built for a "small block" vehicle. Kind of a way to get a lot of power more cheaply than getting a really high end Italian mill to throw in a t-maxx. Not exactly always "cheap", but generally more so than a race engine.

 

[darkslayor24]

ok i got that but ci and cc is measured where??? in the base of the block were the crankshaft is???

 

[Lessen]

Either one, (Cubic centimeter or cubic inch) are a measure of displacement, just like a 1:1 vehicle engine. The displacement is the difference of the volume of open space within the cylinder (above the piston) between top dead center and botom dead center. For instance, my 1:1 civic is a 2.0 liter 4 cylinder. There is a difference of .5 liter of space between top dead center and bottom dead centerof the piston in all four cylinders. Same concept for r/c engines.

 

[hipluther01]

Ok... lets throw another question in the pot... What's the conversion formula for getting CC into CI?

 

[Racer 1966]

1 cubic centimeter = 0.061 cubic inch

 

[hipluther01]

1 cubic centimeter = 0.061 cubic inch

Cool because the guys at my lhs were arguing that the 3.3 was a .18 and I was like no its a .20, but I couldnt remember how to get the answer. One guy told me a 3.3 was like a .179.... whatever.

 

[Racer 1966]

Cool because the guys at my lhs were arguing that the 3.3 was a .18 and I was like no its a .20, but I couldnt remember how to get the answer. One guy told me a 3.3 was like a .179.... whatever.

That'll be great to show'em you were right.

 

[frickenjoey]

1 cubic centimeter = 0.061 cubic inch

Correct as normal Randy ... and you can also use this site that has that as well as a lot of other handy stuff as well....distances, speeds, volumes, weights....you name it. I am bad at math, so this is what I use if I am near a computer.
http://www.onlineconversion.com/

 

[olds97_lss]

Correct as normal Randy ... and you can also use this site that has that as well as a lot of other handy stuff as well....distances, speeds, volumes, weights....you name it. I am bad at math, so this is what I use if I am near a computer.
http://www.onlineconversion.com/

I use this one:
http://www.convert-me.com/en/convert/volume

It has torque as well, which is handy for servos that are rated in Kg's/cm vs inch lb's.
http://www.convert-me.com/en/convert/torque

It's what I used for the numbers I listed above. Rounded most off to 2 points past . .

 

[frickenjoey]

Yeah I have used that one as well. The torque converter is better the one you use.