hi im just starting and i need to know how engine sizes are measured. first of what is the .__ number measuring? Is a .21 bigger or smaller than a .25, and about how much bigger or smaller? if you could just reply and help me out that would be great! thank you!

Engine case? In my opinion, many times the numbers are misleading and probably used more for marketing. I only write this because the engine case may still be a .21 though the "marketing" numbers are bigger and at other times the so-called larger engines still have less horsepower than a "smaller" .21 engine. For example, if you take a larger head and place it on the stock engine case, is the engine larger? Perhaps it is (and perhaps it now weighs more), but it still has the same "engine" case. I guess you could also compare the smaller Traxxas 2.5 (which is measured in cc's) and the Sirio 3.0--they both drop into the T-Maxx, but you can't drop in a .21 without modification. Sirio also makes a hop-up kit for the Traxxas 2.5. I hope that I didn't confuse you too bad since in simple math, .25 is larger than .21 much like 3.0 is larger than 2.5.

Actually the numbers pertain to displacement.

A .12 - 0.129 cu in or 2.11cc
A .15 - 0.152 cu in or 2.49cc
A .21 - 0.211 cu in or 3.46cc

Traxxas 2.5 is actually a .15 @ 0.15 cu in or 2.49cc


Dbow

or the RX21P5 with a displacement of 3.49cc .21 which is .03 cc different from what you posted...
http://www.teamtrinity.com/nitro/eng.../novarossi.asp

Then there is the Sirio .27 Race/Pro with a displacement of 4.42 cc's
http://www.teamtrinity.com/nitro/eng.../novarossi.asp

And here is a link to an engine displacement calculator based on bore, stoke and number of cylinders
http://www.europartsinc.com/zonker/eng_disp.htm

The ROAR rules at page 31, section 6-12, also provide the formula to determine engine displacement.
http://www.roarracing.com/rules/pdfs/2003rules.pdf

Got some free time tonight Tigger?

LOL, just kidding.



New pics of Mai Tai are up today.

It depends on who you ask. Tigger is on the desk and doesn't want me to quit rubbing his ears. Bennie was laying on the 1/4 scale earlier. Meanwhile, I am charging batteries for tomorrow's mini-z run, watching the tube, and surfing or trying to surf. Since I have two monitors hooked up, it's real easy to surf especially since I probably have over 100 R/C links (which is probably not that many considering the different types of cars I have). Actually I did something different tonight and that was use my Reedy Quasar Pro to charge AAA's. It seemed to work a whole lot better than the Hi-Tech charger I had which was made for both AA's and AAA's.

I liked your newest photo of Mai Tai. The photo looks much clearer than yesterday's photo. I don't know how many photo ops I have missed of TNB because I try to catch them using the Tiff setting and they take off somewhere.

The chargers is beeping. Just in time. Later.

BTW, I added a new photo of Bennie peaking over the 1/5 and 1/10 scale sedans. For now, it's the group photo.
http://groups.yahoo.com/group/tnbrcvideos

I agree that there are some variances between some of the manufacturers and different engines, However a majority of the most commonly used engine sizes (ones I listed above) basically hit those specs or come real close.

A large variance would certainly be a concern in a comparison, on the other side the small variances are really null in my opinion.


Dbow