x-dyno questions

[JohnH]

Please post here if you have any questions to the dyno tests.

 

[oldlugs]

Hi Mr. megabyteme, I've got a couple of questions about how the tests were run...

Since the dyno tests are comparing engine to engine for a given displacement, I'd like to know if the same brand and nitro % of fuel was used in all tests, and also if several popular tuned pipes (and lengths) were tried for each engine size. I understand that some engines run better on one brand of fuel or pipe vs another, but without a baseline to start from, it's hard make realistic comparisons... Were ambient temperature and atmospheric pressure relatively constant, or corrected for? Were all engines freshly broken in, still very tight, or some well used? Also, how is the dyno calibrated?

Thanks, Duane

 

[JohnH]

http://www.nitrodynesystems.com/

 

[oldlugs]

That site tells me "Includes weather station input for automatic correction factors", but not much else.
Says nothing about the dyno runs for the engines listed in the database, just about the $5K+ (!) dyno itself. Would be nice to know about engine physical condition and fuel used on all engines tested...

Duane

 

[JohnH]

If I read it right xtreme rc uses new engines and they do the

break in​

per manufacturer specs. they use different fuels and pipe combinations to get the best pulls.

 

[oldlugs]

If I read it right xtreme rc uses new engines and they do the

break in​

per manufacturer specs. they use different fuels and pipe combinations to get the best pulls.

Cool; thanks.

I think they should have used the same fuel on all runs though... I know that my engines run much differently on 40% and 60% fuel (though I usually run 50%). I'm sure the difference between just 20% and 30% is quite noticeable as well.

Cheers, Duane

 

[Zach_406]

sorry if this is a stupid question, I'm a newbie! but i was wondering how accurate the horse power ratings are from brand to brand. it seems to me that some engines with lower horsepower rating seem to be faster than some engines with slightly higher horsepower ratings. it also seems like everywhere you look there is differant information for the same engine. anyone have any ideas?

 

[bin_dubai]

well, you should consider the stroke, ports, bore, all that are counted

like the os VG30 it has 3 ports and awsome HP rated at 1.81, but since its a big bore engine, the massive torque is good, but it wont accelerate faster then axial 28RR for example which is high in stroke/bore ratio

taking a post from a member over here and re-arrange it in axel u will see many factors like rpm, max rpm, torque, some info is missing which am going to get it like bore, stroke, ports

there is another factor which is the compression of the piston also, like the axial 28 and axial 28RR

same engine, same ports, same specs, but still R has more power, i bet its due to compression

 

[JohnH]

There are a lot of factors for engines. Like you said ports, stroke and fuel to name a few. What I couldn't do with the space provided was add the actual grafts. That would show you where the motor ran up to peak HP and torque. That says a lot also. This was done to give people a quick reference on a possible purchase. The engines were run fresh and in a controlled environment. No life span or other than optimal conditions like poor tune altitude or anything else was looked at. That is why it is just a reference but much better than a prop counting revolutions.

 

[bin_dubai]

check my attached picture, u will see alot of variations between the engines, i tryed to pickup the most proper to make it easier for the members to choose from the almost top engines which has more hp and more TQ

am thinking to get N528XR hot mod since it scored high almost in everything, i wonder if i should change my dog bones drive

 

[BIGDAN89]

like mega said theres lots of factors like was it a perfect tune,fuel fresh or old,glowplug,the pipe legnth and chambers and such weather and such.

 

[AB Mods]

I would be glad to answer any questions that i can on the X-Dyno. I have owned an X-dyno for about 2 years now and have quite a bit of experience with it.