Low RPM vs High RPM

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EvhCo

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What exactly would be the benefits of having a nitro engine operate at a smaller RPM range than at a higher one? For instance, by mounting a really heavy flywheel to lower the RPMs. Would the heavy flywheel yield more torque? Would the glow plug wear out at a slower pace?
 
olds97_lss

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High RPM engines usually have their best usable torque higher in the RPM range in general, so you gear low to leverage the rpm's and torque the engine has to offer.

Lower RPM engines usually have their usable torque in the middle/lower end of the RPM range, and gear accordingly.

Typically, a higher RPM engine is ported differently and costs more as it's made out of better materials to handle the RPM's.

High RPM engines work well for on-road and 1/8th buggies. Less weight to get moving and tend to lend themselves to higher speeds.

Lower RPM engines work well in monster trucks and truggies. More weight/rotational mass to get moving and the low end torque works better there.

That's not to say you can't get a high reving engine and gear it down, or a lower RPM engine and gear it up. They just tend to work better when you buy what's needed for the situation.
 
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On That Pipe

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What exactly would be the benefits of having a nitro engine operate at a smaller RPM range than at a higher one? For instance, by mounting a really heavy flywheel to lower the RPMs. Would the heavy flywheel yield more torque? Would the glow plug wear out at a slower pace?
Let me just put this in to context for you. Olds what you wrote above we can all read from a book! ha ha. I think dude wants to know WHY he would want to do something like this (use a heavier flywheel to slow down his RPMs). But I'll deal with you in a minute...:(

EvhCo...it's all about controlling the vehicle. That''s it. The goal of his hobby is to get your vehicle from point A to point B as quickly as possible. These little nitros come in all flavors. It's a preference in what allows people to put their vehicle where they want when they want,.

I worked years with many of the top aftermarket clutch manufacturers (M2C, Buku, OFNA) and was proud to experience some cutting edge things with clutch tuning...so I will break it down for because man I tell you you cannot these vehicles to rip ass without a spot on clutch. Once again...I've never seen one anyway.

Specifically, a heavier flywheel will slow up the spool of the clutch shoes causing them to engage at a lower RPM (centrifugal force). That is the explicit reason heavier flywheels were made. (not to make them stronger as some think--ha ha). So it's the same of having heavier shoes.

Why do you want the clutch to engage later? When you have little traction. The reason is because once they engage they tell tell the wheels to move. If there is not good contact with the ground, the wheels will spin, become 'pizza cutters' and you won't get from point A to point B as fast. Technically the engine's RPM will lag if the c;lutch is too right I see it all the time. Guys want to rock with those light, shiny alum shoes with those thick ass springs (we like that pop, you know)....ha ha. I was the same. But the clutch is begging for more power from the engine.

From a nitro RC experience, it can hurt your tune having a bad clutch system more than it can help having a good one It;s a real must have, It's correct or it's not. Unfortunately there is a lot of misinformation about it.
That's the 1k foot view of it.
 
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olds97_lss

olds97_lss

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@On That Pipe Your not wrong. Everything you say is right.
 
cbaker65

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What exactly would be the benefits of having a nitro engine operate at a smaller RPM range than at a higher one? For instance, by mounting a really heavy flywheel to lower the RPMs. Would the heavy flywheel yield more torque? Would the glow plug wear out at a slower pace?
I am not sure about a heavier fly wheel ,or if you can find a heavier one ,a heavier one would seem like it would knock
RPM's down ,but will probably knock the torque down as well!
Most people ,usually will change from torque to high speed through gear change & tune pipe change ,
an two stroke engines really aren't made for lugging around ,like per-say ,for crawling applications!

If you do decide to experiment ,do be careful an DO NOT try to run a nitro or gas engine with out a
clutch bell over the shoes ,if you do ,then you will be kicked in the face with a horse shoe!....:hehe:

Remember ,safety first!.....:cool:
 
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EvhCo

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if you do ,then you will be kicked in the face with a horse shoe!....:hehe:
Been there already :blackeye:.

Thanks for the explanations, @On That Pipe, @olds97_lss and @cbaker65 . I guess there's a lot more to power than just big wheel big speed vrooom :hehe:.
 

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