Engine Question - need knowledge
05-01-2008, 09:48 AM
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Engine Question - need knowledge
Hey All
Can someone explain how CC's relate to power? The reason I ask is the 30.5cc engine (1.9ps at 18000rpm) from FS seems to have much less power than most 26 or even 23CC. I know a tuned pipe helps, but what's the point in a 30.5 engine with poor power, do you get more torque? Is there a simple mod to the engine that helps? I've read a couple of post that suggest a different coil.
Can someone explain how CC's relate to power? The reason I ask is the 30.5cc engine (1.9ps at 18000rpm) from FS seems to have much less power than most 26 or even 23CC. I know a tuned pipe helps, but what's the point in a 30.5 engine with poor power, do you get more torque? Is there a simple mod to the engine that helps? I've read a couple of post that suggest a different coil.
05-01-2008, 08:06 PM
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RE: Engine Question - need knowledge
A 23 or 26 will seam faster than a 30.5 because it will rev to higher RPM than the 30.5. The 30 will make more TORQUE than the others but in the end it's HP that makes speed. HP is equal to torque x RPM / 5250. From that formula you can see that if torque stays the same,all you have to do is raise the RPM and you get more HP. To your CC question,a bigger engine will make more torque but the longer stroke limits the RPM,and since a Baja or whatever doesn't have a transmission to keep the engine in the narrow RPM range were it makes power,even if it's more power than the smaller engine,the one that will rev higher [the smaller engine]will reach a higher top speed. Clear as mud?
05-01-2008, 09:37 PM
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RE: Engine Question - need knowledge
keep it simple. CC's is the volume of the cylinder in cubic centimeters. its just a measure of how much air can be inside the engine at any given time. higher CC's=more air in=more fuel to burn=more power.
05-01-2008, 09:46 PM
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RE: Engine Question - need knowledge
Ya some of those motor's have bad coils that limit performance in the high rpm's which people are switching to the zenoah coils. I would get a pipe it's good for a big boost in performance about 20% after that i would send it to oniells for 80bucks last time I checked for a full modification that will wake the motor up if it can take it?
05-01-2008, 10:46 PM
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RE: Engine Question - need knowledge
It also depends on compression ratio, bore and stroke, carb, airflow through the engine (efficiency of the ports), exhaust and all that fun stuff. the saying "there's no replacement for displacement" holds true if the goals are the same for two different size engines. bigger isn't always better though.
05-02-2008, 07:29 PM
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RE: Engine Question - need knowledge
ORIGINAL: savagecommander
keep it simple. CC's is the volume of the cylinder in cubic centimeters. its just a measure of how much air can be inside the engine at any given time. higher CC's=more air in=more fuel to burn=more power.
keep it simple. CC's is the volume of the cylinder in cubic centimeters. its just a measure of how much air can be inside the engine at any given time. higher CC's=more air in=more fuel to burn=more power.
Yea,but keeping it simple doesn't answer his question. He asked why the smaller engine was faster.
"its just a measure of how much air can be inside the engine at any given time." The only time a 30.5 will fill it's cylinder with 30.5 ccs of air is if it was to reach 100% volumetric efficiency and that's never going to happen. Yes, a bigger engine will always make more power,as in TORQUE, not HP. You need RPM to make HP [or an S load of torque!] and the longer stroke of the 30.5 is RPM limited.
05-03-2008, 03:35 AM
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RE: Engine Question - need knowledge
when i was running my CY with race ported and 35mm piston and using a +2mm stuffed crank it was pretty powerfull but lacked rpm , then i installed the TS induction crankcase still using a 35mm race ported head with +2mm stuffed crank and the rpms increased dramatically , so does this mean if i go with a (36mm) ESP raceported head still using my TS crankcase and +2mm stuffed crank i should still maintain those extremely high rpm's but get even more HP with more torque , its something thats been bugging my mind and ill never know untill i buy this ESP race ported 36mm head kit and test it out , i hope to get one in a few weeks , thats if DDM isnt sold out again LOL
05-03-2008, 04:05 AM
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RE: Engine Question - need knowledge
ORIGINAL: Briansshop
Yea,but keeping it simple doesn't answer his question. He asked why the smaller engine was faster.
"its just a measure of how much air can be inside the engine at any given time." The only time a 30.5 will fill it's cylinder with 30.5 ccs of air is if it was to reach 100% volumetric efficiency and that's never going to happen. Yes, a bigger engine will always make more power,as in TORQUE, not HP. You need RPM to make HP [or an S load of torque!] and the longer stroke of the 30.5 is RPM limited.
ORIGINAL: savagecommander
keep it simple. CC's is the volume of the cylinder in cubic centimeters. its just a measure of how much air can be inside the engine at any given time. higher CC's=more air in=more fuel to burn=more power.
keep it simple. CC's is the volume of the cylinder in cubic centimeters. its just a measure of how much air can be inside the engine at any given time. higher CC's=more air in=more fuel to burn=more power.
Yea,but keeping it simple doesn't answer his question. He asked why the smaller engine was faster.
"its just a measure of how much air can be inside the engine at any given time." The only time a 30.5 will fill it's cylinder with 30.5 ccs of air is if it was to reach 100% volumetric efficiency and that's never going to happen. Yes, a bigger engine will always make more power,as in TORQUE, not HP. You need RPM to make HP [or an S load of torque!] and the longer stroke of the 30.5 is RPM limited.
timing factors to consider is induction timing,how many degrees of the crank duration the inlet is open, and in the case of two strokes the shape and height of the exhaust port.
05-03-2008, 07:03 AM
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RE: Engine Question - need knowledge
ORIGINAL: Briansshop
A 23 or 26 will seam faster than a 30.5 because it will rev to higher RPM than the 30.5. The 30 will make more TORQUE than the others but in the end it's HP that makes speed. HP is equal to torque x RPM / 5250. From that formula you can see that if torque stays the same,all you have to do is raise the RPM and you get more HP. To your CC question,a bigger engine will make more torque but the longer stroke limits the RPM,and since a Baja or whatever doesn't have a transmission to keep the engine in the narrow RPM range were it makes power,even if it's more power than the smaller engine,the one that will rev higher [the smaller engine]will reach a higher top speed. Clear as mud?
A 23 or 26 will seam faster than a 30.5 because it will rev to higher RPM than the 30.5. The 30 will make more TORQUE than the others but in the end it's HP that makes speed. HP is equal to torque x RPM / 5250. From that formula you can see that if torque stays the same,all you have to do is raise the RPM and you get more HP. To your CC question,a bigger engine will make more torque but the longer stroke limits the RPM,and since a Baja or whatever doesn't have a transmission to keep the engine in the narrow RPM range were it makes power,even if it's more power than the smaller engine,the one that will rev higher [the smaller engine]will reach a higher top speed. Clear as mud?
05-03-2008, 07:05 AM
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RE: Engine Question - need knowledge
ORIGINAL: splcrazy
when i was running my CY with race ported and 35mm piston and using a +2mm stuffed crank it was pretty powerfull but lacked rpm , then i installed the TS induction crankcase still using a 35mm race ported head with +2mm stuffed crank and the rpms increased dramatically , so does this mean if i go with a (36mm) ESP raceported head still using my TS crankcase and +2mm stuffed crank i should still maintain those extremely high rpm's but get even more HP with more torque , its something thats been bugging my mind and ill never know untill i buy this ESP race ported 36mm head kit and test it out , i hope to get one in a few weeks , thats if DDM isnt sold out again LOL
when i was running my CY with race ported and 35mm piston and using a +2mm stuffed crank it was pretty powerfull but lacked rpm , then i installed the TS induction crankcase still using a 35mm race ported head with +2mm stuffed crank and the rpms increased dramatically , so does this mean if i go with a (36mm) ESP raceported head still using my TS crankcase and +2mm stuffed crank i should still maintain those extremely high rpm's but get even more HP with more torque , its something thats been bugging my mind and ill never know untill i buy this ESP race ported 36mm head kit and test it out , i hope to get one in a few weeks , thats if DDM isnt sold out again LOL
Yes, the bigger bore should give you more power. I don't have any experience w/the RC case reed engines [ next on my list!],but I can see how the reeds being in the case verse the piston port intake extends the usable rpm range of the engine. The case reed starts pulling in a fresh intake charge sooner than the piston port motor and that helps w/power all across the board.
05-03-2008, 07:11 AM
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RE: Engine Question - need knowledge
ORIGINAL: Osirisf16
That number from where does it come from? I thought that HP = torque X RPMs
ORIGINAL: Briansshop
A 23 or 26 will seam faster than a 30.5 because it will rev to higher RPM than the 30.5. The 30 will make more TORQUE than the others but in the end it's HP that makes speed. HP is equal to torque x RPM / 5250. From that formula you can see that if torque stays the same,all you have to do is raise the RPM and you get more HP. To your CC question,a bigger engine will make more torque but the longer stroke limits the RPM,and since a Baja or whatever doesn't have a transmission to keep the engine in the narrow RPM range were it makes power,even if it's more power than the smaller engine,the one that will rev higher [the smaller engine]will reach a higher top speed. Clear as mud?
A 23 or 26 will seam faster than a 30.5 because it will rev to higher RPM than the 30.5. The 30 will make more TORQUE than the others but in the end it's HP that makes speed. HP is equal to torque x RPM / 5250. From that formula you can see that if torque stays the same,all you have to do is raise the RPM and you get more HP. To your CC question,a bigger engine will make more torque but the longer stroke limits the RPM,and since a Baja or whatever doesn't have a transmission to keep the engine in the narrow RPM range were it makes power,even if it's more power than the smaller engine,the one that will rev higher [the smaller engine]will reach a higher top speed. Clear as mud?
A quick search pulled this: http://www.largiader.com/articles/torque.html
The relationship between torque and HP as been misunderstood by alot of people for a long time. I'm still trying to figure it out!
05-03-2008, 11:27 AM
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RE: Engine Question - need knowledge
The 30.5cc motor that FS offers is really for marketing purpose only.
It's outright junk.
Any of the motors that offer as an option are below industry standards.
Stick with a real ZENOAH.
23cc / 26cc and build from there
It's outright junk.
Any of the motors that offer as an option are below industry standards.
Stick with a real ZENOAH.
23cc / 26cc and build from there
05-03-2008, 05:51 PM
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RE: Engine Question - need knowledge
mate untill you try the TS induction crankcase you have no idea of the power this thing makes , its a whole new world of power and RPM'S something youll never get with the stock CY crankcases , but if i had no choice but to use a CY crankcase i would use a stuffed crank as compulsory , oh and next thing im gonna try are the HRS ZERO DRAG BRASS CRANKSHAFT SEALS they are on the way to my destination lol
05-04-2008, 10:28 AM
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RE: Engine Question - need knowledge
It's all about gearing... The more torque you have the lower numerical ratio you can run, low torque but high RPM engines you'll run a higher numerical ratio. Most people forget when they change engines they need to change the gearing...
Everyone should start out with an electric car, it's all about having the right gear...
Everyone should start out with an electric car, it's all about having the right gear...
05-04-2008, 10:49 PM
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RE: Engine Question - need knowledge
ORIGINAL: Briansshop
Yea,but keeping it simple doesn't answer his question. He asked why the smaller engine was faster.
"its just a measure of how much air can be inside the engine at any given time." The only time a 30.5 will fill it's cylinder with 30.5 ccs of air is if it was to reach 100% volumetric efficiency and that's never going to happen. Yes, a bigger engine will always make more power,as in TORQUE, not HP. You need RPM to make HP [or an S load of torque!] and the longer stroke of the 30.5 is RPM limited.
ORIGINAL: savagecommander
keep it simple. CC's is the volume of the cylinder in cubic centimeters. its just a measure of how much air can be inside the engine at any given time. higher CC's=more air in=more fuel to burn=more power.
keep it simple. CC's is the volume of the cylinder in cubic centimeters. its just a measure of how much air can be inside the engine at any given time. higher CC's=more air in=more fuel to burn=more power.
Yea,but keeping it simple doesn't answer his question. He asked why the smaller engine was faster.
"its just a measure of how much air can be inside the engine at any given time." The only time a 30.5 will fill it's cylinder with 30.5 ccs of air is if it was to reach 100% volumetric efficiency and that's never going to happen. Yes, a bigger engine will always make more power,as in TORQUE, not HP. You need RPM to make HP [or an S load of torque!] and the longer stroke of the 30.5 is RPM limited.
05-04-2008, 11:21 PM
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RE: Engine Question - need knowledge
The development on the case reed coupled with the stroked motor's are making more power and just as high of rpm's as a non stroked motor.
