Ported Zeonah G320 + Tall gears = Top speed?

[almighty15]

Lmao.... you don't want a G320 or G340 going over 17,000rpm

 

[Ice_2k]

Lmao.... you don't want a G320 or G340 going over 17,000rpm

Why not?...

 

[almighty15]

Why not?...

Because it wrecks the bearing... I've talked about it on the Losi 5ive forum...

And they don't rev to 20,000 anyway.... I run TTO's and never seen an engine higher then a 29.5cc run over 19,000rpm on grass.

 

[Ice_2k]

Well, I never owned one of these engines so I can't say for sure, but that's what OBR is claiming. Both on the website and confirmed to be directly by Sean, via email. I have the stock 32cc and it goes to ~17.000rpm, so I'm guessing an OBR-built Zenoah with reed case should go over that pretty easy....

 

[almighty15]

Well, I never owned one of these engines so I can't say for sure, but that's what OBR is claiming. Both on the website and confirmed to be directly by Sean, via email. I have the stock 32cc and it goes to ~17.000rpm, so I'm guessing an OBR-built Zenoah with reed case should go over that pretty easy....

I run with people who have 32/34c OBR reeds and the TTO's have never gone over 19,000rom in the real world.

They might very well hit 20,000rpm when under no load, Reed engines do also loose top end rpm over the none versions due to the reed valve design.

This makes 20,000rpm all the more unattainable in the real world.

 

[Ice_2k]

I run with people who have 32/34c OBR reeds and the TTO's have never gone over 19,000rom in the real world.

Well, the discussion began with 17,000 19,000 is quite different, especially since you mentioned running on grass. Running on tarmac with tarmac tyres would probably increase that top rpm a bit more.

They might very well hit 20,000rpm when under no load, Reed engines do also loose top end rpm over the none versions due to the reed valve design.

That's weird as it directly contradicts what sean o'neill told me on email, I just rechecked my emails. He said the reed case fm g320 revs significantly higher than the normal fm g320.

 

[Ice_2k]

Ported Zeonah G320 + Tall gears = Top speed?

In theory and sticking to a single speed what could a TT powered by a ported G320 get up to?I've heard you can swap the first 2 gears around to get silly top end but at the expensive of bottom end torque? Something a G320 should cope with much better then the stock engine?

Would 45mph+ be possible?

What about gear ratio's with the best drive?

Getting back to your original question, I tested my Dunerunner today and it hit 40mph at about 17,000rpm. My gears are 29-31-26-24. Replacing the A&B gears would get me to about 44mph, altough to be honest it already seems too fast for such a big rig.

Hope this helps.

 

[talunceford]

Getting back to your original question, I tested my Dunerunner today and it hit 40mph at about 17,000rpm. My gears are 29-31-26-24. Replacing the A&B gears would get me to about 44mph, altough to be honest it already seems too fast for such a big rig. Hope this helps.

Have you looked at the 35/25 gears?

 

[Ice_2k]

Ported Zeonah G320 + Tall gears = Top speed?

Have you looked at the 35/25 gears?

No, what for? I have plenty of top speed and already can't put the power down in low revs, so I don't have any use for either higher or lower ratios.

P.S. Forgot to mention I'm using the HPI Tarmac Busters, which are smaller in diameter than the stock tires so with the stock tires it should gain another few mph in top speed.

 

[almighty15]

That's weird as it directly contradicts what sean o'neill told me on email, I just rechecked my emails. He said the reed case fm g320 revs significantly higher than the normal fm g320.

An engine builder saying a more expensive product is better then a cheaper one......

 

[GTi_Leo]

tire choice is an element to consider, maybe 45mph more like 40, more be would be deluxe custom and alot of something else.

I did the math on stock gears turned around for top end and with XB wheels at 15000 rpm it will do 43mph, not sure how big the TT wheels are over the XBs but you can expect some good speed

its a description of how mill speed is realized at crank level. G320 favors torque. by choosing a shorter stroke motor like 230/270 with stock rod the motor can turn faster. so motor choice is a factor for hi speed as well... its just an example

he G320 still has a 28mm stroke, to say it favors torque more then a 30.5 is not really true at all. rod speed will be much lower then the 30.5 and would favor high reving more then the 30.5 would. what it doesn't favor is high compression as the compressed gas is spread over 38mm rather then 36.

 

[GTi_Leo]

its a description of how mill speed is realized at crank level. G320 favors torque. by choosing a shorter stroke motor like 230/270 with stock rod the motor can turn faster. so motor choice is a factor for hi speed as well... its just an example

he G32 still has a 28mm stroke, to say it favors torque more then a 30.5 is not really true at all. rod speed will be much lower then the 30.5 and would favor high reving more then the 30.5 would. what it doesn't favor is high compression as the compressed gas is spread over 38mm rather then 36.

 

[GTi_Leo]

I run with people who have 32/34c OBR reeds and the TTO's have never gone over 19,000rom in the real world.They might very well hit 20,000rpm when under no load, Reed engines do also loose top end rpm over the none versions due to the reed valve design.

This makes 20,000rpm all the more unattainable in the real world.

I can see the flappers getting in the way at high speed and probably not opening fully to allow this but this is just a theory that comes up I have no full proof as to why the top end won't be as good.

even still 20000rpm is insane reving and its hard to believe things can manage that speed for prolonged periods of time. that's a lot of heat being generated

 

[phreerider]

I did the math on stock gears turned around for top end and with XB wheels at 15000 rpm it will do 43mph, not sure how big the TT wheels are over the XBs but you can expect some good speedhe G320 still has a 28mm stroke, to say it favors torque more then a 30.5 is not really true at all. rod speed will be much lower then the 30.5 and would favor high reving more then the 30.5 would. what it doesn't favor is high compression as the compressed gas is spread over 38mm rather then 36.

it favors torque because of total mass/area of larger piston. doubtful it revs higher AND produces usable power because of same reason. the increased compression and less mass of 30.5 seemingly better balance for both high crank speed AND torque. the bigger volume of gas(32) produces better torque at lower crank speed, at extreme crank speed the reaction is all spin. yes the shorter crank should swing things faster but the mass (i'm guessing) is going hold it back but has higher torque earlier in the power band. i havent looked at dyno graphs and certainly have not done the numbers. it has alot of new parts in the lower end to balance and not sure of actual hi rpm crank speed and usable power, i;ll check a graph and see

 

[GTi_Leo]

it favors torque because of total mass/area of larger piston. doubtful it revs higher AND produces usable power because of same reason. the increased compression and less mass of 30.5 seemingly better balance for both high crank speed AND torque. the bigger volume of gas(32) produces better torque at lower crank speed, at extreme crank speed the reaction is all spin. yes the shorter crank should swing things faster but the mass (i'm guessing) is going hold it back but has higher torque earlier in the power band. i havent looked at dyno graphs and certainly have not done the numbers. it has alot of new parts in the lower end to balance and not sure of actual hi rpm crank speed and usable power, i;ll check a graph and see

I think you may be reading to much into piston weight and RPM, sure the G320 engine might have a larger piston but its only 2mm larger, it also has a larger bearing meaning the hole for the wrist pin is larger which will shed some weight.

also when tuning an engine its not so much about piston weight, while it can help its more about balancing the counter weight on the crank then actually lightening up the whole piston, you can lighten it up all you want if the counter balance isn't to match you're going to get an inconsistent movement, weighted more to the bottom then the top. so in this case its more about the stroke length then the actual weights of the piston.

another thing that should be looked at when taking into consideration of weight, is the fact that additional weight means added inertia, while it may be easier to push it also does not maintain speed as well, which is why to light of a flywheel doesn't always help when it comes to performance, it may increase its revs faster but it also decreases them faster, making it very hard to maintain power, especially when there is more resistance and maintaining high revs is very tough to do and since it is a single cylinder we are only getting one explosion per cycle not multiple like in multi cylinder engines, so some mass is needed to keep the engines momentum.

we can also talk about the larger bearings the G320 uses making it easier for the crank assembly to rotate, but saying that that would also imply a 3 or 4 bearing setup, I'm sure the added side of the oil seals will add extra drag to the crank, making it harder to rotate.

I'm not saying you're wrong, this could very well be true, I'm no engineer but from the knowledge I have about engine performance, I think many people take others word for things and over look the many things effecting things, and the only reason I see a stock G320 having better low end then a G290 is purely the displacement, considering they are still both only 28mm stroke. now we can compare it to a 30.5 stroker motor and its a totally different beast. with equal duration and timing of the exhaust port, the 30.5 will generate higher compression it is higher on the G290 then the G320 to begin with now stroke it and compress and extra 2cc into the same squish area which is a 7% increase, going from 9.9:1 to 10.6ish:1 which is a pretty nice increase compared to the G320 9.7:1 ratio. we can also ask how an engine maker might machine the head to incorporate the extra 1mm of top stroke, if they choose to take 1mm of the squish then they are effectively shrinking the squish area and further increasing the compression, if they just stack the gaskets then they are messing with the timing and can alter a lot of things.

OBR has som power graphs on their site, the G320 reed fully moded on their dyno graph shows it reving to 21000 rpm, and maintaining power up to about 20000 rpm, their reed fully moded 30.5 peaks at about 14500 rpm and rapidly drops and revs to about 20000 rpm. now we can ask why there is such a rapid drop in power but there could be many reasons for the cause, my assumption is excess heat and the engine is suffering from detonation issues, which could be a factor of a longer stroke as well as increased compression, they may be able to combat this by putting in a colder sparkplug or retarding the ignition timing, but on a fixed magneto flywheel its a bit harder and it may effect the peak RPM.

one thing I'd be very interested in seeing is how a G320 would perform if shrunk down to 30.5 cc specs (36mm bore 30mm stroke), it wouldn't be too hard to do, OBR has a G340 with 30mm stroke, all one would have to do is make a sleeve and a new piston .

anyways a lot of info I threw around but until someone can prove it its all just theory and words. take what you want from it I wouldn't mind discussing this topic some more I'm no expert and what I said is not at all fact, just my theories based on my knowledge

 

[GTi_Leo]

wow until I posted that I didn't realise I wrote that much LMAO

 

[phreerider]

no worries, i looked at the graphs and very surprising it has power well into hi rpms,

definitely differnet animal, i was guessing it had more mass total to balance , kinda like big block not allowing more spin. very powerful balanced build

reduced i guess it would rev even higher!

we all get chatty when we love it and want more than just knowledge , its the understanding that allows discernment. good stuff , prolly will get a 320 , esp. since i looked at the graphs!

 

[GTi_Leo]

no worries, i looked at the graphs and very surprising it has power well into hi rpms, definitely differnet animal, i was guessing it had more mass total to balance , kinda like big block not allowing more spin. very powerful balanced build

reduced i guess it would rev even higher!

we all get chatty when we love it and want more than just knowledge , its the understanding that allows discernment. good stuff , prolly will get a 320 , esp. since i looked at the graphs!

I'm sure a G340 might be a bit different then the G320 they as a +2mm stroker to it so it might mess around with things a little bit. I only compared the G320 and 30.5 , it doesn't seem like OBR has any graphs for the 340 so my guess is its going to be similar to the 30.5, more torque but less high revving power.

 

[phreerider]

hey i cannot find graphs i saw recently? the modded goods anyway .

i did see the zenoah stock graphs showing roughly same rpms g320rc(STOCK) compared to (STOCK) 30.5cc

but g320rc with more torque... not seeing 20K + rpms.

early in power band g320rc has more torque than 30.5 has even at peak.

 

[Ice_2k]

G320 only has 3.2hp?