All of rovans engines spec chart

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Z.hb71

Z.hb71

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Engine_Chart.jpg
Kw to hp
26cc - 2.45hp and 1.18 foot pounds of torque
27.5cc - 2.5hp and 1.22 foot pounds of torque
29cc - 2.68hp and 1.22 foot pounds of torque
30cc (what I'm really interested in) - 2.81hp and 1.3 foot pounds of torque
32cc - 3.19hp and 1.46 foot pounds of torque
36cc - 3.45hp and 1.67 foot pounds of torque
45cc (also what I'm interested in) - 4.29hp and 2.07 foot pounds of torque
If you don't believe me here "engine comparison chart"
https://www.rovanrc.com/support-downloads
Not to give my opinion or anything but 4.29hp and 2.07ftlbs is really low for a 45, but then again its a cheapy cheap Motor sso whatever. Just in case anyone was wondering the specs of those engines, here.
 
Polar there is standards here In the states for power ratings. Anything sold here has to abide by them. The old std was a j1940. New spec I believe is a j1995. Engines must be within 95% of their rated hp and torque estimates. The old std was 85%. So for simple math a 10 hp engine on the old std could make 8.5 and still be sold as a 10hp. Now that same engine has to make at least 9.5 hp. Has more to do with machining tolerances and the improvements made to the tools from when the std was originally established.
 
Seandonato73 said:
Polar there is standards here In the states for power ratings. Anything sold here has to abide by them. The old std was a j1940. New spec I believe is a j1995. Engines must be within 95% of their rated hp and torque estimates. The old std was 85%. So for simple math a 10 hp engine on the old std could make 8.5 and still be sold as a 10hp. Now that same engine has to make at least 9.5 hp. Has more to do with machining tolerances and the improvements made to the tools from when the std was originally established.
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Learn something new everyday, never knew that!
 
There are 2 specs they can go off of for small engines. A couple years back there was a class action lawsuit brought against many of the small engine manufacturers. Thus the SAE set the new j standard. The engine have to at least meet that spec. Kawasaki ,for example, holds itself to a higher automotive J standard. So it should be closer to advertised hp. You should be able to go back to any engine mfg. And ask for the test procedures used to verify engine performance. Its nothing new and not voluntary. They have to meet a minimum to be sold in the us.
 
Just because there is a standard doesn't necessarily mean that all the manufacturers are using the same test equipment and testing criteria. This is where the variations can come into play. If Rovan in China are using a Hasashitzu 4000 dyno but in the USA Johnny High Rev's performance shop is using a Bimford SUX50 dyno there's probably a discrepancy between the two. Then there is the fact that many mfg's "fluff" the hp numbers so as to maintain a sales advantage. There's also a method to calculate "theoretical" hp simply by doing a vehicle acceleration run. It tales "X" amount of HP to move "X" amount of weight to a specific time. I'm not bashing HP advertisements, i'm just trying to comment that I see guys get so wrapped up in wanting nothing but the highest h.p rated engine , but in reality there's a lot more involved for success that simply reading a "H.P". I too remember the auto mfg's method of "fudging" the peak hp numbers resulting from the auto insurance industry's pressure. Hp numbers that were measured at the crank, were changed to read at the tires , and other hp numbers were derived at far less than "peak" operating rpm's. However the info on the "J####" series hp standards is good info, as I didn't know there was a standard.
 
Polar_Bus said:
Pay no attention to power rating "numbers" . They seldom are accurate, nor is there any "standard" for uniform testing. Torque is more important than HP for the typical recreational sport engine.
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If this is truth, then Zeb needs to get that 70 slug with a die cast aluminum Traxxas P.O.S Flywheel at least up to 5hp to to beat a $ 125.00 motor! there is no way that kid is going to put a starter cup on that Traxxas slop setup . just plain not going to happen......JOKE
 
baldtire said:
If this is truth, then Zeb needs to get that 70 slug with a die cast aluminum Traxxas P.O.S Flywheel at least up to 5hp to to beat a $ 125.00 motor! there is no way that kid is going to put a starter cup on that Traxxas slop setup . just plain not going to happen......JOKE
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Care to Explain?????? First, not using a starter cu, going pull start, second, that flywheel should be just fine, if not then explain. If it blows apart than so be it, custom flywheel will be made. Third, there is zero slop in my flywheel and ignition setup, wouldn't have proceeded to try and run it if it had because I'm not about to half ass my $2000 plus build. And lastly, I don't appreciate you calling my build a "joke" with zero explanation and you don't even have a single post introducing yourself and showing off your rig instead of coming at long time members for no reason.
 
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