Scooterotica

muggy 225 with 60mm crank and standard rod, 30mm oko carb and sterling pipe sx200 gears with 15/47 http://i1045.photobucket.com/albums/b45 ... torque.jpg
http://i1045.photobucket.com/albums/b45 ... o/paul.jpg

just under 16bhp @ 7000rpm and similar torque. not great i would say for a 375quid kit plus crank??
gonna have some mods done to barrel and then hopefully get another dyno run and see the improvements...

How does it run though?

On the other hand to get approx 60% increase in power over a standard engine sounds good for £500ish.

Hi Wayne

Think there is a problem with your dyno results on the RPM signal i'll try to explain.

The dyno only measure the torque produced at the rear wheel and then calculates the BHP based on the RPM signal and the rotational axis of the drum ( which is a fixed number of 5252 calculated using rotational diameter of force or Pi x 2ft diameter of 6.2832)

1 HP = 550 ftlbs / sec
= 33,000 ftlb / min
therefore 33,000 ft/lb / 6.2832
= this magic number of 5252

So the Torque x RPM / 5252 = the calulated horsepower

So in your case the measured value of 16.37 ftlbs of torque x 6800 RPM / 5252

Should then = 21.19 BHP

as the torque is almost always correct and the 5252 value is fixed then i'd assume the RPM value could be wrong.

Also would be nice to see the air fuel ratio graph

Hope this helps

Pete

Sonny is dead right, there is something big time fishy with those graphs.

Firstly if you could clarify the units as the torque graph is showing NM not Foot pounds.

Either way, one of the key elements to look for is the cross over between the two graphs which takes place at the magical...5252rpm (or there abouts, I put it about 5244 but it is sermantics). Below this rpm torque is higher than BHP and above that rpm BHP is always higher (assuming you are using the same scale of foot pounds to BHP, some graphs will use different scales one on the LH side and the other on the RH side).

Additionally, because of the basic maths that calculate BHP from torque the following features should be evident on the graph. A constant torque reading (flat line) between 5-8K rpm will result in an increase in BHP at a set rate. You graph shows the torque curve following the BHP and this is totally wrong unless I have catastrophically miss-read the graph some where.

Some real basic checks are required as fundamentally it is way off.

I just noticed the scales are different between the two graphs but even account for that it is still not right.

Just noticed as well the torque scale being in NM and not ftlb

1 ftlb = 1.3555 NM so your max torque was 12.08 ftlb


So 12.08 x 6800 / 5252 = 15.64 HP

So the dyno is correct I also had a look at some of the Mugello 225's weve had here on our dyno and they are 15.5, 15.72 to 16.8 so yours is normal but the torque and hp graph should cross at the magic 5252 value which is odd also AF values would laos be a clue to how your engines set up.

Pete

I've heard many conflicting stories on the Mugello 225. I think it's a well known fact that out of the box there no better than their smaller brother the 186. I had my 225 stage 5 tuned by Reaper when i bought it from Cam Lam and when i first had it dyno'd it got 18.5 bhp at Chiselspeed. I've since had to change exhaust from a Scorpion to a Devtour so should get it re-done but the performance is about the same as before.

Sonny wrote:Hi Wayne

Think there is a problem with your dyno results on the RPM signal i'll try to explain.

The dyno only measure the torque produced at the rear wheel and then calculates the BHP based on the RPM signal and the rotational axis of the drum ( which is a fixed number of 5252 calculated using rotational diameter of force or Pi x 2ft diameter of 6.2832)

1 HP = 550 ftlbs / sec
= 33,000 ftlb / min
therefore 33,000 ft/lb / 6.2832
= this magic number of 5252

So the Torque x RPM / 5252 = the calulated horsepower

So in your case the measured value of 16.37 ftlbs of torque x 6800 RPM / 5252

Should then = 21.19 BHP

as the torque is almost always correct and the 5252 value is fixed then i'd assume the RPM value could be wrong.

Also would be nice to see the air fuel ratio graph

Hope this helps

Pete

here is the fuel/air graph to go with the dyno- run http://i1045.photobucket.com/albums/b45 ... ulfuel.jpg

paulski wrote:here is the fuel/air graph to go with the dyno- run http://i1045.photobucket.com/albums/b45 ... ulfuel.jpg

You are running lean.