Moto Laverda recall

[piranha-bro2]

So I thought peak toque occurred at 4500 rpm and that's around where I usually ride at or was till I melted the inlet ring land off 2 pistons. Seems That's considered lugging it and I should be running my race engine, it has been upped to Corsa spec, mostly at 6k and up to avoid damaging it. What did surprise me was the compression reading from a test, it was producing 195psi.

Couldn't think of anything worse! 6k?! If 4500rpm is lugging it, then something ain't right - it's not a ZZR250 Vince!! Just about every modern car on the road is heavily geared to keep revs as low as poss at cruising highway/freeway speeds. I just never labour any engine. Simple. If I can put the car (turbo diesel) in 5th at 60kph with little load (flat or downhill) I'm more than happy to do it.

Hi comp moto engines tell you when they are under loads they don't like - if you have the right 'feel' or 'engineering sensitivity' ... it's what also makes some racers much more reliable finishers.

Glad I'm not the only one confused by the BMEP ...

 

[phil37]

Trying to understand your post, I guess you mean your engine was normally operated in a rev range that didn't coincide with maximum BMEP. Max BMEP (like torque) usually occurs at lower revs than max power. That makes a little more sense because it would be reasonable to assume that maximum bearing load occurs at maximum torque, not maximum power.

Running a motor at Max BMEP - theoretical or not - will demand that the systems supplying it will need to be running absolutely correctly as the motor will be at its most efficient - a not so good spark plug or a fuelling problem will be (IMHO) more liable to cause failure at these RPM.

  This is my "take" as I said - having seen the same thing happen to so many Laverdas over the years. I'm not one for over analysing theories or getting into deep non practical discussions as i'm not a highly technical minded person, I prefer to do practical work and trying out new ideas, having worked with Laverdas for so long and dived in deeper and earlier than most, have formed many observations of my own, they will not, of course, be all correct, but over the years, having never ever had a mechanical failure on my own racing Laverdas, perhaps i got something OK. - Regards - Phil

 

[piranha-bro2]

I have a feeling noone is going to argue any of those points with you, Phil! Respect, as ever. And I definitely believe in the power of 'gut feeling'.

 

[phil37]

I have a feeling noone is going to argue any of those points with you, Phil! Respect, as ever. And I definitely believe in the power of 'gut feeling'.

Don't mind a good discussion or argument Quentin - but my knowledge on technical stuff is limited - like yourself I've still got a few "gut feeling" schemes in mind that may or may not work as well as i hope. Keeps us all busy in this "lockdown" period as well. - Regards - Phil

 

[psg]

For all the Engineering nerds
https://www.roadandtrack.com/car-culture/a32157287/bmep-engine-performance-measurment-explained/

 

[Simonr501]

For all the Engineering nerds
https://www.roadandtrack.com/car-culture/a32157287/bmep-engine-performance-measurment-explained/

Crikey! That guy is pretty darn good at maths and very clever.
However, he spent an awful lot of time to calculate his way to telling us that BMEP is 'Torque per Litre'.

1). So maximum torque coincides with best thermal efficiency of the engine 'best bang for your buck', hotter too!
2,). Higher compression ratios help BMEP and also thermal efficiency.
3). Tuning is VERY important as is design of the engine internals.

However! He didn't mention mechanical efficiency, probably because it's reasonably stable.
Also he was quite unfair with the Rolls Royce! As if people that run these are remotely interested in how efficiently they got to the hotel and perhaps more interested in avoiding spillage of champagne on the way?