Camshafts and Valve Inserts

[SADLOTUS]

Hi all
The dyno chart is mine and is for all to see but please note...
The original Lotus crank was cracked so a Mexico crank was used, and 83.5mm pistons made up, making dispacement 1685cc in the original block, also notice the octane booster.

I run the car on normal unleaded and occasional super unleaded and it goes really well, nice and tractable, sometimes a little hesitant when sitting around in traffic but once it clears its throat it flies.

Paul

[Barney]

Can someone explain ......

What does BMEP stand for And more importantly what does that signify

Cheers
Barney.

[rgh0]

Brake Mean Effective Pressure - It is a caculation of the average cylinder pressures and is back calculated from Torque

cheers
Rohan

[msd1107]

BMEP is Brake Mean Effective Pressure, the average pressure in the cylinder.

IMEP is the indicated pressure, as measured in the cylinder and before friction and other losses.

BMEP is 150.8 * torque / displacement.

This is a dimensionless way to compare the output of different dispacement engines.

A 200 psi BMEP is good for a TC. As a point of reference, a F1 engine gets around 220, and the best engines are above 240.

David
1968 36/7988

[Barney]

Thanks Rohan,
What a great service this is.
A reply in 5 minutes or so!!!!!
It took me that long to type the question.


Barney

[CBUEB1771]

This is a dimensionless way to compare the output of different dispacement engines.

Sorry to be an anorak, but how is lbf/in2 dimensionless? I agree that parameters such as BMEP and brake specific fuel consumption are good ways of comparing engines independently of displacement and absolute torque or horsepower values. But these are not dimensionless. Dimensionless groupings are just that, e.g. Reynolds, Nusselt, Prandtl and others used in assessing fluid dynamic and heat transfer regimes. With these parameters the units of the variables really do cancel and we are looking at things like ratios of inertial to viscous forces (Reynolds number).

[msd1107]

Russ,

You are correct, of course. My fingers felt funny typing dimensionless, better wordcrafting of the sentence would have been best.

If the figures had been presented in Bar, there would have been no problems, but my brain is still calibrated in psi bmep. So I recognize 200 psi bmep as a significant figure, but 13.79 bar doesn't strike a chord.

The professional journals all use bar.

All my spreadsheets accept and display both English and SI units, so it doesn't matter how any person's brain is wired or trained.

David
1968 36/7988