alex.stanley

... when bombing around in VTEC, but does anyone know what the power output of the engine is in non-vtec conditions?

Alex.

Tifosi Red

something around 160/170 bhp at 5500 rpm I think

joecro

Tif is not far off, i looked at an old brochure and it comes in at about 150bhp pre VTECH. But BHP is irrelevant at that speed, it is torque that you wanna be measuring. Torque is what punches you in the back under acceleration.

I read a great article about torque and BHP which in short said that:

1. Torque is measurable from the engine
2. BHP is a calculation [read intelligent guess] based upon the torque and the gearing

It went on to explain that the higher you rev the higher your bhp is likely to be but that doesnt mean that you will continue to increase your rate of acceleration once you have passed the torque peak.

Indeed the benefit of continuing to increase your revs over and above the torque peak is purely so that when you change gear you will come back in at the sweet point in the torque curve. So revving the S2000 to almost 9000 is not going to help you with continued acceleration [at that specific point] but it is going to mean that with a half decent gear change you will be back in the 6000+rpm range which is just approaching max torque at 7200rpm which will aid rapid progress

HTHAIHIR

jc

ianl

Something else to consider - and I never had done until I read about it a week or 2 ago - is the efficiency of the drive train - 240bhp...150bhp...whatever are figures measured at the 'crank' (I think!!!) - what really matters is how much pover is delivered to the rear wheels - apparently there is aprox. a 10% loss of power thro' the S2000 drivetrain - more efficient (ie less power loss) than just about any other car on the road

joecro

Any idea what the power loss with the boxster is?

ianl

Ooooooo...about 65% I expect

joecro

[QUOTE]Originally posted by ianl
[B]

Ooooooo...about 65% I expect

dinsdale

I guess that the efficiency of a tranmission is mostly related to how big and heavy the gears and bearings etc. are, as this is where you're going to lose through friction.

I also think it's the case that how strong a transmission needs to be is mostly related to torque, and not to BHP.

Therefore, if both the above are roughly correct, the gearbox in the S2000 should be able to be more efficient than usual as it can have smaller, lighter components inside for the same amount of power.

Feel free to correct me.


Pete

Turtle

It's somewhat more than that.

If you take the average at the wheels peak power from dynos to be around 200bhp, and assume the engines are all making around the 237bhp claimed, then it's closer to 15%.

That's a little high - 2 contact patches for the tires, on the dyno rollers, rather than one for on the road.

Not quite 10%, but still damn impressive for a RWD car!

-Brian.

ianl

Thanks Brian (I hoped you would be along to add a little technical credibility!)

Do you happen to know typical drivetrain power losses for any other comparable RWD cars - Boxster for eg??????