MG & Rover - XPower Forums banner
1 - 3 of 3 Posts

·
Registered
Joined
·
388 Posts
As a first estimate of the improvement in your 0-60 time, we can assume that getting the power down will not be a problem (probably true in the dry) and that, to accelerate from 0-60, it is only necessary for the engine to produce a certain amount of energy (not true but probably a reasonable first-order approximation.) 30bhp extra over the standard 175 gives an increase of ~17%. If we take the 0-60 time of the stock car as 7 seconds - which most people reckon to be reasonable for the ZS once the engine has loosened up a bit - then that would suggest that an extra 30bhp may cut that to about 6 seconds (7/1.17) - which stacks up nicely with 180boy's observations.

HTH,

S.
 

·
Registered
Joined
·
388 Posts
TonyPal said:
7/1.17 =5.98 but this wouldn't take any drive train losses into account.
If you assume that drive-train losses are a constant percentage, then my maths still holds. However, as I pointed out, the assumption that one just needs to produce a certain number of Joules of energy (at the wheels) to accelerate the car to 60mph is just that; an assumption. Also, the other big assumption that I forgot to mention is that I assumed the 17% power increase to be true at all engine speeds used in the 0-60 run, not just at peak power (usually at a different engine speed). So, as I said, it is a first estimate only; I'm not saying that you will get a 6 second run with an extra 30bhp, merely that it may be around that figure if the assumptions made are reasonable.

S.
 

·
Registered
Joined
·
388 Posts
LordNikon said:
Jerrys Evo has had a 30bhp (now being a 330 rather than 300) I bet he hasn't knocked 1 second off. He'll be looking at realistically .3 - .4 of a second.
But you're assuming that the effect of extra power is linear, when it is not. 330bhp compared to 300 is 10% extra, not 17%. Also, the 0-60 of the 300bhp is less, say 5sec rather than say 7. So 5 * 10 / 11 = 4.55sec - a 0.45 second improvement. And, as I said above, this is subject to lots of assumptions with the most critical, and probably inaccurate, being that the percentage power increase is constant across all engine speeds used in the 0-60 run.

S.
 
1 - 3 of 3 Posts
Top