A.k.a.: Dave Butler Muffin Man
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posted on February 4th, 2014 at 06:38 AM
Quote:
Originally
posted by allanvw
Car and driver should be around the 650 to 660kg. Are you going to get the calulator out Dave ?.
Yes, with all the variances between dynos
and the size of the actual horses(Shetland ponies in some cases!),
some basic maths is an easy way
to compare things on a level playing field.
Even with a poor start,
the MPH in most applications, is within a couple.
(unless you have a car problem).
So once you know the weight,
and have a MPH,
a HP number can be extrapolated,
which is very close to the numbers I have seen from a Superflow engine dyno.
If you have a dyno number already,
you can then determine,
suitable gear ratios,
or how much you can improve,
or even, if you are at the limit of you engine combination.
The numbers this calculation gives are much lower than a lot of people tell, especially in Europe,
but on a world stage,
if you are over 100hp per litre with my formula,
you are doing pretty well.
Quote:
Originally
posted by westi
That's mad Alan.
modnrod
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posted on February 4th, 2014 at 10:45 AM
Dave, are you using a Moroso calculator followed up by a "fudge factor" (sorry, calculation constant! ) like I do to be able to compare to what you know from other rides, or are you using a different set of calcs
of your own or from somewhere?
Just curious really, but weight-shifted is what I use if I need to work something out.
dangerous
A.k.a.: Dave Butler Muffin Man
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posted on February 4th, 2014 at 11:14 AM
Divide MPH by 234.
cube that.
multiply by weight in lbs,
is HP at the FW.
Very close to the moroso slide rule.(but FW hp not wheel)
EG
750kg bug is 1650lbs.
If it runs 100mph at the 1/4 mile,
it has 128hp at the FW.
Another example,
the most powerful n/a VW
engine I know,
makes a tad over 345 at the FW using this formula.
Quote:
Originally
posted by westi
That's mad Alan.
allanvw
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posted on February 5th, 2014 at 05:00 PM
Thanks Dave, I see @ 650kg we have about 255hp at the crank and to get into the nines our speed will need to get to 134 to 135 mph, which means I
need to tune the engine to give 274.5hp. I am still chasing 100 degrees on the exhaust temps of 2 cylinders and I am pretty sure once I can get those
two up, that the engine will produce more power. Then there is always using some oxygenated fuel to get that last 10th of a sec. Got a bit of work to
do before then
) like I do to be able to compare to what you know from other rides, or are you using a different set of calcs
of your own or from somewhere?
