Ok guys. I've sat down and done my arithmetic properly regards these rather
fast alpine/tigers. The original figures I used were from graphs I had made
for my 4 cylinder rootesmobiles from the formulae, but the range was not
high enough (250hp out of a 1725 engine... I don't think so).
Anyway, an Alpine, with a CD of 0.45, a frontal area of 18 sq ft, and
weighing 2400lb would need theoretically 211 hp at the wheels to do 150mph.
211 at the wheels would prob be about 280 flywheel hp (about 75% makes it to
the ground).
I'm not sure how the much weight affects it, up at these speeds, most of the
hp is sucked up in aerodynamic drag, though rolling resistance which is
weight related is still significant. I can't be bothered doing the full
calculations for that but I'd guess another 10 horsepower would be adequate
to haul an extra 350lb of driver and whatever extra weight these engines
are.
So anyway, Eric, with 325hp you should definitely be heading for the 155mph
mark. Scaaarrrryyyy stuff.
Checking my other calculations: a vehicle with driver weighing 1100kg (2425
lb) with 250 hp at the wheels should theoretically do the 1/4 mile in 12.4
seconds. Jims 290 hp tiger is prob about 220 at the wheels, and a bit
heavier at maybe 1250 kg all up (2755lb). This gives a theoretical 1/4 mile
time of 13.5 seconds (compared with his actual of 14.7) The formula for this
though does not include specific aerodynamic factors for diff vehicles, as
at more "normal" 1/4 mile times wind resistance isn't having that
significant an effect.
If anyone is interested in these formulae I'll post them.
I am quite scared at the thought of my new project reaching 115mph.. you
guys are very brave. It's much safer just playing with my calculator.
Greg
----- Original Message -----
From: Greg Locke <glocke(at)ihug.co.nz>
To: Alpine list <alpines(at)autox.team.net>
Sent: Wednesday, 12 April 2000 13:05
Subject: Re: My 55 engine
> Regards Erics 150mph alpine: From my data and graphs here in NZs rootes
development department I
> calculate that an alpine with 18 square feet of frontal area and a cd of
> 0.45 will need approx 250 hp at the wheels to do 150mph. Yeeehaaa!
>
> It will then also do around a 12 second quarter mile.
>
> Greg
>
----- Original Message -----
From: <SSCCRacer(at)aol.com>
To: <glocke(at)ihug.co.nz>
Sent: Tuesday, 11 April 2000 20:47
Subject: Re: My 55 engine
> Greg
> Thanks for the data, the engine I'm useing makes 325hp stock from GM.
(LS1)
> And your right......YEEEEHAAAAA!!!
>
>
> Eric
and
----- Original Message -----
From: <TIGEROOTES(at)aol.com>
To: <glocke(at)ihug.co.nz>
Sent: Tuesday, 11 April 2000 21:14
Subject: Re: My 55 engine
> Greg,
> Interesting numbers considering the weight is similar to a Tiger. My
car
> with the old engine developed around 290 bhp, just a little hotter than a
> factory hypo-289, and with 2.88 gears I ran a 14.71 (at) 101mph.
> Jim
>
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