mgs
[Top] [All Lists]

Re: B on the Dyno

To: MG List <mgs@autox.team.net>
Subject: Re: B on the Dyno
From: Max Heim <mvheim@studiolimage.com>
Date: Wed, 28 Nov 2001 12:04:11 -0800
You are correct in your conclusions, but the explanation is the difference
between SAE "gross" and SAE "net" horsepower. The former was commonly used
into the early 70s, and basically measured the bare engine output on the
test stand. The latter measured the output with all normal accessories
attached -- alternator, fan, air pump, power steering pump, etc. Neither
measures output "at the wheels". The MG was rated "gross", the GTi was rated
"net". The GTi probably grossed more like 125hp, which gives you your
perceived difference.

BTW apparently a large part of the perceived power loss between the early Bs
and the late, "smog-bound" models is due to this change in standards. Of the
"lost" 30 or 35 hp, I suspect 10, 15 or even 20 are just an artifact of this
change. Of course, driveability and top-end performance were also affected.

DIN is a European (German) standard which gives slightly different results
than SAE net.

on 11/28/01 11:36 AM, Brinkman, Gerardo V at
GB127167@exchange.DAYTONOH.NCR.com wrote:

>> Ok, I put the poor old 'B on the dyno today and I am still analyzing the
>> results.  I was actually quite disappointed with what I saw but I am
>> sure I am not really reading them quite correctly just yet and maybe had
>> higher expectations than I should have.
> 
> I have always been dubious of the horsepower figures quoted by MG and others
> of that time period. I had '63 B with a fairly new stock engine rated by MG
> at 
> ~95Hp. I also owned at the time a VW GTI which was rated at 105Hp and
> probably
> less torque. Both were 1800cc and the GTi was somewhat heavier.
> 
> Yet the GTi felt (and was) and lot quicker that the MG, in 0-60 time and
> acceleration
> at different speeds in different gears. I assume that the way engine power
> was
> rated in the '60's and 70's is different to how it is measured today (SAE vs
> DIN),
> but even taking this into account, the MG, I suspect was lucky to achieve
> 65HP
> as it left the factory. The road tests of the period seem to indicate that
> horsepower
> figures seem to bear that out.
> 
> Most Brit cars of that period that I have driven seem to "feel" slower than
> their rated
> horse-power suggests (there are exceptions), I would assume that is due to
> the engine
> designs of the period (long-stoke and small bore).
> 
> gerry
> 


--

Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires

///
///  mgs@autox.team.net mailing list
///  or try http://www.team.net/cgi-bin/majorcool
///


<Prev in Thread] Current Thread [Next in Thread>