In a message dated 9/26/02 7:24:12 AM Pacific Daylight Time,
owner-mgs-digest@autox.team.net writes:
> One of our cars was an Elva
> Courrier,class E Production. This fine little car had
> the 1622cc MG-A engine installed. ... We had large valves, 10.5 to 1
> compression,
> and a race type Crane cam installed. Carbs were SU HS
> 4's. .....We never had it on a
> proper dyno, but at Virginia International Raceway, it
> would do a clocked 122 MPH down the back straight. I
> am guessing we had over 100HP at the rear wheels. We
> never spun the engine over 7000 rpm.
No point guessing about rear wheel power - it's the performance that tells
the tale,and with the low weight of the Elva, yours was certainly going to be
pretty good.
I have also run 12.5:1 1622s and they do indeed make a snappy engine,
although not as much so as my Twincam (clocked top speed 131 mph at a local
venue).
>
> So, to those out there who have tuned both the B
> and the A MG engines...Is the 1622cc engine easier to
> tune to say 120 HP at the flywheel than the 1800 cc
> engine? Just wondering.
>
No, it really just follows the displacement. If you do exactly the same thing
to an 1800 as you did to a 1622, you can expect more torque, and around 10%
more power, although you usually get slightly less than the arithmetic
increase. In other words, if you increase displacement by 15%, don't be
surprised inf the output only increases, say, 12%.
The big advantage of using the MGB engine is that the main bearing diameter
was increased, resulting in a stiffer crankshaft that allows the bearings to
last a bit better (without a 'flexible' crank whipping the shzt out of the
centre main bearing, for instance), and that will run more happily, or at
least for longer, at high rpm.
I am probably in the minority on this one, but I have a lingering fondness
for the 1963-65 3 main bearing MGB engine (heck - I'll bet many on the group
have never even seen one of these!), which IMHO actually produces a tad more
power than the identical 5 main bearing version, despite what they quoted in
the factory ratings (you didn't think they'd quote a LOWER output for their
brand new 5 main, did you?), and is certainly a snappier, more free-running
engine. I use one of these in my Mk 2 Coupe on the street.
Bill
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