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Re: OD

To: "WSpohn4" <WSpohn4@aol.com>, "MG List" <mgs@Autox.Team.Net>
Subject: Re: OD
From: Larry Macy <macy@bblmail.psycha.upenn.edu>
Date: Sat, 16 May 1998 10:01:51 -0400
On 5/10/98 1:37 PM so and so  WSpohn4 said. (And I quote)

><<An overdrive is great if you want a more civilized MGB.  I don't.  I want
>something that screams and whines on the highway.  I'm sick of cars that are
>less noisy, cars that are nothing but isolated little boxes on the road.  >>
>
>Well, this sort of statement surprises me unless you are pretty young, or
>perhaps own a post-74 B which is more sound than fury in any case. May I
>assume that you drive around town in first gear?
>If you want to tear down the highway with your engine screaming, ( a rather
>puerile activity in my book), chacun a son gout, but don't try to argue the
>point that high rpm usage won't wear an engine out sooner than middle rpm
>running.
>
> The actual time that an engine will last is a curve, with accelerated wear
>the higher you run it. Ask any engineer (which I am not) or any engine 
>builder
>that builds racing engines (which I am). 
>
>A propos of engine wear, some of you might be interested to know that in
>development of the Jensen Interceptor, the factory ran an engine on a 
>brake at
>5000 rpm to see how long it would last. It went 30 hours before a bearing 
>went
>and blew the engine in a big way. That was close to the stock redline for the
>big block Chrysler. If it had been run at 3000, it would have lasted many 
>many
>times as long.
>
>Another example - the TR engine, a long stroke 4 cylinder, will last
>indefinitely at up to 6000 rpm, a half hour or so at 6500 if properly
>prepared, and minutes at 7000 rpm. Mind you, if you are in the final lap of a
>race, it is sometimes worth it to run it up there if doing so means that you
>win. But then you have to tear it down completely after the race.
>
>An OD unit lets you maintain cruising speed at an rpm closer to the torque
>peak of the engine, at lower fuel consumption than would be experienced at
>higher rpm.
>Anyone that is too fumble thumbed to flick a switch when they want to pass
>shouldn't be trusted in a car of any type, IMHO.
>
>Bill S.
Well, I tend to disagree with this attitude. I owned a '72 Vega - bad rep 
- not deserved. The engine ran great as long as there was oil running. I 
blew out the pan and had to deal with that. The only time it failed, as 
an engine, was when somebody else drove it as a small block Chevy, which 
it wasn't. I ran the car at high RPMs, and it failed,when somebody else 
drove it like a V-8. The PAID chevy mechs said it was the best condition 
Vega engine they had ever seen. The main difference is an aluminium block 
vs. an iron block. Aluminium block engines, unless lined, need to have a 
higher RPM and consequently increased oil flow, than an iron block 
engine. May sound dumb but I'd love to have a 2300 Vega engine in the 
Midget (can't - too tall). 

The point is - ta da it just depends on the engine, and its design.

OF course none of this addresses the fuel flow and consumption issue. But 
as I recall, I got about 25 mpg, nearly the same as some claim for the 
B's.
I loved that Vega
Let the flames fly!!!

Larry Macy
78 Midget
(96 Neon)
Wish I had the Vega Woody Wagon

Larry B. Macy, Ph.D.
macy@bblmail.psycha.upenn.edu
System Manager/Administrator
Neuropsychiatry Section
Department of Psychiatry
University of Pennsylvania
3400 Spruce St. - 10 Gates
Philadelphia, PA 19104


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