At 08:44 AM 6/13/97 -0400, ebrown@ms.com wrote:
> Okay, here goes one more time. I remember when I was a kid all of the
> hot rodders used to polish and open up the intake manifold and
> cylinder head volumes, apparently to add torque and horsepower, on
> these crude American V-8 engines they were all tweaking. Don't know if
> it did any good at all, but I read an advertisement in the latest
> Miscellany which offered a TR engine which had what sounded like the
> same sort of treatment.
>
> Is this "polishing and relieving" (or whatever the expression is)
> something that Morgan owners have done to their cast intake manifolds?
> I know about tuned exhaust headers (I guess) but don't know what the
> hot set up on the other side is.
>
> I suspect, when I run with the VSCCA and those other guys in Plus 4's
> are flying away from me on the straights, that maybe they've been
> doing some of this. Just a suspicion, mind you!!
>
I'm not sure what to tell you to do but I can certainly tell you what NOT
to do (which I share from intimate experience).
After looking at the intake manifolds on my '61 Plus 4 and '68 Plus 4, I
noticed the '62 is shorter and much larger in diameter. Hmmm, shorter
means I can fit the HS-6s AND aircleaners under the bonnet and larger
diameter means more breathing right?...
As it was explained to me later by much wiser Morgan owners, the later TR
manifold (smaller diameter and longer) develops a greater velocity through
the valve and the momentum effect actually aids the intake ability.
Although it is contrary to intuition, my own experience of VERY sluggish
behavior and no real torque confirmed this. Within a couple of days I went
back to the original arrangement and things are quite satisfactory. I
wasn't intent on really high performance but I thought I could benefit from
some direct exchange. Not so, so tread carefully...
Happy motoring...
"Entropy Happens!"
Michael D. Miles, PE Consulting Design Engineer
(503) 292-1234, FAX: (503) 292-1105, email: mdmiles@teleport.com
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