<VV> LM turbos and no lower shrouds

Eric S. Eberhard flash at vicsmba.com
Mon Oct 24 18:43:03 EDT 2011

I agreed all the way through the sentence ending with "design 
limits"  :-)  I believe that more consistent temps with the correct 
range are a desired end result and that just making it run colder and 
inconsistently and harder to warm up ... not so good.  E

At 08:48 AM 10/23/2011, Mark Durham wrote:
>Eric and all; it is true that the stock systems were designed to
>provide reasonable temp, but there are two sets of baffles/shrouds that
>are worthy of note here, and they both have different functions.
>First, the shrouds that box in the front and back portions of the
>engine, the design of the heads, the turkey roaster and the inner
>cylinder baffles direct the airflow to keep the engine cool. The bottom
>shrouds inhibit that flow when temps are below a certain value so the
>engine temps stay in a determined range so heat is available and so
>engine temps are more consistent. This extends engine life because it
>keeps temp in design limits.
>Turbos do raise the temps and turbo engines, in airplanes and cars, air
>cooled ones, have a shorter life span, or in my mechanic lingo, shorter
>TBO, time between overhauls.
>I found my em 62 with a 270 cam and stroked to a 64 110 runs smoother
>and cooler and hot starts better when I have the lower shrouds off in
>the 90 plus temps we get in the summer when I Don't need heat. Mark
>Sent from my Windows Phone From: Eric S. Eberhard
>Sent: Saturday, October 22, 2011 11:30 PM
>To: virtualvairs at corvair.org
>Subject: <VV> LM turbos and no lower shrouds
>I am always puzzled by this discussion which comes up every so
>often.  The car was designed well from the factory.  If you have
>everything correct -- all the shrouds as well as seals and so forth,
>there is no better system.  I am in AZ, totally bone-stock, at
>altitude (3500-8000 feet), summer temps of 110 ... and I NEVER have
>even gotten remotely close to overheating.  Our speed limit is 75 and
>I can go up a 6% grade at 80, no over heating.  From my 3500 to 7500
>feet happens in 6 miles, no overheat even at 80.
>I believe that those that overheat and think they need to
>remove/modify shrouds simply have other problem they are compensating
>for.  Mine is a 62 EM and perhaps it is different, but I have had to
>EM turbos as well and neither ever had a heating problem.
>And we get 20 degrees in the winter, so having those shrouds on then
>is crucial and I don't need the hassle of swapping them on and off.
>One writer pointed out the correct heat is required for quick
>boost.  Correct.  Some people even wrap their exhaust to push temp
>even higher, for that reason.  Some people mistakenly use a "free
>flowing" muffler which actually reduces boost and is bad.  I used an
>NOS turbo muffler.
>Keep it stock and it will be absolutely reliable (my only mods are
>electronic ignition and related upgrades).
>If you have heating problems -- are your plugs too hot?  I use Nology
>Silverstone plugs and they perform very well with a 38 gap and hot
>ignition, no overheating.  They are made for vintage cars.  They are
>expensive, but I have over 30k on them and they are clean as a whistle.
>BTW -- opinions are like belly buttons and so I have one.  I respect
>others, as other people have done neat things.  I am not a good
>enough amateur mechanic to re-engineer things.  But I believe a
>properly set up stock system -- not all that hard to achieve -- is
>going to be reliable.  Doing the ignition and putting a Judson on one
>of my cars is sort of the limit of my explorations.  However, my
>Spyder always has instant boost (no lag), boosts at 2000 rpm in 4th,
>pulls to redline, and I can't overheat it.
>So if you are in the mood, you might try making it factory spec
>first, seeing how that goes, and then modify.  Otherwise, you might
>mask a problem that later gets ugly.
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Eric S. Eberhard
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