<VV> LM turbos and no lower shrouds

jvhroberts at aol.com jvhroberts at aol.com
Tue Oct 25 19:54:51 EDT 2011

 Eric, YOU don't buy a Corvair for speed. I do, and a lot of us most certainly do!!


John Roberts


-----Original Message-----
From: Eric S. Eberhard <flash at vicsmba.com>
To: Ron <ronh at owt.com>; carlton55 <carlton55 at comcast.net>; jvhroberts <jvhroberts at aol.com>
Cc: virtualvairs <virtualvairs at corvair.org>
Sent: Tue, Oct 25, 2011 3:57 pm
Subject: Re: <VV> LM turbos and no lower shrouds

My point!  You don't buy a Corvair for speed, not any more, they are for fun. E

At 10:52 AM 10/25/2011, Ron wrote:
>If your definition of fun is just stomping on it, have your joy with 
>a Corvette!
>----- Original Message ----- From: <jvhroberts at aol.com>
>To: <flash at vicsmba.com>; <carlton55 at comcast.net>
>Cc: <virtualvairs at corvair.org>
>Sent: Tuesday, October 25, 2011 3:30 AM
>Subject: Re: <VV> LM turbos and no lower shrouds
>>Also not to get into a war...
>>Marine engines are overcooled all the time, but look at their 
>>cooling source! As such, not particularly applicable to an air 
>>cooled engine!!  :)
>>Corvair engines aren't water pumpers, no matter how much SOME 
>>people want to spray water all over and into them!! <G>
>>In my experience, overcooling a Corvair engine is just about 
>>impossible. And yes, mine had all the seals in place around the engine, etc.
>>Design parameters assumes things were designed for the intended 
>>application. Given that the 80 through 180 HP Corvairs have 
>>essentially the same cooling system, I have little doubt the 
>>cooling system was designed based on cost. GM simply figured if 
>>they didn't overheat to destruction while cruising, that's fine. 
>>They didn't really care beyond that, where obviously I do! ALL 
>>Corvairs, if driven hard (and if you have a 140, a turbo, or just 
>>like having fun, why wouldn't you?) will run hotter than ideal, often by a 
>>So, yeah, there's room for improvement. A LOT of room for improvement.
>>John Roberts
>>-----Original Message-----
>>From: Eric S. Eberhard <flash at vicsmba.com>
>>To: Carlton Smith <carlton55 at comcast.net>
>>Cc: virtualvairs <virtualvairs at corvair.org>
>>Sent: Mon, Oct 24, 2011 9:01 pm
>>Subject: Re: <VV> LM turbos and no lower shrouds
>>You are most welcome.  See my response to Mr. Roberts who disagrees
>>and is knowledgeable and well respected.  In this case I think he is
>>wrong, and more than wrong.  What many people consider "stock
>>cooling" is not stock cooling.  You can't have a lot of extra holes
>>in your firewall.  You must have proper seals all around the
>>engine.  The bellows must function properly including proper
>>adjustment and making sure they are good.   And my caveat is "close
>>to stock car" -- meaning a 300hp 3 liter dual triple Weber monster is
>>a different can of worms.  A built turbo with Weber and and big
>>pistons and big turbo, another can of worms.  When you do a lot of
>>mods, you start changing everything ... and unless you know how to
>>engineer that ... for example if you put a Weber on and do nothing
>>else my guess is you will knock.  So you slowly start going down the
>>road of one mod leads to another.  And in the end, perhaps, the stock
>>cooling fails.  My cars are all stock Corvair with the exception of
>>ignition system (I hate points and setting the dwell, just lazy) and
>>my coupe also uses the 260 cam (bet money that has no affect on
>>heat).  Oh yeah -- making sure those vanes are clear and the jugs are
>>not packed with grease ... that is important.
>>The car was designed to run at those temps, that is correct, and I
>>would not assume that "cooler is better" and maybe that is why you
>>get a different answer from me than Mr. Roberts.  I am not say it is
>>not cooler without the shrouds.  What I am saying is that a stock
>>engine will run within design parameters under any driving condition
>>(speed or outside temp) with a stock cooling system -- no matter how
>>spirited you are.
>>If you run cooler and warm-ups take longer, you likely are cause WAY
>>MORE WEAR than driving it at temp.  Have you ever wondered why people
>>ask when looking at a used car "city miles or highway miles" or why
>>almost all diesels are left on when drivers go into store, truck
>>stops, eat dinner, whatever?  Answer -- starting a car is like
>>driving 100 miles.  Starting a COLD car is like driving 1000
>>miles.  That is because oil drains off the engine parts and when you
>>first start it is a little
>>And it is so much worse if cold and allowed to run cold, the oil is
>>NOT circulating well.  Which, BTW, is why you need sure to make sure
>>you use an oil that has enough ZDDP (zinc etc).  Like Mobil 1 15-50
>>(note each mfg most oils do not have enough zinc, but usually they
>>have something with enough zinc -- not all Mobil 1 has enough).  You
>>can use Clarks zinc additive although I don't trust that as much as
>>an oil made right to start with.  In fact, for long term wear on your
>>engine your oil choice is crucial.  I hope you did not break in that
>>new engine with dinosaur oil that did not have the zinc ... hard on the cam!
>>What I am saying is when not driving in a spirited way, just toodling
>>along, you may be running so cold that the oil is NOT doing it's job,
>>the oil is thicker, and you may be harming your engine more.  It was
>>designed around the stock cooling system and you cannot be hurt going
>>that way.  However, when you go down modification road ... unless you
>>are very knowledgeable, one problem can lead to another or you could
>>have unintended consequences (particularly in this case from running
>>too cold).  You can actually contribute to building up sludge in your
>>engine.  That happens when temps are not high enough and I would
>>suspect that when you take the shrouds off you could easily be
>>running oil temp that are WAY too low.  You need something like
>>200-220 oil temps.  Oddly I have one car that has cylinder head and
>>oil temp gauges (my toy) ... when oil temps hit 270-280 cylinder head
>>temps are 425+ ... this is a good place as this is about max (any
>>more and the stock temp idiot light goes nuts).  Cylinder head temps
>>are way more volatile than oil temps (e.g. it takes forever to get
>>oil temps up or down, cylinder temps change almost instantly from
>>super hot to cool).  I would guess that if you are running 300-325 on
>>the freeway that your oil temps could easily be in the 200-220 range
>>-- meaning probably TOO COLD.   http://www.synlube.com/sludge.htm
>>(note they recommend synthetic as I do, with zinc!!!!!!).
>>So my recommend is still, run it stock assuming it runs within stock
>>parameters, use good oil, and a good ignition system.
>>I should point that I have heard of stock manifolds cracking from
>>getting real hot and then zooming through a puddle of cold water.  I
>>suspect it is a minor risk, but real.
>>So that I don't get in a war with Mr. Roberts whom I usually agree
>>with -- I agree it runs cooler without shrouds.  But it cools
>>CORRECTLY with the shrouds and maintains the engineered
>>tempuratures.  It is possible to run too cold as well as too
>>hot.  Otherwise there would not be thermostats in water cooled
>>cars.  Engines are designed to operate within a specific temperature
>>RANGE for optimum efficiency. A properly functioning cooling system
>>with the correct heat RANGE is absolutely essential for  good fuel
>>economy and performance as well as prevention of sludge buildup in
>>oil passages and the heads. A thermostat that causes the engine to
>>run too cold can experience up to a two mpg loss in fuel economy ...
>>Here is a posting on running too cool an
>>I believe it is still better in all ways stock, due to exposing the
>>engine, possible cracks, running colder than you should.  I think you
>>could compare it to removing the thermostat in a conventional
>>car.  It would be slow and hard to warm up, and run too cold at
>>times.  If you know exactly what you are doing and want to fiddle
>>with it, fine.  Otherwise, stock works.  It is a matter of do you
>>trust the original engineers to make a system that is best most of
>>the time, or do you want to try and do better and take the risk of 
>>doing worse?
>>At 04:02 AM 10/23/2011, you wrote:
>>>Hi Eric,
>>>Thanks for your opinion. I am seeking those with experience and you have
>>>shared yours.
>>>I have owned my particular 1965 turbo Corsa since 2007. The previous owner
>>>had rebuilt the engine in 2000. It was totally stock with the exception of a
>>>Clark's 260 cam. On the highway in the Midwest if I went over 65MPH for any
>>>length of time  on a 75-80 degree day the head temp would reach 425-450
>>>degrees (the gage is accurate as I have a infrared temp gun). The engine
>>>always had a couple of (loud) clacky valves that were lifter/cam oriented. I
>>>decided to have the engine rebuilt last winter by a professional Corvair
>>>mechanic. The engine was totally rebuilt stock, head veins cleared as much
>>>as possible, correct valve geometry restored, etc. We discovered the bad
>>>Clarks cam grind on 2 lobes is what was causing the 2 clacky valves and
>>>replaced it with an Isky cam of the same 260 spec. (I checked with others
>>>and found they also had problems (on occasion) with this particular Clarks
>>>cam). Anyway I now have normal quiet engine now. However, with the shrouds
>>>on I still would go to 425-450 degrees on long distance highway traveling.
>>>So I decided to try the shrouds off option and it usually travels at 300-325
>>>degrees and on a hot day might go to 350. I am told by may turbo owners and
>>>the folks at Clarks that the shrouds on temperatures are absolutely normal
>>>for a turbo. Also that those temperatures will eventually shorten the life
>>>of the engine as compared to a standard engine. I drive the car every day in
>>>the summer and garage it in the winter. I drive it as long as I can every
>>>year so that does involve fall and spring days in the upper 30s and 40s. I
>>>can still get heat in the cab from the upper shroud hose so that is ok with
>>>me. However, I don't like having the bottom of the engine exposed all of the
>>>time to possible road debris (rocks, etc.). I am a little worried about the
>>>start up/warm up factor although it seems it warms up fairly quickly. So you
>>>can see I am already at the point of making a possible mod decision. I am
>>>interested to know what John Roberts is suggesting.
>>>  Thanks for your input Eric!
>>>  Regards,
>>>  Carlton Smith
>>>-----Original Message-----
>>>From: virtualvairs-bounces at corvair.org
>>>[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Eric S. Eberhard
>>>Sent: Sunday, October 23, 2011 2:29 AM
>>>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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>>>This list sponsored by the Corvair Society of America,
>>>Post messages to: VirtualVairs at corvair.org
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>>>  _______________________________________________
>>Eric S. Eberhard
>>(928) 567-3727          Voice
>>(928) 567-6122          Fax
>>(928) 301-7537                           Cell
>>Vertical Integrated Computer Systems, LLC
>>Metropolis Support, LLC
>>For Metropolis support and VICS MBA Support!!!!    http://www.vicsmba.com
>>For pictures:  http://www.vicsmba.com/ourpics/index.html
>>(You can see why we love this state :-) )
>>This message was sent by the VirtualVairs mailing list, all 
>>copyrights are the
>>of the writer, please attribute properly. For help, 
>>mailto:vv-help at corvair.org
>>This list sponsored by the Corvair Society of America, 
>>Post messages to: VirtualVairs at corvair.org
>>Change your options: http://www.vv.corvair.org/mailman/options/virtualvairs
>>This message was sent by the VirtualVairs mailing list, all 
>>copyrights are the property
>>of the writer, please attribute properly. For help, 
>>mailto:vv-help at corvair.org
>>This list sponsored by the Corvair Society of America, 
>>Post messages to: VirtualVairs at corvair.org
>>Change your options: http://www.vv.corvair.org/mailman/options/virtualvairs

Eric S. Eberhard
(928) 567-3727          Voice
(928) 567-6122          Fax
(928) 301-7537                           Cell

Vertical Integrated Computer Systems, LLC
Metropolis Support, LLC

For Metropolis support and VICS MBA Support!!!!    http://www.vicsmba.com

For pictures:  http://www.vicsmba.com/ourpics/index.html

(You can see why we love this state :-) )  


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