<VV> LM turbos and no lower shrouds

Tue Oct 25 14:34:31 EDT 2011

 Well, I do have a Nissan 300ZX Twin Turbo, which also pisses off Corvettes... <G>

John Roberts

-----Original Message-----
From: Ron <ronh at owt.com>
To: flash <flash at vicsmba.com>; carlton55 <carlton55 at comcast.net>; jvhroberts <jvhroberts at aol.com>
Cc: virtualvairs <virtualvairs at corvair.org>
Sent: Tue, Oct 25, 2011 1:52 pm
Subject: Re: <VV> LM turbos and no lower shrouds

If your definition of fun is just stomping on it, have your joy with a 
Corvette!
RonH

----- 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 lot.
>
> 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
>
>
> Carlton,
>
> 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
> dry.
> 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
> engine:
> http://www.sailnet.com/forums/atomic-4/53480-will-running-cold-cause-engine-damage.html
>
> 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?
>
> Eric
>
>
>
> 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.
>>
>>Eric
>>
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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
>
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>
> (You can see why we love this state :-) )
>
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