How tough are Corvair engines?

Builders,

Below, two photos of damage inside core engines from running cars (not aircraft). The top was a motor run without oil, and one with finger tight rod nuts, the bottom was run with the belt off the cooling fan.

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The damage shown in the pictures didn’t happen in a second, nor in a minute either, and the engines still ran, very poorly, but they were not locked up.

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Over the years I have seen perhaps a 1,000 core motors, and very few of them had this kind of issue, almost all of them were simply worn or tired, but still capable of running acceptably when the car was parked. The major problem that makes some core motors unusable is being stored outdoors and getting water inside. You can check this easily when looking at a core engine by making sure it rotates 360 degrees before buying it. Ones that have had water inside, will not turn.

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The examples below are from cars, but I have plenty aircraft examples also; An engine run for 11 minutes turning a prop at 2,200 rpm (about 45 hp) without any oil in it. It stopped but only did $700 in damage; The guy who’s ‘local expert’ set the timing for him, but thought the 0-8-16 timing marks were 0-3-6, so he set the timing for about 60 degrees advance, which blew out 3 head gaskets. the static rpm dropped from 2,700 to 2,000 rpm but the builder actually flew it 2 more times because he had a long paved runway at his airport; the 30,000 hr airline pilot who flew a cross country with a bad enough oil leak that the pressure went to zero, twice, and he felt comfortable adding a “quart or two” and proceeding. This doesn’t even touch on the several dozen people who damaged engines by never setting the timing, but thought they were getting away with it because their engine didn’t stop abruptly, it just tolerated the blown head gaskets and broken rings without quitting. The list is endless, but let it be said that the intelligent Corvair builder has a very robust engine to work with.

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Above, two rods from car engines; the bottom was run for more than 10 miles with no oil in it. Notice that the rod bolt and nut are still intact. The bearing melted, and took out the rod, but the motor did not stop, the driver just reported it “made a lot of noise” on the drive back home. The top one was from the shop of a “race car builder” who rebuilt the engine and it lasted long enough to leave his shop, where he claimed no further responsibility. Without question, the “race car builder” forgot to torque the rod nuts on these bolts. The driver reported it ran poorly, but he drove it around for a while that way. The piston was just jammed at the top of the bore, and the engine kept going.

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Damage tolerance isn’t a primary engine selection criterion in experimental aircraft, the way it was when the US Navy specified that it would only accept air-cooled radials for combat service in WWII. Many newer engines cease to run the first moment any small piece of material gets loose in the engine, but the Corvair has more in common with the damage tolerance of radials than it does with modern engines.

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The majority of the general public when looking at photos like these will say “I would prefer to have an engine that will never break” much the same way that children have a decided preference for unicorns despite a historic supply problem that suggests the perfect engine and the unicorn will be delivered on the same day hell freezes over.

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For people into a higher level of discussion, I can point out the design features of the Corvair that give it an extraordinary resistance to stopping when damaged. First and foremost, go look at your core engine and see that the cam and crank timing gears, the only part of the engine where a chip of metal can not be allowed to pass, live in their own part of the crankcase, and don’t share the same compartment with the rest of the parts in the case. There are many other elements, like forged components which are not brittle, and particularly being air-cooled and having no possibility of loosing coolant into the engine, etc. If you like machines, it is a very interesting study.

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Above, a core engine that came to our shop in 2005, from a person who drove their Corvair for a week with no cooling fan belt on it. Both the valve seats in the above cylinder have been beaten into the ports and broken up, yet the engine continued to run on the other bank of cylinders. Notice that neither valve head come off the stem. The rusty bits imbedded in the head are broken up valve seat.  While your engine will obviously never look like this inside, it is a very desirable characteristic of aircraft engines that they be able to sustain some damage without complete failure. The next time somebody points out to you that a Corvair engine is slightly heavier than a VW, Jabbaru or Rotax, tell them that you accept this because there are robust qualities to the Corvair that you appreciate.

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Larry Nelson’s first Engine run for his Zenith 601.

Builders:

In 2015 I wrote about 150 stories for this website, and they, and the older stories drew about 350,000 page reads. Out of all new stories, this one was clearly the most popular story of the whole year: Acceptable methods of payment for Corvair parts . It was about how a Zenith builder from Arizona named Larry Nelson paid his parts bill at Corvair College #34 (Photos from Corvair College #34 at Zenith A/C) in ammunition………

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“Benjamin’s, plastic or lead?  All are fine, as they all have understood value. Above, Larry Nelson’s engine on the bench at Corvair College #34.  The engine is a 2700 with a Dan Weseman bearing, outfitted with all our Gold System parts from our catalog.”

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Today Larry send word that he ran is engine on the front of his plane this weekend.  He send this you tube link for everyone to get a look at:

https://youtu.be/Asb9IRWJX0c

(Notice that it does have the new engine required cooling baffle on top of his engine)

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Larry is an Aviator, outdoorsman, and a family guy. He has long proven himself to be the kind of guy who shows up early, and works to make sure events are made better for other builders, most of whom he is yet to meet. He does this stuff without anybody asking him, it is just his style to put back a bit more than he got from things. He is living proof that taking rugged individualism and liberty very seriously is completely compatible with gregarious service to communities of others.

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-ww.

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Something to consider: About a week ago I got an email from a builder asking why I occasionally  had pictures of with firearms in my web stories, particularly after a number of violent incidents in our country in the last year. Instead of writing the guy back, or being ‘offended’, I walked out to the shop, picked up the phone and called him so we might actually communicate.

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I explained that I come from a very diverse family, and some members have very strong opinions against firearms ownership, which is their right, but the opinions are unfortunately based of media provided myths and stereotypes rather than personal exposure. I pointed out that when any of these members of the family say “Gun owners are…” They are making a blanket generalization about 100 million people, based on maybe meeting 5 of them, and in some ways it is just as repugnant as people who make blanket statements about ethnic groups.

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I shared that I also found the violence of criminals in our society horrific, but I said that my photos of responsible  sporting or utilitarian uses of firearms to have absolutely zero to do with the actions of criminals.  I don’t think husbands and wives should stop being intimate because we have a serious sexual assault problem in this country, I think they have nothing to do with each other. I pointed out that many people who knew nothing of general aviation wanted to end it after 9/11 because criminals used it as a small part of their plot, but no one suggested we take down our J-3 cub pictures because they would be ‘distasteful’ after the terrorists struck.

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In a few minutes, I shared that even though Florida was considered a ‘pro firearms’ state, most of the things he had heard about it were wrong. The state has real time background checks on sales through a state wide database, you have to have ID, and fill out an extensive BATF form, the entire process is videotaped, and if the info on the form doesn’t agree with the database, you not only are denied the sale, you will likely not make it out to your car before you are arrested. You also have to sign a form saying that if you buy the gun for someone else who is not eligible, you will go to jail for 10 years, no plea bargain, period. I explained that every “buy a gun on the internet” story is also a myth, because it has to be shipped to a federally licensed dealer, and he will do the above checks and forms.  While theoretically one individual can sell to another, no rational person does this, because they have no way of knowing who the buyer is or what they are going to do, or why they are not buying from a licensed dealer, and the civil liability follows the seller. I pointed out that it isn’t “the wild west” down here in the sunshine state, because since the 1970s Florida has a law called “10-20-Life” expressing what happens to people who display, discharge or kill someone with a firearm in the course of a crime. It is law in this state that even displaying a weapon” in a rude, careless, angry or threatening manner” gets one a guaranteed year in prison. For these reasons law abiding Floridians don’t screw around, and criminals here get a lengthily all expenses paid trip to a gated community. These are all facts, but they are rarely brought up because they don’t support the national urban media narrative that my home state is populated with dangerous red necks.

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