Aluninum cylinders

[dvanalmelo]

Anyone rebuild an engine with 'NIKIEVAIRS' Nikasil plated aluminum full fin cylinders? Corvairspecialties.com

[erco]

Is he still in business? No website updates in 4-1/2 years:

These are the high-quality parts and services I offer...last updated 12/26/19.

[66vairguy]

Anyone rebuild an engine with 'NIKIEVAIRS' Nikasil plated aluminum full fin cylinders? Corvairspecialties.com

Never heard of them. What is your interest? Some Corvair books claim Chevrolet had planned on aluminum cylinders with liners for the Corvair, but it didn't work out. Various "opinions" are given. Considering how light the cast iron cylinders are, I doubt much weigh would be saved with aluminum, especially with a liner.

My "opinion" is the cast iron cylinders were found to be the best solution. They have nearly the same expansion rate as the head studs!!!

Nikasil (a coating) should not be confused with Alusil which is a aluminum silicon alloy. Both allow liner-less aluminum cylinders. GM and Alcoa used an aluminum silicon alloy for the Vega block and we all know how that went. After some serious accusations, it was found the GM factory managers were not following the strict rules for handling the Alcoa alloy that resulted in defective engine blocks.

[Dennis66]

Having had 6 or 7 Vega / Monzas, the problem seemed to be more overheating than just blocks wearing (usually scored cylinders. The earlier Vegas had a small radiator that was only about 12'' square. Those were the ones we always found in the boneyards with the heads pulled off and the cylinders usually damaged. After 1974 when they added th ecatalytic converters, they had radiators that were just over twice the size. Saw those engines hold up a lot better. I used to steel sleeve the earlier ones and they were good to go (unless cracked heads from overheating). I did a couple of the later ones where I just pulled the pistons, ran a quick hone through the cylinders, new rings and good to go. Dennis

[vairmech]

While the Nikasil cylinders are nice they are not needed unless you are trying to save every ounce of weight you can get rid of. Porche used the Nikasil cylinders and they worked but are NOT cheap.

[66vairguy]

Having had 6 or 7 Vega / Monzas, the problem seemed to be more overheating than just blocks wearing (usually scored cylinders. The earlier Vegas had a small radiator that was only about 12'' square. Those were the ones we always found in the boneyards with the heads pulled off and the cylinders usually damaged. After 1974 when they added th ecatalytic converters, they had radiators that were just over twice the size. Saw those engines hold up a lot better. I used to steel sleeve the earlier ones and they were good to go (unless cracked heads from overheating). I did a couple of the later ones where I just pulled the pistons, ran a quick hone through the cylinders, new rings and good to go. Dennis

The later Vega/Monza cars were a lot better, but the damage was done. I always wanted to do one of the Buick/Olds/Rover aluminum V8 installs on the nicer looking early Vega and upgrade the suspension/axle with parts from the Monza cars. After looking for a clean, rust free, early Vega I gave up. Only ones that seem to survive are the later ones with the ugly cow catcher front end with BIG bumpers. Another paper project that never happened. Having driven an early GT Vega company car, I have to say they were fun to drive and handled well - that said it was an unreliable, oil burning, rust bucket of a car. However, it never did overheat.

[Nashfan]

There's been problems doing this with Corvairs... 2 different builders have tried on 2 separate engines each, for a total of 4 engines, all four kept popping head gaskets. Many different torquing strategies were tried. None worked for long. One of the builders got so frustrated with the whole thing he had his full fin all aluminum Nikasil coated cylinders bored to accept iron liners. They did not try dilvar head studs like Porsche used... theres a good reason for that. $$$$$$$$$$$$$$$$

[joelsplace]

Was there a problem with the top of the cylinder? What was the failure mode of the head gasket?
I love the idea of aluminum cylinders and Nikasil.
Nikasil is much more durable than iron.
Dirt bikes went to Nikasil back in the early 90s and still use it today. The Nikasil cylinders would often last the life of the bike where the old iron liners needed bore jobs every season or even more often.
Most dirt bikes have short studs that hold the bottom of the cylinder to the case and then short studs holding the head to the cylinder. I wonder if that was done to eliminate expansion issues?

[66vairguy]

Nashfan --- that is interesting. I wonder if it was the cylinder sealing due to the alloy or the expansion rate. As I mentioned earlier --- the Corvair cast iron cylinder and head studs have nearly the same expansion rate. As many have learned --- torquing heads studs to more the 30ft lbs. might result in pulled head studs.

Joel - Yes the Nikasil is durable, but I've pulled apart Corvair engines with over 80K miles and I'm always surprised by the minimum cylinder wear. I wonder if the cast iron alloy was superior or if it is just the generous oiling of a flat boxer cylinder layout.

I know in the mid 60's Oldmobile's new engine blocks used a cast iron alloy superior to what Chevy used and the Olds big blocks are known for durability that made them popular with the boat racers back then.

[Dennis66]

I always wanted to do one of the Buick/Olds/Rover aluminum V8 installs on the nicer looking early Vega and upgrade the suspension/axle with parts from the Monza cars. After
Having driven an early GT Vega company car, I have to say they were fun to drive and handled well

I had a '72 GT wagon with a steel sleeved engine (second hand) and a 4 speed. it was one of my favorites. Fun to drive. It did use some oil, but the previous owner of the engine hadn't taken care of it.
My absolute favorite was a Buick Skyhawk with the 231 V-6, a 5 speed and the rare "moon roof" option (completely mirror tinted glass roof over front seats with headliner and cut out the size of a regular sun roof - chrome / mirror look from outside, looked like regular sunroof on inside.) They only made a few hundred of these and only on the Buick Skyhawk and Olds version of that body style. Only gave that car up for my Datsun 260Z.
On the aluminum cylinder / cylinder head head gasket thing, probably wrong head gasket material. Between Corvairs, VWs, all kinds of motorcycles, all had iron cylinders and aluminum heads. All the "aluminum / aluminum" engine I ever remember(small air cooled and 4 banger and 3 banger Metro), they all had graphite sandwich head gaskets. I don't remember ANY aluminum / aluminum engines with copper or metal head gaskets.
On the aluminum cylinder small engines, the Briggs and Strattons always seemed to hold up the best. Tecumsehs didn't last. The Briggs (vertical shafts) had a paddle wheel oil system that bathed the whole insides with oil (lubrication AND cooling). The Tecumsehs had a piston pump pressure lube system and cylinders and rings just didn't last. Tecumseh didn't have a problem with the same lube system and their older cast iron sleeve engines. Dennis

[joelsplace]

IIRC the aluminum cylinder/aluminum head motorcycles from the 70s with chrome bores used copper head gaskets.
All the later Nikasil stuff used o-rings. Maybe Viton? but they were water cooled.

[jimc]

Joelsplace,

I don’t believe the Nikasil cylinder was the cause of many air cooled Porsche 911 motors with loss of compression. Many a 911 motor with newer dilivar head stud material and thermal reactor exhaust system failed due to dilivar corrosion and higher operating temps of the thermal reactor.

Having owned both early model 911 with steel head studs and a later 911 with dilivar material i experienced a failure with dilivar stud material which became brittle due to exposure to road splash and higher operating temps of thermal reactor exhaust system rather than a traditional catalytic converter. These dilivar studs actually broke in some cases. Remember Porsche 911 air cooled motors did not have lower ducts like Corvair or high temp catalytic style exhaust. Exposure to water and operating temps caused failure of dilivar material that lead to pulled studs and even some broke. The repair included a tear down and replacement with steel studs.

[66vairguy]

I had a '72 GT wagon with a steel sleeved engine (second hand) and a 4 speed. it was one of my favorites. Fun to drive. It did use some oil, but the previous owner of the engine hadn't taken care of it.
Dennis

The cylinders could be an oil burning issue, but the valve lifter design also resulted in oil burning. GM used the cam on bucket (lifter) on top of the valve similar to the GM Vauxhall, not a good design that forced oil past the valve stem seals. A shame they never used the Opel OHC cam on rockers. The Pontiac OHC six used a similar design like the Opel with hydraulic pivot points for the cam followers back in 66. Trouble free and allowed high revs without issue.

Of course the Vega engine was designed to be cheap to build, and it was cheap. Ford used their German Ford OHC engine (in over 90% of early Pinto cars while the little four was offered) that was bullet proof (if maintained). Ford moved production to the Lima, Ohio plant and revised the cam oiling design to cut costs "because American drivers don't drive like German drivers". HA! -- those Lima engines had cam failures until the "American" design was revised back to the original German engine plant design - or so I've read.

[joelsplace]

What about the bucket caused oil consumption? Motorcycles have used buckets for decades with no issues.

[jimbrandberg]

Comparing Vega engines to aluminum Nikasil cylinders is like apples and oranges.

Aluminum Nikasil cylinders are also different than the old Salih cylinders which were basically a steel liner with aluminum fins surrounding it. Bigger ones like 3 9/16 and 3 5/8 are the only ones I ever saw. I couldn't use my favorite ring compressor.

I haven't heard of Corvair Specialties for several years. I bought some red and blue roller rockers, longer studs and stud girdles from him several years ago for the La Boa Corvair Sports Racer engine. I had to modify some stuff for it to fit.

I once held a VW aluminum Nikasil cylinder in my hands and fell in love. Light and full finned and lovely. My old Machine Shop guy said they were about impossible to deal with if they had a flaw, that Nikasil coating is so hard.

There was quite a discussion on dilivar studs and such on Fastvairs a number of years ago. It's hard to remember fact from fantasy but the price of all that stuff left me wanting someone else to try it. I thought one theme was that aluminum cylinders and cast iron cylinders did indeed have different expansion rates.

I would think the best stud in the world could only be as good as what it's screwed into. I'd hate to start pulling studs out of the crankcase in an airplane. The Corvair aircraft and Corvair racing people don't seem to buddy up very much but then how would I know.

[Nashfan]

Nashfan --- that is interesting. I wonder if it was the cylinder sealing due to the alloy or the expansion rate. As I mentioned earlier --- the Corvair cast iron cylinder and head studs have nearly the same expansion rate. As many have learned --- torquing heads studs to more the 30ft lbs. might result in pulled head studs.

The builder attributed the problems to "over squeezing" the gasket. My personal "theory" is that the stud bolts are being overstretched- the problem isnt the expansion rate by itself, its the expansion rate over TOO MUCH DISTANCE- basically the distance from the head nuts all the way to the crankcase for an all aluminum cylinder plus the heads vs the distance from the head nuts to the top of the cylinder bore for a stock iron cylinder. The difference is HUGE. Even for a temperature difference of only 200 degrees, an all aluminum cylinder is going to try to get something like .020" longer! Add to that the wimpy stock studs that are only .270" vs a Porsche stud that is 3/8" in the thinnest spot (this is a 93% gain in AREA so is a 93% reduction in stress for the exact same force!) and you can appreciate what is probably happening- the stock Corvair studs are more than likely permanently stretching every time the cylinders get to temperature.