Lamborghini Block Heating Expands Crank Clearances So Much That A 50 Weight Oil Is Required

Aluminum does expand quite a bit when warm. It was interesting to see just how much. The work I did in years past on automotive and race car engines was always on iron blocks. When pushing 700HP out of 4 tiny cylinders, nodular cast iron blocks were king, with the strength of cast steel! Even then, we did strive to keep the block and crank very true, and main bearing clearances tight and accurate, to facilitate good connecting rod oiling.

Also of note, some aluminum race engines require significant preheating prior to startup. A buddies V8 Hayabusa powered racer won't even turn over when stone cold. And yes, it does require some rather robust oil. The engine is a tiny thing that can almost be carried under one arm.

3.0l+NA+V8
 
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Cujet said:
Aluminum does expand quite a bit when warm. It was interesting to see just how much. The work I did in years past on automotive and race car engines was always on iron blocks. When pushing 700HP out of 4 tiny cylinders, nodular cast iron blocks were king, with the strength of cast steel! Even then, we did strive to keep the block and crank very true, and main bearing clearances tight and accurate, to facilitate good connecting rod oiling.

Also of note, some aluminum race engines require significant preheating prior to startup. A buddies V8 Hayabusa powered racer won't even turn over when stone cold. And yes, it does require some rather robust oil. The engine is a tiny thing that can almost be carried under one arm.

3.0l+NA+V8
Click to expand...
I definitely want to see/read more on this!!! Any videos of it running?? Wow...
 
So, he measures how much the block expands in size, but then just “wishes away” the crank and rods because “they don’t grow much because they’re steel”?

It‘s interesting, but his conclusion is specious. He doesn’t actually know the increase in main clearance when it reaches operating temperature because he: 1. Fails to measure at operating temperature and 2. Fails to measure the crank expansion.

Unless the pressure drops to an unacceptable level, then the clearances didn’t grow to an unacceptable level. I guarantee that Lamborghini measured and accounted for the differential expansion of steel and aluminum.
 
Here’s a bit of rough math. Steel expands by 0.07% for every 100F.

So, in his test, he heats the block by roughly 100F, from shop at 65 to 150, and the bearing internal size grows by about 2.5 thousandths. Then he claims that the bearing clearance grew by that much “because steel doesn’t expand”.

But steel does expand, it just does so at a different rate.

So, call the crank journal 2.0 inches. With 100F increase, same as the block was heated in the video, the crank will expand by 1.4 thousandths.

So, no, the bearing clearance didn’t increase by 2.5 thousands at 150F - the actual clearance grew by 2.5 - 1.4 or about ONE thousandth.

Because he failed to measure the crank expansion, overestimates the clearance expansion by a factor of three.

That is a huge fail.
 
Astro14 said:
So, he measures how much the block expands in size, but then just “wishes away” the crank and rods because “they don’t grow much because they’re steel”?

It‘s interesting, but his conclusion is specious. He doesn’t actually know the increase in main clearance when it reaches operating temperature because he: 1. Fails to measure at operating temperature and 2. Fails to measure the crank expansion.

Unless the pressure drops to an unacceptable level, then the clearances didn’t grow to an unacceptable level. I guarantee that Lamborghini measured and accounted for the differential expansion of steel and aluminum.
Click to expand...
There is a lot to this. In the turbine engine world, we now "actively cool" the outside of the turbine case for greater efficiency. Yes, the superalloy blades grow a bit when fiery hot, but the circumference of the inconel housing grows like crazy, remember, it's a large circle, and while the metal expands at a somewhat similar rate, there is a whole bunch more to expand in that big loop than just the length of one turbine blade.

Aluminum expands at about double the rate of steel. So the combo of geometry and materials lead to excess clearance. While he may not be a scientist, he does get it largely correct. It is also possible there is a temperature differential involved between the block and the crank.
 
Cujet said:
There is a lot to this. In the turbine engine world, we now "actively cool" the outside of the turbine case for greater efficiency. Yes, the superalloy blades grow a bit when fiery hot, but the circumference of the inconel housing grows like crazy, remember, it's a large circle, and while the metal expands at a somewhat similar rate, there is a whole bunch more to expand in that big loop than just the length of one turbine blade.

Aluminum expands at about double the rate of steel. So the combo of geometry and materials lead to excess clearance.
Click to expand...
Not arguing that clearance doesn’t expand, of course it does. Big issue with titanium blades and aluminum casings.

Point is, by failing to measure the expansion of the other components, he’s off by a factor of three.

He “assumes“ the expansion of the other components is zero. That’s simply poor thinking.
 
Tens of millions of cars with billions of miles over the last 30 years running 20 grade oils goes against his conclusions. Also, Lamborghini has not had any engine issues running 40 grade oils on the track. And it seems that many 40 grade oils thin to a 30 grade oil with hard use. I have not had issues running 20 grade oils in all sorts of 600plus BHP engines. I believe this is a poor experiment giving these conclusions.

Ali

PS
I am currently running 0W-5 in my Lincoln Navigator.
 
AEHaas said:
Tens of millions of cars with billions of miles over the last 30 years running 20 grade oils goes against his conclusions. Also, Lamborghini has not had any engine issues running 40 grade oils on the track. And it seems that many 40 grade oils thin to a 30 grade oil with hard use. I have not had issues running 20 grade oils in all sorts of 600plus BHP engines. I believe this is a poor experiment giving these conclusions.

Ali

PS
I am currently running 0W-5 in my Lincoln Navigator.
Click to expand...
Your iron blocked Navi is nowhere close to this marvel of an engine. Lambo does not specify 20WT oils for very good reason... totally different worlds here and completely irrelevant to your Lincoln.
 
racin4ds said:
Your iron blocked Navi is nowhere close to this marvel of an engine. Lambo does not specify 20WT oils for very good reason... totally different worlds here and completely irrelevant to your Lincoln.
Click to expand...
He's also used 0W-20 in his Ferrari.
 
AEHaas said:
I am currently running 0W-5 in my Lincoln Navigator.
Click to expand...
since 0w5 is not a recognized oil grade can you provide the specs of the particular oil you are using?

A fully formulated 0w8 such as motul might be nearly the same viscosity and a better choice.
 
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