Engine Update

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davemotohead
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Re: Engine Update

Post by davemotohead »

What scotty was trying to point out is,,yes it takes longer to heat up 3qts of oil compared to 1qt of oil,,but it also takes longer to cool 3qts of oil compared to 1 qt of oil,,So yes it takes a longer amount of time to heat up,,but takes an equal amount of longer time to cool off, the oil has a certain amount of cooling properties but its primary funtion is to lubricate the rotating engine parts,The oil needs to come up to proper operating temp to lubricate and do its job,the cooling fans function is to cool the engine,,so if the fan is not doing its job the entire Volume of oil will heat up slower but will also cool slower and maintain heat longer than a lesser volume of oil,Once its too hot then you have alot of over heated oil to cool,,but even if you maintain oil temp the oil is not going to keep the engine from over heating and say driving a valve seat deeper into the hot soft aluminum head or have the seat fall out,,the Air from the Fan is what the engine needs to run at the proper temp,you have oil in the cases and below the piston,,and you have oil in the valve covers lubing the moving parts and providing a certain amount of cooling, BUT you dont have oil on top of the piston,on the cylinder head chamber,the intake or exhaust runners,,there is no oil in the hotest part of the engine,,the head/cylinder fins and fan is what cools the hotest part,not the oil, the baffels under the cylinders are there to circulate the cooling air around the cylinders to keep them from being cool on top and Hot on bottom and then warping out of round,the stock fan set up works on presure and volume of air controled by the engine rpm,at low rpm the engine is not producing as much heat and the fan spins slower and requires less HP to provide the presure and volume of air need to cool,At higher RPMs the engine is producing more Heat and the fan spins faster needing more HP to provide more air presure and volume to cool the engines hotter operating temp, so going up a long hill in 4th gear the engine is struggeling to pull the tall gear and the engine gets hot because its making heat due to the HP needed to pull the high gear at a lower RPM and the fan is not spinning fast enough to cool the engine and it starts pinging,,so you downshift to 3rd and now the engine rpm increases as well as the fan speed/presure/volume providing more cooling + the engine can pull the hill in the lower gear more easily and the engine cools off and stops pinging,,it takes the same amount of HP to pull the hill in 4th as it does in 3rd,,but in 3rd the fan does its job better and its easyer on the engine, at 3000 rpm the fan needs say 7 Hp to cool,,at 6000 rpm the fan takes lets say 25 hp to cool,,the fan speed changes in unison with engine speed providing the proper amount of air presure to cool at that given engine speed,,The problem I see with an electric fan is,,the fan speed/air presure/volume is a constant and does not change with the engines needs/requirements,,even with a properly working stock system you can over heat on a hot day going up a long hill if your not careful,,,so to conclude my long winded Post! :tongue: IMO adding more oil is not going help cool the engine,,its just going to take a bit longer to heat the oil,,kinda the same as adding more air is not going to lubricate your rod bearings,,each system has its own job to do,,adding oil will not make up the difference of a weak fan,,BUT I do wish you Luck Herb and the fact your giving it a go and doing something different is Realy Cool! And I hope you can come up with an electric fan set up that works good and you can drive anywhere anytime and then we can say Finaly someone has found the magic combination and soon we will all be running them! :tu: If someone Can make a system that works,,I would own one! :cool:
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bbodie52
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Re: Engine Update

Post by bbodie52 »

Sorry I should have put it a little better. Heat the one quart first take the temp. then heat 3 quarts and take the temp. and see what the deference is. You will fined that the 3 quarts is lower in temp. because of volume, in other words the more oil you carry the longer it takes to heat it.
This has been discussed by others quite well, but I wanted to throw my :my02: in. Certainly it would take longer to heat a larger volume of oil on a stove, given the constant of a fixed BTU rating on the burners limiting the heat transfer rate to the oil. But if you consider your engine to be the "stove", taking longer to heat a larger volume of oil to the DESIRED operating temperature would be a negative thing for an engine, because it would take more time to get the larger volume of oil up to the desired operating temperature. But once it is heated, most of the heat stays in the fluid, whether it is five quarts or seven quarts, unless you give the oil a way to exchange the heat to the outside air. In a racing engine, a deeper, baffled sump and a longer oil pickup that sits near the bottom of the sump might be desirable to prevent the oil pickup from being uncovered by the oil sloshing around during hard cornering, braking and acceleration. With a poorly designed oil pan and pickup, the racing speed G-forces can starve the engine for oil. But the deep sump and larger oil volume has nothing to do with cooling the engine. If you want to ask the oil to take on a secondary job of cooling, as well as lubricating the engine, you have to give it a way to transfer the engine heat to the outside air, just as you do in a water-cooled engine by giving it a radiator and fan. That is the function of the cooling fins and posts in the Otto Parts oil pan and valve covers, and it is the function of the Corvair oil cooler and possibly an auxiliary oil cooler. The added radiating surfaces in the oil pan, valve covers, and oil cooler(s), plus the required air flow, allows heat to be extracted from the oil and moved to the airflow. An oil cooler without good airflow is useless, which is why it is important to keep dirt and leaves out of the Corvair oil cooler fins. That is also why adding a secondary racing oil cooler is no good if it is not properly placed where it will receive good airflow.

The mention of an oil thermostat can be compared to the water-cooled engine thermostat, in that it allows the coolant, or oil, to be heated more-quickly by the engine by bypassing the external radiator/oil cooler until the coolant/oil reaches the proper operating temperature. The thermostatically controlled doors on the Corvair engine perform the same function, by restricting air flow until the engine heats to the proper operating temperature. Without them, the cooling capacity of the Corvair engine is actually too great, and would cause the engine to take too long to reach proper operating temperature -- causing excessive wear, the chokes to stay on while driving for too long a period (i.e. poor performance and gas mileage), and poor performance of the passenger compartment heating system.
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Re: Engine Update

Post by cad-kid »

:goodpost: dave & brad
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scottydont
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Re: Engine Update

Post by scottydont »

Just to add one more wrinkle.....

About 20 years ago, when I was really worried about the temps in my VW, I spoke to a valvoline tech (not a sales rep) and he gave me the following information. It was obviously brand specific, but I've applied it as an across the board rule of thumb ever since.

Non synthetic, straight weight oil begins to break down more rapidly as the temperature increases. The valvoline rep told me that the max recommended operating temp for their non synthetic oil was 200 degrees with an absolute max of 220. Anything over that was out of the design range. Further, he recommended that for every 20 degrees beyond 180 of oil temperature (average operating temp), one should take 1000 miles off the normal oil change interval (or was it cut it in half?... crap, too much time gone by) to account for break down of viscosity controllers, detergents, and the oil itself. It wasn't part of the discussion, but since then, I've learned that multi viscosity oils (which I despise, but that's a different conversation) break down even quicker and in worse ways than straight weight oils.

Not sure what the max oil temp on a corvair engine might be, but as a similar example, VW's routinely run 225 degree oil in hot climates and extended highway driving (which for a VW is high rpm, heavy load). That means (if you follow the tech's recommendations) oil changes every 1000 miles.

I worked very, very hard to get the oil temp in my VW down to 200 degrees under all but the worst case driving scenarios in order to preserve the oil and engine life. it would still creep up on the highway during the summers, but around town it wasn't too bad. Nowadays, synthetic oil is within my budget so I might not work as hard to get oil temps down.

The main lesson here, Keeping the oil (relatively) cool helps the oil as much as it does the engine.
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Re: Engine Update

Post by Corvair1 »

Hi Scotty, Interesting, something I changed a long time ago is my oil. My girl gets the best. It is Z-Rod Amsoil oil 20 50 synthetic with zinc. I don' know if you have this brand where you are but you can fined it on the net http://www.amsoil.com/. My head temperature has never gone over 375 deg. Here in Canada the oil runs me close to $14.00 a liter. You want the best you got to pay the price.... ::-):
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Re: Engine Update

Post by scottydont »

I'm a big fan of Amsoil. I (and my father too for that matter) got introduced to their products via their 2cycle motorcycle oil. There's a local supplier here, and it's starting to show up on the shelves of our local NAPA, which is nice. Almost all of the synthetics have better high temp characteristics than traditional oils, but I cant attest to the consistency of characteristics from brand to brand so it's worth calling whoever peddles your favorite oil to get detailed specifications.

If 375 is characteristic of corvair head temps, then I'm surprised at their reputation for overheating and damaging valve seats and the like.... My old VW's would sit at 425 for extended periods of time, and go higher under heavy load with never a failure (and I always thought the cylinder head was the weakest part of the VW engine design).

Regarding the multi viscosity oil you selected (the 20-50...)
1)older engines weren't designed for it, so why run it? The tolerances of even a nicely blueprinted 60's vintage engine don't require MV oil to get adequate startup lubrication.
2) MV oil is actually just oil with a base viscotiy at or below the minimum viscosity rating (20wt in your case) which has a polymer added. The polymer molecules curl as they heat and get "tangled" thus increasing the oils viscosity. That all sounds well and good except that the polymer itself isn't a lubricant and MV oils have lower lubricity than straight weight oils as a result. And as the polymer molecules break down from heat and mechanical wear the oil once again becomes a single viscosity oil, but of appreciably lower viscosity than the engine was specified for. It basically becomes whatever the 20wt would deteriorate into, except with built in particles of "non-lubricant" to assist in engine wear. All these things are exacerbated by the amount of polymer in the oil, so if you HAVE to use MV oils (like most newer cars do), then finding one with the narrowest acceptable range (IE 10-30 instead of 5-40) will get you a better lubricating, longer lasting product. But you should STILL check and change it more often than the manufacturers state. I even go so far as to add a viscosity additive to my ranger about 2000 mi into the oil life because I've noticed timing chain rattle due to slack in the oil pressure driven tensioner (a known problem in older ford 4.0's) as the oil begins to break down.
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Re: Engine Update

Post by Corvair1 »

Hi Scotty, Wow! I guess you are never to old to learn. I don't understand all the viscosity stuff and I don't pretend to but I do, do my home work and I had a good discussion with the Amsoil tech and my good friend that is helping me put my engine together. He has been racing cars for the last 30 years. The Z-Rod Amsoil oil was specifically designed for the vintage car. Here is a link to all the TYPICAL TECHNICAL PROPERTIES on this oil, if you are interested http://www.amsoil.com/shop/by-product/m ... motor-oil/. Know that you mention all this maybe I should change my head sensors just to be on the safe side. Hey! I have changed everything else.... ::-):
It is time get some more :zzzz:
See you when the sun comes up
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Re: Engine Update

Post by scottydont »

Don't get me wrong, I'm not saying that MV oil will kill your engine or anything. It's just my opinion that where feasible, straight weight oils are a better choice. That's just my opinion and nothing else.

Race-prepped engines can be finicky things and a lot of the rules that one applies to street driven engines go right out the window in their case. Race cars also have the benefit of shorter service intervals so things like oil breakdown or even excessive part wear don't come into play the same way as they would in a daily driver. If you're building that engine to race (didn't realize that was the case), I doubt it will ever go 3K miles between oil changes, which is a huge benefit under any circumstances. Most of my experience is with modified street engines, so I tend to think in terms of longevity instead of absolute performance in most cases.

For what its worth, straight weight oils ARE getting harder and harder to find. I don't think Amsoil makes a straight weight racing oil anymore, which is a shame in my opinion, but some other manufacturers still do.
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Re: Engine Update

Post by Corvair1 »

I understand what you are saying, all I'm trying to do Scotty is cover all the bases for that electric fan conversion or have a good starting point. Based on the test results changes can be made to suit the system, but time will tell if Keith ever gets his tush moving.
I have been getting a lot of good information from both forums on things I should look out for and the ones that make a lot of sense to me have been incorporated into my build. I just received my aluminum covers and oil pan an all my gauges that will monitor the system. Their is not to much more I can do with this.
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Re: Engine Update

Post by Corvair1 »

Here is the latest addition to my engine, they should be able to monitor things pretty well,
and Clark's aluminum covers and pan is on the way as well.
gauges.JPG
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Herb (Corvair1)
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Re: Engine Update

Post by Scott V »

scottydont wrote:About 20 years ago, when I was really worried about the temps in my VW, I spoke to a valvoline tech (not a sales rep) and he gave me the following information.

Non synthetic, straight weight oil begins to break down more rapidly as the temperature increases. The valvoline rep told me that the max recommended operating temp for their non synthetic oil was 200 degrees with an absolute max of 220. Anything over that was out of the design range. Further, he recommended that for every 20 degrees beyond 180 of oil temperature (average operating temp), one should take 1000 miles off the normal oil change interval
oil tech has changed a bunch in 20 yrs. 230f isnt a problem for a good/modern oil - non sync. a good sync can run @/higher temps. 180f is too low for a average oil temp. you need to be over 190f to 210f just to start boiling off water & other dilutions.

-Scott V.
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Re: Engine Update

Post by Scott V »

scottydont wrote:Don't get me wrong, I'm not saying that MV oil will kill your engine or anything. It's just my opinion that where feasible, straight weight oils are a better choice. That's just my opinion and nothing else.
it would be real hard to find a non-race use for a straight weight oil that would be better than a multi viscosity oil. what you say was probably true 20+ yrs. ago.

-Scott V.
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Re: Engine Update

Post by scottydont »

Scott, last time I checked, "modern" non synthetic oils still adhere to the same API ratings that they did when I was younger. It's hard to believe that the performance of the oil has improved but it hasn't been reclassified to a higher grade. I won't argue that modern technology has the ability to create better performing oils like the synthetics, high mileage oils, and others. But (my opinion here) that doesn't mean that technology has been applied to every line of oil. Anyway, I told the story mainly to help illustrate the point that keeping the oil cool is beneficial to the oil as well as the engine itself. This will be true of all motor oil to one extent or another.

Multi viscosity oils do have benefits, and I'm not out to start a straight vs MV debate.... But for my nickel at least, the positives do not outweigh the negatives for older engines which were designed with clearances that do not even require the benefits that MV oil offers.
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Re: Engine Update

Post by Scott V »

scottydont wrote:Scott, last time I checked, "modern" non synthetic oils still adhere to the same API ratings that they did when I was younger. It's hard to believe that the performance of the oil has improved but it hasn't been reclassified to a higher grade.
the api classifications have changed a few times since you were younger. :chevy: the older oils cant come close to the newer oils / newer api rating. this is true for both non syn or syn.

-Scott V.
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Re: Engine Update

Post by scottydont »

I'll have to go looking when I have some time, but I think I have a bottle or two of decades old valvoline somewhere. If I can find them I'll get the API rating info off of them. It shouldn't take more than a few minutes of research to compare the API ratings by year. Until I see that there is actually a difference in N or SN ratings from 20 years ago to today, I'm going to stick with the assertion that all oils of a certain rating meet the same minimum standards no matter what the age.

I won't argue that the detergents and conditioners have changed for the better over the years, or at least gotten more diverse (which is why every manufacturer has 17 different varieties of 10-40 instead of just one or two), or that the "premium" oils which represent the best product available are better than what used to be available; but more than that is a leap of faith that I'm not willing to make without some kind of evidence. I haven't seen anything to make me believe that the garden variety, non-premium oils have any better protection against heat than they did in the 90's.
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Re: Engine Update

Post by scottydont »

Herb, are you engineering an electric fan conversion kit or buying one off the shelf? I stumbled across this this morning http://www.corvairspecialties.com/streetfankit.html and thought about you. I'm assuming you've probably seen it, but it's new to me.
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