350 Late model stock car racing engine, oil temps high with great water temps, any help?

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Jsmathers50
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350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by Jsmathers50 »

I'm not a mechanic at this level and don't want to sound like a complete idiot but I have a high end Pro motors late model stock car racing engine that runs hot, over 240 (damn near 250) with water temps 195-200. I have installed the reducer in the outlet neck in order to slow down the water inside the motor. They live in the same world here so what am I missing? Any help is much appreciated!! It's a circle track NASCAR late model stock car engine. I have attached screenshot of the engine rules in order to direct the right minds to the type of motor we're dealing with. Again, I appreciate any help!
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by FC-Pilot »

Let me get this straight, your oil temps are 240-250 and your water is between 190-200? And it holds that temp all the way through each heat? If it holds those temps right there, then I would call it a win. But that is just me. If I misunderstood something please set me straight.

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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by Baprace »

Jsmathers50 , three things come to mind , 1st oil level is too high by perhaps a 1/2 quart , 2nd your pan may be a little shallow 7 inch ( 7 1/4 is as shallow as I like to use ) if I am worried about oil temperature, 3rd if it is a stroker engine 3.75 then the pan may be too close to the crankshaft, I used to run Aviad oil pans back in the day and they were very shallow (for ground clearance ) and our oil temps were also very high while water temperature was normal , I don't like a restrictor in the water outlet , you are telling the engine what temperature it will be running at next week while not knowing what the weather will be or are you in traffic , I like a 195 - 205 * thermostat as it can adjust the water temperature as needed , ALSO I like to run the water pump approx 20 - 25 % under driven , last high oil pressure contributes to higher oil temperatures. Your not in any real trouble but I would like to see that oil temp down a little.
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by mag2555 »

If your oil pressure is over 55 psi hot then that is adding to the high temps as posted above.
You just don’t need pressure over that if there is no pickup side restriction or choked off oil filter.

I will assume your running a fully synthetic based oil such as Amsoil , or royal purple, if so I would not fret over the oil temps you are seeing .
Here’s a chart of the life expectancy of a mineral based oil and even at 250 it has a 73 day rating!

Another big thing to always keep in mind is that heat is power when it comes to driving the reciprocating assy!

It was found long ago that out of all the heat a internal combustion engine produces that 20% is just radiated off the motor, 20% is lost to the cooling system, 35% goes out the exh and only 25% is left to spin the crank!
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by RCJ »

I wouldn’t worry with those numbers at all. A wet sump stock car will have a high oil temp over a dry sump or open wheel car. I have seen 320 after a race that went green to checkers on a high bank track. We ran a 8 quart pan with 7 quart 260-270 was normal.
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by ClassAct »

Jsmathers50 wrote: Fri Aug 20, 2021 10:00 pm I'm not a mechanic at this level and don't want to sound like a complete idiot but I have a high end Pro motors late model stock car racing engine that runs hot, over 240 (damn near 250) with water temps 195-200. I have installed the reducer in the outlet neck in order to slow down the water inside the motor. They live in the same world here so what am I missing? Any help is much appreciated!! It's a circle track NASCAR late model stock car engine. I have attached screenshot of the engine rules in order to direct the right minds to the type of motor we're dealing with. Again, I appreciate any help!
I figure your engine will be no different than a lot of the circle track stuff I’ve dealt with over the last 40 plus years. First of all, your engine temperature isn’t that high. If you can get it to 180 and keep it there you’ll make more power. Second, keeping the coolant in the radiator longer is ass backwards. It’s dead wrong. Think it through. While you are forcing the coolant to stay in the radiator longer, the coolant is in the block longer, where it’s picking up more heat. It’s a viscous circle and slowing the coolant down is always (almost anyway) wrong.

A good cooling system with everything as it should be will drop the coolant temperature about 20, maybe 30 degrees. That’s all it can do. And that depends on several things, ambient temperature being a big factor. If the ambient temperature is 100 degrees out and the coolant temperature leaving the engine is 200 degrees the ability of the radiator (heat exchanger) to drop the coolant temperature may be only 18-20 degrees. At best. That means the coolant returning to the engine is now at best 180 degrees. Obviously on a day where the ambient temperature is say 70 degrees the temperature drop can be much greater.

One can easily see that trying to force the coolant to stay in the radiator longer only makes it much more difficult to control engine temperature. Your thermostat controls the minimum operating temperature. Once it’s open, it’s open. Let’s say you are running a 180 degree thermostat and your coolant temperature is 200 degrees on the track. That means your cooling system isn’t capable of keeping the coolant temperature at the thermostat opening point. It also means there are probably some things you can do to correct that.

Number one on that list is getting a radiator that is capable of cooling the engine. IMO it can’t be too big. If you can’t get the engine temperature as high as you want or need it, install a thermostat.

Second to that is FLOW. Air flow through the radiator AND coolant flow. You just about can’t get too much of either. Don’t make the mistake of running a three or four core radiator. You want a two core radiator with at a minimum 1 inch tubes. 1.25 or even 1.5 inch tubes are even better. Two 1 inch cores will flow more than three .75 inch cores. And it’s all about flow.

To that end, you MUST have a damn good high flow water pump. That is important. Since you run a Chevy you have many options. Stewart Components is a good option. I think but I’m not sure that Flowkooler also makes a nice pump for the SBC. I don’t use that brand so I’d be surprised if they didn’t make a pump for the SBC. I know they have a reputation for high quality and if I couldn’t get the Stewart Components pump Id look into the Flowkooler.

Now we will get to the part that always gets the most hate. It is 100% necessary that you turn the water pump FASTER than the crank. That’s right, you need to overdrive the water pump. At the very minimum you need to be 1:1 crank to pump speed. That is a huge mistake guys make and it’s a big no no to under drive the pump. I know it is and has been chic and trendy to under drive the pump but that don’t feed the pit bull. Coolant speed is critical to controlling engine temperature. I know many will say you are pissing away horsepower speeding up the pump. And I say, and have proven it so many times over the years i no longer even argue about it. It is what it is. If you can drive the pump 15% over, you will MAKE horsepower. You’ll have a net horsepower gain, because what little bit of power it takes to turn the pump is gained back and then some by being able to keep the coolant temperature at say 180 degrees rather than 200 degrees. And it’s all about the net gain. Over drive the water pump s much as you can. You’ll be rewarded with a cooler engine and more horsepower every time.

Finding pulleys to over drive the pump can be problematic because like I said, under driving the pump is trendy. And the aftermarket loves trendy. The trend eventually is exposed as folly and then they sell more product. Do whatever you have to do to get the pump over driven.

The last thing are fans and shrouds. I’ve seen some horrible shrouds over the years. The shape of the shroud is important. It shouldn’t have an abrupt edge real close to the radiator where it starts heading back to the fan. It should be nice radius and a long taper to the fan. In some chassis it’s near impossible to get the shroud long enough to get a nice shape. As the shape of the shroud gets worse it starts to impede air flow. That’s a giant no no because it’s all about flow. More than once I’ve removed a bd design shroud and used spacers to get the fan within an inch of the radiator and it dropped the coolant temp a bunch. The shroud was actually impeding flow in those cases. A shroud can be a good thing, a not so good thing or it can be junk. Don’t assume all shrouds are good.

I’m a big fan (no pun intended) of fix blade mechanical fans. I’m not into “clutch” fans, flex fans or any other trickeration with fans. If you have the best pump, a big radiator and under a caution you see the temperature climbing you can bet it’s because the fan isn’t right for the job, or you are turning the pump too slow. Since the pump and the fan are hooked together if the pump is turning too slow so is the fan. After a long caution I’ve seen guys pass two or sometimes three cars because they engine temperature was where it should be and the other cars were hot enough they lost enough power that they were easily passed. I’ve also seen a long caution knock cars out because the got so hot they puked the coolant out and they were done.

It’s all about flow and getting the right components. You should easily be able to run at 180 degrees if you have the cooling system correct. And you need a systems approach.

Just my .02 and it’s worth less than what you paid for it.
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by dannobee »

Those temps are exactly what I like to see as a super late model crew chief for a couple of decades. Run it as is and have fun.

Are you aware of the water and oil temps that current Cup cars are running?
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by RDY4WAR »

Your oil temps are actually on the low end of what some of those engines run at. Up to 280°F oil temp isn't uncommon.
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by V12MECH »

What oil weight are you using? We ran a Jag 6 cyl. in vintage racing a dozen years ago with 20w -50 @ 275 + temp. , switched over to 10w-30 and oil temp dropped 10-15 degrees depending on track temp. Both syn amsoil, better flow carried heat away from high load areas,bearings and valve train faster? That's the theory, now only use 5w-30 syn. No discernable wear problems since.
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by swampbuggy »

Thank you Class Act for the nice long read, Mark H. Interesting :idea:
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Re: 350 Late model stock car racing engine, oil temps high with great water temps, any help?

Post by PackardV8 »

RDY4WAR wrote: Sat Aug 21, 2021 3:00 pm Your oil temps are actually on the low end of what some of those engines run at. Up to 280°F oil temp isn't uncommon.
For true. Like all the good advice above, 240-250 is not a worry. Oil temperature is a function of load/power/time. All else being equal, more power and/or longer time puts more heat into the oil.

FWIW, as mentioned, coolant temp is a function of ambient temperature. On known good Stewart-Warner mechanical temp gauges, the coolant would stabilize, rising much more slowly than oil temperature, but oil temperature would continue to climb as the laps put more heat into the oil than the cooler could extract. If we'd run longer races on very hot days, we'd have had to increase the oil cooler capacity.

I've heard from race teams when they went to oil squirters under the pistons and on top of the valve springs, the result was a multi-variable regression analysis. What they had known about cooling which had worked in the past had to be remapped for each track.

Yours is a round track application, but those who want to run filled blocks on the street had better have an accurate oil temperature gauge. That mass around the main bearings kills oil before they know it.
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