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Safe Operating Temperature


jacob80

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Hey guys,

 

Tried searching, but couldn't find an answer to my question. Right now, we have a 160 degree thermostat installed in our L28ET with an aluminum radiator and front mount intercooler but stock water pump. Running semi hard, we had it pumped up to 207. Isn't that dangerous to be running that hot? The temperature gauge shows thats 250 is dangerous (according to the 'red' indication on the gauge). Keep in mind that we are not running the ZXT oil cooler. Thanks guys!

Edited by jacob80
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Here's a thread I started a while ago with a similar topic: http://forums.hybridz.org/index.php?/topic/68330-thoughts-on-this-aluminum-radiator/page__hl__radiator

 

From JohnC's response in post 17:

215 on the track on a hot day is nothing and its not something the aluminum radiator is going to improve. L6 engines put a lot of heat into the oil when running on a track. Adding an oil cooler will do more to bring the coolant temps down then going from a 4 row brass to a two row aluminum.

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Here is how I categorize water temps

 

170-205-----just right

206-220-----turn the fan on

221-235-----keep your eye on the gauges a bit more and cruise around a little

236-250-----drop the motor to idle and idle off the track, or back into the pits

251-300-----shut the motor off and pull off the track immediately, but leave the fan/water pump on and hope for the best.

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Based on some dyno testing I saw back in the mid-1990s and again in the early 2000s, the L6 will make the most power with a stable coolant temperature right at 200 degrees. That assumes there's no nucleate boiling back at the exhaust valve seats on number 5 and 6.

 

For a street car the temp ranges Hoov posted above make a lot of sense. Also, make sure your temp gauge is accurate. Most are not.

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Based on some dyno testing I saw back in the mid-1990s and again in the early 2000s, the L6 will make the most power with a stable coolant temperature right at 200 degrees. That assumes there's no nucleate boiling back at the exhaust valve seats on number 5 and 6.

 

For a street car the temp ranges Hoov posted above make a lot of sense. Also, make sure your temp gauge is accurate. Most are not.

 

John,

 

What temperature are you running on the track? Are you turbo?

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Track coolant temps were stable (after I corrected a bleed issue) at 200F. Oil temps were stable at 240. NA race engine (13.6 to 1 CR).

 

You test temp gauges on the stove with the probe in a pan of water. Should read 212F when the water boils.

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depends where you take the temp as well...

As JC mentions back at #5&6 you will see actual water temperatures 20F higher (minimum) than you will at the standard thermostat mounted sensor location.

So when guys think they are at 215 and "OK" at the back of the head, expect to see at least 235F...

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depends where you take the temp as well...

As JC mentions back at #5&6 you will see actual water temperatures 20F higher (minimum) than you will at the standard thermostat mounted sensor location.

So when guys think they are at 215 and "OK" at the back of the head, expect to see at least 235F...

 

Whats the explanation for heat in these cylinders?

 

Also, turns out I had a bum injector causing cylinder 5 to run lean/hot and I was experiencing temperatures of 215 with a 160 degree thermostat. Just replaced the injector and now I've maxed out at 175. I reached that temperature after a hard run idling using an MSA aluminum radiator, single fan on an L28ET. Is it normal to see this temperature with a 160 degree thermostat?

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Check out first sticky. Great read!

 

Could you link me?

 

Is a temperature of 205 acceptable for normal driving?

 

What I'm trying to figure out is what temperatures are too high for normal driving and occasionally getting on it, but nothing harsh. I see that John is seeing a temperature of 200 degrees on the track, while i can easily see that while beating on my car a little bit while not even being very hot out (77 degrees). Keep in mind I hav a turbo motor without an oil cooler, but I am running an aluminum radiator with a front mount intercooler. A new injector lowered my temperatures dramatically (one cylinder was running lean/hot), but its still a little high for what I'm used to. Thanks fellas!

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  • 2 months later...

Hey guys, bringing this back to life.

 

My car is running phenominally! I've been watching my temperatures and here is what I've gathered:

 

Right now, I have an L28ET with the stock '73 4 speed and a 300zx 3.7 R200. On the highway, I cruise anywhere from 3100rpm to 3300rpm (which seems high for me, but its probably my gearing). At ~83* fahrenheit outside temperature, I peaked a temperature of 197* after a 25 miles drive while not beating up on it. I came to a stop and attempted to let the coolant temperatures come down from 197*, but after about 4 or 5 minutes, the temperature held steady at 197* and I was forced to shut down (late for work). Is this acceptable?

 

Like I said, this is a stock L28ET with an MSA aluminum radiator, front mount intercooler, and no oil cooler and running some crappy O'Reillys oil (just finishing up break in, will be converting to synthetic this next oil change).

 

Thanks guys!

Edited by jacob80
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Hey guys, bringing this back to life.

 

My car is running phenominally! I've been watching my temperatures and here is what I've gathered:

 

Right now, I have an L28ET with the stock '73 4 speed and a 300zx 3.7 R200. On the highway, I cruise anywhere from 3100rpm to 3300rpm (which seems high for me, but its probably my gearing). At ~83* fahrenheit outside temperature, I peaked a temperature of 197* after a 25 miles drive while not beating up on it. I came to a stop and attempted to let the coolant temperatures come down from 197*, but after about 4 or 5 minutes, the temperature held steady at 197* and I was forced to shut down (late for work). Is this acceptable?

 

Like I said, this is a stock L28ET with an MSA aluminum radiator, front mount intercooler, and no oil cooler and running some crappy O'Reillys oil (just finishing up break in, will be converting to synthetic this next oil change).

 

Thanks guys!

 

Its fine.

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John,

 

Good to hear that from you. What kind of temperatures would you expect me to see on the track? I'm holding off on the Midwest Z Fest track registration (which I hope you all are attending)until I know my temps will behave.

 

Thanks!

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  • 3 weeks later...

Hey guys,

 

I sure beat the heck out of my car and got up to a temperature of 228, I'm a little worried.

 

What kind of temp should I see on the track with my turbo motor? I'm really afraid these temps are too high and I don't want to damage anything on track day. The car runs great, just very worried about coolant temps.

 

Thanks!

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Get some Redline Water Wetter and put it in there, then report the resultant temperatures.

You should be pleasantly surprised.

 

I've been told it's got a surfectant action, and that mixing Dawn Dishwashing Liquid should have the same 'wetting' effect, but have not been inclined to try that yet! For the price of a bottle, I just mix and fill. It's best with pure water, but it will work with a Glycol Mix as well.

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