Tommycourt

I was watching the NASCAR race in Texas today, which I am an avid fan of and a statement was made about the cooling system. One of the drivers, and please forgive me as I don't recall who it was, had some "debris" over the air intake area. He radioed to the crew chief and stated he was getting hot. Crew chief acknowledged and said NOT to let it exceed 290 degrees. True they are running at 9K-95K rpm and 200 mph however it was the temperature comment that sprang to my attention. A month ago I called Rick Hendrick's "Corvette specialist" in Kansas City and he said if it ran up to 250 degrees then shut it down for a little while and let it cool. He didn't give me any statistics but did not sound alarmed when I told him that at times I have been close to 240 degrees and higher. He kind of chuckled and said they are built to run hot. He just said to run it and have fun! I am wondering if anyone at all has any total temps on how hot the TPI engines can run before detonation. Let me know how hot yours has run and let's see who has been the hottest and the outcome of it.
Tommy

Cliff Harris

I have seen temperatures in the 230 and slightly higher range many times on over 100° days with the AC on at 70+ MPH.

vetrnz06

it was kevin harvicks car.

playsdixie

160 degree t stat program fan on 180...aux fan is manual..never see 200 in s florida....

WW7

It's always puzzled me why they say (our cars are made to run at higher tempertures).......Why would these 350 engines be made to run at higher temps and all the other 350s in the world not be made to run at higher temps??? ..Maybe they should change it to (These cars are "forced" to run at higher tempertures) because lower temps have quite a few advantages........The problem I have with the higher temps are mainly because it causes the components under the hood to have a shorter life span, or to crack or break prematurely because of the excessive heat..( How many of you have gotten a cracked brake Booster because of excessive heat)..I have the Dewitt's high speed fan on my 89, mainly to get the excess heat out of the engine bay to keep the components cooler..My car never goes over 200 degrees with the Dewitt's radiator and fan, and the fan is programmed to come on at 196 degrees and off at 180....My cruising temps are around 180-183 degrees with a 180 degree thermostat.........I believe these are more realistic tempertures for the street......WW

DanielRicany

Mine has been up to 245 once. Accidentally left the belt off when I was in a rush. Lol

Joe C

FWIW, my son saw 295 (dashboard indicated) on my old iron head 85 due to a failed waterpump gasket. didn't seem to hurt anything. that was several years ago, and still running strong. I don't think aluminum head L98's would fair so well.

c4cruiser

One of the reasons the C4 coolant temps are a little higher than other cars is for helping with emissions. And the whole cooling system design being a "bottom breather" was something that was not really seen with the typical coupes and sedans of the era.

I have never had any sort of cooling issues with either of the two C4's I have owned ('92 and now an '87). What I did do was to make sure that both the A/C condenser and radiator were as clean as I could get them. Allowing for the maximum amount of airflow you can get is paramount to efficient cooling.

One thing about NASCAR cars is that their engines are better able to handle higher coolant (and oil) temps. For all I know, these cars may get different radiators and possibly different thermostats based on where they are racing. The ambient air temps at Texas last night were much lower that one would see at other tracks at different times of the month. Even the air temps from daytime to nighttime could be a big difference in coolant temp ranges.

Does anyone know what the coolant is for NASCAR rigs? I would bet they do not use a 50/50 mix of an anti-free type of coolant and water. Sure, a 50-50 mix can help to raise boiling points, but higher pressure in the cooling system can also raise the boiling point of other coolant mixes.

Tom400CFI

By detonation do you mean "pinging" or pre ignition? A TPI engine can do that at 170* depending on conditions and fuel. Or do you mean it "toasted" the motor -ruined it?

Not a TPI but similar long block, Back when I was a dummy, I had an '83 Trans Am w/an LG4 (that is a carb'ed 145 hp 305) that I overheated incredibly badly, multiple times and it suffered no discernible affects.
1. On a trip from CO back home to Mass, I started my drive home, engine temp went into the red as we entered Kansas. I shut off the AC and opened the windows. Temp went down to just below the red, then after a few hours, wend back up, into the red. I turned the heat on full...we were sweating our asses off! Temp went down to just below the red, then after a few hours, wend back up, into the red. By this time, I'd stopped for gas, visually inspected and found nothing out of order. I felt the gauge was faulty. We got back on the highway and I put the windows up cranked on the AC and the gauge want right off the scale above the red...well over 300*, I'd guess. Car ran fine, no audible pinging and we drive that way from middle of Kansas, back to Mass. When I got home, I pulled the original copper radiator and it was so corroded that I could twist the end tanks and it would "rain" green copper from the radiator. Gauge was working. Car ran over 300* for over 1000 miles.
2. Same car, I was still a dummy. Took my mechanical fan off because, you know...those things consume power! I can't have that, right? As long as the car was going over 30 mph, it was fine w/no fan. Well one day, I started it up cold at work. High idle (carb'ed, remember?). Forgot something in side so went inside. One thing led to another, and 20 minutes later, the owner or the business runs out back and exclaims "TOM, You're car just exploded!" "Oh, f-k.", I thought, instantly thinking about it running for 20 minutes at 2000 RPM, no fan. I went out there, it had blown off the lower hose, dumped all coolant, and it wasn't running. I'm pretty sure there is no "safety shut off" for temp (or anything) on an'83 TA. I think it seized. I re-attached the blown off radiator hose, filled w/coolant, cringed and twisted the key...."Ra, ra...vroooommm...la-la-la-la-la..." nice smooth idle.

I sold that car w/200.000 miles on it to a friend. He sold it with 245,000 miles...still running well.

....then you get other engines that never overheated, never beat on, and blow a head gasket at 80k. Go figure.

Tom400CFI

Since you brought this up, I'm going to comment something that I've thought of many times, but never posted, in these temp threads. Some people think these should run at ~180 -200. Others say that "they're meant to run hot" meaning up to the fan temps of 230 or so. I've agreed with both; I feel "better" (personal thing) when my car is below 200...but know that it was designed to go to 230 or higher.

Here is the question: Where did GM want it to run??? 180? or 230? They put a 180 stat in the thing which implies that they want it running no cooler than 180, but they'll know that in most conditions, it will run between 180 and 195 probably; mine will run as cool as 175 on a cold day. So highway driving, we're talking <200. GM would know that, and so I assume they think that is the right range for highway cruising.

But then we talk about higher temps for emissions, fuel economy...but we don't' typically see those higher (220+) temps unless we're stopped or in traffic....at which point GM designed the fans to not turn on until 230.

WTF? That is a 50* range that the engine is expected to operate in...after it's "fully warmed up"! That is a substantially wide range of operating temps and not what I'd consider to be "well controlled". If GM wanted the thing to run <200 all the time, as it typically does at speed, then they should have set the fans for something like 205. If they wanted it to "run hotter" for emissions, efficiency, cylinder bore life...whatever, then they should have put a 215* T-stat in the thing and run it between 215 and 230. THAT would be "hotter running" for sure.

The motor can "take it", either way, and will last longer than "long enough" either way, but it makes one wonder...."What temp DID GM want this thing to run at, anyway??"

GKK

I think the best word description, is "Compromise."

Cooler temps on the highway and Hotter temps in city traffic where engine Emissions are at the Highest levels.

Tom400CFI

IDK about that. I'd prefer the fuel economy and emissions when I'm on the highway; where I consume the most fuel. I'd think most would too...including the designer. Doesn't make sense to crank up the engine temp at idle, where there is no air flow under hood, in the name of efficiency...then where most fuel is consumed (driving), lower the efficiency and "increase" emissions"? IDK. Maybe.

WW7

I have my motor running between 180-200 degrees, because 200 degrees is hot enough to burn off any moisture in the oil, and cruising temps of 180-183 are high enough to reduce excessive wear on the motor...When I first installed my 383, my tuner wanted to have my fan temps set to 185 degrees on/ 180 degrees off to keep the temperture under tighter control..I was afraid this would make my fan run almost constantly so I had him set it to 196 degrees on/ 180 degrees off ..To me this made more sense for the street....WW

leesvet

To the O.P.

I've seen 260 due to a blown hose and being "trapped" in traffic in Phx one summer.

Amazing how fast that digital read-out climbs....as fast as you can say it out loud.....231 232 333 234 235...etc

Been to 250 quite a few times, 240's in traffic with a/c is not unusual when there was a 100+ degree ambient.

Its NOT the max temp that you should be concerned with. Its how fast it climbs and how fast it drops !

Never "shock" an engine (metals) by letting temps shoot UP or cool off too fast. Rapid cooling will kill it.


The days of stuffing a water hose in the radiator filler neck and shooting cold water to an engine that's gone dry and last seen at 265 degrees....went away when Lt metals appeared.

I've heard THIS statement a thousand times....mostly in the 1970's...

"...as long as its running you can put all the cold water you want in the radiator"
....uhhh, not MY engine you won't !

If it took 30 seconds to overheat,. take 30 minutes to let it cool.

Its ok to run a hot engine if you have to as long as you do not abuse it or let it go higher. As previously stated, once it hits 250 its time to shut it down and let it sit for awhile.

I've idled in traffic in the 240's a LOT in Az and Tx in summer. Even stayed in the 250's and let it run ONLY because I knew I'd be rolling again within seconds. It seems to want to climb uncontrollably once it reaches 245-250 so you MUST move again at 30 mph or better. Mine takes about 5 miles at 50 mph to fall from 250 back to 220 or less...where I start to cool again.

For those that still do not 'get it' ....in these situations all you have to do is learn to sweat. Turn OFF the a/c to STOP sending HOT air to the radiator. You should not expect a decent heat exchange to occur and remove heat from the radiator, if you are trying to cool it with air that's been collecting HEAT from the a/c condenser. The hotter it is IN the cabin, the more of that heat is being carried directly TO the condenser for disposal....where the fan(s) take that HEAT from the condenser and BLOW it straight into the radiator !~

heat + heat = more heat

Someone will inevitably claim that a condenser that gets THAT hot is caused by a broken a/c system.
I beg to differ....its the ambient that causes the problem...a cabin that's 140 degrees inside when you start up is gonna provide a TON of heat at the condenser...it will be TOO hot to touch.

So, if ya cool it off (engine) TOO fast, I can almost hear the "clink" of some piece of aluminum cracking. Iron expands at different rates than aluminum. Contracts different too...
There are different types of 'ferrous' metals as well. Iron, steel, all a little different in what they do when hot and cooled. Some completely indifferent to temp extremes. Others, warping anyone ?

Made to run hot? not exactly. These cars are "made" to operate in a fairly wide window...of about 195 to 240....knowing that idle and no air flow drives temps UP...and movement and fresh air flow removes heat and lets the temp fall...gently and safely !
No real surprises there. The hard part is the driver, and keeping his/her imagination from being on the 6:00 news by causing a traffic "situation" of some sort..
In the case of the extremes....its almost better to have one of those people that never LOOKS at their instruments ! Ignorance is bliss.
The car will probably survive....

Just my $0.02 worth

Enjoy the winter !

I have to install a higher T-stat ! believe that s*** ? 'Cause if I don't, all the cooling upgrades will keep my engine under 165 for the next 6 months and THAT ain;t good !

Cliff Harris

The stock thermostat in my car is 195°. I have heard that later cars have 180° thermostats, but I don't know when that started. Maybe with the LT1s? I think it had something to do with the reverse flow cooling system.

Tom400CFI

All '92-'96 have a 180 stat. LT1-LT4.

May have something to do w/Reverse flow cooling...IDK. What ever the case, it is a huge range. Even an L98, you're talking a 30-40* range. I don't know of too many other cars (or trucks) that allow such a large range of coolant temps for "normal operation". My Silverado, for example, runs at about 185....all the time. The radiator is huge on the thing, so there is no shortage of cooling capacity, and the T-stat must be a 180. It warms up to about 180 and with the mechanical fan, it stays there, no matter the ambient temps, hwy, traffic, idle, towing...185. You'd think it would be easier for engineers to have that tight control for the 'Vette too both for emissions/fuel control and also for mechanical component life (gaskets, bores, clearances, etc). I just think it's odd that they put in a stat for one temp, then fan control for another temp, 40-50 degrees difference.

When I built a two speed electric fan set up for a Trans Am I had, I tried to control it more tightly like WW7 did above, keeping it between 180 and 200 in about all conditions.

Tom400CFI

IDK...my car runs cooler w/the AC on. Fans are running and drive the temps down. Last auto x event I did, my wife and I duel drove the car, meaning, no breaks for the engine, and it was 100*+. I ran the AC the entire time, temps never went above 215. Had I left the AC off, it would have been running between 220 and 235 or so.

bjankuski

Your car is designed to operate over a wide range from 195 degrees to 240 degrees, I would turn it off or try and figure out how to reduce the temp once it hit 250 degrees. Even though the car was designed to operate as high as 240 degrees it is in reduced power mode at those temperatures to protect itself from detonation. The factory timing curves starts to pull timing at 220 degrees and by 240 degrees it has pulled 6 degrees of timing out at any real load point. (The factory car has to contend with, low octane fuel, high underhood air temperatures, high intake temperatures from heat soaked intake and runners)

A NASCAR on the other hand keeps, the engine heat high which helps with power but keeps the intake charge cool which also helps with power. The intakes and carb are fed cool outside air, they use high octane race fuel that resists detonation, and the intake is separated from engine oil and heat. A dedicated race engine set-up properly can use heat in the correct places to its advantage.

GREGGPENN

I’m surprised there hasn’t been discussion/mention of oillimits. IIRC, dino oils have aflashpoint around 260 deg – with synthetics pushing 300+. That extra 40-50 degrees is the extraprotection that synthetics “offer”. That said, I question if a 1970’s engine could really run over 300-degfor any period of time. It seems likethe oil would burn and the pistons seize. Temperature gauge accuracy comes to mind.



The original question is about an L98 that has a 195-degstat. (LT1’s used a lower temp stat becauseof the difference in water temps. Theyare measuring temps on the frontside where L98’s are measuring on thebackside. I don’t believe the lowertemp stat was to run more aggressive timing with their higher compression…sincewe all know the bottom-end of the temperature range is what’s controlled by thestat. Engineer’s only want temps highenough to burn cleanly for emissions.



Considering the huge difference in combustion temps versuswater jacket temps, it’s hard to guess what cylinder wall temps are…especiallyonly a couple inches between combustion and water. It’s on the backside/outside of thosepistons that the rings are riding on a super thin layer of oil.



Of course, the question of timing/detonation was the otherpossibility. As Brian mentioned, timingis pulled in response to temps AND in response to pre-detonation. LOTs of timing can be pulled before audiblepinging occurs – and pinging doesn’t mean damage is happening.



Most threads I’ve read over the years seem to point to theflashpoint of your oil as the reasonable ceiling to what your temperature limitshould be. If I was worried, that’swhere I’d be looking. For overallrunning range, Vizzard has a chart of what he believes you should be shootingfor. (It’s based largely oncompression.) Mostly, his chart isgeared toward minimizing/eliminating effects of timing being pulled via knocksensor feedback. After all,performance is a big part of his bag.

desertmike1

I drive an 014 Silverado with "Electric fans", and it runs 210°f up hill, down hill, and idling..

For that matter, every one of my cars; except the Vette run consistent temps..