Set up is in my sig-

Temperature doesn't break above 235-240, but sometimes will run at that temp for some time while driving. Ultimately, the AC is the culprit (slowly creeps back to 210 once I turn it off), but I live in Arizona and it's a little warm this time of year.

My question is, what would you consider the max "healthy" running temp for my LS1? I want to get as many miles out of the stock bottom end.

 

240 is quite high. The PCM does a lot of power reduction at those temps. Those temps will be really testing the coolant systems ability to maintain pressure and keep the fluid liquid.

Are these high temps in traffic or while cruising? Either way you need more airflow and/or a better radiator.

 

240 seems way too high. Maybe time for a double core radiator?

 

I agree...240 seems to be getting quite high. Check your radiator for dirt/debris. My LT1 ran upwards of 240 at autocross even being a reverse flow system. Turns out my radiator was so gunked up that NO fluid would come out when I pulled the drain plug...only had 70K mi on it.

New Griffin dual core radiator and I sit around 170-195.

 

Yeah 240 is way to high IMO. The stock fan settings I think have it around 225-230 at the most and even that a lot of people feel is too much.

I personally like to keep it right around 200.

194-198 while cruising and 204-206 while going slowly around town with the AC on. Once it gets past 210 I don't freak out but I try and readjust things.

 

When I say 240, it might have peaked at that temp for a VERY short time period. After the AC is on for a while, it will typically creep up around 220-230 and maintain, but when I kick it off, it's back down to the 200-210 range. Granted, the last few days have been 106-110* out here.

Regardless, I may look into the double core radiator. Are there typically any clearance issues? Not a ton of room with my twin 4.5" intercoolers..

 

I went with a custom install using a universal Griffin radiator that is the same size as the AC condenser but twice as thick as my stock unit. It is the one the turbo guys use to stand straight up for more room. Also had to custom make a fan shroud to retain the OEM fans. You can look into picking up a LT1 radiator from the parts store since LT1 radiators are thicker than LS1 radiators. BeCool offers a dual core direct replacement, but it's at the expense of $600. A parts store replacement+new coolant+blowing out condenser could be your cheapest option and give you cooler temps.

I would think 180-200 is optimal range.

Edit: My readings are coming from the factory head location using an aftermarket SpeedHut Revolution gauges. Which I expect more accurate readings than OEM unit.

 

Contrary to what most may have you believe. That is actually normal for these cars. Most settle for that little dummy needle on the dash and go to bed feeling warm and fuzzy at night. On a stock engine the high speed fan doesnt even come on till about 223 or something around there. So we know, and can expect, to be in that area when we are in the hottest part of the country, running ac, and in stop and go traffic. While I have never seen 240, I have seen about 237 in the above mentioned conditions. I noticed no lack of power or detonation. So while that was normal, I definitely understand its on the upper edge due to conditions. It would not be a bad idea, if you see those conditions frequently, to try to prevent it. Suggestions? Aluminum radiator off ebay, blow out condensor and radiator (they accumulate a lot of crap over time), maybe a water wetter type product, better fans, turning off or turning down the ac when motor temps get that high.....

 

I would think oil also comes into play for optimum temp. Oil needs some heat to do its job to its fullest, but what ideal engine temp that is I don't know. I would also be concerned with detonation or spark knocking.

This is something I'm interested in hearing from the more experienced guys as I'd like to lower my temp, but don't want to go too far.

 

With it being a 98, I was initially not too concerned about seeing ~235, as I've heard the 99+ thermostats will read 210 on the gauge but could range from 180-240 of actual running temp. Not sure how valid the claim is, but I've heard it from many experienced LS/F-body guys.

Appreciate the input from everybody. I'll look into some options, but would like to refrain from any fabrication, if possible. Budget isn't really the issue, but I'm trying to keep as much in the bank as possible..I know forging this thing eventually is inevitable

 

Ebay aluminum radiators are about 150, and blowing out the condensor and existing radiator is free.

 

before you start blowing money on radiators and all these fan setups, get a 160 tstat if you dont have one yet and adjust the fan settings in the tune to come on earlier. when my car was stock it was seeing 230ish temps in the heat sometimes a little higher, now with the 160 and my fan settings changed i see 180 cruising and 200 with the ac on in traffic.

 

The temp gauge is a dummy gauge. Get it on a scanner to see what it's actually running at. It shows 210 when the temp stabilizes and the second fan is able to kick on and off. For example, my car runs at 185-190 in the summer in Florida with the a/c on (as monitoring the ECT via HPTuners). It shows 210 on the gauge.

 

Also could just make sure your cooling system is clean. If the radiator has built up some crud over time in some of the passages it can reduce its cooling capacity a fair bit. Fairly cheap to do a coolant system flush. I had to do that to my old car as it started to run warmer than it should have and flushing the system made a huge difference.

 

This guy seems pretty bright, I didn't mention the specifics of the factory gauge bc he appeared to understand how it all worked. Its pretty hot and sticky here, with no ac, aluminum radiator, some low speed idling, and 3 dig races I saw temps get to 230 the other day (i have an external gauge). So, I definitely feel for this guy.

 

This is absolutely correct. The '98 gauge is not the same as the '99+, it's a 3-wire sensor that actually does register small changes in temp unlike the '99+ cars which generally stay within a hairline of "210" for anything in the ~185-235° range. The needle on my '98 will move around noticeably for changes as little as 5-10° within the above range.....but my '99, '00 and '02 did no such thing.

While the '98 gauge is much better than '99+, it's still not an exact science as the markings and size don't really translate into an ideal readout. A scanner is really the best way to verify exact temps.

What are your current fan settings?

The stock setup is as follows:

Low speed on/off: 227°/218°
High speed on/off: 235°/228°

So really, these temp ranges are pretty normal for a stock car in very hot weather, especially with the A/C on. But with your setup, I imagine there has been some tuning done which probably also included fan adjustments. It seems as though your cooling system is maxed out in these severe (106°F+ ambient temps) weather conditions when the A/C is running, which is to be expected with the setup you have.

A colder t-stat probably won't help, all this does is regulate minimum temp but won't reduce maximum temp if the system is pushed beyond its capacity to cool. To reduce maximum temp under those conditions, you will need to increase airflow and/or coolant capacity, and/or do things to reduce engine bay heat (such as header wrap, ventilated hood, etc.)

Considering your climate and setup, I would agree with the folks suggesting a larger capacity radiator. Also make sure that there are no blockages in airflow (such as debris in the condenser fins or missing air dam pieces) or clogs in the cooling system, and that the water pump is in good working order.

 

160* stat besides being too cool wouldn't be any different than a 185* at those temps. They'd both be open all the way. My GTO with stock stat runs 190-195 * measured on the highway and rarely goes over 200* anytime. I do have my fans programmed to come on earlier than stock.