Overtemping at idle or low RPMs

[Naf]

I have noticed that my V is overheating quite a bit now at or around idle.

I have attached my tune for your reference.

I am running the following specs on the engine

415ci with all forged parts
Ported LS9 Heads
Stock water pump
Ron davis RAD
1 7/8" headers
3" to 2.5" exhaust system
FAST 102 with 100mm MAF
Stock fans
160F stat
NAF Hood for MAX hot air scavanging

I have had the ECT get up to 112c while stuck in traffic had to turn off the AC just for it to drop 4 degrees

I heard if i increase the timing i should be able to cool the ECT, but i am hesitant...

[Sid447]

For what it's worth,

112c isn't anything much to worry about. I know it's not comfortable seeing it there, but GM purposely want the ECT's higher these days for better emissions.

The factory GM fan settings for example on a stock ZO6, CTS-V and Pontiac GTO are Fan 1 on @ 108c off @ 104c with the 2nd fan only switching on @ 113c and then off @ 109c.

Fitting a 160f stat won't change the ultimate operating temp, it just takes a while longer to get where-ever the system will eventually run at. In a cooler climate with a decent sized rad a stat would probably control the system, but in the desert there's not much chance. Also during the extended time you are below around 85c your emissions will be higher and also the engine will suffer higher wear in the cylinders.

I assume your car is an auto(?) If so it maybe has an oil cooler built into the water radiator. This isn't helping much, the trans temps are usually a bit lower than ECT's in the summer and it clearly won't be doing any "cooling" of the trans fluid in this situation; the opposite will occur.

You could consider buying a decent sized stand-alone oil cooler and when fitting it, disconnect the fluid lines to the rad, block them off and feed the lines to the oil cooler only. Ensure the cooler is mounted with an air gap between it and the a-c condenser (at least 3cm) and that should help some along with having either Dex 6 or a good fully synthetic oil in the transmission and something like a 10w60 (which is very popular in the UAE) in the engine.

You could also consider fitting a stand alone engine oil cooler also.

Also search for Evanscooling.com they do very good water pumps for the LS series.

[Naf]

Its a stick, I have a 10 pass perma-cool competition oil cooler with starlite hoses which is located at the lower grill inlet. The rad has no coolers built into it at all...and clearances are tight.

I am usin synthetic 10w30 as recommended by the engine builders. but i change the oil every 5000kms

I use to be runnin 92-95c which was on a 180 stat, but that was on a stock block with HC heads and headers.

If i can get back to that i would be happy, but at low speeds and low rpms the temp gets too high for my comfort. I am runnin dexcool 50:50 but still 110 in this car cannot be good. As for the AC condensor spacing stock was about 1cm and now with my larger rad its cut down to about 5mm. Ever since i got this new engine i have been havin issues like this and many others...

[Sid447]

Yep,

went through all of this before; mine is M6 also.
Fitted a PWR V8 supercar all-alloy rad (with no built-in cooler) a 30 x 30cm engine oil cooler with a remote-mounted oil filter (it's big -holds about 750ml of oil in just the filter alone). Removed the undertray to allow more air to circulate around the sump and doing all that helped. Already tried a cooler stat and found out what I told you in the first reply (using a scanner to verify everything). So went back to running a stock 88c stat as the PCM is set up for this. At times it will still go to 110c in traffic, just like it did with the cooler stat.
When air temps drop below 35c I can maintain 88c all day on the highway and will go to around 92c on the street.

I run 25% dexcool 75% water. It's more effective for cooling. Along with an 18psi cap.

If an engine develops more heat (power) than the stock version the problem is always going to be compounded, especially in the desert heat. I just take it easy on the car through the summer months, as like you I don't feel comfortable if ECT goes above 100c and look forward to October every year.

Couple of interesting articles attached.

[Naf]

Hmmm, thats a lot to swallow. I have to admit i am runnin LS9 valves so i should be fine, as the SC does excert a lot of temp and pressure on the heads...

I will research about the timing as well and install a EGT sensor to make sure i am not exceedin 1400F

Could i wrap the headers and install o2 sensor heat extractors for better heat suppressin?

[Mr. P.]

I would agree that is pretty hot (112* c = 234* f) but no hotter than my best friend's 2010 Z06, it's ECT is 230-ish. Is the engine always that hot, or just at low speeds? If the ECT is fine at freeway speeds then the radiator is not the issue, it is lack of fan airflow and/or coolant flow when parked. Another possible, the factory water pumps on LS motors do not circulate much water at idle, we run into this on trucks a lot of the time and increasing idle to 1000-RPM for a couple moments has in a few cases brought the temps down 10-15 degrees, but on our projects "hot" for us was 210 not 234!

Mr. P.

[Naf]

I would agree that is pretty hot (112* c = 234* f) but no hotter than my best friend's 2010 Z06, it's ECT is 230-ish. Is the engine always that hot, or just at low speeds? If the ECT is fine at freeway speeds then the radiator is not the issue, it is lack of fan airflow and/or coolant flow when parked. Another possible, the factory water pumps on LS motors do not circulate much water at idle, we run into this on trucks a lot of the time and increasing idle to 1000-RPM for a couple moments has in a few cases brought the temps down 10-15 degrees, but on our projects "hot" for us was 210 not 234!

Mr. P.

Well, the fans are workin the same way as before, the. Only variable is my engine. Its a 415 rather than a 350.

I will try and flush the rad just in case its not workin as efficiently as before. The tempp does drop one I move but only to 95-98c not my norm by far.

I am also droppin my timin slightly, I have a feelin too much timin may be the case of my issue.

[Sid447]

Naf,

with the fan settings you have set (F1 78/75 F2 82/79) which is impossible to reach; you will probably burn your fans out pretty quickly.