CHJ In Virginia

I got tired of having to back off, short shift, etc. due to excessive oil and coolant temps. Last year I installed a DRM oil cooler kit that worked wonders, dropping the max oil temps almost 30 degrees. This year the project was the installation of a DeWitts high capacity radiator in my 03 Z06. Unboxing and examining the unit, I can say that it is very well constructed total aluminum radiator. No crappy plastic side tanks and a much better design drain valve which won't break the first time you use it. Construction is fully welded - wish I could run a bead that nice.

INSTALLATION - the unit was an easy install with all the brackets, hose nibs, etc. in proper location. It took about 4 hours to complete the install, change belts and all hoses. The only install problem was a minor fan shroud clearance issue with the driver's side hose connection. I had to use the Dremmel to trim about 1/4" of plastic off the bottom of the shroud brackets to allow them to slide in place. Other than that small adjustment the unit is truly an exact size replacement.

RESULTS - I ran the NASA HPDE event this weekend in association with the UTCC event at VIR. Sunday was the ultimate test - 107 Degree ambient temperature during the second run group at 2:30 in the afternoon. REALLY FREEKING HOT !!!! I never saw coolant temps above 226 even at the end of the 30 minute session. I used to run high 230's in much lower 90 degree ambient days, and have to back off to cool the engine down. As a bonus, the oil temp dropped about 3-4 degrees due to the engine running much cooler.

I am definitely a satisfied customer. The radiator installed easily and kept the engine operating at acceptable temps even on a 107 Degree day !!

drivinhard

I was amazed at how the fluid temps would take off between the morning and afternoon sessions.

90 degrees, not that big of deal
100+ degrees, oil/coolant through the roof

with only a ~10 degree swing in ambient

that's the hottest ambient I've ever run my car. I was getting hot and my car (currently) is only a 2-3 lap and in car.

sothpaw2

Great! I might do that next year since I have the DRM oil only cooler now. What water temp did you used to back off at --239? How high did your oil go? I was surprised on a 101 deg day to hit 271 oil with the cooler. Fortunately, the sessions were short at 20 min.

CHJ In Virginia

Southpaw - I uses to back off at 235-240 deg on coolant - the engine starts pulling timing at 230 so it is a waste to try to push after that. Prior to oil cooler I used to see 280 - 290 deg oil regularly, yesterday the highest I saw was 266 on the oil. The radiator adding extra engine cooling definitely helped the oil temp also.

filmjay

Awesome! Thanks for sharing the info.
I'm getting ready to install the LG radiator and was looking for some benchmarks.

0RAAMaudio

I was towing around 1,000 lbs of 1946 teardrop trailer, beer and race tires, 105 degrees, 4,700ft elevation, up towards Park City, not sure the altitude, oil hit 262, water and trans 232, decided it was time for the cooling I had planned, now!

It was either a Dewitts or RD for my C6 and the Dewitts was quite a bit less money. I was out in the shop looking at my C5 ex race car beat up RD and it was still working fine, no leaks, etc when pulled, I decided to spring for the Ron Davis.

Either one would of been plenty for my needs I am quite sure.

Randy at DRM took care of the order for me, thanks buddy

It will be here soon and with the secondary trans cooler, oil cooler, etc, should do a fine job for my needs. (This is the only performance car I ever bought with a slush box but it is no longer that slushy

Rick

johninar

Good write up. I just got back from Hallett and I'm still working with higher temps than I should have. I put the Dewitts in and my car is stock. It was 100 ambient this weekend and I would see north of 235 water and 265 oil. The oil temps are okay, but I really should not see 235 water. Hallett is a relatively short course (1.8 mile/ 10 turns) and I never saw those water temps with my other C5.

I've done the usual, clean the condenser, changed the t-stat. I'm running distilled water and water wetter. My last oil analysis was last month and came back without any issues.

I'm not sure where to go next.

drivinhard

change tires? stickier tires allow a higher duty cycle on the engine for a lap.

I've run 25 degrees cooler hoosiers vs nittos, pushing the car as hard as would allow for either. When the tires just don't allow as much throttle and speed, it will run cooler.

0Tom@Dewitt

That does sound way too high for the system you have. Check the core for ballooned tubes or crushed fin. You should be able to slip a zip tie right through core fin but if it looks like this, the radiator is toast.

Armycop

well now I'm confused...
My last outing at Autobahn in June I was running water around 230 and oil went to 292, which scared me and so I backed off a few laps to cool 'er down. But even at these temps I had no loss of power, like the engine was pulling timing. Hell, if I hadn't glanced down at my DIC I would have never noticed the oil temp to begin with!
I read frequently on here about our LSx's running warmer than iron blocks and liking it that way. Up until this post I wasn't concerned about these temperatures. The usual track stint is 30 minutes, give or take an off track incident, which puts the actual go-fast times at around 15-20 minutes a session. Another 30min-1hour cool down and I'm at it again. Since becoming addicted to the track back in 2008, this is the highest temp's I've seen at any venue. Am I being paranoid (probably) or is there a real danger of grenading a piston here?

whatsaytheforum?

CHJ In Virginia

My rule of thumb for engine longevity is keep coolant temps to low mid 220's max and oil temps to low 260's max. Other opinions may vary since they are like belly buttons and everyone has one. The stock ECU programming starts pulling timing at 230 Deg coolant and I think 300 deg oil causes the warning bells to go off. Ambient temperature makes a lot of difference - a 107 deg day requires MUCH more cooling than does a 90 deg day. Humidity levels also come into play in the cooling equation.

DRUGschnorr

Have been dealing w/ the 100+ temps in central texas for a few months.. In May i was seeing 250 water temps. the Nanny comes on and whines after ~15 of track time.one lap in 5th gear brings temp to 230 and i'm off to the races. Oil was hitting 300 and i would start cool down 2 laps before the white flag.
I had install a VRAM CAI and wondered if it was stealing a bit of air from the cooling systems..Taped the shrowd cuts w/ gurillia tape and was rewarded w/ peace of mind. June trake day exchanged the Z51 oil cooler with a Z06 oil cooler( added extra 3/4 qt of oil to system).. water still in the 245-250 range. oil never over 285
July added Dewitte cooler and dual fan....July in Ft worth water never saw 235.. oil was 275... this month will plumb the oil cooler to the radiator cooler ( air cooling then water cooling) hoping for increase of total oil volume ( got to have oil lines made to complete the job.
Y'all were right when you said you time and money go to the car when you get the bug. The fuel mileage is only exceded by the smile mileage.

I'll report back august 16th after the MSR Houston run... expect 100 plus and 95% humidity..

johninar

The radiator is new. No damage that I can see. Temps really didn't change any after the install. Same tires I ran last year.

I'm just stumped. Can water pump partially fail? What to check next?

dbirdz06

That's a bad radiator??

BADZ

Ttt

So it's best to run just regular H20 and water wetter during these hot summer days?

johninar

I think so. Antifreeze does what it says. I just add enough in the fall to get me through the winter here. Then drain and flush in the spring before the start of the new season. Many threads on the subject here.

After blowing the radiator hose twice at Hallett I learned my lesson. The first responders were beginning to really dislike my car. Some tracks will not allow antifreeze on their tracks. It sure is slippery.

varkwso

The Delta T is not always linear for every degree of temp change. Mostly due to latent heat not removed...

And the bottom feeder gets the radiant hot air right off track surface.

0Tom@Dewitt

Yep, it should look like this

geerookie

It will work better if you do water before air. Water cooling is more efficient. Think about when welding metal, if it air cools it takes longer than if you dip it in water...even 200 degree water.

Gray Ghost GS

+1 for the DeWitts radiator! I had one in my C5 for many years before I damaged it and had to install my OEM (back up). I was very impressed with the price, quality and performance of this radiator on the road courses. I need to get a new one soon - the heat this past weekend was incredible! Tom, you guys make a superior product! Mike