apex26

Just did 2 days at the Glen, Monday was chilly and the oil temp stabilized at 280. Tuesday got to 80 and the oil temp got to 300--with the heat on max, so I had to call it a day at noon. The car has the LG radiator with integrated oil cooler, 160 thermostat, and the track spec hood vents. It was turning about 2:11, probably some 2:10 lap times with 4 year old (well stored) almost used up Hoosier A6's, T1 bars, and poly A arm bushings, stock motor. Joe at Phoenix said make sure all the cracks are plugged and the center hinged air scoop is working properly. His next suggestion was to remove the A/C, which cooler blocks the radiator. Last resort would be things like another cooler in series, or a whole different setup. Joe is great, super helpful, but I'm afraid he's going to have to fab up another cooler in series or change out the radiator and start all over. I'm so sick of it I'm going to get his expertise on it to solve it once and for all, then headers, intake and dyno tune by his experts. Anybody run another cooler in series, or other input much appreciated. Definitely removing the A/C--but doubt that will be enough. I'd prefer overkill rather than half measures, it rarely sees streets, and it will run more HP with the minor mods.

synner

Personally on my camaro I deleted the stock system and went massive with an improved racing thermostat. I didn't like the propensity for leaks in the stock system and internal coolers never seem to be enough for seriously tracked cars. I went through a couple different sized coolers before settling on an extra wide 50 row Earl's. It's about as tall as my radiator, haven't seen a temp above 245 in blistering heat. Added a bigger radiator, trans cooler, and diff cooler; now no more heat issues ever.

I'm sure someone can help you size what fits in a C5 but going big early will save you headaches of going back later when its not enough or you add power. Just have a thermostat for those days it does see street duty.

kmagvette

Just get a dedicated oil cooler like the one Rippie sells nice easy install. You are going through the same progression path I went through. After going to a dedicated oil cooler, you "should" be fine with just using the water cooling part of the radiator, Water Wetter helps some too...for now. Your oil lines (at least the top one) should be long enough to reach the Setrab.

With the dedicated oil cooler, I see a max of 245* at The Glen, on the hottest of days. That said, My cooling has gotten a little nutty.

• Ron Davis Radiator with all extra plastic on the shroud removed
• Setrab Oil Cooler (in front of the radiator)
• Setrab cooler for the Power Steering (in front of the radiator)
• Forced air cooling on Radiators for Diff and Tranny
• Removed the A/C, all the parts sell quickly on eBay

And a 160* stat. It runs too cool on the road with the stat. I need to put Saran Wrap on the oil cooler for street use...but I rarely drive on the street.

Hope that helps, and hope to see you at The Glen.

Spaggs

I had Rippie Racing fix me up with a Satrab 925, bigger than they advertise, and it keeps oil nice and cool, even on hot days at the track. Next thing I do is a bigger radiator and new hoses.
Spaggs

Quickshift_C5

First time I've seen anyone mention a larger cooler than the unit DRM calls "race". What is your max oil temp using the 925? How was fitment?

I've seen reports of oil temps still a bit high using the 625 cooler as well. Temps of 260F. It looks like the 925 is 3" taller and 3" wider. That would still fit very easily. Setrab rates the 625 for 325-425HP, and the 925 for 400-475HP. Interesting. I have a 625 sitting in a small pile of parts waiting to be installed along with a Dewitts radiator. I'll be purchasing the SPAL fan upgrade to go with the combo.

bellwilliam

OP: what's your water temp ? if that's not the issue, why trying to swap out radiator ? if oil temp is an issue (300F is okay, hot, but not crazy hot), then an additional oil cooler would do. no need to go crazy with too big of an oil cooler, it blocks too much flow to radiator, and cooling would be an issue for street.

that said, I believe simply removing A/C will be fine, it probably will bring oil temp down to ~270F, which is perfect.

bj1888

External cooler. Even with temps in the mid-90s, I'm not hitting 280. And make sure your radiator is sealed really well. With the added flow from the vented hood, you want to keep the air from being sucked around the radiator.

JHrinsin

That is the reason and the beauty of using a thermostatically controlled adapter like ones from Improved Racing. It only allows the majority of the oil to flow through the cooler loop when the oil gets hot enough that it truly needs to be cooled. If the oil is not hot enough, 95% of the oil flows back into the engine without going through the cooler loop. Its the only way the oil cooler setup should be plumbed for a car that is also driven on the street.

3X2

Let's start with something simple. Is the radiator clear of debris? try blowing it out from the engine side frontward. I've built many C5's and C6's with in radiator EOC's with no overlt high oil temps. If you still have a/c, then that may be an issue.

paul69camaro

How long are your sessions? What weight oil are you running? Just as a point of reference, with the Ron Davis Radiator with the built in EOC, I'll get the 5-30w oil up to 265F in a 25 minute session at Cota in 85 degree weather. Water temps never really move from around 212F. Reason I ask about the oil is if you are running something thicker that can cause some extra heat.

apex26

Just returned from dropping the car at Phoenix. Joe said pull into the showroom, he put down a blanket and crawled around looking for problems. No debris, and only a few bent fins blocking flow. The center hinged scoop is working as designed. He called out mechanic Kurt (2x National champion) who said best solution is as stated above, a cooler in series. He said the oil pump is plenty strong if it has good pressure now--they use the same pump on dry sump systems, very good pumps. He said packing the cracks is very important, and removing the AC helps. Told him the power steering got notchy when the car got so hot, he says that happens to his car, and he knows it's time to change the fluid. They don't use redline synthetic, mentioned another brand I forgot but will get info on, they like better. I stressed with Kurt that as far as cooling, too much is just right, can always block it off. I was running Amsoil 5w30 per their tech's advice, but Joe said that's way too thin. They run 15/50 Mobil 1, BUT, they don't ever put a load on the motor until the oil temp is 125 minimum. One customer went out and romped on his motor when too cold, and spun every bearing in his 15k motor--didn't listen apparently. They did ask water temps, which were 220 when the oil was 300. Their cars run 260 to 270 oil temps all conditions. My brother the engineer read somewhere that antifreeze reduces cooling efficiency by a whopping 25%, so he suggests water and water wetter for anticorrosion, get rid of the antifreeze right away. Joe also said he had a vented hood but didn't think it was doing much, if anything, so when they wanted to penalize him with weight for the vents, he went back to a stock hood. Thank you guys for excellent inputs. We'll see what size cooler they write up, I think overheating will end, even though the car will have more power.

paul69camaro

NSFW

Would a C6-style bumper for front-feeding the radiator help?

Dan H.

I'm going to WGI in a little over a week, excited to be back up there. I have the stand alone DRM oil cooler unit. Highest temp I've seen is 272 on a really hot day. I'm not quite at your pace at the glen, but my goal is to be pretty close on this trip.

apex26

Just more info update: Joe doesn't like K&N air filters, he says people don't clean them and when you drive in the wet all the debris forms a paste that blocks flow. He recommends the stock GM paper filter. JHrinsin mentioned the Improved Racing thermostatic cooler adapter block, can't find the receipt in the massive records, but believe my car has that one already, the best choice, especially if going to a thicker oil--which is dependent on final temps. When GM was designing the C6, they went to the race team and said give us your wish list--number one on the list was more air in the front. There is a kit to hack up the front license area, but it looks like crap, and guys like Dan above solved the problem without it.

Bill Dearborn

When I had my C5Z I installed the DRM Ron Davis Racing Radiator kit with the built in oil cooler. At the time I purchased the kit the oil lines ran from a line adapter block fastened in place of the oil filter and a large remote filter was mounted to the radiator support bar. I ran that system in the Z for close to 6 years. On the hottest days with a stock thermostat I would see a max coolant temp of 200 degrees and max oil temp of 230 degrees. This was when I was running Phoenix CMR's 40 minute sessions.

I did find I had to clean the radiator and the AC condenser now and then. Not for the typical grass and road debris but for stuff I picked up on track like Speedi Dry. That stuff embeds itself in the fins and is very difficult to get out. The radiator was the easy part because I could take it out and drop it face down on the driveway a few times and the Speedi Dry would come out of the fins. Three or Four drops from about 2 ft above the surface usually resulted in a fairly deep pile of crap. The AC condenser wasn't as easy since I didn't want to discharge the refrigerant. With that I used a small pick filed down so it could go into the fins and pick out the Speedi Dry. That was a real PIA and before I was finished I felt like I was going to go blind. Using water pressure from the rear and the pick from the front I finally got it clean. That helped a lot.

Keith may remember the reason I got into the Speedi Dry clean out. We were at a Phoenix CMR event and somebody didn't pay attention to what was happening to their car and oiled down close to half the track. They had to use 120 bags of Speedi Dri to clean up the mess and the track was shut down for a couple of hours. When we finally got back on track we were driving in clouds of Speedi Dry. Enough that it was difficult to breathe the mess. The cooling system started acting up right after that. Years of driving through much smaller amounts of Speedi Dry can cause the same issue.

Another major factor in C5 cooling is making sure the seals between the AC condenser and the shroud are in place and not damaged. Under high heat and lots of air pressure they tend to blow out into the engine compartment letting a fair amount of air bypass both the AC condenser and the radiator.

The center air dam on the C5 is spring loaded to protect it from objects on the road but the spring will let the air dam bend backwards at speeds above 100 mph. I found that using some duct tape wrapped around the bottom of the radiator support and looped over the top of the center air dam would keep it from bending backward. It took just three short pieces of duct tape to hold it in place. One on each end and one in the middle. I didn't even need to replace the duct tape that often. I think I replaced it once in 5 years.

Bill

apex26

Hi Bill! Always great to hear from you, since you've done HPDE since C4's were new-a walking encyclopedia. I'll tape up the center section for sure. Having had shoulder surgery and going to PT, struggling with this stuff just now might not work well. Also, Joe has sets of headers that are take offs and sells them for half price. After a dyno tune, the little C5z will be more capable against the new monster HP cars, as well as not overheat.

kmagvette

Wasn't me Phoenix CMR is a Ford event, so oil leaks are common

Any one doing the Chin event at the Glen on 5/14->15. Bill, is it time for you to migrate north for a few days, yet?

Dan H.

Yup, I'll be there. Garage bay 14. I have a blue C5 and my buddy has a black E36. Stop by and say hello!

Dan

pocorojo

I'm looking for help here in Phoenix AZ. I have a 2001 Z06 with an LS2 punched out to 427 CI. It puts down 515 at the rear wheels, but the oil temps in regular driving here in Phoenix get to 240 degrees. I have a Ron Davis radiator but the engine builder didn't want to use the cooler in the radiator. The car has a Tiger Shark front and rear facia. The shop that built the car(for the previous owner) isn't in business anymore. Can anyone make recommendations for a shop in Phoenix that can install a remote filter and cooler setup for me. I'm 61, recovering from prostate cancer treatments and really can't do the work myself anymore. Any suggestions or guidance would be greatly appreciated.....Thanks