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Hey guys, just got back from another track day and it looks like I still need more cooling on my 90' ZR1. Before my last track day I installed a 2 row cold case aluminum radiator. It was a significant improvement and did well at the track when ambient temps were in the 60's, but pushing hard yesterdat with temps in the 90's it couldn't keep up. Oil temps hit 265 and water temp got up to 250 in one afternoon session.
Does anyone have experience with a dewitts spal fan upgrade? How about big mouth radiator intake? What other options am I missing?
I am anxious to install my turbo kit, but want to get my cooling system sorted first.
Last edited by jrtoffroad; 09-24-2022 at 05:48 PM.
You really should have gone with the 3 core radiator since you are apparently heavily tracking the car. The ZR-1 does have a mediocre system that can cause issues.
Having the upgraded fans is not going to solve your issues on track. Your airflow at track speed is more than sufficient to cool the car.
You could have a blockage in the oil cooler or AC condenser causing poor airflow performance getting to the radiator.
The other item could be the internal vane on the waterpump. Depending upon system maintenance you could having pitting/holes in the vane that would result in poor performance.
The other item is your driving style. Continuous high rpm usage while in a lower gear may feel fun or like you are getting better times, but you may find the ability to be in a higher gear and not having to transition the shift will result in a more consistent time. The added benefit is you are not over taxing the waterpump and cavitating the circulation.
There are ways to get the system in the ZR-1 to work better, but you will always be compromising i between is it a race car or a street car.
Sweet. a LT5 on the track.
Ouch. that temp range is enough to start breaking oil down
Factory thermostat is a 180 correct.
Do you have the stock water pump.
I see flowkooler makes a HV pump.
I can vouch on a "SBC"Coolant temp drops 10 deg with a HV pump. Also makes the bottom hose collapse. I made a copper coil to eliminate the hose from collapsing.
If i were you. I would find someone that tunes LT5 PROMS. Pull your OE and save. Get a 2nd PROM customize the tune for track day's.
Increase fan speeds, Fan on. Temp.
I flashed my LT1 fan settings dropped temps down 10 deg.
never looked at the LT5 Bin file. For other tricks.
i always wanted to tune a LT5 that would make fantastic power from just a tune.
Dont these come with the deep Z51 air dam?
And yes the BMAD really does what its supposed to its not a gimmick.
You could fab one that sticks out a few more inches not really needed though.
Kick **** oil cooler is always a plus
Once a yr on al my cars esp vettes I (from the backside of the radiator) flush the fins out with a garden hose...
That is the best habit of P.M. ive gotten into. AC gets cooler quicker fans run less its a win/win. And its free
Seen guys mod their hoods with air extractors of all kinds, more the merrier
Really like the late model one on the ZR1? not sure if one could make one similar if there is even room.
Can always go get a spare hood and hack it up
I respectfully disagree about 2 vs 3 core radiator. This radiator uses large tubes. A larger tube 2 core has been proven superior to traditional 3 or even 4 cores. Most manufacturers use smaller and smaller tubes as they add cores, so although a 3 core sounds better, often they are not.. Here's a picture from summit racing as an example:
Pump cavitation does not seem to be the issue. I have tried changing my driving to reduce the rpms and it does not seem to significantly cool even if I bring the rpms way down.
Wish id brought my ir temp gun, would be nice to know the actual radiator temp to help determine if there potentially a bypass, cavitation issue, or wp issue.
The oil cooler and ac condenser are in excellent shape, I cleaned and inspected them thoroughly when I installed the radiator about 3 weeks ago.
My car does not run hot in normal spirited driving, just repeated hard laps on a hot day.
Sweet. a LT5 on the track.
Ouch. that temp range is enough to start breaking oil down
Factory thermostat is a 180 correct.
Do you have the stock water pump.
I see flowkooler makes a HV pump.
I can vouch on a "SBC"Coolant temp drops 10 deg with a HV pump. Also makes the bottom hose collapse. I made a copper coil to eliminate the hose from collapsing.
If i were you. I would find someone that tunes LT5 PROMS. Pull your OE and save. Get a 2nd PROM customize the tune for track day's.
Increase fan speeds, Fan on. Temp.
I flashed my LT1 fan settings dropped temps down 10 deg.
never looked at the LT5 Bin file. For other tricks.
i always wanted to tune a LT5 that would make fantastic power from just a tune.
I'm running a stock waterpump. A lot guys actually try to slow the lt5 water pump down to help prevent pump cavitation and reduce radiator bypassing (there is a circuit the allows coolant to bypass the radiator at high rpm in the lt5).
I'm actually running a megasquirt ecm. So its been fully tuned with fans turned down and they are kept kept on regardless of vehicle speed.
Over time found a thinner radiator with good fans is better than a thicker core with good ones.
Quicker air is pulled through the better it cools...to a point.
Pump cavitation does not seem to be the issue. I have tried changing my driving to reduce the rpms and it does not seem to significantly cool even if I bring the rpms way down.
Wish id brought my ir temp gun, would be nice to know the actual radiator temp to help determine if there potentially a bypass, cavitation issue, or wp issue.
The oil cooler and ac condenser are in excellent shape, I cleaned and inspected them thoroughly when I installed the radiator about 3 weeks ago.
My car does not run hot in normal spirited driving, just repeated hard laps on a hot day.
Everything you are describing points to cavitation.
When I can run an LT5 for 2-6 hours on track with no overheating of oil or coolant, id say my system is functioning pretty well. But I’ll step out of the conversation.
Everything you are describing points to cavitation.
When I can run an LT5 for 2-6 hours on track with no overheating of oil or coolant, id say my system is functioning pretty well. But I’ll step out of the conversation.
Not sure why you'd step out of the conversation. Sounds like things are working great for you. What are the specs of your engine and cooling system?
That's awesome your able to run that long. Do you compete in endurance racing with your car?
The only reason I doubt cavitation is that dropping the revs doesn't magically fix the issue. I would expect when the pump stopped cavitating i would see a nice reduction in temp fairly quickly. This does not happen, not even on a cool down lap. Once its hot it takes a long time to cool off. But, that doesn't mean I'm right.
I am running a 368 with 60 to 70hp more than stock, so it does tax the cooling system a little more than stock.
To give an idea of the environment, here's what the course and my speeds look like. It's about 4900' elevation and the weather was low to mid 90's yesterday. Outside temp is a big factor, car was much happier in the morning.
I tried the "super" spall fan = did not see any real difference. Just more noise. Wrapping the headers helped the most so far.
A club member ( years ago) added 2 fans in the intake under the car, under the license plate; He said that worked well. If I remember correctly, they were 8" fans.
Another friend had opened the license plate area and made an adapter to funnel the air into the rad. He said it worked.
If I keep the car I'm going to replace the factory pusher fan with 2-8" pushers (in front of the rad) and add an oil cooler.
Oil temps hit 265 and water temp got up to 250 in one afternoon
this tells you everything right here. Your oil temps are too high to transfer to your coolant and then cool via radiator. You need a (larger) oil cooler, I would personally go with a stacked plate design. This will have the added benefit of increasing your oil capacity, which will also keep your oil cooler. There's a reason that c6 Grand sports with similar hp use 11qts in their dry sump system...
I'd look for a spot with some decent airflow and out the largest derale stacked plate oil cooler I could fit in it. Maybe two small ones if you have to. You could remove the fog and cornering lights, 3d print up a little air intake and box for a pair of small.oil coolers, and use some LED strips for turn signals somewhere else.
I tried the "super" spall fan = did not see any real difference. Just more noise. Wrapping the headers helped the most so far.
A club member ( years ago) added 2 fans in the intake under the car, under the license plate; He said that worked well. If I remember correctly, they were 8" fans.
Another friend had opened the license plate area and made an adapter to funnel the air into the rad. He said it worked.
If I keep the car I'm going to replace the factory pusher fan with 2-8" pushers (in front of the rad) and add an oil cooler.
Fans don't help at speed. in fact, they impede flow, that's why most oem fan shrouds include a bypass for at speed, the air won't get pressurized by the fan blades impeding the path of the air.
Fans are only.for xooling your vehicle in stop amd go type.situstions. And before anyone says it, a lower temperature thermostat will NOT help at all. Thermostats set your minimum operating temperature, nothing more.
Fans don't help at speed. in fact, they impede flow, that's why most oem fan shrouds include a bypass for at speed, the air won't get pressurized by the fan blades impeding the path of the air.
Fans are only.for xooling your vehicle in stop amd go type.situstions. And before anyone says it, a lower temperature thermostat will NOT help at all. Thermostats set your minimum operating temperature, nothing more.
This is interesting. this rule should apply. Fans could block/ impede natural air flow.
My experience with C4's coolant temp after dropping in a 383 My temps went up driving at speed.
No problem at idle.
I installed an aftermarket aluminum 3 core radiator. This improved temps. However pushing at the track. And datalogging my new tunes. I did not like seeing temps 200f+. My oil temp was slightly high as well.
I cut my front plate panel made a ram air. 94 already has a channel formed into the styrofoam reinforcement. This also improved coolant temp. I experimented with my PCM.
factory fans are split Fan 1 / 2 parameters.
3.5k RPM , Oil temp. Fan1@ 132f/ fan2 @ 136f
Not good enough for my likings.
I Increased fans RPM to 4.4k
Decreased oil temp. Fan1@ 104/ fan2 @ 109f
Coolant/ Oil temp resolved. Never hit temps above 192f.
You are spot on with this poor LT5 oil temp is actually elevating the coolant temp. the resolution is
Either doubling the oil capacity. Best option routing the oil into a cooler and or fan assisted.
After. This should allow attacking this course with comfortable temps.
May the torque be with you.
I experimented with my PCM.
factory fans are split Fan 1 / 2 parameters.
3.5k RPM , Oil temp. Fan1@ 132f/ fan2 @ 136f
Not good enough for my likings.
I Increased fans RPM to 4.4k
Decreased oil temp. Fan1@ 104/ fan2 @ 109f
Coolant/ Oil temp resolved. Never hit temps above 192f.
been a hot minute since I’ve actually looked at fan speed parameters for an LT1/4 car, but the LT5 is either off or on for fans. You have controls for fan 1 and fan 2 and desired temps for them to come on.
Originally Posted by THE 383 admiral
You are spot on with this poor LT5 oil temp is actually elevating the coolant temp. the resolution is
Either doubling the oil capacity. Best option routing the oil into a cooler and or fan assisted.
After. This should allow attacking this course with comfortable temps.
The ZR-1 is already equipped from the factory with an oil cooler.
Not sure why you'd step out of the conversation. Sounds like things are working great for you. What are the specs of your engine and cooling system?
That's awesome your able to run that long. Do you compete in endurance racing with your car?
The only reason I doubt cavitation is that dropping the revs doesn't magically fix the issue. I would expect when the pump stopped cavitating i would see a nice reduction in temp fairly quickly. This does not happen, not even on a cool down lap. Once its hot it takes a long time to cool off. But, that doesn't mean I'm right.
I am running a 368 with 60 to 70hp more than stock, so it does tax the cooling system a little more than stock.
I’ve eliminated the thermostat housing and thermostat. Eliminated the bypass, running a larger pulley on the waterpump to slow it down. Also ran a larger fluidyne oil cooler, but it seemed like overkill. And of course no AC condenser.
No additional scoops going to the radiator, fans only commanded on by the driver when coming into the pits. Car has been run in ambient temps around 105 and track surface temps way higher. Thank god for cool suits.
been a hot minute since I’ve actually looked at fan speed parameters for an LT1/4 car, but the LT5 is either off or on for fans. You have controls for fan 1 and fan 2 and desired temps for them to come on.
***Understood. The point was. After increasing my fans RPM and forcing the fans to start before factory. Helped my temps.
The ZR-1 is already equipped from the factory with an oil cooler.
What about dedicated fan to push/ pull air flow on the oil cooler.
I’ve eliminated the thermostat housing and thermostat. Eliminated the bypass, running a larger pulley on the waterpump to slow it down. Also ran a larger fluidyne oil cooler, but it seemed like overkill. And of course no AC condenser.
No additional scoops going to the radiator, fans only commanded on by the driver when coming into the pits. Car has been run in ambient temps around 105 and track surface temps way higher. Thank god for cool suits.
Reducing/ slowing down the water pump RPM with a larger pulley.
Did this net any gain on the LT5 did this help reduce coolant temp?
09-24-2022, 03:31 PM
Track Cooling Mod Results?
