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I've done a fair bit of searching and forum reading but still haven't come to a great conclusion.
The car in question is a conservatively tuned lingenfelter LS7 C5 that makes 500whp
the issue is the stock radiator plus lingenfelter oil cooler (mounts to aluminum engine cradle and measures 11x4x2) cannot keep up with track duty.
after a warm up lap and 1-2 hot laps oil temperatures are quickly approaching 290-300 degrees, a cool down lap and then pitting in brings temperatures back down a little ways before shutting the car off until the next session.
I'm looking to drastically improve cooling to get back to my stock ls6 temp levels of being able to run a 20 minute session worry free while also using a new radiator setup as the foundation of my front end aero modifications.
Things I think I know: (can edit as better info is found or provided):
stock radiator dimensions: 24.8125" x 17.5" x 1
general rule of thumb for front breathing setup: mouth opening is 33% of radiator surface area.
acp front breathing setup is 24"x4" and claimed to be good for 475 hp
stock C5 fan CFM: 1600 (per Dewitts claim of 3200cfm fans being double stock)
forward tilting radiators generally remove 2" from the overall height of a c5 radiator.
radiator angle is somewhat unimportant provided there is good ducting into and out of the radiator. (more angle allows for larger radiator while fitting within c5 nose height restrictions)
The questions I dont know the answers too:
short of calling and speaking with radiator companies is there a general rule of thumb to determine optimum radiator size/surface area?
I've seen the Dewitts short radiator's for blower setup which is 2" shorter than stock and I don't see many complaints about it not sufficiently cooling which leads me to believe a 24.8125 x 15.5 x 2 is sufficient.
how thick is too thick? It seems most aftermarket upgrade c5 radiators are dual core 2" thick, would going even thicker be better? at what point do you wind up hurting air flow through the radiator and cause a loss of cooling efficiency? The thought here is if a thicker core allows you to run less surface area it might become helpful for routing/ducting the radiator and running the intake setup.
If you've got pictures of custom radiator setups you'd like to share or know the answer to my questions (or want to correct some of my statements) by all means post away!
My current goal/thought process is to get as much cooling as I possibly can, if I wind up too cold I can remove some of the radiator opening to get more heat into the system and improve front aerodynamics, win win!
Last edited by klodkrawler05; 12-10-2015 at 02:36 AM.
I had the Ron Davis Racing Radiator with built in EOC in both my 97 and 03Z. It required a little trimming of the radiator mount rubber trim and the rubber piece that goes around the stock drain cone on the passenger side bottom of the radiator. It provided excellent cooling for the LS6. In fact I had trouble keeping the oil warm enough if I was driving in cool temps and not running on the track. I am not sure how much more heat you will get with 135 more HP to the rear wheels but with your Lingenfelter oil cooler and the RD radiator you will probably be able to do what you want. When I installed the radiator in my 03Z my oil temps dropped from 319 to 230 and the coolant temp was 200 where it was held by the stock thermostat.
klodkrawler05,
I'm working on getting the cooling system ready for this upcoming summer track day season right now also. I'm keeping an eye on your thread and results, should be some good info coming in.
I just picked up a heat extractor hood....are you using any type of heat extractors out the hood for increased air flow through the radiator/heat exchangers?
I noticed that the stock radiator shroud is pretty restrictive for airflow if not going through the fan opening area. I've seen some people that race the C5 platform claim they removed the fan and shroud assemblies since at race speeds the fan and shroud actually limit air flow through the radiator. Any ideas on that? (Obviously not going to work for a street driven car in stop and go traffic) I've also seen some people install flaps on the fan shroud that stay shut when the cars fans are creating vacuum through the radiator but flap "open" when driven at race speeds and there is more pressure between the radiator and fan that can physically flow through it. I wonder if this is a viable option for the C5 shroud??
Since my car is a bottom feeder, I was planning on building a bigger version of the air dam for track use to force more air up into the radiator. I don't care if it scrapes on the track, just trying to force more air into the radiator and oil cooler. Any reason on not doing this?
I've heard good things about Ron Davis radiators but you might want to call them and discuss your situation. On the Viper platform, they found that going too thick of a core was detrimental to the cooling on the track. I'm no radiator expert, but I would guess that thickness and how the radiator is designed would matter. Maybe the C5 platform is similar where too much thickness either slows the air flow down too much or the coolant takes too long to get through the system.
On my previous cars I've always used the thermostat as flow control and not temperature control. Have you played with different thermostat temp ratings to see how it effects on track temperatures?
I had the Ron Davis Racing Radiator with built in EOC in both my 97 and 03Z. It required a little trimming of the radiator mount rubber trim and the rubber piece that goes around the stock drain cone on the passenger side bottom of the radiator. It provided excellent cooling for the LS6. In fact I had trouble keeping the oil warm enough if I was driving in cool temps and not running on the track. I am not sure how much more heat you will get with 135 more HP to the rear wheels but with your Lingenfelter oil cooler and the RD radiator you will probably be able to do what you want. When I installed the radiator in my 03Z my oil temps dropped from 319 to 230 and the coolant temp was 200 where it was held by the stock thermostat.
Bill
excellent feedback thank you!
Originally Posted by TrackAire
klodkrawler05,
I'm working on getting the cooling system ready for this upcoming summer track day season right now also. I'm keeping an eye on your thread and results, should be some good info coming in.
I just picked up a heat extractor hood....are you using any type of heat extractors out the hood for increased air flow through the radiator/heat exchangers?
I noticed that the stock radiator shroud is pretty restrictive for airflow if not going through the fan opening area. I've seen some people that race the C5 platform claim they removed the fan and shroud assemblies since at race speeds the fan and shroud actually limit air flow through the radiator. Any ideas on that? (Obviously not going to work for a street driven car in stop and go traffic) I've also seen some people install flaps on the fan shroud that stay shut when the cars fans are creating vacuum through the radiator but flap "open" when driven at race speeds and there is more pressure between the radiator and fan that can physically flow through it. I wonder if this is a viable option for the C5 shroud??
Since my car is a bottom feeder, I was planning on building a bigger version of the air dam for track use to force more air up into the radiator. I don't care if it scrapes on the track, just trying to force more air into the radiator and oil cooler. Any reason on not doing this?
I've heard good things about Ron Davis radiators but you might want to call them and discuss your situation. On the Viper platform, they found that going too thick of a core was detrimental to the cooling on the track. I'm no radiator expert, but I would guess that thickness and how the radiator is designed would matter. Maybe the C5 platform is similar where too much thickness either slows the air flow down too much or the coolant takes too long to get through the system.
On my previous cars I've always used the thermostat as flow control and not temperature control. Have you played with different thermostat temp ratings to see how it effects on track temperatures?
I forgot to mention that, presently I'm running a set of the trackspec motorsports hood vents with the stock LS6 they helped drop on track temps by about 20 degrees but the ls7 seems to run so much hotter I'm going to need more drastic measures.
I've seen several others mention radiator thickness and going too thick being unhelpful so I'm hoping someone smarter than I can chime in on that and if there is a calculated maximum thickness thats effective.
I have not played with thermostats yet I'm running a stock ls7 unit, if I'm reading your post correctly going to a colder thermostat would increase flow some marginal amount and potentially up the cooling? (assuming the coolant doesn't move too quickly resulting in loss of cooling efficiency)
My stroked 402 making around 516rwhp has the DeWitts.rad. Even at VIR on July 4th weekend when it was 106*, temps never got above 205* running the full sessions. The last session on Sunday, there was only me and a sc Viper left. I can't imagine the DeWitts not being enough cooling and a few less $$s than the RD.
As for oil temps, I had a small permacool to start with, but temps got to 300* to fast. I have a homemade Setrab 625 set up now. Oil temps never get above 260* no matter how hard I push it.
While car was down, I added these to the hood:
Just sitting at a redlight, you can see the heat coming out. Has to help at the track.
Thats great to hear that the common Ron Davis and Dewitts radiators seem up to the task for most of the tracking folks are doing.
as I'm thinking about this more my coolant temps don't usually get much abover 230-250 so the common upgraded radiators will suffice!
The bigger challenge will be getting my oil temps under control (those are the ones skyrocketing to 300 within 1-2 laps)
I'm thinking perhaps I remove my front grille blockoff plates (shown above) and locate the oil cooler directly behind there with a duct into a low pressure zone. I can't imagine its getting much cool air with its present location near the power steering rack behind the radiator and ac condenser.
also my oil cooler is the setrab 613 so maybe I need to go up a couple sizes too
Last edited by klodkrawler05; 12-10-2015 at 08:21 PM.
If you have the ability to do custom fabrication, or are willing to hire a qualified person to do so, there are better options than off the shelf radiators. I built a custom dual pass system quite some time ago. I used a griffin universal stock car type radiator in dual pass with dual 1" rows and a loose fin count. Of course I had to add mounts, etc. to make it all work. For fan I used a single spal 16" curved blade puller fan. There are several available. The one I used is the second highest flowing one (at least at the time). Pulled around 20 amps. The one above pulled well over 20 amps and I did not want that. Anyway, seems as though the fan I used cools better than the factory fans. Besides freeing up space and being lighter/simpler/less cumbersome, it opens up the exhaust flow from the radiator as opposed to blocking the entire core as does the factory setup. I was able to build a plug in harness to use the factory wiring with no splicing, etc. For oil I used a laminova cooler plumbed into the lower radiator hose. If you search around I have posted photos of my setup. There is not enough room for a large enough built in oil cooler unless one modifies the frame rails or places the radiator so it is not restricted in width by the frame. The off shelf radiators with built in coolers are not enough to cool the oil on a track/race car.
Thanks, Trackboss, I'll search around for your pictures, I'm absolutely capable and willing to do custom fab work which was more the goal of this thread although it is nice to see multiple people using off the shelf with success.
for aerodynamic reason's I'll be going to a forward tilting radiator and ducting it out the hood.
Thats great to hear that the common Ron Davis and Dewitts radiators seem up to the task for most of the tracking folks are doing.
as I'm thinking about this more my coolant temps don't usually get much abover 230-250 so the common upgraded radiators will suffice!
The bigger challenge will be getting my oil temps under control (those are the ones skyrocketing to 300 within 1-2 laps)
also my oil cooler is the setrab 613 so maybe I need to go up a couple sizes too
Eager to see how the vents do at the track. I have my oil cooler mounted on the rad/skid plate in front of radiator. Seems to get enough air flow to keep everything cool, but I don't do any class racing so I am not pushing my car to the limits. Here is a typical lap for me:
So here is something no one considers...a track collision that does not completely disable your car and external oil coolers. In clubracing we are supposed to be non-contact but are really far from it. A few times the only casualty has been some punched in rubber nose fascia. That will not keep you from racing. However, damage to an external oil cooler tucked in the nose will. IMO the radiator IOC is the way to go because it is protected. When the EOC is in the license plate nose area or around the brake duct area they are vulnerable. When in front of the radiator they steal airflow and once in a while the lines will catch and get ripped out from an off track excursion. These are not frequent happenings but in my years of racing vettes I have seen it often enough to seriously think hard about where and how I do my EOC.
Thinking bock to when I did this I think I actually have dual 1.25" rows instead of 1" as I mentioned above. It was upon the recommendation from griffin. If I had a situation where I needed more cooling I would use 1.5" rows with the same loose fin count. The 1.25" and the single fan seem to flow well enough to keep the car cool at idle and low speed which leads me to believe increasing the tube size would have very little to no effect on cooling at low speed and certainly not at any speed on track. The only down side of going bigger in any dimension is added weight mostly because of the additional water capacity.
Fatbillybob makes a good point about the oil coolers. Even a small leak from a puncture can cause a huge headache. In my case, the laminova is very robust. It could be run over by an entire field of cars and probably stay together. I'd say the hose ends would be compromised before the cooler. In addition, the unit is modular and easily serviced/repaired as opposed to needing complete replacement.
I forgot to mention that, presently I'm running a set of the trackspec motorsports hood vents with the stock LS6 they helped drop on track temps by about 20 degrees but the ls7 seems to run so much hotter I'm going to need more drastic measures.
I've seen several others mention radiator thickness and going too thick being unhelpful so I'm hoping someone smarter than I can chime in on that and if there is a calculated maximum thickness thats effective.
I have not played with thermostats yet I'm running a stock ls7 unit, if I'm reading your post correctly going to a colder thermostat would increase flow some marginal amount and potentially up the cooling? (assuming the coolant doesn't move too quickly resulting in loss of cooling efficiency)
One thing I forgot to mention is the stock radiator fan support in the 97 provided better cooling air flow than the almost identical one in the 03Z. The 97 had flexible (maybe rubber) flapper valves located in several locations on the lower back side of the support. When the car was running over a certain speed those flaps opened up and provided more area for the hot air to exit the radiator. When the car was going slow enough (35 mph) to engage the cooling fan the flaps closed to reduce the amount of air leaking past the support/ shroud from the rear. The 03 radiator had those same locations filled with plastic.
One thing I forgot to mention is the stock radiator fan support in the 97 provided better cooling air flow than the almost identical one in the 03Z. The 97 had flexible (maybe rubber) flapper valves located in several locations on the lower back side of the support. When the car was running over a certain speed those flaps opened up and provided more area for the hot air to exit the radiator. When the car was going slow enough (35 mph) to engage the cooling fan the flaps closed to reduce the amount of air leaking past the support/ shroud from the rear. The 03 radiator had those same locations filled with plastic.
Bill
That is great info Bill,....can that radiator support be swapped into a 2003 Z06? I was doing some searching last night and it appears the VW Touareg and Porsche Cayenne use a similar system (among other cars).
For those shopping for aftermarket fans, the cfm ratings for Spal and Maradyne are the most truthful....many other manufacturers exaggerate their CFM ratings. The amp draw is a good barometer to gauge CFM....you need "X" amount of power to make "X" amount of CFM. No way to break the laws of physics, although many marketing departments try.
So here is something no one considers...a track collision that does not completely disable your car and external oil coolers. In clubracing we are supposed to be non-contact but are really far from it. A few times the only casualty has been some punched in rubber nose fascia. That will not keep you from racing. However, damage to an external oil cooler tucked in the nose will. IMO the radiator IOC is the way to go because it is protected. When the EOC is in the license plate nose area or around the brake duct area they are vulnerable. When in front of the radiator they steal airflow and once in a while the lines will catch and get ripped out from an off track excursion. These are not frequent happenings but in my years of racing vettes I have seen it often enough to seriously think hard about where and how I do my EOC.
great point on location of the cooler, this goes back to the you can't win if you don't finish mindset and something to certainly consider.
Originally Posted by trackboss
Thinking bock to when I did this I think I actually have dual 1.25" rows instead of 1" as I mentioned above. It was upon the recommendation from griffin. If I had a situation where I needed more cooling I would use 1.5" rows with the same loose fin count. The 1.25" and the single fan seem to flow well enough to keep the car cool at idle and low speed which leads me to believe increasing the tube size would have very little to no effect on cooling at low speed and certainly not at any speed on track. The only down side of going bigger in any dimension is added weight mostly because of the additional water capacity.
Fatbillybob makes a good point about the oil coolers. Even a small leak from a puncture can cause a huge headache. In my case, the laminova is very robust. It could be run over by an entire field of cars and probably stay together. I'd say the hose ends would be compromised before the cooler. In addition, the unit is modular and easily serviced/repaired as opposed to needing complete replacement.
excellent, so up to at least 3" would be ok.
Originally Posted by Bill Dearborn
One thing I forgot to mention is the stock radiator fan support in the 97 provided better cooling air flow than the almost identical one in the 03Z. The 97 had flexible (maybe rubber) flapper valves located in several locations on the lower back side of the support. When the car was running over a certain speed those flaps opened up and provided more area for the hot air to exit the radiator. When the car was going slow enough (35 mph) to engage the cooling fan the flaps closed to reduce the amount of air leaking past the support/ shroud from the rear. The 03 radiator had those same locations filled with plastic.
Bill
Bill this is great info! so either "upgrading" to the 97 style shroud or cutting some holes in the stock shroud would probably work well. although cutting holes would diminish cooling efficiency at low speeds. (with an upgraded radiator and oil cooling system that may not matter)
Originally Posted by TrackAire
That is great info Bill,....can that radiator support be swapped into a 2003 Z06? I was doing some searching last night and it appears the VW Touareg and Porsche Cayenne use a similar system (among other cars).
For those shopping for aftermarket fans, the cfm ratings for Spal and Maradyne are the most truthful....many other manufacturers exaggerate their CFM ratings. The amp draw is a good barometer to gauge CFM....you need "X" amount of power to make "X" amount of CFM. No way to break the laws of physics, although many marketing departments try.
Great info on the CFM ratings as well, I'll be going through updating all the comments/suggestions from folks in the morning.
looks like the c7 uses flaps too:
late model c5 fan shroud:
early model c5 fan shroud: I've gotta do some more digging to see if they can be swapped and if its just a shroud or if the fans have to swap too.
I wanna ask about the heat exchanger D3 performance engineering, does it comes with inter cooler only or with other different parts? And how much will cost?
I don't have 500hp, but I do run my car hard enough to be on the pointy end of the podium on occasion.
After I went to an aero setup, I started having trouble keeping the temps under control - despite having an oil cooler that would make the roundy round guys jealous. After opening the front bumper cover in multiple locations, going to a Spal fan, and adding hood vents, it helped but the stock radiator just could not keep up in the high 90 degree temps at last year at Nationals at Road Atlanta.
We put in a stock replacement, "over the counter" DeWitts from Summit Racing and have not looked back. Coolant temps went from climbing well into the 230's and pulling timing to staying under 213* in many championship races in the heat.
My point: Don't over think it. Concentrate on air flow and you will be good. One key to that is plenty of air in and PLENTY of air out. One key to that will be an open shroud fan that does not hinder air flow through the radiator at speed. A fan only helps in the paddock. I have a 16" Spal on my car, but I would go with a 14" next time around as I am sure it would flow plenty of air under 35mph and not block any air flow above that.
If this is not a 100% street car with AC and whatnot, you don't need a shroud. A shroud funnels air through the radiator and though the fan when the fan is running while you are idling or barely moving. AT SPEED, the fans turn off at 35mph and now the shroud becomes a blockage to free air flow through the radiator. Anything other than a bare fan is going to block air flow while on track.
I don't have 500hp, but I do run my car hard enough to be on the pointy end of the podium on occasion.
After I went to an aero setup, I started having trouble keeping the temps under control - despite having an oil cooler that would make the roundy round guys jealous. After opening the front bumper cover in multiple locations, going to a Spal fan, and adding hood vents, it helped but the stock radiator just could not keep up in the high 90 degree temps at last year at Nationals at Road Atlanta.
We put in a stock replacement, "over the counter" DeWitts from Summit Racing and have not looked back. Coolant temps went from climbing well into the 230's and pulling timing to staying under 213* in many championship races in the heat.
My point: Don't over think it. Concentrate on air flow and you will be good. One key to that is plenty of air in and PLENTY of air out. One key to that will be an open shroud fan that does not hinder air flow through the radiator at speed. A fan only helps in the paddock. I have a 16" Spal on my car, but I would go with a 14" next time around as I am sure it would flow plenty of air under 35mph and not block any air flow above that.
If this is not a 100% street car with AC and whatnot, you don't need a shroud. A shroud funnels air through the radiator and though the fan when the fan is running while you are idling or barely moving. AT SPEED, the fans turn off at 35mph and now the shroud becomes a blockage to free air flow through the radiator. Anything other than a bare fan is going to block air flow while on track.
More great info and another data point thank you!
The car does still have AC and I still enjoy taking the wife on dates, driving to the beach on a saturday night etc. but I wouldn't be opposed to having a shroud I have to remove at the track.
general rule of thumb for front breathing setup: mouth opening is 33% of radiator surface area.
acp front breathing setup is 24"x4" and claimed to be good for 475 hp
forward tilting radiators generally remove 2" from the overall height of a c5 radiator.
short of calling and speaking with radiator companies is there a general rule of thumb to determine optimum radiator size/surface area?
I've seen the Dewitts short radiator's for blower setup which is 2" shorter than stock and I don't see many complaints about it not sufficiently cooling which leads me to believe a 24.8125 x 15.5 x 2 is sufficient.
how thick is too thick? It seems most aftermarket upgrade c5 radiators are dual core 2" thick, would going even thicker be better? at what point do you wind up hurting air flow through the radiator and cause a loss of cooling efficiency? The thought here is if a thicker core allows you to run less surface area it might become helpful for routing/ducting the radiator and running the intake setup.
:
1. The 1/3 rule of thumb is a great place to start. Always leave is bigger because it's easier to block off then to cut.
2. You can always open up this opening!!! Tom (angel) has a great before and after picture that has been floating around here for 10+ years.
3. We have used the standard height radiators in forward laying radiators.
4. There is no perfect answer to the opening vs surface area.
5. Most supercharged cars are not out in 100 degree heat road racing. The tanks on the "shorter" radiators are full height and the biggest gain is the additional charge pipe clearance.
6. Stay with pretty close to normal fins per inch, thickness, and you will see great results without blazing a new trail, when there is one already laid down.
12-10-2015, 02:35 AM
Radiator tech and discussion
