Last night I started making an insulation blanket to put around the intercoolers to keep temps down. (I got one done, and one left to go) I was shocked when I started the car up stone cold after sitting for 24 hours and the intercoolers started getting hot in less than a minute after start up. With your hand on the intercooler it was very warm after 2 minutes. I figure there are two possible sources for the rapid temperature delta. 1. The coolant lines that run under the coil packs and just above the exhaust manifolds are transferring all the heat from the exhaust into the pipes. or 2. that the AC condenser has enough heat coming off of it to heat up the intercooler radiator sandwiched between the AC condenser and the radiator.

Welywick, I believe you insulated the coolant transfer lines. Did that help you out much? Has anyone rerouted the lines to get the metal tubes away from the exhaust? Perhaps this is significant contributor as to why we have such a terribly problem with the intercooler temps?

It seems like the intercooler circuit is plumber right into the heater lines!

 

Well I finished up making my intercooler insulation blankets and did some more testing when I finished. What I found is that the heat came from the AC condenser which sits right in front of the intercooler heat exchanger. I was surprised how unbelievably hot the AC condenser gets when idling. That hot air heats up the heat exchanger immediately.

I checked the intercooler temp right at start up and it got warm almost immediately. I touched the AC condenser and it was super hot. I turned off the AC and rechecked and it was still super hot. After double checking the rear AC was still on even though the front was off. As soon as i turned it off the intercooler temp dropped immediately. The AC condenser cooled right off real quick. Mystery solved. I drove the car for awhile ( AC off) and the intercooler cores were only warm to the touch. The rest of the engine compartment was hot like usual.

I sure wish there was a way to lower the underwood temperatures. Anyone know how to wire the main fan to run on high?

 

Interesting stuff. Your car is different to mine, in that 600's have the half-height IC HE in front of the AC condenser, while the 65's have the full-height IC behind the AC. My modified HE is still in front, but it doesn't seem to affect the AC too much. Most car manufacturers seem to put the AC at the front, then the IC HE or FMIC, and then the engine radiator. I think the reason for that order is down to the amount of heat that each stage puts out - least first, greatest last. In this case, I'd expect the AC to be culprit, as the exhaust manifolds do get very hot, but it takes time. If your engine was cold and your cabin was hot, I think the AC would be the first thing to warm up.

Yes, I did insulate both the charge coolers and their metal coolant lines. I wouldn't recommend doing that as its more trouble than its worth. I only tried it because I happened to have them out last year. The coolant lines are a tight fit, and its difficult getting them back in afterwards. I haven't taken any measurements, but my pump controller does display the coolant temperature, and it seems to heat soak just as much as before. Its quite a significant effect actually. The V12TT warms up pretty quickly, but takes hours to cool down. If I park a warm car for an hour, the IC coolant temp is at the top of the scale, and it takes miles of driving to get it back down again.

In future, the only heat insulation measure that I would try is to make up a metal plate to mount underneath the turbo compressor outlet tubes - the ones that feed the charge coolers. Those tubes sit directly above the turbines, right in the infra-red firing line. That's more a solution for fast driving, rather than heat soaking, but I suspect there's a lot to gain. Brabus add reflective gold film to the turbo feed and return pipes AT THE FRONT of the V8TT engine. They're nowhere near the turbines. Maybe it helps a tiny bit, but the V12TT has far worse problems.

Nick

 

I totally agree that the massive underhood temperatures are our biggest challenge. I have thought of trying a couple things to see if it helps. I will try removing the rubber seal at the back of the engine compartment to see if it will help let some of the heat escape. Second i would like to find a way to command the engine fan to run on hi, that would get more flow through the engine bay. The last thing is to try running without the undertrays under the motor and transmission. This would allow a place for the heat to escape.

Other ideas are to open up a pathway on the inner wheel well to vent some of the heat out of the engine compartment.

In the end it will probably prove futile. A huge V12 coupled with the heat load of two turbos, AC and intercoolers will be difficult to overcome.

 

Interesting finds when AC is needed in summer, and you don't want such a loss in performance, a decision must be made. Knowing the cause is half the battle, now solving the problem becomes the tough part. Even though it wasn't mentioned, its funny to think of the Killer Chiller as more of a Ponzi scheme.

As far as the path of the coolant lines, someone with a CL600 relocated them to pass along the edge of the fenders to avoid the heat of the turbos and heads. I don't know how effective it was.

I have a supplemental heat exchange mounted in front of the oil cooler down low which may help with the heat absorbed due to the location of the sandwiched stock HE. Also, a trunk tank helps delay the longer term heat soak with additional volume. Losing the plastics may help with the heat, but will there be any undercarriage turbulence? Catless downpipes help since the cats tend to hold a lot of heat, especially in a tight engine compartment. Even Superman has Kryptonite, I've come to accept there is only so much that can be done, but at the same time its nice to hear others findings.

 

Since replacing both my radiator and heat exchanger on different occasions, I've been able to appreciate just how much development and manufacturing effort Mercedes put into managing the under-hood airflow. I've never seen anything like it.

The intention is that almost all the air entering the engine compartment goes through the radiator.

Almost all the air leaving the engine compartment leaves past the exhaust cats.

If you change anything, it won't work the same any more. So in particular, I wouldn't try removing the undertrays - I think that would change too much.

However, removing the hood seal wouldn't affect flow past the turbos too much, and it would allow the heat to escape (albeit slowly) from the top of the compartment, where temps are highest. That would allow some convection cooling flow. It would be slow, but compared with how things are now, it might make quite a difference. I think that would be worth experimenting.

Nick

 

I thought of adding a matching hood grille just in front of the weather strip, a few inches off of the stock one, to help with heat escaping. Hoping that it could look like a stock piece and a stock setup.

http://www.ebay.com/itm/00-06-Merced...-/110998710237

It would probably work well when the car is moving with air coming in through the grille and existing up top, but idling would still be a problem, unless the fans were wired to a sensor based on temps under the hood.

My only concern was I was afraid the second grille would look a little out of place, resembling the Family Truckster. LOL

https://www.mecum.com/lot-detail/HA0...gon/Automatic/

 

Great information and feedback. I always enjoy both of your perspectives and experiences.

Welwynnick, do you suppose a 600 series half heat exchanger would mount in the existing radiator and AC condenser packages on a 65? I have seen the exploded views of the 600 HE but I guess I need to see one in person to see if both HEs could be used together.

Racehorse,

I got a good laugh out of the family truckster comment. If you think you hate it now just wait until you drive it!

One thing to remember is that the cowl area of the hood is under high pressure at speed so air will go in and not out. That is why NASCAR has their air intake there and why Trans ams and cowl induction hoods work well. It will vent nicely at idle and low speed when flow is the lowest. It might also duct some cool high pressure air at the base of the windshield by the intercoolers and the top of the engine to cool that blast furnace. If you could move the vent location to a low pressure location near the wheel well or fender or front of the hood it would work much better.

As for the Killer Chiller I actually think they would work well. You in theory could remove the heat exchangers which would increase flow through the radiator. The AC condenser is hot already so the killer chiller would not add too much more heat load. It would keep the intercooler cores nice and chilly with liquid temps way below ambient. Of course this will come at an expense of lower AC. Performance. If I did one I would put a shot off in line,to turn off the killer chiller if desired to get 100% AC performance when it is really hot outside. Once the cabin is cool it could be turned on to be in kill mode. Since there is now easy way to keep the engine compartment cool you might as well get the intercoolers as cold as possible.

What kind of IAT changes did you see with the additional HE and the trunk tank?

Thanks again for the comments, ideas and feedback.

 

good info.

I had removed the belly pans on my car without and issue.

this is what i had on my car S600

 

I added a few comments in bold I hope it makes sense, I thought I'd share some of my findings and thoughts.

 

Shardul,

Do you think there is room for small fans behind the lower HE that you have pictured if it was used with a S65 factory HE?

Those are nice looking HEs!

 

there is not enough room for a pull fan. Both the heat exchangers were custom made.

 

RaceHorse,

It would be easy to determine the flow pattern at that location in one of two ways. Either doing a tuft test with some yarn or with a oil dot test. The Yarn is the least messy. Get several 6 inch pieces of yarn and tape them to the hood at your proposed location. Just tape down one end and then observe the flow direction at speed and see which way they are going. There is a possibility they may be going backwards but the windshield rake is not too steep so there still may be laminar flow there. If the yarn ends are flailing around in all different directions it would most likely represent a high pressure turbulent area.

You can also do an oil dot test to determine the flow. My good friend Neil wrote this article when we were at Bonneville a couple years ago helping Lee out with his Datoyna. (Lee's car is the epitome of cool) It is a good read.
http://www.snmagcurrent.com/publication/?i=135777&p=58

 

In response to the Killer Chiller, The recommendation is to get rid of the heat exchanger all together because it usually just heats up the water even more (Ambient is hotter than the liquid in the system). A set up like yours that has a trunk tank would be perfect so that you have the volume available to keep the water cool during longer runs. While the AC compressor does disengage at full throttle there only needs to be a small volume of cold water to keep the intercoolers cold. Most agree that the max flow through the intercooler lines and cores is around 3 Gallons per Minute. That means that in your 10 second 1/4 mile pass only about 1 quart of water went through each intercooler ( 1/2 gallon total flow in 10 seconds/ 2 intercoolers). You don't need too much cold water volume for drag racing but your 1 and 1.5 mile runs would be different. Do you happen to happen to have a time estimate for your 1.5 mile run?

 

Thanks for the simple testing methods. I doubt I'll be hacking a hood up any time soon. I will have to go back and read up on the oil spots a little more.

As far as time of the 1 & 1.5 mile passes, they are about 22-25 seconds for the mile and more or less 30-35 seconds for the 1.5 mile run. Some of the hard core guys (as you probably know from the salt flats) have push cars so they ONLY run the car for the pass and that is it. My hot lapped passes were about 12-13 minutes apart giving some recovery time. Based on what you are saying with a reduced volume and no heat exchanges, would the killer chiller be able to provide instant continuous cooling similar to how the newer hot water on demand setups don't require a storage tank?

 

I don't think the killer chiller has the ability to cool water that fast at max flow rate. The people running the systems says it takes afound 5 minutes to get a couple gallon tank cold. With your 1.5 mile runs being around 30 seconds, that equates to roughly 1.5 gallons of flow through the intercoolers. I am not sure what volume your trunk tank is but it should be adequate for a full pass run once cold. Just remember the AC shuts off at WOT so your cooling load will have to come from your storage tank. We also have to take into account the warmer water re entering the trunk tank which will partially increase your fluid temp. My personal feeling is that it will keep the intercoolers way cooler than using just front mount HEs.

Just think what driving around all day would be like running ice in your tank.

I do wonder if the intercoolers are cold enough to drip lots of condensation all over the top of the motor when using either ice or a KC.

200 MPH is really cranking. Great effort indeed. Do you feel it was still accelerating?

 

I have to say I'm sceptical about Killer Chiller for our applications. With cooling systems I think you have to think in terms of heat and power, rather than temperature. The different cooling systems are intended to meet very different cooling needs:

Engine cooling: several hundreds of kW
Charge cooling: several tens of kW
Aircon cooling: several kW

I don't think AC is in the right ball-park.

Nick

 

I agree, I'm having a tough time thinking it can cool quicker than the heat generated by the turbos. The Killer Chiller may need to used as a combo including a large storage tank for less temperature fluctuation, and maybe other cooling aids like meth. I don't want to discourage anyone from trying, the real people to make suggestions are those from Killer Chiller. Maybe they have other turbo platforms that have found a good setup to work. We are not the only turbo cars battling heat.

 

I don't think the killer chiller has enough capacity for long duration road race type of events but several people have had very good luck with supercharged cars. On the street they sure seem to work well.

From my research the killer chiller definitely works best with a reservoir of at least a gallon and a half, more would sure help. The heat load on the intercoolers is really low just driving around but when we go full throttle and the mass flow increases dramatically that cold water in the intercoolers would sure help IATs.

One of the CL55 guys has lots of videos of his KC install and shows IATs about ambient driving around for awhile with water temps in the intercooler a bit above freezing. Wouldn't that be nice for our constantly hot cars.

 

These are from Nidyanazo's previous posts for reference.

 

killer chillers work well when you have a 10 to 15 gallon tank in the back to store the chilled water feeding to the IC

 

Do you have any personal experience with one? 10 to 15 gallons of water is sure a bunch, that is about 100 pounds of water in the trunk plus all the tank and plumbing weight. I sure would like to get some good data from a V-12tt application. Sounds promising.