Hello All, just want to confirm a few things and ask a quick question or two. The forward line on the C4 is the pressure side and the rear is the return. Also, with auxillary coolers you should fill from the bottom up not the top down, correct. I know many plumb auxillary coolers "inline and downstream" of the radiator cooler. Does anyone run just an auxillary cooler? I ask because the radiator cooler is quite small and is in contact with radiator fluid. This provides better heat transfer but in both directions. So, if the trans fluid is cooler than the radiator fluid you will actually heat up the trans fluid! Or, if the trans fluid is warmer than the radiator fluid it will cool. I purchased a higher quality plate type cooler that is better than the cheaper tube/fin coolers. I'm thinking of running just he auxillary cooler as this would always provide cooling unless the ambient air temperature reaches 195 degrees! Thoughts?
I sometimes wonder these things.. Therefore I am considering installing a trans temp gauge so I know for sure what the temp is..
On my 74 parts car, the cooler was in front of the radiator. The guy I bought it from said he had no problems with it getting too hot or overheating. I never drove it to find out before I removed the engine and tranny.
optimum trans temp for C4 is near 140-170 degree's I believe, having it in radiator may help it reach that temp faster while the auxiliary cooler should keep it in check. A lot of manufacturers are doing that on their HD trucks nowadays. That being said if your really worried I would get a trans temp sensor and install it in your trans pan if you can as that will provide most consistent readings
Install it inline, get the largest Hayden they make, and get a trans temp guage. I did and it works great! on the hottest days in bumper to bumper I barely hit 150. In very cold weather, 130 .My water temp is always 180-5 degrees, your theory about the engine water heating the tranny fluid is wrong, in practice. I put pics on this thread http://mmb.maverick.to/showthread.php?t=81958&page=2 of my install. THe legendary PaulS said he never saw a tranny die from running too cold only overheating!
Captainmack, heat always transfers from warm to cold. Pure physics! Especially when the material separating the fluids transfers heat well (aluminum). Maybe you are suggesting in this application it doesn't matter that this happens? (BTW, great pics in the link provided above). I think zoomzoom is suggesting this, as the factory appears to be doing this on trucks! Interesting idea of heating it faster with the radiator and then maintaining with the auxillary cooler. I'm not that concerned about the trans heating up to much, rather I'm installing new trans lines and was considering bypassing the radiator cooler all together. Thanks for all of the responses.
It happens as you say. To elaborate; what you are not realizing is; the water temp at the top is 180... at the bottom of the (radiator on my car), where the tranny cooler touches it is 105...(infrared heat gun) so the "theory" of tranny temp rising to the same engine water temp is flawed..in "real world" no! Yes it has heat transfer and yes it doesnt wind up heating, by contact, but it COOLS because when the tranny heats up, the tranny fluid is HOTTER than the water in the bottom of the radiator it is feeling through the copper wall!!!
also I fill from the bottom, and I have the cooler placed against the radiator so that it is useful in slow traffic. That's when the tranny wants to cook... when the rpm's are below the stall speed! It has not affected my water temp, that I can notice, which surprised me.
I run just a cooler also, and it is infront of the radiator, but it is not mounted to the radiator.....................gives a little better cooling as the air can circulate completely around the cooler and does not transfer any heat nor absorb any heat transfer. Since my car is race only car and I use a transbrake it generates a lot of heat, and with a trans gauge I never get over 190, even after back-to-back runs. You need to remember that trans fluid starts to brake down over 200 and over 210/220 you are in jepordy of frying the trans if you keep running at those high temperatures. If I was running a 16V system I would use a transcooler with a built in fan and the biggest I could find. I have also run the finned cylinder type (22"L) on my hot rod with PA C4 and never got over 160...........but that was behind a motor that only made 315HP.
Captainmack, that makes more sense to me. So, the trans fluid would equiliabrate to whatever the temp of the fluid is at the bottom of the radiator. That would explain why the factory plumbs through the radiator then to the aux cooler. At 105, the coolant would generally be cooler than the trans fluid under virtually all conditions. Still follows the concept of heat traveling from hot to cold, but the coolant is "always" colder than the trans fluid. Olerodder, you indicated that you ran the old tube/fin cooler on a 315 horse motor that never ran hotter than 160. Was that the cooler only not through the radiator?
Sorry, I ran the cylindrical cooler as a secondary cooler to my radiator cooler. Mainly because a 1932 style radiator has a very small capacity on the bottom for trans cooling......................and I also mounted the finned cooler on the inside of the frame so air would pass over it when moving. Even cruising with the blower motor (which ran at 190 in stop and go cruising traffic) the trans temp never got over 160. Also, don't put the temperature sensor in the line because it will not give the true temperature of the trans........................it needs to in the trans pan.
Olerodder, I've seen the cylindrical coolers but they don't get very good reviews. I considered those at one point. Typically used by the hotrodders due to space issues. But, you had a finned cooler in addition to the cylindrical cooler so you had a lot of surface area for cooling through the radiator and both coolers!
I can appreciate the needs of a drag car are different. On a street car if the cooler is not mounted against the radiator, then the fan can't pull air through it, thus the cooler is vastly reduced in it's ability to dissipate heat in low speed or stopped traffic. I was very aprehensive about doing this, as I feared my water temp would go up, but it didn't. At freeway speeds obviously the cooler would be better with air going all the way around it, but that is when it is called upon least to be efficient. I installed my tranny temp guage first, before installing the cooler, and was able to see exactly when the tranny wanted to heat up. It was at bumper to bumper traffic, and when going through the gears fast driving late to work.. on the highway at 70 it was 160... at slow n go traffic it was boosting to 190-210. And once moving fast again, it just couldn't cool down again. That was a big eye opener..I couldn't wait to get the cooler in! With cooler now it rarely gets to 150!! Engine temp stays around 180-5, and even pulling hills in second gear for 20 miles at 7-9000 ft elevation it was 150. It's the rpms below torque converter stall speed that does it, in my obseration. I have a stock C4 inline 6 200. Also, I changed all the tranny fluid, which was a total mix of many different fluids, to straight Type F.
