This is something I've always wondered about, as my car hasn't had any of the pans since I've owned it, yet until a few years ago, the cooling system worked flawlessly, so I've always been a little skeptical that they really do a whole lot. It's always been on my list to buy at least the middle one, but I've never gotten around to it. Anecdotally, it seems that a lot of 968's pans are missing, but I'd like to confirm. In your response, also please add a sentence or two about how well you car's cooling system seems to be working. This is my first poll, so I hope I did it right... Thanks.
I have them all. Although the bat wing was replaced with the DR1splitter. The water pump is 3 years old, as are the hoses, radiator is 12 years old. I also have had to replace the heater core. I run 100% glycol.
At freeway speeds, on a 100+ degree day, with the aircon on, the temp. gauge is at 8 o'clock position. In stop and go traffic under the same temperature conditions, it rises to about half way between 8 o'clock and 9 o.clock if the zircon is on. When the aircon is not on the cooling fans come on at about half way between 8 o'clock and 9 o.clock. If I am out driving the car hard on the backroads, without aircon, the temperature does come up a little bit, but never more than 9 o'clock. This past July 4th it was 106 out in Livermore where the winery is and the coolant temperature never wavered, even in stop and go traffic.
My observation is that the car does run cooler with the splitter at freeway speed than it did without.
Three, but batwing (front apron) has see better days
All three, but I have recently seen my temperatures go from never above 9 to slightly above and even up to the second white line. I changed my thermostat, fan switch and lower rad hose and that may have had a positive effect, but not entirely.
I have all three. The temp normally runs a hair above 8 o'clock pretty much the same as Chris. In stop & go traffic the needle will go to 9:30 and 1 fan will turn on. The water pump is two years old and was replaced at 115 K as a "as long as I'm doing the belts, rollers etc" p.m. Turns out the pump was in new condition. The heater core was replaced in 2006 due to a vibration induced crack at the coolant joint. I replace the a/f every two years using European (VW, Audi) non phosphate antifreeze. The only time I have had a problem was when some trucker pulled in front of me going to the Colorado Parade and proceeded to climb a 10,000 ft pass in 100 degree weather at 5 mph. When the dash light blinked a couple of times I turned off the a/c and the engine temp went down and the car temp went up along with my temper.
~tom
I only have batwing (front apron).
Temp was always fine until recently i did thermostat, radiator cap, removed radiator to clean, and new thermo switch. Now back to 8-8:30 mark on gauge.
I have never seen the middle or rear pans, i will have to check other cars next chance i get.
Thanks for the responses. It's very early, but I'm struck by the variation in cooling performance in these cars. My quick history is as follows"
2006: Bought car with no pans, RacerX chip, stock exhaust. Never saw the gauge go about 8 oclock under any conditions here in sweltering central Texas
2008: Replaced water pump as part of belt job in the spring. In the summer, noticed that the car was running hotter than before, so I did a ton or troubleshooting, and ended up replacing the thermostat with an RS Barn drilled one, and also bought a new reservoir cap from RS Barn. These items helped a little, but the car still didn't run as cool as in the first two years of my ownership, but I lived with it, as it never got close to overheating, and I was out of ideas.
2011: Suddenly, it started running A LOT hotter, getting above the 10 oclock line in stop-and-go traffic on a moderately hot (low 90s) degree day. Strangely, it ran hotter with the AC on.
2011 - early 2013: Car underwent a complete transformation to a mostly- track car, including an engine rebuild, hoping I would stumble into the cause of my sudded very hot running. As it turned out, I did! (or so I thought) - I discovered that the insulation on the wires coming from the fan switch had torn off, causing the wires to touch each other, and maybe even the chassis. I repaired the wires.
Mid 2013: Got the car back on the road, and it's running cooler than before the rebuild (thanks to the wire fix, I assume), as it's holding at 8:30 - 9:00 in stop-and-go traffic on a very hot day, but it's still not as cool as when I got it, and it goes up to 10 oclock after a few runs of full throttle acceleration.
[quote name='Qfrank' timestamp='1375984853' post='146816']
I only have batwing (front apron) (front apron) (front apron).
Temp was always fine until recently i did thermostat, radiator cap, removed radiator to clean, and new thermo switch. Now back to 8-8:30 mark on gauge.
I have never seen the middle or rear pans, i will have to check other cars next chance i get.
[/quote]
Thanks; just to clarify, when you say it ran fine before you replaced the t-stat, cap, thermo switch, and cleaned the radiator, do you mean it ran cooler than it does now, or is it about the same?
Also, did you vote in the poll? I'm still seeing only one response in the "no pans" group, which would have been mine.
All three on mine. Runs slightly above the first mark (8'Oclock) on a 108 degree day.
Interesting that there are more "posts" than "votes" for this thread!
I have the batwing (front apron), the plastic lower piece, a side piece, and the aft metal pan. I don't typically run with the aft metal pan as it increases the heat in the header area and interferes with the header.
My coolant temps are pretty solid around the lower white line except when first warming up they go nearly to the upper white line prior to the fans and thermostat doing their things...At the track I see the upper white line regularly. However, I think I need a waterpump and a headgasket, so I may not be the best data point. My car is fine on the street, but I'm guessing I have pinholes leaking combustion by one of the cylinders. Seen it before...
Maybe I'm a little dense, but would you have a picture that shows the three pans so I can check?
I'm running a little hot during my track events, and that might be one of the things that causes it...
[quote name='Cloud9...68' timestamp='1375979156' post='146806']
This is something I've always wondered about, as my car hasn't had any of the pans since I've owned it, yet until a few years ago, the cooling system worked flawlessly, so I've always been a little skeptical that they really do a whole lot. It's always been on my list to buy at least the middle one, but I've never gotten around to it. Anecdotally, it seems that a lot of 968's pans are missing, but I'd like to confirm. In your response, also please add a sentence or two about how well you car's cooling system seems to be working. This is my first poll, so I hope I did it right... Thanks.
[/quote]
[quote name='hk968' timestamp='1375992051' post='146823']
Maybe I'm a little dense, but would you have a picture that shows the three pans so I can check?
I'm running a little hot during my track events, and that might be one of the things that causes it...
[/quote]
Well, since I don't have any of mine, I'm definitly not the one who can provide a picture. Does anyone who has them have any pictures? I know they sit right under the engine, along the bottom of the car, and than they (particularly the middle one) are sometimes discarded because they make oil changes even more of a pain than they already are. I also think the rearmost one was only installed the first year or two of the 968's production.
[quote name='Langley968' timestamp='1375986168' post='146819']
Interesting that there are more "posts" than "votes" for this thread!
[/quote]
Yes, I'd noticed that. Could those who have responded but not voted yet please go ahead and vote? Thanks.
i've said this before, but it seems to be missed. this is basic fluid dynamics. the issue is pressure. a cooling system works best when there is positive pressure in front of the radiator, and negative pressure behind it. running with no pans lessens the negative pressure behind the radiator. this will become more evident at higher speeds, as more air finds it way under the car. the result is less air flowing across the radiator. when running hard, more heat is applied. with less efficiency of the cooling system, you see the engine run hotter.
as for it being "fine" before, i would suggest that a couple of things are at play here.
1. you have likely added more mods, which make the engine run hotter (basic thermal dynamics here - more power means more byproduct heat)
2. you are running the engine harder, which makes it run hotter
3. the more miles you put on an engine, the hotter it will run.
do NOT run without the pans.
as for the third one messing with the "header", it only does so with the aftermarket header. it works perfectly well with the OEM header. if i ever find the time, i will modify another OEM header, like i did mine, and dyno it. my gut, and seat of the pants meter tell me that i actually got more gains out of the modified OEM header than i did out of the 4 to 1.
I don't disagree with the mechanism that the presence of the pans ultimately improves air flow through the radiator - I have no doubt it helps some, but I think you're exaggerating the degree to which this actually helps the cooling. My particular car didn't cool "fine" with no pans for the first two years I owned it - it cooled spectacularly. I tracked it in the middle of the summer in Dallas, and I don't remember seeing the gauge ever get above 9:00, and it NEVER got above 8 oclock in any other conditions.
My car currently cools a little better than it did before the rebuild (probably thanks to fixing the wires from the temp switch), but not nearly as well as when I got it, so I strongly doubt anything I did in the rebuild has any impact on its current behavior. It was pretty much a standard rebuild - no hot cams, dramatically higher compression, oversized pistons, not even a set of headers. I did, however, do a couple of things that should have helped it run a little cooler, namely ceramic coating all the hot internal surfaces, and adding the dual oil coolers. My priority was longevity, not maximum power output. I do share you concern about the cam timing, however, as I don't know of any way to confirm I did it correctly, other than the fact that my butt-o-meter says the car is running very strong.
I have no problems at high speeds - the temp gauge comes down to around 8:30 once I'm up to freeway speeds, even on a 100+ degree day. My problem is at high rpm/full throttle acceleration. I bet I could get it above the 10 oclock line on the gauge without ever exceeding 30 mph.
If running without the pans were such a problem, we'd be hearing about a lot more people without them having overheating probelms. That's why I started this poll - I'd like to see the data. I'd like nothing better than to be wrong about this, as it would be an easy fix for my problem.
Having said all that, I am trying to find someone locally who has at least one of the pans so I could test out the impact of adding it/them. One of the guys has responded, but he unfortunately doesn't have the pans, so I'm down to one prospect. He also told me, by the way, that his engine stays cool in the summer heat.
If my other prospect has a set he can lend me, I'll report on the results.
I guess it is time to find some pans.
Anyone have some for sale??
I need 2nd and 3rd. All i have is batwing (front apron).
FQ
"Strangely, it ran hotter with the AC on."
Makes sense, the a/c evaporator is getting hot and now you have two fans blowing hot air across your engine radiator.
If the engine coolant gets hot enough the second fan will turn on even if the a/c is off..
tom
Good luck finding the batwing (front apron) (front apron), they can also be pricey. I found one on fleabay.
My car runs around 8:00. I have a low temp fan switch as well.
Did I mention my car is for sale <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" />
this is sounding more and more like a perfect storm scenario, and less and less like a single issue.
first, new engines ALWAYS run hotter for the first 500-1000 or so miles. there is a lot more friction on the parts until they break in
as a general rule (and every engine builder worth his salt knows this) every half point you raise compression will increase the running temp 5-10 degrees. that may not seem like a lot, but if the system is marginal to begin with (like ours) it could push it over the edge.
i would question the ceramic coating and its effect. i have heard horror stories about overheating as a result of coating the wrong parts. i've even made that mistake before. not everything likes coating. bearings are ok, but not necessarily pistons and such. the internal combustion parts are designed to dissipate heat. when there is a coating on them that essentially contains heat, they cannot do that, and the heat has to go somewhere. it is left only to the cooling jackets, which we already know to be too small. this coating also increases compression ratio, as it takes up part of the chamber. (remember that it only takes a few thousandths of an inch to raise compression a half point). to repeat, that adds more heat
you may well have created your own problem. been there done that. welcome to experimentation at the edge of the envelope
regarding the cam timing, if you find it running particularly stronger up top, you likely have a fair amount of ignition timing advance (which if memory serves means cam retard). if it's running particularly stronger down low, then it would be the opposite.
as for running with out the pans, and people reporting it, they have been doing that for years. most of us know that it can cause higher running temps, when the conditions are right (high ambient temp, stop and go traffic, track use, etc). this is not new news. not sure why you haven't read this already. there is quite a bit about it all over all of the websites. yes, you can run a street car in street use about 80% of the time and have zero issues. however, the other 20% will attest to the needle running a full width higher or more. depending on your fan temp switch, compression ratio, and many other factors, this can cause high running conditions.
My problems were the reverse, I got a very hot engine when running very high rpm's on the track - everything else was fine. If I short shifted for a while, the temps dropped, if I went back to full noise, it came back up.
Normal day to day driving, no problems.
I found, as Flash attests, that without the top cover on the radiator, I was getting too much air spilling over the radiator, rather than going through it.
I run the D1 splitter (prior to that the undertray) and the plastic cover for the engine (but, I don't have the third covers - never have).
Could it be air/fuel ratio? Are you getting any engine codes?
Given the car cools down once moving, it sound more like an airflow issue - so fans or ductwork, or a coolant flow issue. It could be a coolant issue (wrong type or mix), or even a head gasket issue (but you would expect to see this in the coolant).
Same if the AC is on - is the system properly charged and the positioning of the components right (spacing, etc).
Mine currently has no pans but I'm working on putting that right, on the basis that if they weren't needed Porsche would've left them off and saved themselves the cost! Didn't they do away with the rearmost pan altogether midway through the 968's run but keep the other two?
For what it's worth, mine doesn't display any cooling/heating problems,
but I've not run the car hard at all, apart from the odd squirt through first and second to frighten passengers, despatch optimistic boy racers or just enjoy the fact that I finally have my Porsche <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" /> The temperature needle generally sits just above the mark at 8:00, with the fan coming on at around 9-10:00, whether around town or on a run.
Michael