hot?! double insult..

[bigchillcar]

100 degrees in little rock today as i make the 45 minute drive up from pine bluff around noon..notice my recently charged a/c is blowing..almost warm..

coming back about an hour ago, i go to the car and check cabin temp..120 degrees..great. not long into the drive i realize i'd rather just have hot air blow the crap out of me, so i roll down both windows and open sunroof. the a/c had done SOMETHING because the cabin temp had cooled to a frigid 100 degrees prior to this.

okay, sailing home with my recent oil change done, winter's 10w-40 to summer's 20w-50 (all castrol)..i decide to go fast (90 mph) and i have a geo metro camped on my tail (geez)..watching the temp..it goes up from it's normal 220-230 at 75 mph..up to 250. the metro basically wanting to pass, so i finally give in and let it pass..my porsche..911..because..i..can't..drive..any..faste r..in..this..****ing..heat..without..a..****ing..a ux oil cooler..when..it's..100..****ing..degrees. and i need to get serious about finding my leak/upgrading a/c..rant over. heat sucks..i;ve been dealing with this situation for years and i just about can't take it anymore! okay, rant really over..i'm majorly temperature limited..
ryan

[911mot]

Kinda begs the question of where you got your username from

[jbrinkley]

for a while, maybe years, I've seen your ID and thought, maybe he's got good A/C. Now I'm thinking that's a movie, right? Same car that was in the movie? I'm never all the way with it when the heat index is over 100, and i haven't been with it for days, maybe weeks.

[Dantilla]

Ever think about Elephant Racing's oil cooler and finned oil cooler lines?

[Jim Sims]

I had a similar crisis before installing an external trombone oil cooler and reinstalling my A/C while driving my '76 across Wyoming one August with my wife. Having to slow down because of the heat (excessive engine oil temperatures) and dripping with perspiration prompted some soul searching. If I was going to drive this car in high summer I was going to have to learn some "hands on" A/C skills. It took a while, but I had my revenge last weekend zipping across the Mojave desert with the old 2.7 running well and cool and the A/C chillin us. It was like stepping out into a oven when we stopped in Needles, Ca. Keep at it, it can be done. Jim

[bigchillcar]

Kinda begs the question of where you got your username from

lol..yep, it's because of the car william hurt drove in the flick 'the big chill' from '83..i think the car was actually a '72, but not certain..and who wants to 'go on record' on this board?

not familiar with chuck's cooler i hate to admit..or the finned lines, but obviously sounds worth investigating..

thanks, jim..i'm counting on pm'ing you this fall as i gather funds, parts and roll up my finally dry sleeves..
ryan

[ianc]

Wow. Blown off by a Geo Metro.

Ferdinand is rollin' right now...

ianc

[bigchillcar]

guys:
don;t know if this makes it any better, but i just remembered that the ****ing car i was 'holding up' was a focus..is that a ford??
ryan

[yasir]

Originally posted by bigchillcar
guys:
don;t know if this makes it any better, but i just remembered that the ****ing car i was 'holding up' was a focus..is that a ford??
ryan

Nope Focus is made by Chevy,wanna bet

[azasadny]

Ryan,
Bite the bullet and get the aux oil cooler. My '74 never went over 220 last weekend when it was 100 degrees here in Wyandotte.

[jtfreels]

I feel your pain it was really hot in Memphis today as well.
I'm still looking for my first 911, so with all these horror stories on a/c I've been turning off the a/c in the BMW and driving with the windows down for practice!

Jay

[bigchillcar]

art,
did you or a po add the aux oil cooler in your car? which one do you have?

jay,
you're getting close..but turn off the a/c and roll the windows back UP if you wanna get closer to the true experience..
ryan

[azasadny]

Ryan,

The PO put the Carrera oil cooler on the car about 10 years ago. It was used and a German auto repair shop in California installed it and I believe it cost him about $1200. My usual temp is 190 degrees unless it's close to 100 outside and I'm sitting in traffic, then in may go to 220 or 230.

[Halm]

I had a Carrera oil cooler installed 2 years ago and it might be the best thing I have done for the car. Driving to and from Hershey last week it was hot. It had to be in the low 90's. Oil temps on my car never broke 190 even when caught in traffic on I-95 going around DC.

[safe]

BTW what is the optimal rpm to get the bset cooling for a hot car, if you know what I meen?
I read somewhere that after a hard run its best to let the engine cool of at an "elevated idle".

[bigchillcar]

thanks, art..i suppose you have the electric fan, too? i understand from scottb i can pick up the parts and diy it for about $300.

i've heard that it's a good idea to wait a minute before shutting down after a hard run, but to let hot gasoline circulate into the tank (i think). as far as optimal cooling, it appears from my experience that once it gets hot, the closer i am to 4,000 and above the hotter it would continue to get, so i slowed to 65-70 and the car cooled to 230-240..best it seemed it would get before getting home and that rpm is about 3,000..so that would be my guess as the best compromise between making the engone drag at too low an rpm and making it work harder and hotter at high rpms..
ryan

[Grady Clay]

The “cure” so to speak, is the combination of many things. Yes, you need to keep the oil cooler. In my opinion 180-210F running thermostatically controlled is about right. That takes a serious front oil radiators and fan. Even then there are times when the heat dissipation requirements will exceed the capacity of the system and the oil temperature will get above the 210F range and perhaps 220-230F.

Note that Porsche competition cars from 906 & 911R all through 935, 956, & 962 did not use an oil cooler at the engine. This was so all the fan driven cooling air could keep the cylinders and heads cooler.

The source of the problem is not dissipating enough heat where it is generated – the cylinders and heads. The 1.82:1 fan ratio of the “Turbo Fan” setup helps solve the problem at the source. There is the added benefit of pumping more air across the engine grill A/C condenser. That improves the A/C performance.

Speaking of A/C performance, all of these systems will benefit from more heat dissipation capacity (more and larger condensers) that are not putting the heat into the engine cooling air. IMHO, the engine deck lid mounted condenser should be the last (coolest) in a series of condensers. The hottest should be in the LR fender (an already hot location), the intermediate ones in LF fender and front center, and the final cooling at the engine lid. There are other tricks such as using the cool refrigerant after the evaporator to additionally cool the high pressure line just prior to the expansion valve.

Needless to say none of this is particularly effective if the systems need maintenance or repair.

Here in the high West we have environments that test the limits of any automobile. In addition to high temperatures; Denver, Santa Fe (Los Alamos), Flagstaff and more have thin air due to high altitude. This dramatically reduces the ability to transfer heat to the air.

Driving technique also has a large effect on cooling the engine and A/C condensers. The engine cooling fan is not pumping much cooling air at low RPM. Keep the revs up. Drive along in the next lower gear at 4500+ RPM, not 3000 RPM. When stopped at a light or in traffic, keep the revs at 4000+. So what if you get funny looks, you and your 911 engine will keep their cool. There is also a significant technical reason; the piston cooling oil nozzles don’t open when the oil pressure is below 3-4 Bar (42-56 psi). Consequently the pistons aren’t getting that cooling unless the engine is at higher speed.

Best,
Grady

[vash]

bigchill, i just finished my carrera cooler install last night.

in it about $380. used cooler, rock guard/shield, shortie hoses, and 3 rubber bumpers, for $275 @partsheaven. new spal fan, $42, and new bottom bracket mount for OC. $60. took about 10 hours of work. just need to get the bottom bracket welded on, and i will test it in our 95 deg temp. i called or emailed partsheaven basically every 2-3 weeks, for 8 months, stalking spencer like he was jodie foster, until i found a clean one.

[bigchillcar]

grady,
always a pleasure to read your posts. i have seen you refer to the turbo fan ratio before..i take it that my stock '74 does not have this (what's my current ratio?) where do you come about locating one? would this single mod do much to reduce head temps (and consequently oil temps) on my temp gauge? i've been feet dragging to add the aux oil cooler at next rebuild time..unfortunately at 90,000 miles, the car is still running strong.

sounds like you're a proponent of multiple a/c condensers (damn the physics involved in extracting cooling from a rear-engined, air-cooled car!) what do you think about jim sims' use of an inline 'subcooler' in his cars (mounted near the front skid plate)? and if you ran 2 condensers in the fenderwells, would you still need the decklid condenser or simply delete? you're right..that's a buttload of stuff and more crazy miles of hose..

but i'm perplexed some about the rpm question: my car reached 250 yesterday because of my increase in speed in 5th gear..90 mph at around 3800 rpm. i backed off because i can't imagine that were i to INCREASE speed to say 100 mph and over 4000 rpm would make it begin to run cooler? what am i missing here? thanks.
ryan

[Carl83911]

Solve your overheating issues..

GET A "COOL COLLAR FOR YOUR OIL FILTER" IT'S COOL.