911 Carrera RallyCross Project

10 minute(s) of a 245 minute read

While the cars racing career is on hold we got it some new numbers to wear so it can help promote the new 17" BZ wheels.





They also fit on the RALIVAN quite nicely

9-14-2015

No exciting modifications or racing exploits to report sorry. The wheel business is keeping me close to my desk. We did get chance to take the car to a German car show recently in Frankenmuth, Michigan called Northernworthersee and won BEST PORSCHE! Our friend Tim's Group B Audi Quattro won BEST EVERYTHING ELSE including BEST OF SHOW. The event was very well attended and included some interesting German specimens along with the usual mix of lowered Golfs and slammed Audis. Here are some pictures and a video at the end.

 

10-20-2015

Because it's only 70f out we decided it was time for winter tires LOL







During the process we discovered this rather worrying damp patch. Could it be the flexible line? Found out one of the mounts is broken too. How much trouble are we in?

10-23-2015

So to troubleshoot the damp patch we cleaned up the area as best we could. It's not very accessible on the front side and our UR Quattro has squatters rights on the hoist till it's done but we did our best with a floor jack and a flashlight. While doing this we discovered that the outer line was loose where it connects to the oil cooler. We, of course, tightened it up but, not wanting to jump to conclusions and looking for an excuse to test drive the car took it to visit Oakland University's Formula SAE team as they need some wheels for next year's car.





During the "test drive" the oil never got hot enough to open the thermostat to the front oil cooler so that didn't tell us much. We had to let it idle in the showroom for ten minutes more to open it up but we were still not sure if we still have a leak or not. The suspect line is still soaked with oil so we can't tell if it is getting more soaked and the front of the cooler is still caked in dirt and oil and we can't see it. The only hint of a leak was from around the ferrules at each end of the suspect line but we think that was brake cleaner boiling off as oil would just seep and this was bubbling.




So what to do?

a) One idea is "nothing". The car is probably not going to get hot enough to open the oil cooler thermostat till next June and we did find a loose connector which is a pretty obvious red flag.
b) Take the oil cooler out, clean up the connectors and replace one or all of the mounts.
c) Same as above but replace the lines too.

For now I think we will go with b) Agreed?

11-18-2015

So we went with b) Take the oil cooler out, clean up the connectors and replace one or all of the mounts.

The lines were a bit tight. Well, one of them was. Had to use a heat wrench on it but it freed up. The bottom mount that wasn't broken broke so we only had to unscrew the top mount then the cooler came out easily. This left us with a damp oil cooler with two broken mounts. The top mount that was was still attached to the cooler refused to budge; the nut was so rusted as to not resemble a nut at all. So then we had three broken mounts to try to remove. Fun!



The two bottom mounts we drilled out on the drill press. The top mount we hack-sawed off. Then we cleaned out RallyCross debris from between the tubes and we were ready for our new mounts we got from Pelican. Only about $5 each. Some parts for these cars are very inexpensive. Some aren't.








Before re-installing our cooler we wrapped it in cardboard as we wanted to see if it had any effect on oil temperature as we experience what we consider very low oil temperature in the winter. Unfortunately our phone died so we have no pictures. Once the outside temperatures head south our 911 barley gets out of the first notch on the temperature gauge. We were always taught that gauges are designed to read straight up or level when at the ideal temperature or pressure or whatever so you can just glance at them and know everything is OK. So just above that first bar (ours is like on the left) always felt low to us but without numbers on the gauge we never really knew what the temperature was. Then we found this face-plate picture which gave us some clues.



So we were getting around 140F on the coldest days in Michigan when it can be -20F outside. That's actually not as bad as we thought. Then we remembered that the engine thermostat is designed to open at around 185F which means that's the operating temperature Porsche expect the engine to stabilize at. If you look on the face-plates that's not that high up. If it can't manage that it opens the external thermostat and sends oil to the front oil cooerl too; the one we just blanked off. A test drive at 50F resulted in our gauge indicating around 180 with the front oil cooler lines still cold, suggesting that the engine oil cooler was doing its job and our attempts to raise the oil temperature by wrapping the front cooler were both unnecessary and futile as it's not even in play.



This temperature was verified by an infra red thermometer aimed at various parts of the engine. However, when it's really cold out the temperature often never even gets out of the first segment so something else must be keeping it cold.

The first winter we ran the car we don't remember it struggling to make heat. This only started the second winter after the engine had been out and a few "while you are in theres" attended to. We always wondered if we'd accidentally improved the cooling while we were in there but recently realized one other thing we had done to the car since the first winter: added a whale tail. It is now our theory that that scoop is a lot more effective at ramming cold air through the deck lid to the fan and is preventing the oil from reaching proper operating temperature during very cold weather. Therefore our next project is to take off the cladding from the front oil cooler and rig up some sort of restrictor for the deck lid and test in lower temperatures that are surely on their way.

Does all this sound plausible?

11-20-2015

So, the first attempt (after thinking about it) to add some oil temperature in the winter: block off the engine (primary) oil cooler airflow to some degree, after removing the front (secondary) oil cooler cover we made the other day of course. Here's the bottom of the primary oil cooler. Air from the big fan blows down through this and around the cylinders.






The piece of card we cut to block off most of that flow:




Installed:






And the result after 20 minute sprited driving in ~40F outside temperatures:




Looks like about 170F so not very conclusive but we don't exactly have data on what it normally does when it's 40F outside. At least it didn't overheat. In fact it didn't even open the secondary thermostat.

Next we try it in colder temperatures (excpected over the weekend and/or remove the rear whale tail.