911 Carrera RallyCross Project

Is that Tim Maskus? Fantastic car.

DaveEstey wrote: Is that Tim Maskus? Fantastic car.

Why yes it is. Fantastic bloke too.

Urban assault vehicle.

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?

I've been waiting for this thread to pop up again.

Since you guys have had some time under your belt, how's rallycrossing a rear engined car?

I've been thinking about rallyxing a Corvair. While it doesn't have as much power as an early 80's 911, I thought it would be a interesting if not fun experience.

In reply to SyntheticBlinkerFluid:

I asked the same question of Aircooled the other day as he is a Corvair guy. He said it certainly should have excellent traction, which I think would go a long way on loose surfaces. Although he said he didn't have any experience with them off road. One popped up locally pretty cheap was the reason I asked.

In reply to Nick (Not-Stig) Comstock:

Yes Corvairs get excellent traction on slippery surfaces. My biggest concern is understeer. Power is also a concern, but not as much as not being able to turn. They're great at autocross, don't see why they wouldn't be at rally cross.

If you have not already, most 911 guys that spend time driving the cars hard wire up a fan on that oil cooler to try get some additional airflow. We found a large 12v pc fan. (120mm I think) and zip tied it to the fan then ran the wires into the trunk and to the relays and wired it in to switched power.

this gave us a MUCH cooler motor when we are stuck in traffic or driving like crazy during the heat of the summer.

iF I recall correctly that is a common failure point of the oil cooler. Also, check the lines running to the front of teh car. (right under the sill on that side.) home mechanics that do not understand using the jack puck point. (on the side of the car). tend to crush those lines and you will have to replace them if they are crushed.

Yes, sorry. We've been focused on our 85 Quattro most of this year. That thing needs to get finished.

My experience of RallyCrossing this has been amazing. I have total and utter respect for the car. The engine is in exactly the right place 95% of the time and when it isn't it does try to address that by swapping ends. That's not to say it's hard to drive, it's just that the shear amount of throttle-on grip is nothing short of addicting, right up until you exceed it then there's no getting it back. It's a positive feed back loop; the more gas you give it the more grip you get; the more gas you give it. Just don't lift mid-corner though. This is not to say it understeers either. Understeer is not a trait I would attribute to this car. It turns in probably better than our Outback Wagon did after spending a ton of money on "turn in you bastard" parts. And our 911 is still essentially stock in this department.

I can honestly say this is by far the most competent car I have ever driven, but I have never driven a Corvair.

SyntheticBlinkerFluid wrote: I've been waiting for this thread to pop up again. Since you guys have had some time under your belt, how's rallycrossing a rear engined car? I've been thinking about rallyxing a Corvair. While it doesn't have as much power as an early 80's 911, I thought it would be a interesting if not fun experience.

Actually now that I think about it, with all your rallying the oil lines running forward might be pretty trashed up and due for repair anyways.

The later cars came with an oil cooler fan but not this one. I have seen elevated temperatures when stuck in summer traffic but to be honest I have more concerns about getting it warm in colder weather than it getting too hot. The reason I took the cooler shield off was to see how I might block the cooler with some cardboard for the winter as it almost never gets above 180F once the thermometer heads south. I've Googled the crap out of this issue but the community consensus seems to be that it's not an issue. Regardless, I'd much rather thrash the engine with a bit more oil temperature if you don't mind.

Last time I had the engine out I tested the engine thermostat and it opened right where it's supposed to (180?). I was hoping it would open sooner so I could replace it and restore proper winter oil temperatures. I read up and it seems the auxiliary oil cooler thermostat is the same part number so it also opens at 180F. To my mind this suggests that once the main oil cooler opens the auxiliary one does too. This seems odd but is borne out with my cheapo infra red thermometer hence the cardboard project. I may also look for a high opening secondary thermostat, if I can get the current one out that is.

Mad_Ratel wrote: If you have not already, most 911 guys that spend time driving the cars hard wire up a fan on that oil cooler to try get some additional airflow. We found a large 12v pc fan. (120mm I think) and zip tied it to the fan then ran the wires into the trunk and to the relays and wired it in to switched power. this gave us a MUCH cooler motor when we are stuck in traffic or driving like crazy during the heat of the summer.

We have covers on most of the front oil cooler lines. The only part that's really unprotected is at the top of the front wheel arch, about where these damp lines are.

Mad_Ratel wrote: Actually now that I think about it, with all your rallying the oil lines running forward might be pretty trashed up and due for repair anyways.

good to hear. Dad bought the car and his were crushed. oil cooler was doing NOTHING for the motor.

You could probably manually bypass the cooler in the winter. basically put a loop line in there to connect the in/out together.

teamilluminata wrote: Yes, sorry. We've been focused on our 85 Quattro most of this year. That thing needs to get finished. My experience of RallyCrossing this has been amazing. I have total and utter respect for the car. The engine is in exactly the right place 95% of the time and when it isn't it does try to address that by swapping ends. That's not to say it's hard to drive, it's just that the shear amount of throttle-on grip is nothing short of addicting, right up until you exceed it then there's no getting it back. It's a positive feed back loop; the more gas you give it the more grip you get; the more gas you give it. Just don't lift mid-corner though. This is not to say it understeers either. Understeer is not a trait I would attribute to this car. It turns in probably better than our Outback Wagon did after spending a ton of money on "turn in you bastard" parts. And our 911 is still essentially stock in this department. I can honestly say this is by far the most competent car I have ever driven, but I have never driven a Corvair.

SyntheticBlinkerFluid wrote: I've been waiting for this thread to pop up again. Since you guys have had some time under your belt, how's rallycrossing a rear engined car? I've been thinking about rallyxing a Corvair. While it doesn't have as much power as an early 80's 911, I thought it would be a interesting if not fun experience.

I didn't expect you to know what a Corvair was like to drive.

I was just curious about the mannerisms of a rear engined car on the dirt.

Like I said before, the 911 has enough power to not have to worry about it, but my Corvair (which I'm not going to use for RC) only has 160hp and weighs about 2600 lbs.

My plan is to get one solely for this purpose and rallycross the crap out of it. I'm debating whether to use my drivetrain or keep the one that would be in the car I get, which would only end up being 110 to 140 hp.

Yes, I did think about that. I think there's still a lot of cooling capacity in the lines themselves though.

Mad_Ratel wrote: good to hear. Dad bought the car and his were crushed. oil cooler was doing NOTHING for the motor. You could probably manually bypass the cooler in the winter. basically put a loop line in there to connect the in/out together.

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?

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?

It all boils down to how much cooling is being done by the air and how much is being done by the oil. I doubt you can keep enough heat in the engine compartment with cardboard to reduce the air cooling capacity enough at those temperatures, but it's an interesting experiment. They must have this issue in Germany where winter is properly cold if it is in fact an issue.

mazdeuce wrote: It all boils down to how much cooling is being done by the air and how much is being done by the oil. I doubt you can keep enough heat in the engine compartment with cardboard to reduce the air cooling capacity enough at those temperatures, but it's an interesting experiment. They must have this issue in Germany where winter is properly cold if it is in fact an issue.

Well, the air blows around cooling fins on each cylinder and also round the engine mounted oil cooler so I guess it's doing all the cooling. You'd think this would be a common enough concern especially in the colder places but I'm not finding much info out there. At least nothing definitive.

Right, what I mean is that the fan will still be sucking the air around the fins. The whale tail let's that air get out of the engine compartment a bit more efficiently, but the bulk of the cooling is already done by then.
I didn't realize there was a second engine mounted oil cooler, I thought there was just the one up front. Is there a thermostat in that one like the front one? I would see if I could restrict air flow to the engine mounted one and leave the front one alone to retain cooling capacity if needed through the thermostat opening.

mazdeuce wrote: Right, what I mean is that the fan will still be sucking the air around the fins. The whale tail let's that air get out of the engine compartment a bit more efficiently, but the bulk of the cooling is already done by then. I didn't realize there was a second engine mounted oil cooler, I thought there was just the one up front. Is there a thermostat in that one like the front one? I would see if I could restrict air flow to the engine mounted one and leave the front one alone to retain cooling capacity if needed through the thermostat opening.

Actually the air goes the other way: is sucked in through the deck lid and blown down through the engine.

Yes, the engine cooler has a thermostat too. opens at around 186f. My current thought is to restrict this one a bit, un-wrap the front one as backup and see what difference running without the whale tail makes.

This is where I'm the embarrassed Porsche owner who didn't know which way the air flowed.
Solid plan.

Does the oil pressure gauge say...druck press.?

The older cars have an oil cooler on the motor, then the sump, and an external.

the motor really was oil cooled in hot climates. I've been in dad's 83 with it hitting 220*F, we flick the switch on our rigged up fan on the front cooler and watched it drop to 180.

Druck is german for oil I believe.

mazdeuce wrote: This is where I'm the embarrassed Porsche owner who didn't know which way the air flowed. Solid plan.

Or I'm wrong!