eyeball kid

Thanks again guys.

Jeff N.

Here's the hardpipe detail. Note how the hardpipe turns out and avoids the fan housing. It's pretty tight.

951Saga

Has anyone successfully fit this cooler with A/C intact?
Looks like it would interfere with the Brake duct once spaced to clear the A/C lines.

Jeff N.

So I hear you can have dual coolers AND A/C if you don't have an early version of the car. Friend of mine on the other side of the state swears he has both dual coolers and A/C. I'm waiting to see the car to see how it was done.

Supposedly the A/C condensor lines are different on a later model.

With my 86, there was no way to do both. And agree there's not enough room to 'stand off' the cooler so the A/C lines fit. And if you did come up with an approach I think you'd need to rig some addtional bracing to keep the cooler from torquing off at high speeds.

Love to see a pic of someone who's got both working. Or, a close-up of the condensor pipes on a later model car be enough....

eyeball kid

Since mine is an 88, I also would love to see this configuration.

Thom

Jeff and Van, did you notice oil pressure drop with the twin ol cooler set up over the original single cooler set up?

Jeff N.

Thom - that's an interesting question that I've wondered about too. Few notes

- Not sure how to measure it well when (I think) the oil cooler circuit is only open when the oil temp thermostat opens, right?
- When I added in my cooler I also swapped in a different OPRV.
- I didn't make specific notes on my before pressures to compare to my post cooler installation pressures

That said, I have observed the following:

- my upper end oil temperatures are not as high on the track as before; clearly have more cooling.
- my cold start oil pressures seem a bit lower than they were before. Maybe 4.8 bar vs. 5 bar? Is this the due to the OPRV or cooler? I'm thinking the OPRV.
- my around town oil pressures (~180 to 200) seem the the same. 4.5bar.
- my idle pressures when hot (220+) seem a little bit lower than before. Maybe about .2 or .3 bar less?
- my max oil pressure when hot at 4k+ RPM also seems just a bit lower than before. Again, maybe about .2 or .3 bar less?. About 4 bar when I seem to recall them being just over 4 bar before.

This is all taken from the factory dash gauge, not an aftermarket gauge. Also, my car has quite a few miles on it and I can't attest to how tight all the bearings are in the bottom end.

But, given the above, it seems quite possible that I did loose a little hot oil pressure due to the second cooler.

I was briefly chatting oil pressures with a local, respected Porsche race car builder here in the area and he suggested that the second cooler probably induced about a 10psi drop in the system. His comments seem to line up with my observations on before and after pressures. He also quickly showed me a 951 racecar with a customized oil pump and ridiculously huge single oil cooler feed by giant lines. The setup would have never fit on a street car.

So, my thinking is yes - there is some pressure drop with a second cooler but there is also some offset to the loss with the lower oil temps. Another interesting and maybe relevant question would be to ask about the impact of the cooler to oil flow volume.

Thom

Jeff, thanks for your feedback.

I am wondering now if upgrading to a second oil cooler would really be worth it on a 100% road car. As far as I see it, more oil cooling should result in less fluid oil, so logically the oil pressure should read higher?
The problem is to find the right balance between increasing pressure drop & cooling capacity.

Does anyone know if it's possible to find a fitting that would allow connecting two original oil line couplers together?

Jeff N.

For a road only car? No, I don't think there's a need unless you have some huge modifications and are running the car extremely hard for an extended period.

Re connecting factory hoses together - is that what you want to do? If so, you need a 26mm metric male to male extender. BAT Inc in Florida sells them, I'm sure others can provide them as well.

Re As far as I see it, more oil cooling should result in less fluid oil, so logically the oil pressure should read higher? - Yes, generally so. I think it would be interesting to swap out my 10AN lines for 12AN to if I pickup any more pressure. It's not clear to me if my drop is more in the lines or in the cooler.

Thom

Well, on my 3.0 I noticed that oil pressure on idle, when the engine is warm, reads 3.1 bar when I drive it sedately and drops to 2.5 after I have pushed it hard. I didn't get this difference on the 2.5 engine where idle oil pressure wouldn't read any lower than 3.5 bar, with the same oil. My 3.0 has 12k miles with all new bearings, the 2.5 had 155k when I took it out, with original untouched bottom end.
To me this means the 3.0 produces a lot more heat than the 2.5, so I think I should still do something to improve oil cooling.

Thanks for the address, I will get in touch with them.

Jeff N.

Just a thought - an oil temp gauge might be your first step. If your oil never get's above 230 or so, I would think you are fine. 2.5 bar on idle isn't really a problem based on everything I know. I'd be more concerned if you're seeing lower pressures at higher RPMs; that's where it really matters.

Thom

Yes, installing a proper oil temp gauge would ultimately be the right to do, however I think I can trust the oil pressure gauge and work it with it for now.
I also see a difference in oil pressure when on gas. When pushing the car hard it reads 4.3 bar, after I let it cool down a bit on cruise it reads 4.8 bar.
(when cold it reads 5.0 bar)

Well, bigger lines should result in a higher pressure drop...?

Droops83

Having just done this modification, I can add a few notes:

1. I had to remove my A/C condenser like Jeff did (I also have an '86, I will look at the '89 we have in the shop and report back if it can be kept on a later car). Luckily I was going to remove it anyway due to a noisy compressor that I did not want to spend money on to replace . . . .

2. I ran into the same problem w/ the wiring harness that Jeff did. However, I was throwing this cooler in the night before a track event and did not have time to move/modify the harness. My solution? I spaced the cooler out from the side of the radiator housing by about 2 inches using some airbox mounts I had on the shelf (a big stack of washers and bolts would work as well!). I stuffed some foam padding in between the cooler and the radiator housing to fill the gap and used it in conjunction withe the factory plastic shrouding ensure no cooling air gets past the cooler. I made a bracket to help support the bottom of the cooler using existing threaded holes. Even with the cooler spaced out a bit, I still had room to squeeze my aftermarket brake cooling duct to the right of it and still be exposed to cooling air from the factory front valence.

3. I work at a shop, and I found some factory early 911 oil hoses (part# 901.107.331.12, engine case to oil tank hose) that worked without modification: it has the correct 22MM metric hose ends, 90 degrees at one and and straight at the other. Now 45 degree would be better than straight, and the hoses were a bit long but with some creative routing I got them to fit out of harm's way. Now these hoses are expensive list price, and if you make your own hoses you can route them perfectly and make the exact length, but once again this was the night before a track event and I used what I had. You can also get a place that makes hoses to make you a hose using the existing M22 fittings from old factory 951 hoses if you don't want to mess with AN adaptors (those things are pretty expensive from BATINC!) Just make sure that you measure correctly!

4. At least according to the factory gauge, I notice no extra time to build up oil pressure on cold start, nor any reduction in pressure when hot. In fact, my oil pressure at idle is now HIGHER when coming off track due to the oil temps not being quite as high. Before the extra cooler, my idle oil pressure would be at ~1.5 bar coming off track (130K on engine, never rebuilt); yesterday on a 102 degree day at Streets of Willow I had just below 2 bar (caveat: I changed from Mobil 1 15W-50 to Total Quartz racing 10W-50 at the same time I installed the extra cooler, so I don't know if that is due more to the oil or the cooler; I certainly use less oil at the track since the switch).

5. Not only are the oil temps cooler, but the coolant temps stay down as well. I still run the factory auxiliary water pump/wet turbo setup since this car is also my daily driver, and on a 100+ degree day at the track my coolant temp would creep into the red about 5-10 minutes into the session, and I'd have to back off a lap or 2 till the temp went down. This past weekend it was over 100 both days and the temp stayed at 1/2 between the white lines all day hammering on it for 20-25 minute sessions. Now removing the condenser from in front of the radiator may have made a small difference but I'd say it was mostly due to cooler oil.

Hope this helps.

Mighty Shilling

It all starts with cylinder #1

Jeff N.

Thanks Chris, what sort of hot pressure are you seeing? Any chance you have an oil temp gauge?

Re the cooling temps, I wonder if your condenser was really blocking the airflow. I haven't had any cooling issues at all and didn't notice any water temp change with the oil cooler.