911 cooling mods

The fan sits with the one fin almost vertical and the other one off to the left, directing air to number 4, which runs hottest on 911 fan conversions. 1 and 2 usually run way cooler, like 50 to 60 degrees, then 3, then 4 hottest.

Then I built some cylinder tins, like sled tins on a beetle, but reversed to push the air rearward since I have a mid-engine. My problem was rising cylinder head temps at idle or in stop and go traffic. Underway, above 30 mph was never a problem. My thinking was the hot air blasting downward was bouncing off the ground and getting pulled back into the fan intake. But with higher speeds the hot air would get sucked back and away.

First I made paper templates, then cut some 0.030" aluminum with some snips, bent, hammered, and riveted it to fit. I used a set of bails to hold them on the valve cover end, and bent some tabs to bolt on the case side like real sled tins. I had to cut a J-tube hole in each one as well. And clearance for the shift rod and it's U-joint.

I had also always been frustrated by the CB thinline sump and it's weird silicone seal to the pickup. I also eliminated the CB screen as it is VERY restrictive IMHO and I have an external one-quart filter. So I got an oil pickup tube extension. I roughed it up and JB welded it on as well as using the hose clamp(safety wired) and also a spring to make sure it cannot move. Overkill? Maybe.

I'd also always hated removing all the bolts to drop the oil, and milled a flat, and then tapped/drilled for a plug. The things we do to make our lives easier....

Got a nice Allen key plug which is way thinner to replace that big ugly hex head at the VW dealer. I think it fits a modern Golf/Jetta, 14 X 1.5mm thread.

Anyway, temps are what is important here. I used to run 270-280 in cylinder number 4, which is my hottest one. In traffic, it would creep up slowly when stopped to 340! But once the speed picked up it would cool down considerably back to 270.

Oil and fan thermostats are set to 180, and the VDO combi-gauge with no numbers on it sits at slightly less than 1/3 from cold. The fan turns on more often, as I'm dumping hot air from the cylinders toward the cooler, but stays controlled.

Now, it runs 250-260 CHT, and creeps up at slow fan speed at idle, but never gets over 300. It only creeps up when parked, and it takes a lot longer to do so. Before it would be a couple minutes, now it is about ten. Any car movement at all and the head temp doesn't move, so I'm calling this a success.

I have a remote 96 plate cooler over the trans and oil and electric thermostats to control oil flow and cool the cooler. I'm using a Wix 1515 filter(1 full quart) and obviously full flowed, with a Berg cast iron pressure relief cover. Full capacity is 6.5 quarts, about 5.5 for an oil change.

Yesterday I pulled a long grade going up a mountain in 4th doing about 55-60 and 2400-2500 rpm. The CHT never moved. It was 85 ambient. I can run 3-4000 rpm at 70-85 for as long as I want up hills and it doesn't seem to care. It just stays at 250-260. Down hills off-throttle it cools down to 220.

Now I can drive cross-country and not worry about desert temps!

List of all my mods

Changed the alternator wire to an 8 gauge, added 8 gauge feed to fusebox(both were 10 gauge)

Fabricated a usable dipstick tube and dipstick

Cooling mods above^

Drain plug and oil pickup extension^

Rebuilt trans

Fixed shifter U-joints, greased and booted

Changed fuel hose to hard line except for short pieces, used spring clamps instead of hose clamps, new German hose

Fabricated front engine mount and went back to German rubber mounts for trans

All new Airkewld discs, front 4 piston Wilwood, rear single piston with e-brake

SS brake hoses and new master cylinder, fabricated new e-brake cable attachment

Plug holes and paint 911 shroud

Strip flaking powdercoat, sand, prime, repaint chassis

Fabricate new battery mount

Fabricate spare tire mount in back as original

Added 1 1/4" receiver for track/tire trailer to be purchased

Cleaned, stripped, repainted a lot of small parts

Danny,

I like the spring on the end of the oil pick-up extension tube.  I have an extended sump as well and hate the idea of that hose clamp in there thats hard to tighten.

Great job, Danny! I especially like what you did with the lower cylinder sheetmetal, and putting a drain plug in the sump plate was a smart move. How are the Airkeweld discs working? Are the fronts vented? What did you have for brakes before?

Nice work Danny-very impressive.My 1914 cc runs the best it has in 2 years since you adjusted the webers at Carlisle. East coast Bruce told me that you worked on 5 cars at Carlisle.

The engine is much smoother around town since I installed the Velocity Stacks that you insisted I get.

I plan to bring the speedster to the show at Bear Mt. next Wednesday weather permitting-hope you can make it.

Joel

Joel, I may be able to make it to Bear mountain June 3, but it always depends on the weather and my kids....

Al, thanks. Airkewld are solid, drilled discs front and rear, no option for vented. They stop well, I have a high and solid pedal(braided lines help here). They seem to be very easy to modulate and really pull you down, but they are wider than stock by a good amount, about 3/4" a side. The CSP solids I had are 3/8" a side wider than stock. My existing front wheels had the centers moved out to push the tires in a bit, and now I need to move them more, as I have some rubbing issues on the front now. They were easy to install, the only thing I had to do was get longer rear hoses, and slightly mod the e-brake cables, as well as trim the inner fenders a bit for the calipers. Fronts are bolt-on.

Bleeding is straightforward, but you need to have somebody pump it well to get all the air out of the rears. The front Wilwood 4-pots have a bleeder for each side of the caliper. I mounted the rear calipers with the bleeder facing up so I wouldn't have to do the usual move-the-caliper gymnastics for bleeding.

I still haven't bed the brakes in yet, have been driving conservatively due to the rebuilt trans and tire rubbing. I should be changing the gear oil this weekend to some Redline High Shock Load synthetic.

I have to ask... Don't you want the bottom open to let the hot air out? Seems you would not have proper heat dissipation with the bottom sealed like that.

It isn't sealed, the air goes backward, just like in a Beetle with stock heat exchangers and "sled tins".

Rusty, here is another view, it is wide open toward the rear.

Al, I forgot to say I had stock Beetle drums in back. The old CSP fronts are a solid rotor, and use a GM single piston cast iron caliper, Pontiac 6000 or similar.