My 1883cc Porsche 356 912 Blog

Chronology of a hot-rod street Porsche 356/912 1600 to 1883cc conversion based on LN Engineering's Nickies big bore kit.

Monday, July 31, 2006

Fan Belt

I had been working on my 356 and noticed that the contitech fan belt was tighter than the fan belt on my 912, which had a Gates belt procured from Napa. It also would appear that the Napa belt was also a bit longer by how it sat on the pulley. The top of the belt was roughly at the o.d. of the pulley, and even with one shim only between pulley halves, the belt had at least an inch of deflection.

I decided to try installing a Contitech belt, 10x825, that I bought from Zims. With very little deflection, probably a hair higher than the factory spec, it took four shims between pulley halves rather than the single shim before wth the Napa belt.

Now to the oil testing results. From my last run with the Napa belt, here were the results:

Stop 1: 204F
Stop 2: 214F
Humidity: 60%
Barometer: 29.86 In Hg Falling
Outside Temp: 95F (109F heat index)

Now, with the Contitech:

Stop 1: 202F (200F)
Stop 2: 202F (200F)
Humidity: 64%
Barometer: 29.82 In Hg Rising
Ouside Temp: 97F (115F heat index)

It would appear that the new, correct diameter belt helped reduce the oil temperature. I also noticed that the head temperature dropped significantly, about 25-35F and once the load was reduced, the head temps dropped faster.

Moral of the story, make sure you have the right fan belt :-)

Sunday, July 30, 2006

Oil analysis results

I just got back my testing results from Staveley Services on the Royal Purple Max Cycle 20W50 I was running. With some odd 4000+ miles on the oil with extremely high oil temperatures, the oil still managed to come in spec for the viscosity of a 20W50. As far as the TBN, it was reduced from the initial 8.5 to a little below 7. Likewise, the Zn and P levels were reduced about 15%, still leaving in excess of .12%+ Zn and P. I would expect under normal circumstances, this oil would indeed perform the recommended 15,000 mi drain intervals per Royal Purple's recommendations. I would however say that filter changes every 3,000 mi are a must (they recommend every 5,000) when using a high-filtration Mobil 1 filter, as they filter more and hence, fill up with contaminants faster. Of note, there was an abnormal level of copper in the oil, which may be reminants of the initial break in and dyno testing, as I was still running the same oil that was in the engine when it was run in. Staveley recommended to retest, but since I drained the oil already, I plan on re-testing in roughly the same amount of time and miles.

Cooler Performance


Stop 1: 204F
Stop 2: 214F
Humidity: 60%
Barometer: 29.86 In Hg Falling
Outside Temp: 95F (109F heat index)

Before: (temps in paranthesis are corrected for outside temp)

Stop 1: 220F (239F)
Stop 2: 226F (245F)
Stop 3: 218F (237F)
Humidity: 63%
Barometer: 29.90 In Steady
Outside Temp: 76F

The second stop on the before was at 3/4 of the course I laid out as a stopping point to let the oil cool off. Since the oil was running so cool, I didn't need to stop at all.

From my earlier testing, for every 1F hotter or cooler outside air temp, I registered a 1F increase or decrease in oil temperature. That said, if we were to translate the before #s to todays hotter outside temperature, the highest 226F would have actually been closer to 245F or hotter. The 240F we had registered on an 85F day would have been 250F. That said, our highest temperature of 214F shows that the oil cooler at worse, was worth about 35F cooler max oil temps. Not too shabby!

External Oil Cooler Installation

Since my last post, we've come to the conclusion that something is ary with the stock oil cooler. I've decided to plumb in an external oil cooler. Typically, a full flow setup is required to put an external oil cooler (or) the stock oil cooler has to be blocked off and an in/out adapter put in it's place.

Since I am running the Precision Matters full flow filter cover, I came up with a third solution. Mocal manufactures various sandwich adapters that are designed to go on in the place of the oil filter. This particular one has a thermostat built in that bypasses 90% of the oil going to the cooler until the oil is up to 180F. Just so you know, the Precision Matters filter takes a 3/4-16 filter thread, so the sandwich gets installed between the housing and the Mobil 1 M1-208 filter, which is the preferred filter provided as OE by Precision Matters.

I chose to use Aeroquip AN-10 lines and fittings and use their socketless hose, for ease of installation. Their socketless blue hoses are good for 250 psi. I also used some "firesleeve" aroung the lines that were closest to the exhaust collector.

To prime the cooler and lines, I filled everything before attaching the lines (a messy ordeal), but it did take 2 qts extra oil and only took some 30 seconds of turning over (with the plugs still installed) to get the idiot light to go out. I turned it over for an extra few minutes to just make sure all the air was out.

I chose to install the oil cooler and fan assembly in the driver's side rear fender, behind the tire. Airflow is ok, better than nothing. I did a test run with the fan in the off position and the oil was about 10F cooler than on my last test, granted the outside air temperature with this test was much higher, with the heat index above 100F.

This morning I wired in the fan off the ignition coil so that it is on whenever the engine is running and took a second drive.

Stop 1: 204F
Stop 2: 214F
Humidity: 60%
Barometer: 29.86 In Hg Falling
Outside Temp: 95F (109F heat index)

I also noticed that if I floored it, the temperature would go up as I passed the slower cars, but when I returned to cruise, the oil temperature would slowly go back down. Prior to installing the oil cooler, I marked the gauge in the car with a line corresponding to 210F, as read at the sump with the Mainely Custom by Design oil temp dipstick. After I installed the cooler, the guage did at Stop 1 read higher than the 210 F mark, but the dipstick read only 204F. Just a curious observation.

In all, the some odd $500 spent on the cooler, fan, lines, fittings, and hardware was a good investment.

And since someone made the comment about the lines going in on the bottom - I filled the entire cooler and the lines, bled them, then installed everything into the car. I plan on unmounting the cooler when I change the oil / filter to ensure that there is no air trapped at the top of the cooler. It's a matter of three bolts and it swings down very easily (and quickly).

Also, as to the location - I got the idea from the back of a Pano or Excellence magazine of an a/c condensor installed in roughly that same location.

Now, some pictures...

Wednesday, July 12, 2006


I finally decided to try closing up the cold valve clearances from the recommended .008" to .005". Most definately, it's quieter. I also readjusted the idle mix and double checked my max advance which is and was set to 30 degrees. I just have to go back in and replace the valve cover gasket on cylinder bank 1/2, since it didn't seal up this last time. I guess there is only a finite number of times the valve cover gasket will reseal!

New pressure reliefs and more oil testing

I received the oil pressure relief springs and pistons from Stoddards on monday. I prepped them and swapped out the older parts. The new springs were slightly longer and stiffer than the ones in there. I'm not sure what it did for my oil pressure, but here's what I found with the oil temperatures. 

I chose a route from Momence to just east of the Indiana border @ Route 41. It's a good 15-20 miles each way and has some great spots for going WOT as well as plenty of chances to pass slower big rigs. This is the same route I have taken every time I make a change, to be as accurate in my data collection.

The first roundtrip was on Delvac 1300 Super, barometer 29.90 in Hg and 63% humidity, 76F. The second roundtrip was on Royal Purple Max Cycle. Same barometer reading and 76% humidity, 69F. I measured oil temps at the sump with a Mainely Custom by Design temp dipstick. I chose three spots to check the temperatures and held 3500 rpm constant in 5th with exception of passing, and I made sure only to pass once and took the car to the same head temps each time, about 380F.

Run 1: Stop 1 220F, Stop 2 226F, Stop 3 228F
Run 2: Stop 1 212F, Stop 2 222F, Stop 3 218F

Even with the lower ambient temperature on the second run, i'm willing to say that I was running a tad cooler with the RP, but most definately, the RP was much better at sheding the heat. I'm going to stick to RP from now on in this engine and continue with 3,000 mi oil change intervals unless my testing results from Staveley suggest otherwise.

Between the mileage I put on the car testing the oil and running errands, I'm now up to 4200mi.

Thursday, July 06, 2006

Replacement parts

To once and for all eliminate the possibility of worn springs and / or pistons in the pressure reliefs, I called up Stoddards (800-342-1414) and ordered replacements for both the vertical and horizontal pressure reliefs, along with new crush gaskets and screw in plugs. All together, the parts ran $51.36. For those wondering, it takes qty 2 of each of the following parts: 616-107-511-00, 999-521-016-00, 900-123-025-70, 999-064-010-02.  Not too bad for peace of mind. Should be here by next Monday or Tuesday.

Wednesday, July 05, 2006

Pressure reliefs

I pulled both the horizontal and vertical pressure reliefs to see if something might be caught up or improperly installed. 

Here are some of my observations. The vertical spring is shorter than the horizontal spring and the vertical spring is a lower tension spring- I would have to say that it's about 65% of the tension of the horizontal one. Both pistons were scuffed, so I polished them up till they were smooth to the touch with some very fine emory paper. They now slide in and out easy- getting them out was a tad more difficult.

Idea: Maybe, just maybe I switched the springs on accident, or maybe they were that way to start? Should the taller spring be in the vertical pressure relief. It would sure make sense to me that I'd want the stiffer one there, since replacing the spring in the vertical pressure relief with a spacer would force all the oil through the cooler.

I'd like to say thanks to Ron LaDow of Precision Matters for helping me troubleshoot the pressure reliefs. Hopefully we can get to the bottom of this. I just want to make sure that indeed it is the oil and not some other external factor throwing my oil temperatures off.

Tuesday, July 04, 2006

More on oil temp

I again drained the Delvac 1300 and refilled it, but this time I used a racing oil additive supplied by CMW Racing that had been blended with the Royal Purple, just to make sure it wasn't the reason for the lower temps. I again took the same drive and the weather conditions were the same, with exception of humidity, which fell from 71% to 51%. The oil gauge again registered 240F after some spirited driving, but the dip stick measured lower by at least 5F lower than what the gauge indicated, which I can probably dismiss as climatic changes or gauge error. I now plan on switching back to RP to see if I can duplicate the results I had previously attained. Some may squirm at the thought of 240F oil, but you have to remember that I'm running oils designed to see prolonged high temperatures. Even the delvac 1300 super, which is a dino oil, is rated for continuous temperatures up to 150C.

Oil temperature vs. viscosity

I've isolated that it wasn't the 10w60 Castrol TWS being bypassed by the pressure relief and not being cooled. I took the 912 for an extended drive across the border into Indiana about 20 mi each way and actually had to turn back to Indiana since there was a slow freight train blocking the route. The oil took longer to warm up, but this time I traveled with my calibrated oil temp dipstick and recorded 240F. The weather conditions were 85F, 71% humidity, and 29.98in of Hg. I noticed that very quickly, the oil would drop some 5-10F just by pulling over to check the temperature. I also tried keeping it out of 5th to keep the rpms up and that was good for a few degrees, about 5F cooler at the max. Either way, it's hotter than with the Royal Purple.

Monday, July 03, 2006

Yet another oil change

It occured to me that possibly the 10w60 was too thick at operating temperature causing it to be bypassed from the oil cooler. Considering the cost of the Castrol TWS 10w60, I carefully cleaned the drain plug area and collected the almost new oil (<500mi) for later use. 

To see if indeed it was the fact that the oil wasn't going to the cooler and hence the 15-20F higher oil temperatures, I chose to replace it with Delvac 1300 Super, which just so happens to have about the same TBN and percentage of additives like Zn, P, and C. Not to mention they both also don't have moly and have equall PPMs of boron, which if my hunch is correct, is one reason for the oil pulling more heat.

To be sure that it wasn't the fan belt slipping, I had already pulled a shim out and retensioned the fan belt. I also verified the 28 degrees max advance, so the timing is also spot on.