So my rebuild is done and is finally tuned and dialed in. 2.0 liter to 2.7.
The oil temp averages 240 running on 20 50 regular oil and averages 217 on 5 30 synthetic. Seems like the 20 50 would run cooler as the 5 30 would be to thin.

The rings seated fine so I see no issue there.

Thoughts? Ideas?

I was thinking about a different oil cooler with a fan but if the synth runs cooler, why get one? Would the thinner synth eventually have a problem? I tried with both regular gas and premium.

Funny thing is the engine seems to run smoother with the 20 50.


I also posted this on the bird board.

One of the theories I have heard is that the molecular size of syn oil is very uniform and smaller than dino oil. This means perhaps that more molecules are in contact with the surface and able to carry away heat. Probably badly explained but hey, I do better with human medicine so I am not ashamed

Bettern I could put it! =^)

The synthetic was running cooler at 217 than the rd 20 50 running at 240.

Here's my question to Amsoil and their response below it.
Question:
Hi, I recently had my 75 Porsche 914 aircooled 2.0 liter engine rebuilt and have about 1000 miles on it. I first put in 20 50 regular oil for the first 500 miles so that my rings and bearings would seal and seat. The engine is running smooth and no oil leaks, but the engine temp is running at 240 degrees. I next put in Mobil 1 synthetic 5 30. The engine temp ran about 217 degrees which is ok but i wanted it to run cooler around 190-200 degrees.The engine was bored out to 103mm to a 2.7 liter size and has 78mm stroke. (stock is 71) I also replaced the fuel injection system to a SDS 4E and there is a mild cam in there. I would like your thoughts about using your (TSO) Series 2000 Synthetic 0W-30 Motor Oil in the next 100 miles. Is there another weight I should consider or will the 0W-30 be acceptable? Let me know if you have any questions so you can advise and I'll do my best to answer them. I'm not a mechanic but do understand a few things. Thanks Eddie


It is normal for an oil that is too thick to run at hotter temperatures as the thick oil makes the oil pump work harder, creating heat and the thicker oil does not transfer the heat as well. I think you will be pleased if you change to AMSOI< 0W30 oil, but do not try to keep the oil temp under 200-210 degrees as this will allow moisture to accumulate in the oil and contaminate it. (Above 200 or so, it boils off.)



Thank you for this opportunity to respond to your question(s). As always, please feel free to contact us again if we can be of further assistance.

I disagree with using 0W anything in an aircooled motor. 20W minimum...
Interesting combo. I would think that those cylinders don't have enough mass left to transfer heat. I know those combos have been done for years though. I guess it would depend on the cam and such if you could get heat out of it. External cooler right???

Welcome to the land of cast iron 103s... The land where uncontrllable oil temps are the norm and head leakage will occur in less than 5,000 miles.

You'll soon be realizing the reasons why I haven't buil;t a single engine with a bore larger than 96mm since 199 without real "Nickies" cylinders.
You have added almost 10mm of cylinder diameter and all that extra friction surface area will make for higher oil temps, less efficiency and this will be compounded if you haven't coefficiently added intake volume.

External cooler right???

No external cooler at this time. That's the next step.

And to Jake,
A Japanese Celica GT intake was put on the engine. It seems to be getting enough air in there.

Here's the Dyno Chart from after the rebuild. Disregard the date it was done in August. The number reflect at the wheel.

The valves were just adjusted and were not tightening up.Click to view attachment

Why wasn't the engine taken over 4,400 RPM on the dyno? Torque and HP cross at 5252 RPM and without taking an engine to that point it is impossible to verify a dyno run's accuracy.

The 901 tranny soaks up about 25% so that would mean the 2.7 netted about 146 HP at the flywheel before the drivetrain losses, about the same as one of my lesser tuned 2270 engines with 7mm less bore size. When compared to much larger engines is when the 2270 really shines.

BTW_ I'll bet you have another 30HP in the exhaust system, an engine this large is VERY exhaust dependant, it never ceases to amaze me that people always enhance the effects of adding intake and disregard exhaust and thats what kilols their combo time and time again.

I'm using a Bursch exhaust I put on about 5 years ago. That is another element I'm contemplating along with the external oil cooler. Not sure what I want to put on there at the moment though. Got a suggestion? Just 1 thing at a time as the $$ allows. It's still a wip. But it is now a running wip. The dyno was done before we retuned the SDS system. It' will get another one after I figure out the temp issue and possibly exhaust.

WOW....
The Bursch is maxxed out for sure, its a wonder you are making as much power as you are!

That exhaust is more than likely killing your exhaust valves and seats- if the engine can't exhaust it may not be running for very long.

exhaust dictates most everything with these engines, I'd rather see someone have inadequate intake or ignition as inadequate exhaust!

What goes in MUST come back out!

Nothing wrong with running 0W-40 oil. It is nice to engines when they are cold. One of the benefits of synthetic oils.

So I tried 0W30 Amsoil synth 2000 and it runs at 240.
I put the mobil 1 synth 5-30 back in and it runs at 217.