Oil Changes Subaru Flat 4 vs Porsche Flat 6
 

I have been reading various threads about disconnecting crank sensor and going the whole hog by removing spark plugs do do a simple oil change.

Anyway, I have read elsewhere previously 911's with their flat 6 engines have sumps/engines which take 12-16 litres of oil!

This got me thinking if you reduce this by 50% (i.e. 6 to four cylinders) this would give an oil requirement of between 8 and 10 litres!

If the scoob engine had a lot bigger sump would all these stories of big end failures be massively reduced and is it a case that the sump on the subaru 4 pot is simply just too small?

I am of course assuming 911's don't blow their big ends as frequent as scoobs as I don't know. Maybe '911' can comment on this?

p.s. I hope this makes sense as I have had nearly 2 bottles of wine.

Damian.

The 911 is air-cooled, and the engine is at the rear of the vehicle. The oil cooler is not, and the pipework has to run from one end of the car, to the other, then back again. So, not only do we have a car with an engine that is cooled purely by air, and the circulation of oil, we have masses of piping to move the oil around the car.

Plus, and possibly most importantly, the 911 is a dry-sump based design, which means the oil is stored in a nice big tank rather than within the engine.

If you fancy a laugh, go find out what you have to do to change the spark plugs on a Porsche 964 :). The car suffers just as many annoyances as the Scooby - the engine is squeezed into it's location(which is inherently wrong), and compromises have to be made with most aspects of the vehicle.

Really, it's a very bad comparison as the designs are so different. A fairer comparison would be a 1.4 K series Rover lump, and a 1.8 Ford Zetec lump. Same design, same basic principles. One blows a head gasket every 40-50k, and the other doesn't. Why? ;)

Enjoy your wine :).

--Rich

I think you mean the 1.8 K series Rover lump ;)

Couldn't fault the 1.4 in the 3 years of ragging I did in my Metro GTI (and I do mean RAGGING!!!) and I did 25k a year in it:eek:

Being the owner of the Sti and a 911 (1973 vintage):

The 911 is exactly as Rich says.
''You dont know the meaning of Excitment until you oil change a 911 for the first time''

You have never seen so much oil (going onto the garage floor...)

The only precaution I take is to get the 911 hot so the external oil cooler
thermostat is open (most 911's have 2 oil coolers)

Wearing thermal gloves open the dry sump bottom plug and get well back, as it re defines 'dumping' :norty:

About 2 lites comes from the engine and a litre from the huge horizontally mounted filter.

The 911 runs a dry sump (very low C of G engine) and a high volume/low pressure lubrication/cooling principle.
At tick over mine shows almost zero psi, and at full chat, 60psi hot.

You cant compare the 2 engines at all, the Sti is so different, but you could compare it to the flat 4 Alfasud engine?

911

Technically air-cooled porkies are oil-cooled, so the oil is doing alot more work that on a watercooled unit.

Better off comparing a porky engine to a Norton 850 commando engine - dry sump, air-cooled and lasts a 10th as long ;)

btw dyney...I've seen ALOT more 1.4 k-series with blown head gaskets than 1.6 and 1.8's put together....but they all blow em anyway. Still, it's good for business though ;):D Not seen a 1.8 turbo yet though or a KV6, but time will tell :D

No, the 1.4 K series is damned awful. You were lucky to do 75k without taking the head off ;).

--Rich

Fair does the two are not comparable.

lol at the rover engines. A guy at work has just had the head gasket go and he has rebuilt it only for coolant to be seeping out where the head gasket is. :rolleyes:

I know someone who had so many things going wrong with his rover it miracously caught fire and was a write off! ahem! ;)