Classic Bottom End.....
 

Iv been reading through alot of threats on here and there seems to be alot of stories or peoples bottom ends going...

Being pretty new still to the Scooby world I was wondering what causes this? Iv got a 2000 classic shape sport special, is my car also likley to suffer from this problem?

Cheers,

ScoobyStu :thumb:

Not so common on the Sports Stu. Mainly they go after the engine has been tuned without upgrading pistons, rods ect. Also poor maintanence can cause failiure. If serviced regular and treated well it should last for years and years:thumb:

its the plate on back of oil plate comes loose which in turn oil pressure drops and you end up with crank/bottom end failier or pressure relief valves sticks but regular oil changes will help ten fold and if you havent got one yet fit an oil pressure guage its a must on all performance cars its the only way to keep a good eye on it other than that all will be fine

The main reason is Subaru designed the engine to run stupidly narrow big end bearings 21mm. So heat and load transfer is over a relatively small surface area making the engine more prone to big end failure. Many motorbikes run wider width big end bearing so the Subaru engine is very temperamental and doesn't cope with knock etc very well, compared to some better engines.

as u know stu my sport was knocking ..that was only cos the previous guy was an idot and didnt take any car on his car...should last long..i bloody hope so cos im intending to keep this as long as poss...hahaha

As already mentioned if you care for your car corretly you shouldn't have any problems, most failures occured on 1997 > V5/6 Imports cars at which time Japan switched to using higher 100 octane fuel at the pump. But many Imprezas once imported were driven on 95 octane fuel without being remapped causing the engine to experience detonation.

The detonation caused by pockets air/fuel mixture exploding outside the normal combustion event and not controlled by the spark plug (ignition). The shockwaves produced by the detonation causes pressure spikes in the cylinder chamber which then exerts an extra load on the piston down the conrod and through the big end bearing and onto crank. The impact of the shock causing the bearing or conrod to eventually fail.

Many P1's were driven on unsuitable fuel and encountered engine failures as a result.:thumb:

P1's were British and mapped for UK fuel. That doesn't make sense.

But the maps were taken from a JDM STi and not tweaked for UK fuel. :)

:eek:

I'm going up tomorrow so I'll have a word with the lazy people at prodrive.

The JDM Sti & P1 share identical maps, Prodrive wanted to alter the ignition timing to suit 97 octane fuel but it was rejected at Subaru in Japan, so extra knock correction was agreed instead over the JDM map as it was an easier fix. Which resulted in Subaru replacing many P1 engines under warranty, costly error!;)

It was nothing to do with Prodrive it was Subaru's decision to save money.:thumb:

Also the extra amount of timing pulled to allow for knock correction for 97 octane fuel, this didn't account for lesser octane fuel being used. So broquet tablets where placed in all P1's to increase the fuel octane levels closer to Japan's 100 ron. But the knock control did not allow a further 3 degrees or more of timing to be pulled for 95 octane fuel.