Re Breather Mods

 

The current threads on the above have reminded me of the Cossy mods I did some years ago and the same would effectively work on the zed with some slight variations.

 

From the drawing below it can be seen that by linking the two breathing area's (sump & cam cover together and using an oil separator that the oil is scavenged and returned to the sump, a collector can be used in place of the sump return but the system becomes a two way system as apposed to a three way and the benefits of this.

 

From the diag and assuming engine is running at high revs and boost level is high, vacuum levels are nil, any blow by at the piston rings which may normally pressurise the sump is digested by the intake without first passing up to the engine top, as the pipe from the sump runs upwards and a height differential exists very little or no oil will pass up this way.

 

Now assume low revs and a closed throttle plate, vacuum is very high and any build up of pressure top of the engine is digested by the intake, the air hits the oil separator plate at high speed resulting in oil splatter on it, the air continuing its journey to the intake. Any left over oil in the air is trapped by the gauze filter and returns to the sump. (drips)

 

When I initially tried this out on my Cossy I fitted a temporary catch bottle and was initially surprised to find that little or no oil was in the bottle after 3 or 4 days. However it soon became apparent that if driving on high boost around town or on the local duel carriageway that oil entered the catch bottle. This had then proved that blow by at the piston rings had been previously ending up in the intake tract via the oil ways up to the cam cover and then the breather, after re-routing the catch bottle pipe to the sump, the usual weekly oil top up became a monthly affair .As a further addition, when the engine was later removed and disassembled for inspection and upgrades the bores were found to be within Fords new engine tolerance!! which at 137K miles speaks volumes for the regular and quality oil changes I had done (27 oil & filters in 3 years and 48 k miles!)

 

There is a variation on the theme in that a one way valve can be added (maybe) would depend on the characteristics of the engine and a little testing would be required. Also the level at which the unit is mounted can alter performance with the unit upright the input tube from the cam cover must be higher than the engine top to prevent excessive breathing into the separator and possible oil run out.

 

When I constructed the one for my Cossy I used 35 mm copper tube cut down and a flat piece inserted before the top and out lets were fitted. Copper was used as it is so easy to work with and can be polished or painted to suit.

 

The units available at the moment for the zed are a variation on the original Cosworth breather system and as such will work for a healthy untuned engine, having said that so will the original Nissan one ! So seems I might be doing a bit of testing the next week or so to confirm my theories ...or not. Jeff TT

 

 

 

 

I had a similar bailey motorsport breather on my escort but I still dont understand why we cant just vent the breather to air unless this affects the PCV in some way or you need a vacumm to pull the gasses out. I have always found the stuff that accumulates in catch tanks and breathers to be a bit white and slimey so do you really want that to go back into the sump?

Paul