Cam cover - hole where Apollo breather was

[Shaun_E]

Having bought a dry sump system I have removed (and sold) the Apollo tank. This leaves a hole in the cam cover where the breather from the top of the Apollo was connected. What is the best way to fill this hole? Is it worth fitting a breather filter to it or should I just block it up completely?

 

Yellow SL #32

For Sale: chrome headlights, sill protectors

[Bob Corb]

It needs to be blocked up or else your dry sump scavenge pump will just suck air into the engine leaving the oil in the sump and therefore not in the dry sump tank or engine galleries! Best to get it welded up. (Or swap cam covers with the appollo tanks new owner)

 

BC

[V7 SLR]

There has been a lot discussed in the past about whether or not to allow air to enter via the cam cover of a dry sumped K. Basically, the head scavenging is poor. The engine is tilted over, leading to pooling of oil over the exhaust followers. The head only drains through the head bolts which are further towards the centre line of the engine than where the oil tends to pool. As the oil sloshes around the head it passes over these drain holes for a finite time. If you could increase the *speed* of drainage, you would be helping your engine, therefore allowing some small amount of air into the head could be beneficial.

 

Search for Peter Carmichael's thoughts on this. Very worthwhile.

 

There may also be some benefits in running an engine in a vacuum although this is less certain. Historically race teams tend to do this but no-one really has any measurements as to whether it's a good idea. The principle is that an engine running in a vacuum suffers less from windage losses, and therefore can produce more power but without any figures to back this up, it might all be hokum.

 

With this *theory* in mind, and the need for better drainage, the good bet might be to allow a little air into the head, therefore increasing head drainage but also maintaining a partial vacuum. You'd need a very small hole for this.

 

I think Peter implemented a one-way valve and filter on his. The valve was to prevent any blow, and the filter to prevent the ingress of any grit. I've tested mine from idle to WOT and there is never an occasion where it blows, so a valve seems unecessary. For filtration it might be suitable to simply implement a pipe to the filter backplate.

[Allen Payne]

I put a bolt in mine to seal it

[Bob Corb]

We did some measurements on a touring car engine and the windage loss does reduce as you reduce the crankcase pressure. There was an optimum value but I doubt the caterham dry sump scavenge pump will get the crankcase down to this low a value (It would pull all the oil seals in too).

 

I've done a few transient flow simulations also which back this up.

 

BC

[Shaun_E]

Wide variety of opinion then 😳. I have read through some of Peter's posts on this and has given me food for thought.

The car is running with the standard single throttle body/plenum setup and there is a tube from cam cover to plenum as well, so there is already a filtered source of air for the top of the engine. I wasn't clear from Peter's writings what happened to this as I presume his car runs separate throttle bodies.

I'll re-read Peter's posts and have also contacted Caterham for their view.

 

Yellow SL #32

For Sale: chrome headlights, sill protectors

[Shaun_E]

Quick reply from Caterham is to put a bolt in it using copper washers to ensure a good seal.

 

Yellow SL #32

For Sale: chrome headlights, sill protectors

[Bob Corb]

I mentioned this in the office. One idea was to connect the old dipstick tube to the hole in the cam cover via a non return valve, then the pressure pulsations from the crank would pump gas into the cam cover and blow back down the bolt holes carrying oil with it?