Hey team - looking to try something new in the Evo cylinder head.
Kiggly HLA reduces the pressure at the lifter oil gallery, this also reduces the amount of oil that gets shot out on the camshaft lobes.
Rocker holes are ~0.7mm, which gets fed oil from the top of the lifter.
I tested the Kiggly HLA over the weekend. Oil pressure with the normal HLA was 52psi @ the lifter gallery. Kiggly HLA dropped that to 12psi.

My idea to further limiting oil in the cylinder head is blocking the 2x 1mm holes at the end of the lifter oil gallery.
I'm guessing this is just a bleed system, maybe to help regulate oil pressure at the lifter also (doesn't really seem to).
These bleed out A LOT of oil, they will certainly be contributing to head filling up.

Has anyone tried this on a working engine?
I cant really see a downside to doing this, apart from the lifter's maybe getting some air in them. Which will purge out eventually anyway.

 

Just a hunch, but Im guessing it could be similar to the drilled hole on a MBC to vent pressure. And then one per bank.

 

what negatives can you see on blocking them off?

 

If you vent the engine from the block, or run a dry sump with a sealed engine, you can machine off those two vent channels in the head and increase the oil return capacity from the head massively...

as for kiggley... there was some story about the lifters pumping down at high rpm and high lift cams in engines using it... this was on lancerregister but it was not discussed further...

 

Kiggly HLA could be very easily modified with a heavier spring. I took measurements and dimensions. It's 400g per 10mm rate (0.04kg / 1mm).
I was surprised with the pressure being so low. Changing this to 20psi or 25psi would be simple.

Modifying the drains and removing the channels would help with draining, sure. A couple of 12AN breather lines from the block to the head would make up for the lost venting.

But - the point of this post was to reduce the amount of oil being dumped into the head in the first place.
Kikiturbo have you heard of anyone blocking these venting ports off?

 

no I did not.. I wonder if these jets have some sdditional use.. like cam oiling ?

 

Cam lobe oiling is from the small holes in the rocker arms. I can post a video.
The ports at the end of the lifter oil gallery is what I'm interested in blocking.

 

@RSMike couldn’t you drill/tap the holes, plug them and pump the oiling system prior to running the engine to verify that you are getting oil in the correct locations at reasonable amounts?

 

Yup - drill/tapping holes with the engine already assembled is a bit of a pain though.
I've spun the oil pump with those holes blocked on my dummy engine and everything looks ok.
I was thinking about designing a clamp to block those holes off, which can be installed in place and reversed easily.

 

My guess is they're for flushing contaminants that make their way into the head. The space to transfer oil from the head to the lifter is pretty tight (under a thou IIRC) so giving somewhere for any particulate to escape easily keeps the lifter bores from being damaged.

If you're confident in your engine's ability to keep the oil perfectly particulate free then it could be beneficial for keeping excess oil out of the head. Would certainly make for an interesting test.

 

The space for the lifter to get oil is the entire center of the body that isn't machined to fit the lifter bore. It's much more than .001"

I think it's as Mike thinks, which is it's probably for faster air bleeding from the lifter supply lines.

 

Sorry, I wasn't clear with that, I meant for the lifter body to be lubricated, not filling the lifter with oil. The clearance for the lifter to the lifter bore is pretty tight. I could see it being an air bleed as well, would be curious to see if the lifters have issue pumping up without the bleed.

 

The air would come out eventually, just might take a bit longer.

 

I've taken an educated punt and blocked the two lifter bleed holes off.
4mm ball bearing fits perfectly, hole punch on the aluminium to lock it in place.

 

Thats ballsy (pun intended)