Weston Dillard

I flogged the heck out of that block for 5 years and it was in perfect condition when I pulled it out for my 3.3L upgrade. I'm a believer!

West

blade7

Windage ports with liners seems to be a bit of a minefield though.

PF

Agreed but from what I have seen that even with liners installed a large part of the windage holes still are unobstructed by the liners so much of the windage holes advantages should still be in function.

blade7

I've seen a picture that looked like the liner obstructed over half of the port.

PF

Seen that to but still air moves easily so I would think even half the hole would help alot but Its a tradeoff with liners.

V2Rocket

The liners are so long (5.75" or so total cylinder length) vs the piston skirt+stroke that cutting a hole through the liner should pose no problem.

You're not going to get all the air under one piston moved to its adjacent cylinder but every bit of pressure relief should help.

I just bought a block that the PO had LR cut the ports, i can take photos if desired.

fortysixandtwo

If it's a fresh build, have the liners machined by their manufacturer. I had Darton do this on my sleeves.

blade7

Not sure that could be done on thin wall liners?

fortysixandtwo

Darton managed to figure it out on a set of dry sleeves. Initially they omitted the port openings on the custom liners we ordered. We were going to add the port openings ourselves but couldn't figure out how to cleanly add them without risk of distorting the liners. We sent them back to have the openings added, but Darton decided to make a new set instead of reworking the existing ones. Based on their decision to scrap the first set and start over, the port openings probably need to be machined before any ID or OD machining.

michaelmount123

Here's what no one has mentioned: Honing a cylinder with a windage port at the bottom is problematic in that it's difficult to keep round. For this reason, when I sleeve a block I use as short a sleeve as possible, and put up with the port being partially blocked.
MM

blade7

Who's liners do you use, and what length with a 3.0 crank?

sherry66

Might have been the photo with my podgy fingers sticking through the ports after liners installed .
I used flanged Westwood liners uk .All the liners are cut to length to suit .

blade7

Probably what helped me decide to stick with Alusil, if I ever have to build up a 3.0.

schip43

Hmm OK all this talk about adding windage ports to the block?? It seems like a lot of expense and trouble to relive "pressure in the oil pan" and from underneath the pistons?? You can make 300 hp+ on a little old 4efte 1.3 Toyota motor with a breather can on a Toyota motor all you need is a dash 4 or 6 an fitting for in and out on the valve covers (for in and out to the can) and it's job done. That won't work on a 951?? Just asking cuz I have no idea???

951and944S

With the 944's lower crankcase, the route for transfer of the air/mist/cloud to the adjacent cylinder is more blocked/restricted than most engines.
It's not really "pressure" in the oil pan (IMO, the ports would be better defined as "transfer") as a whole but creating a route of transfer from one piston displacing area as it travels downward into a void created in the area being created by the piston next to it moving upwards.
So, instead of this air having to make it's way around the lower crankcase's main bearing mass (where more oil/suspended mist are) to transfer, it now has a dedicated path higher up in the upper crankcase.
An inter-cylinder breathing effect if you will.
One cylinder exhales, the next one inhales....., balance transfer.

T