Block posting- anyone done it

[Slow96GSR]

As long as the posts are the same material they will expand at the same rate. The bad part is that when the cylinders expand you'll start to force them to be out of round. This is bad. The outter block walls aren't really an issue. They don't expand as much or as fast as the cylinders. I don't nor would I use posts over sleeves, or even a block guard. I still wouldn't use a block guard, but that's just my opinion.

[EfiOz]

EfiOZ maybe you can enlighten me. The problem I have with posts is this you are dealing with three metal expansion points. First you have the cylinder walls & sleeves, the posts, and then the other walls of the block to deal with. As we all should remember from physics classes when metal is heated it has to expand.

So lets start with the cylinders (and sleeves) if they have posts poking them on just two sides and they start to expand wouldn't the cylinder have more resistance to expanding at the post sites and therefore the unsupported sides would be able to expand easier making the cylinders go oval shape not round? And how could you check with the head on if this is happening?

Next you have the posts themselves from the physics classes again we know long objects like the post bolts expand longitudinally (down the long length not getting thicker) and since the cylinder gets hotter quicker it then expands out toward the post bolts but at the same time the bolts are getting longer putting more force toward the cylinder as they warm up so I would think you would be getting differing forces on the cylinders as they and the posts heat up at different rates and therefore expand at different rates as the cylinders are being heated by direct contact with combustion forces while the posts are just being heated by the coolant so I would think there would never be constant measurable force being directed at the cylinders because of the different rates of expansion and again how could you measure it with the head on?

And finally the outer block walls that the posts are screwed into. As they are the furthest from combustion heat they should expand the slowest of all three components. But the problem is the posts are screwed directly into this surface so while the the cylinders and posts are getting heated faster the block is getting less heat and expanding less slowly so again the forces being put onto the cylinders are being increased when the block is warming because the cylinders and posts are expanding quicker than the block walls but then when the block is fully heated it expands outward making the forces less because the screwed in posts are moving with the block outward making the force less.

So the bottom line is how do you work with/control the differing expansion rates of the three major components?

Until someone can explain how they solved the problem I'd vote against posting.

True, hence my advice against using it in a turbo app. My post answers your questions already. We ran NA (although big CR) and almost cold coolant temps.

[EfiOz]

We used aluminum bolts for the expansion problem. If you use stainless or a denser metal with different expansion properties you get issues with them loosening and tightening as well as corrosion (unless it's a good grade of SS).

[BlitZ]

We used aluminum bolts for the expansion problem. If you use stainless or a denser metal with different expansion properties you get issues with them loosening and tightening as well as corrosion (unless it's a good grade of SS).

yes and from my understanding, endyn makes the post bolts/thread out of the same material as honda manufactuers there blocks

[BlitZ]

EfiOZ maybe you can enlighten me. The problem I have with posts is this you are dealing with three metal expansion points. First you have the cylinder walls & sleeves, the posts, and then the other walls of the block to deal with. As we all should remember from physics classes when metal is heated it has to expand.

So lets start with the cylinders (and sleeves) if they have posts poking them on just two sides and they start to expand wouldn't the cylinder have more resistance to expanding at the post sites and therefore the unsupported sides would be able to expand easier making the cylinders go oval shape not round? And how could you check with the head on if this is happening?

Next you have the posts themselves from the physics classes again we know long objects like the post bolts expand longitudinally (down the long length not getting thicker) and since the cylinder gets hotter quicker it then expands out toward the post bolts but at the same time the bolts are getting longer putting more force toward the cylinder as they warm up so I would think you would be getting differing forces on the cylinders as they and the posts heat up at different rates and therefore expand at different rates as the cylinders are being heated by direct contact with combustion forces while the posts are just being heated by the coolant so I would think there would never be constant measurable force being directed at the cylinders because of the different rates of expansion and again how could you measure it with the head on?

And finally the outer block walls that the posts are screwed into. As they are the furthest from combustion heat they should expand the slowest of all three components. But the problem is the posts are screwed directly into this surface so while the the cylinders and posts are getting heated faster the block is getting less heat and expanding less slowly so again the forces being put onto the cylinders are being increased when the block is warming because the cylinders and posts are expanding quicker than the block walls but then when the block is fully heated it expands outward making the forces less because the screwed in posts are moving with the block outward making the force less.

So the bottom line is how do you work with/control the differing expansion rates of the three major components?

Until someone can explain how they solved the problem I'd vote against posting.

similar ot what i was thinking, but into more depth...

[EfiOz]

Thanks, EfiOZ didn't realize you were running cold coolant temps. Any hints on how you guys figured out they were loosening and tightening when you can't see inside the block with the heads on.

When you strip them down you can see that they've moved from their depth. Welding was a better but much more time consuming and difficuly option. We just placed aluminum rods instead of bolts and welded them in place.

I'll take a pick of a flogged out block and post it later. It'll have to wait until Tuesday. I'm off to Adelaide in the morning.

[ALLMTR996]

i was talking to dynodave about this a while back, he didn't seem to like the idea -citing heat spots as an issue.

Not heat spots he said pressure spots where the post sits on the outa sleeve,and has seen what it does to a bore/pistons after an engine ran a little hot.
ALLMTR996

[TODA AU]

Really...
Funny you say that...

[tinkerbell]

Blitz, FWIW - i have not 'posted' my B20B and it seems fine after 20'000km...

mind you , i have no idea what to be looking for!

anyone know what to look for when determining if a block needs to be 'posted'?

[tinkerbell]

I'd install new sleeves.

exactly the answer if you are concerned about sleeve integrty!!

[BlitZ]

wah piston head looks so clean.

..
Yeah ... ive read amillion and 1 of your posts tink... basically compression cracks the b20s.. if rod and head bolts are upgraded and running close to std comp, it will last forever...

..

Not really referring to b20 specifically.. but am wondering the pros and con's of a poor mans reinforcement, posting..

[tinkerbell]

and those are re-cut valve reliefs too...