Unswept volumes

[*Glenn* 854]

I've been looking all afternoon on the net trying to find out what the unswept volumes (cc) of an M52B28 and a M54B30 engine are. Anyone know a site that has this info ??..... will probably have to measure these myself if I can find somebody with both heads

[westy 614]

Try here.

Some interesting info.

Edited September 17, 2010 by westy

[*Glenn* 854]

Try here.

Some interesting info.

Thanks Tony... I was looking in there for over an hour as well my search obviously was either misspelt or something else... can't remember now.

Still more to research though. Headgasket thickness, piston crown machining for valves and shape of the piston crown are also included in the unswept volume as well. Haven't read the whole thing...I will in the morning.

Edited September 17, 2010 by *Glenn*

[thorburn 121]

Not sure how exact you are wanting. I'd imagine that after reading PEI330Ci's post you will be after something more in depth.

But if not here is my average estimate of what the unswept area is of an m52b28 (second attempt )

Compression ratio = 10.2:1

Bore = 8.4cm

Bore area = 22/7 x (8.4cm x .5)squared = 55.43 square cm

Stroke = 8.4cm

Swept area = 55.43 x 8.4 = 465.6 cubic cm

Unswept area = 465.6 / (10.2 - 1) = 50.6 cubic centimetres

Feel free to correct me if i've done something wrong in this

[*Glenn* 854]

Didn't think of working backwards with the Calc's. Thanks James. Trying to work and think of project calc's is a bit hard

So with those figures. Changing the stoke to 91mm with 84mm bore and standard headgasket I'd achieve a compression ratio of 10.9:1... This is getting interesting now. It will also give me an engine capacity with standard pistons 3026 CC's or 185 C.I.

Bore oversize to 85mm will give me 11.1:1 compression ratio & 3098cc 189 ci engine capacity

Edited September 17, 2010 by *Glenn*

[thorburn 121]

The numbers you have worked out will be correct if the dome of the pistons are the same. You could find that the cylinder head volume of the m54 might be larger than the m50/2. As a result the pistons would have a larger dome. Putting the larger dome m54 pistons in a smaller m50/2 head volume will result in a higher compression ratio.

I have no idea of the cylinder head volume of the m50/2 so it could be larger or smaller then the m54.

With a larger bore the compression ratio could only be determined if the volume of the piston dish is known

Now you have an m54b30 I'd love to hear what the real world volumes of everything is. Also how close the real compression ratio is compared to what bmw states

[*Glenn* 854]

The numbers you have worked out will be correct if the dome of the pistons are the same. You could find that the cylinder head volume of the m54 might be larger than the m50/2. As a result the pistons would have a larger dome. Putting the larger dome m54 pistons in a smaller m50/2 head volume will result in a higher compression ratio.

I have no idea of the cylinder head volume of the m50/2 so it could be larger or smaller then the m54.

With a larger bore the compression ratio could only be determined if the volume of the piston dish is known

Now you have an m54b30 I'd love to hear what the real world volumes of everything is. Also how close the real compression ratio is compared to what bmw states

I get the M54B30 block on Monday and I'll progress from there...more research needed but at least I've got something to start with. I'm probably not going to use BMW pistons...more like something starting with for....

My present path is:

M54B30 crank & rods

M50B25 Vanos cast steel block

M52B28 Vanos Head

Edited September 18, 2010 by *Glenn*

[Lucan 196]

Wanting more oomph after the last track day Glenn?

[*Glenn* 854]

Wanting more oomph after the last track day Glenn?

That... and the fact I've always wanted to do & always do something a bit different.. rather than follow what every other person does... we'll just have to see what the result is