2.8L M20 build - Now with 2.7L!

[acolella76]

I recently rebuilt an 885 head. All new valves, new Febi rockers, 272 billet cam, the works. Then tossed it on my 2.7L flat top bottom end and thus created the 2.7L budget stroker that put down 150whp/148tq when it wasn't even tuned. It was fine for a while but I've recently noticed that the rings seem to be letting go of some oil and I decided to rebuild my bottom end. But not just ANY rebuild, I am building it to 2.8L!

Build specs:
M52 crank
130mm eta rods
Short skirt B25 pistons
Hoping to eventually run MegaSquirt

This weekend I tore down the spare engine that I will be getting my bottom end from. This way I can build a 2.8L while I can still drive my car.

Engine before teardown


The transmission, he is called Steve.


Can you tell I was cutting corners? :)


Ghetto fabbed breather tube rofl




Me thinks there was oil in the coolant...


Also got the rods and pistons out yesterday, but forgot my camera. Going back today and I will get some pictures. Really hoping to be able to drop off the block at a machine shop some time next week so I can start the assembly process.

[LJ851]

Sweet.
You know to not let the machine shop acid/caustic dip the block, right?

[Sagaris]

Exciting!

I would really appreciate some commentary about your dealings with megasquirt when you get things up and running. I am going to be watching this thread.

[Killacortes]

What are the short skirt b25 pistons out of? The m20b25 or the m50b25?

[acolella76]

Sweet.
You know to not let the machine shop acid/caustic dip the block, right?

I did not! Thank you for the help! How should I ask them to clean it, or should I do it myself?

Exciting!

I would really appreciate some commentary about your dealings with megasquirt when you get things up and running. I am going to be watching this thread.

I will do my best! I am probably going to go with a DIYPnP made by WhodWho, I've heard a ton of good stuff about his boxes. Plus it saves me the trouble of making my own!

What are the short skirt b25 pistons out of? The m20b25 or the m50b25?

Late model (89+) M20B25

From left to right: Alpina 10.2:1, US SETA, M20B25 short skirt, M20B25 long skirt

[Sagaris]

What would be advantageous about short skirt pistons other than possibly being lighter weight? and are there certain years that they came in?

I am going MS via. whodwho also. I was scared of MS until I talked to him about it a bit.

[LJ851]

I did not! Thank you for the help! How should I ask them to clean it, or should I do it myself?

The plain bearings that the intermediate shaft runs on are pressed into the block and you cant (or at least you couldn't last time i checked) buy them without buying a block. An acidic solution like a lot of shops use will destroy the bearings which obviously is a bad thing. Any non acid cleaner is fine, soap and water, brake cleaner, parts cleaner.

[acolella76]

What would be advantageous about short skirt pistons other than possibly being lighter weight? and are there certain years that they came in?

I am going MS via. whodwho also. I was scared of MS until I talked to him about it a bit.

They are lighter and less has to be machined off of the crank to clear the shorter skirts. Although I have heard some people that they did not need to machine anything.

The plain bearings that the intermediate shaft runs on are pressed into the block and you cant (or at least you couldn't last time i checked) buy them without buying a block. An acidic solution like a lot of shops use will destroy the bearings which obviously is a bad thing. Any non acid cleaner is fine, soap and water, brake cleaner, parts cleaner.

Cool, thanks for the info! So something like Simple Green would be fine?

[Cinnabar325is]

The plain bearings that the intermediate shaft runs on are pressed into the block and you cant (or at least you couldn't last time i checked) buy them without buying a block. An acidic solution like a lot of shops use will destroy the bearings which obviously is a bad thing. Any non acid cleaner is fine, soap and water, brake cleaner, parts cleaner.

When I built my 2.8 back in March, I bought brand new IM shaft bearings at the dealer for $4 each. So no problem getting them at all. The catch is that the shop needed to make a tool to install them (though some people have told me a standard cam bearing install tool should have worked. The other thing is that the I.D. must be finalized after the installation of the bearings. All told, it cost me $175 for the shop to install the new bearings. But my old ones were toast, it was a must.

[LJ851]

When I built my 2.8 back in March, I bought brand new IM shaft bearings at the dealer for $4 each. So no problem getting them at all.

Good to know, i had not checked the dealer in a while. (obviously)

[Killacortes]

Good shit man!

[red_e30]

nice sub'd to see progress and how this turns out, i see you are going to use a 272 degree cam is it not going to be dropping power at high rpms (not enough flow) or you didnt want to get custom pistons for a higher cam to work

[acolella76]

When I built my 2.8 back in March, I bought brand new IM shaft bearings at the dealer for $4 each. So no problem getting them at all. The catch is that the shop needed to make a tool to install them (though some people have told me a standard cam bearing install tool should have worked. The other thing is that the I.D. must be finalized after the installation of the bearings. All told, it cost me $175 for the shop to install the new bearings. But my old ones were toast, it was a must.

I appreciate the info, you don't have a part number handy do you?

nice sub'd to see progress and how this turns out, i see you are going to use a 272 degree cam is it not going to be dropping power at high rpms (not enough flow) or you didnt want to get custom pistons for a higher cam to work

I bought that cam for my 2.7i stroker because the 2.7s are notorious for dropping power after 5k rpm so I wanted to keep that power band for as long as possible. Now I am using it in the 2.8 because it would be pointless to rebuild another head to the same specs.

Just put in a ton of work. Broke that crank bolt free, got the crank out, rods out, everything in my trunk ready for machining :)

BMW approved crank holder :)


Front timing cover off; this engine will need some SERIOUS cleaning.


Bye bye crank


Everything all packed up


Question though: Does ANYONE know where I can buy new OEM wrist pins or will I be fine re using the eta pins? My M20B25 pistons I bought didn't come with the pins.

[SkiFree]

Looks good so far, I like your garage.

Wrist pins should still be available new (at least they are for the M10) from the dealer or your favorite supplier (who would be going through some dealership to obtain them).

If your planning on going with new febi's instead of the IE HD's then consider polishing the rockers to reduce any potential stress risers. Especially on the weak eccentric arm undersides.

[red_e30]

I bought that cam for my 2.7i stroker because the 2.7s are notorious for dropping power after 5k rpm so I wanted to keep that power band for as long as possible. Now I am using it in the 2.8 because it would be pointless to rebuild another head to the same specs.

yea see what you mean