strokin' it. M20B31 build (finished!)

[LJ851]

Take it to the dyno.

[Zasz]

Uhn.

[ak-]

:)

[lambo]

that thing is red hot!!

Quite literally!

So sexy......

[schtozo]

that thing is red hot!!

[Raxe]

Another weekend, another update!

Assembled engine on stand to make sure we had all of the hardware/gaskets and everything needed for install day.



Pulled the remainder of the old engine out:





New engine went in piece by piece, much easier to hook everything up in stages and I didn't want to remove the exhaust and deal with that. Converted from the dual mass flywheel to a stock solid one, replaced the clutch slave and hose, release and pilot bearings. Clutch disc is still like new :D. Installed new engine mounts and lowered the block in:





And finished:



Filled it with cheap oil and ran it for a while. Loud as hell, after about 10 minutes the shop started filling with smoke haha. Coolant cook-off anyone?



The car has no fan at the moment, going to install an electric pusher fan in the near future as it overheats when idling for a few minutes.



Drained oil and filled with GTX 20W50. The valvetrain chatter is completely gone, not even any ticking. Unfortunately the flywheel rattles with the different cam, but I can live with that. Took it for a test drive at the end of the day - fantastic!!

[LJ851]

Since you putting all this work into building this engine, have you considered timing the cam where it was designed be? That kind of is the point of an adjustable cam gear, you get to set the cam timing and compensate for milling the head/block and variation in how the cam was ground.

[Raxe]

Small update this time. Finished assembling head v2 and adjusting the valves. Installed stock cam gear to test clearance.



Clayed the valve reliefs in the pistons, installed the timing gear, bolted down the head and turned the crank... about 3.5mm of valve clearance with the stock cam gear. Swapped out the stocker with the blue adjustable IE unit and advanced half a tooth and tried again - about 2mm. I think I'm just going to run it with the stock gear. I know there is some tuning potential with the adjustable one but after the last head failure I don't feel like it's worth the uncertainty.

[e30m3s54turbo]

I can't wait for dyno numbers & how it sounds.

[325ix]

Thanks guys! If everything goes well it should be finished and running by the end of the month.



My crank spacer is from IE, someone on here makes them as well but it was combo'd in with the pistons I ordered through them. Nothing complicated really, the inside edge facing the block is beveled but other than that it looks to be pretty much a solid ring. Need to heat it up well to install.



Perhaps someday haha, it's not getting tracked with this engine (maybe an autox or two) so I'd like to keep it as street-able as possible. It's also being driven 2000km through the mountains to the Picnic and other places, and in those conditions I don't want any funny business in the fuel department. Honestly my goal with the car for the last 7 years has been to build it as BMW-like as possible using OE+ parts and styling, so with these specs it's basically an M20B27... but bigger, and with a 6000rpm redline. Around town I'll run a 91 octane map. :)

Man, I woulda like to have seen the 3.1l with 11.0 compression or so and a decent sized cam like a 288. You should have the displacement to still provide better than stock torque even with the aggressive cam.

Regardless, still an awesome build!

[Raxe]

Thanks guys! If everything goes well it should be finished and running by the end of the month.

Where did you get the crank spacer, and is there anything special about it? Possibly a keyway or something?

My crank spacer is from IE, someone on here makes them as well but it was combo'd in with the pistons I ordered through them. Nothing complicated really, the inside edge facing the block is beveled but other than that it looks to be pretty much a solid ring. Need to heat it up well to install.

going turbo? why 9:1? who builds a 3.1 liter to run 87 octane? :p

Perhaps someday haha, it's not getting tracked with this engine (maybe an autox or two) so I'd like to keep it as street-able as possible. It's also being driven 2000km through the mountains to the Picnic and other places, and in those conditions I don't want any funny business in the fuel department. Honestly my goal with the car for the last 7 years has been to build it as BMW-like as possible using OE+ parts and styling, so with these specs it's basically an M20B27... but bigger, and with a 6000rpm redline. Around town I'll run a 91 octane map. :)

[nando]

going turbo? why 9:1? who builds a 3.1 liter to run 87 octane? :p

[downforce22]

wow very nice! Look at the difference in piston and rod sizing!

Where did you get the crank spacer, and is there anything special about it? Possibly a keyway or something?

[dude8383]

Love that last pic!! Good job :)

[dougie30]

wow sorry to see all that metal carnage on your head, but looks like things are shaping up quite well! good luck man!