The 15 Y/O Turbo M42 Build Thread (Now Holley EFI Terminator X Controlled)

[Il Duce]

Jesus, it's beautiful.

[Dj Buttchug]

What a sight to behold.

A brand new M42 Cylinder head.

17 units left in the world per BMW apparently.

$2,900 OTD

[Dj Buttchug]

Was it running quite lean at any point?

Not since I installed the new engine management. Lean conditions could have been present during my Mega squirt days. I had a lot of troubles getting the car to run correctly in the beginning. The skirts on each piston have a some slight wear on each side indicating some issues.

[econti]

Was it running quite lean at any point?

[Dj Buttchug]

All because of a $12 spark plug

Brings back some memories of building this engine when I was in tech school.

Some scoring on my cylinder walls is a bit unsettling. There are areas on cylinder 1 and 4. The majority of damage is in hole 3 where the plug dropped. All areas are .002 or slightly deeper :(

I have a new set of pistons and rings. We will do the same treatment as the m50. Cerakoted block and components. New oil squirters, the works. Crank, rods, and all bearings are in great shape so that is good news.

It will be better than it was. I'm pissed, but it's not the end of this car. The M42 will live on.

Here are a few photos.

[2mAn]

No luck on the WTB here? Bummer...

[Northern]

I think the same crack issue happens on the 24v stuff. Not common but not super rare. Seems mostly random

[econti]

I would doubt the crack is from that. I think most likely from high exhaust temps, or over tightened head studs but I wouldn't expect that mistake.
Could also just be one of those things on an old motor, maybe it was overheated before your time.
Such is the game for more than doubling the power out of old engines. Doesn't make it any cheaper however.

[Dj Buttchug]

Shit go. What from?

A while back I dyno tuned the engine and cylinder 3 spark plug failed at about 5k rpm under 15psi. The insulator broke off inside the combustion chamber. The gouges in the cylinder head outer area are the result of that. I was unable to see this when I borescoped the cylinder. I cannot confirm this same event caused the cylinder head to crack but it is possible.

My #3 piston is also a bit beat up.


New OEM old stock m42 cylinder head from Germany via Turner Motorsport. $2,900.00
New CP piston set at a discounted rate due to the sales rep feeling bad for my situation $800 shipped.
85mm ball hone to revive the cross hatching in all cylinders after 10 years of incorrect overfueling/megasquirt love and care $116

Expensive Lesson.
Only use REAL (not fake chinese copies) NGK spark plugs. Failed plugs were DENSO brand. The only real surprising thing here was the cylinder HG and cracked head has lasted almost 2500 miles of everyday driving until it finally gave up resulting in a constant misfire on #3 due to coolant intrusion and cylinder head crack between valves.



The 318 is gonna be down for about a month or so until the parts arrive.


Fun right?

[econti]

Shit go. What from?

[Dj Buttchug]

Do you see it.

[zwill23]

I really think 300whp is the perfect amount for this chassis, with the right setup everything is well balanced and it's not a burnout machine. I've opted to not push the pisseyes as well and I think it's the only reason the engine is still together 30k miles later. M20 but same philosophy.

[econti]

17.4 pisseyes

Barely even breathing. Nice result

[Northern]

I would've shit a brick at the sight of that plug

[Dj Buttchug]

Greasy torque curve. How many pisseye?

17.4 pisseyes