Das Beast: My E30 track / street build

[dvallis]

Lord Of the Rings

Feeler gauges organized. I hate dicking around with all of them on a key ring.



Insert ring



Seat with handy ring tool



Check the gap



Grind, just a bit. Drill turns toward INSIDE of ring



Measure again. Repeat until within spec. We used 0.022" for the 2nd ring per Total Seal.



Ring set installed on piston. Tops are "gapless" which is really two rings with big gaps, but they overlap and interlock. 2nd ring seated correctly with notch inside and down. Bottom is a 3 ring sandwich.



Ubiquitous blue tape holds clocked rings in place.



Repeat 6 times. Done.

[Digitalwave]

Keep 'em coming!

[dvallis]

Original piston assembly weight 256.4g



New piston assembly weight 200.7g. Looks like we're saving about 0.75 lb on the rotating mass.



Rod bearing shells are the right size. Unlike the 1st build :-)



We dorked around forever installing the first set of rod pin clips. You know the drill: sore thumbs, clips flying across the room, crawling around the floor looking for lost clips. So, we made a tool that does it in 10 seconds.

Get a thin wall tube about 0.85" in diameter
Cut it off about 4" long
Get a solid plunger that fits inside the tube
Insert ring in tube a shown



Insert wrist pin temporarily. It gives the clip a surface to push against.



Put tube perpendicular to piston with gap up



Insert plunger. Press down with smooth firm motion. Ring will click when it seats



Voila



Slightly remove pin. Insert rod. Repeat on opposite side.



More next time

[dvallis]

Started on the rebuild today.

Did a light de-glaze on the bores


Started installing the rings. Oil ring was good out of the box with 0.0015" clearance.



2nd ring needs 0.0022" per total seal specs.


After checking online we realized ring gapping tools come in three varieties: cheap junk, over priced and unavailable. We built our own. Made the platform large enough to support the entire ring, decent thickness aluminum for rigidity with a clamp point underneath for the vice. Variable speed AC drill finishes it off. Looking forward to trying it next time.

[dvallis]

Glad to have helped. Rob and I frankly knew nothing about M20 engines when this whole adventure started, so it's been fun sharing the learning along the way. We have a "Wall Of Shame" for all the funny screw-ups: Bent valves, upside down rings, "plastic shard of doom" that lunched the first turbo. Will have some more good details with this next bottom end re-assembly.

[halesyeah]

Hey amazing build thread. Been following it the last few years in awe. I want to thank you for documenting the process so thoroughly, especially all the mistakes. I'm putting together a 2.9L stroker and got the bottom end together a few weeks ago. Put the oil pan on and then remembered your whole oil ring fiasco. I of course couldn't remember if I checked my 2nd rings to see if they were directional. Nothing in the documentation about it. So reluctantly I pulled the oil pan and scraper and 2 gaskets and checked the pistons one by one. Sure enough #5 and #6 rings were upside down. And they are clearly marked TOP on the rings. So thanks for saving me from trying to diagnose a smoking engine by putting all the good and bad in this thread.

[ForcedFirebird]

It's not the lawn mowing I am concerned about with the oil pan, debris is also a culprit. Besides "two off" is a legal pass, even in TT. :p

[moatilliatta]

I would take. Flat edge to the gasket surface to confirm flat before bolting it up. I do this even if a baffle is welded and most get hit on a big belt sander.

[dvallis]

We kept about the same depth, just scaled out. Wanted to keep the same flow dynamics around the oil pump pickup. I'm sure Hans has some engineering into it.

We refer to Hans a lot in the garage. Usually "F@#$ HANS! You HAD to put that bolt THERE?"

If it gets to needing a skid plate, Crew Chief's reply is "Stay on the track, idiot."

[zwill23]

Looks nice! Did you maintain the same overall pan height as stock? I forget if you're running a heavy duty skid plate, but that seems like some good insurance on track.

[dvallis]

Trap door large sump oil pan is done. Nice job by Ernie's Welding.

[Northern]

By scraping the crank, it's effectively minimizing how much oil can be flung back up into the engine, and maximizing how much is going down in at least the general direction of the sump.

[dvallis]

All parts here. Rebuild starting.

[ForcedFirebird]

I've lost two motors in the lasy ~8yr of enuro racing, both on long right handers, not lefts (two weeks ago, we were able to save #3 motor, just ate the rod bearings).

When pulling over 1g the oil most certainly goes up the side of the block, and since the engine is leaned over, the oil easily goes up the passenger side - essentially at 1g, it's like rolling your car over about 45°. It's not like it happens all of a sudden - if you use a fast acting digital or non-fluid filled gauge and watch the oil blipping at +1g when the oil level to the stock "full" line. Motor #3 was losing pressure over a 3hr period before we brought the car in. We had a spare motor on the trailer with a blown HG, so I grabbed the rod bearings out of that motor, stuck them in the car through the oil pan,and continued to race the 8hrs left of the 14hr. When the car came in for low pressure, I immediately checked the level and it was just over the stock "full" line. At full tilt, we tend to burn about 15gal fuel and .5 qt oil every 2hr, obviously someone forgot to check in the hot pit :/

No, the scraper wasn't designed to remove the oil and put it in the pan, the scraping action of the scraper is to reduce windage. When Kevin at IJ invented that scraper, it was a two fold design, scrape the oil off the crank and create a baffle for the entire side of the engine that it leans to. Scraping the oil off the crank does two things - one is lighten the crank (yes, it's only ~15-30gm, but at 7k rpm...), the second is to keep suspension to a minimum. It seems to work as well as knife edging the crank to reduce wind resistance and cut through the oil mist that's saturated the engine interior. If the windage tray wasn't useful (along with the oil drain-back tubes dumping directly in the pan), BMW wouldn't have changed the design with the introduction of the next generation(s) of the baby six. In street car-situations, you have a lot more vacuum on the crank case, helping the oil droplets fall quickly (as well as decreased wind resistance for the crank/pistons), but in racing situations, there's hardly vacuum since the engine is usually under acceleration (TB open to atmo).

I would love to put accusumps in our cars, but they cost too many points. :/

EDIT: We change the bearings every other year, provided there's no issues, which is about 75-85hr. For a spec car to see that kind of mileage, it would have to race approx 30 weekends to match our hours. Most spec races are 30-45min, and FL is the only region that has 4 races per weekend, everywhere else has two AFAIK. So, each hour of an enduro is like 1.3 45min sprints, so a single 14hr race is like doing 18 sprints back-to-back in a single day. Most regions have about 4-6 spec races an entire calendar year.

[kronus]

scrapers don't do much for oil starvation. how much oil do you think there could possibly be covering the crank counterweights?? there's no way it would be enough to make a difference when your sump is sucking air.

accusumps work. I've seen a bunch of them in lemons over the years. cheap insurance, and easy to see work if you plumb a gauge to it. we have a 3L one waiting to go in.


install deck restrictors. install a baffled pan. run over full. fundamentally, these motors rely on gravity to drain oil back into the sump. during long lefts, if you're pulling enough lateral g, it doesn't.