Das Beast: My E30 track / street build

[whodwho]

The inner spring look odd to me, they look too small of a diameter. Usually part of the purpose of the inner spring is to give stability to the outer spring at high RPM and they have an interference fit, these must just be for added spring rates.

I have a set of VAC springs (Eibach makes them) and it is hard to push the inner spring thru the outer spring.

[dvallis]

You're right. Schrick catalog has seat pressure for outer,inner as 240,90 N (54,20 = 74 lb) and fully compressed as 610,220 N (137,49 = 186 lb) There's actually a typo in the Schrick catalog listing spring forces as [mm].

Good catch. Nice to know someone's reading this. :devil: At any rate, new valve springs are never a bad thing.

[staysideways]

You're right. Schrick catalog has seat pressure for outer,inner as 240,90 N (54,20 = 74 lb) and fully compressed as 610,220 N (137,49 = 186 lb) There's actually a typo in the Schrick catalog listing spring forces as [mm].



Good catch. Nice to know someone's reading this. :devil: At any rate, new valve springs are never a bad thing.

I am so glad to see this. Someone actually building an M20. It's not that bad of an engine after all. The Danm thing is un kill able if you oil it and keep it from over heating it goes a long way


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[sonomabimmers]

after reading this thread i feel tad bit smarter every time haha. loving it

[digger]

The inner spring look odd to me, they look too small of a diameter. Usually part of the purpose of the inner spring is to give stability to the outer spring at high RPM and they have an interference fit, these must just be for added spring rates.

I have a set of VAC springs (Eibach makes them) and it is hard to push the inner spring thru the outer spring.

yeah not all springs use the damping effect of having the inner and outer coils rub

[dvallis]

Engine re-assembly mega post

Finally, getting to engine reassembly. Pistons back from the machinist. First step, clean all gunk from ring seats and oiling holes. Soap & water works best.



Got them perfectly clean, then balanced all pistons to the lightest. Final weight was 366.0 g each. Stock M20B25 pistons are 391 g, so we are saving 150 g rotating mass on pistons alone.



Next was balancing all the rod weights. We worked on a setup to balance large ends using the small end as a pivot, but that was an abject failure. Could not build a repeatable rig. It was too sensitive to position of the rod with respect to the scale. Changing position of the big or small end by 1 mm results in changes of several grams. You see a lot of youtube videos of guys "balancing rod ends" with scales, and I think they are total BS now. In the end we got 100% repeatable measurements by standing the rods end on like this.



Removed very small amounts of material from the rod large ends with a belt sander, matching all weights to the lightest rod. Final weight was 641.5 g each.



I splurged for some high quality Deeves rings. They have a 4 piece 3 mm oil scraper, with inner expansion ring, top middle and bottom ring. This is along with the standard 1.5 mm top and 1.75 mm middle ring.



Here they are installed. You can see all the pieces I was talking about above.



Here are the completed piston and rod assemblies. Each weighs 1142.2 g +/1 0.1 g. Original weight per cylinder was 1190 g. Total rotating mass removed: 286.8 g, or 0.631 lbs. This thing should rev significantly quicker than a stock engine, and behave much better at high RPM due to the balancing.



Nice new main bearings.



Crank back where it belongs.



ARP main stud installation. ARP does not tell you that these can be screwed TOO far into the block. Notice the stud on the left. When it's all the way hand tight, the stud sits too low for the cap to grab threads. If you install these things, make sure you do it like the stud on the right, with a bit of thread showing.



Torque main studs to 40 ft-lbs in the following sequence, then do it again to 70 ft-lbs. (ARP only. Stock spec is 45 ft-lbs)





Here's a test of the crank installed. It's SMOOTH. Really nice. Can literally turn it with two fingers.



Rented a piston ring compressor for the next step :getting pistons into the block.



Pistons slid into the block fine. Here's the rod against the crank journal before end cap is added.



Rod caps on, ready for torque. ARP rod bolt spec is 35 ft-lbs. Stock is 15 ft-lbs in Bentleys! Seems way low to me.



Just for grins, here is a piston with the crank bottom dead center for this cylinder. Notice the piston skirt sticking out of the cylinder? It's TIGHT in there. Clears the crank fine though.



With the crank in, pistons installed and rod bolts torqued the crank is pretty hard to turn over. We can do it, but takes a 10' pipe and socket on the crank bolt. It's obviously not the crank, so has to be pistons. My buddy working with me on this build says it's normal, since performance rings have more friction. He builds V8s, and they don't even try to turn them over without the starter. Anyone familiar with building M20s care to chime in?

[dvallis]

Darn. I think we have rod caps swapped, one or more rod caps backwards or wrong rod bearings. Not the end of the world and totally fixable.

[whodwho]

With the crank in, pistons installed and rod bolts torqued the crank is pretty hard to turn over. We can do it, but takes a 10' pipe and socket on the crank bolt. It's obviously not the crank, so has to be pistons. My buddy working with me on this build says it's normal, since performance rings have more friction. He builds V8s, and they don't even try to turn them over without the starter. Anyone familiar with building M20s care to chime in?

This is so not right, hopefully this is better after you fix the rod caps. Rings will not add enough drag to need a 10' pipe!!

I don't put those rings in the performance category, they are a decent replacement ring set and should be around stock ones for tension.

Performance rings are usually less drag to gain performance from friction losses(boosted and nitrous application may have more then NA as needed).

A V8 with stock rings is like 30ish lbs to turn a short block from the crank, performance it like ~10lbs

[digger]

the performance guys measure breakaway friction with a torque wrench with lower being better 10-15ft-lb seems like a ballpark number for a hotish V8 ive seen thrown around. the high performance stuff with low tension rings is much lower to

are the ring groove depths deep enough for the rings?

rods clashing on something inside?

mixed rod caps could cause issues. did you make sure the crank counterweights clear bottom of pistons at each location?

[dvallis]

Thanks guys. Will pull it apart tomorrow & start checking rods / pistons with the crank one by one. 10 ft-lbs force to break friction seems more reasonable.

[george graves]

Nice to see some proper engine building!

[dvallis]

Pulled all the pistons. Left the crank in place because I DON'T want to buy new main studs.

Here's the piston installed on the crank, sticking out of the bottom of the engine. So, do you think my rod bearing friction is too high? That's about 50 ft-lbs right there. The whole engine had roughly 300 ft-lbs or more rotating friction. FOOOK! Removed the rod bearings and everything rotates smooth as glass. No side to side binding or piston interference.



Checking with a digital caliper, rod bearing inside diameter with rod cap fully torqued is 44.75 mm. WTF? All six rod journal diameters are 44.95, so THERE'S a huge problem.

And here's the money shot. I ordered 45.00 mm nominal "standard" rod bearings. What I got was 0.25 mm "undersize", which matches my measurements exactly. Grrr.



Moral of the story: Read the frigging box before installing bearings. At least my crank main bearings are perfect. :devil:

[Tex_E30]

This is going to be naughty.

[digger]

Moral of the story is plasti gauge and bore gauge/ micrometer

[dvallis]

That too