Das Beast: My E30 track / street build

[dvallis]

Dammit! Spreadsheet error. Thanks for the error check. We're both wrong though. Installed height should be same as original spring, which was 33 mm (1.299")

So .... (1.825 - 1.299) in x 120 lb/in = 63 lb, but if you look at the spring data here, it shows 1.300" as 46 lbs. Quite a difference. Their data is weird though. Spring rate is not linear.

I'll measure it tonight with a gauge and find out for sure.

[peterman]

The data may not be incorrect if it is a progressive spring which is likely the case. Considering that it is a valve spring, and is probably used in a DOHC 4 valve motor, the required holding force for valves is decreased drastically over that of a 2 valve motor. So there is probably a low k to help with the initial jerk of the cam and the low holding requirement (freeing up power to the wheels), then a larger k value to reduce valve float.

Time to search mcmaster for an appropriate spring.

[dvallis]

So, it's a progressive spring. The manufacturer's data for length and lbs show that rate increases with compression.

Deleted psi data as its wrong. See posts below.

Height Comp lbs Rate
1.400 0.425 34 80
1.350 0.475 39 82
1.300 0.525 46 88
1.250 0.575 51 89
1.200 0.625 56 90
1.150 0.675 62 92
1.100 0.725 68 94
1.050 0.775 74 95
1.000 0.825 81 98

[peterman]

What is the max allowable pressure on the turbo bearings? Are they journal or ball bearings? You certainly do not want to blow those seals.

[dvallis]

Precision says 85 psi max for a journal bearing turbo with 4AN feed line. Mine is 3AN, so even better. Setup proven by Kameron.

[dvallis]

Zach, you're going to college for mechanical engineering, right? Should have caught this and called me out. :devil: We HAVE all the data to calculate oil pressure exactly with the new spring.

Free length: 1.825"
Installed height: 1.300"
Rate: 88 lbs/in
Diameter: 0.945"

Pressure = compression x rate / area

psi = lbs/in x in / in2 = lbs/in2

Oil Pressure = (1.825-1.300)×88 / ((0.945/2)^2 x 3.1415)
Oil Pressure = 66 psi

Perfect.

I'd say we engineered the he'll out of this enough. Spring goes in tomorrow so this build can keep moving.

[peterman]

Z

Free length: 1.825"
Installed height: 1.300"
Rate: 88 lbs/in
Diameter: 0.945"

Pressure = compression x rate / area

psi = lbs/in x in / in2 = lbs/in2

Oil Pressure = (1.825-1.300)×88 / ((0.945/2)^2 x 3.1415)
Oil Pressure = 66 psi

Perfect.

I'd say we engineered the he'll out of this enough. Spring goes in tomorrow so this build can keep moving.

Make sure you're using the working area of the valve, not the flange area (if there is one)

Since you are adding another passage for the turbo you will effectively be lowering the idle oil pressure across the engine since your pump V dot does not change but bearing V dot decreases due a portion of it now going to the turbo. It may be negligible, but something to consider if you have low pressure at idle.
Apparently the 524td engine used a higher flow pump 11411275093.

A 3AN fitting will restrict flow to the turbo.

If it is supposed to use a 4AN hose, you should probably supply enough oil for that hose.
Cross sectional area (I think these numbers are correct, not possitive though)
3AN = 0.0276 in^2
4AN = 0.0491 in^2

By using a 3AN fitting and hose you should have sufficient oil pressure, but you reduced oil flow by 50%! This has overheating implications since the fluid velocity will be slower to leave the working area of the turbo.

edit: the oil flow will not be reduced by 50% but you will be requiring a higher exit velocity from the bearing orifices to maintain proper pressure. I would still be concerned about the possibilities of overheating the oil.

[dvallis]

Weekend Update

So, in the end we decided not to do the oil pressure relief valve delete. The math made sense, spring rate was right when we tested it .... but there's enough invested in the engine that it's not worth the risk. We figure there's a reason they put a pressure relief valve in the pump and block. No sense blowing turbo seals and whatnot if the pressure is too high.

Moving on. We had to get the Lump off it's stand and back onto a hoist to install the new rear crank seal. Pretty easy when you use the motor mounts and a block lug as lift points. You forget how heavy this damn thing is. Electric hoist is handy.





Crank scraper and gasket going on. This takes patience. Stack up looks like:

OIL PAN
PERMATEX
CORK GASKET
PERMATEX
CRANK SCRAPER
PERMATEX
CORK GASKET
PERMATEX
BLOCK



Oil pump, scraper, and pressure relief valve in place.



Getting the oil pan bolts on was a PITA, given all the layers of cork and goop but it worked out. Block is sealed up. Ready to start bolting on the "fiddly bits".

[dvallis]

Timing Belt Smackdown

Thermostatic valve. Before. Looking pretty ugly.



After a dunk in the parts washer, with heater core delete.



Timing belt installed. It was a one hour smackdown. Feels like I've been wrestling a gorilla. Once you figure out the method it's not too bad. (Hahaha. Sure)

1. Loosen tensioner bolts
2. Compress spring and tighten top bolt
3. Put first 5 mm only of belt on pulleys
4. Check timing marks
5. Dork with crank slightly to get slack on tensioner
6. Slide belt over tensioner last
7. Tighten bottom tensioner bolt, not all the way
8. Slack upper tensioner bolt to let spring expand
9. Tighten both tensioner bolts
10. Rotate crank clockwise. Check timing.
11. Realize you are one tooth off. Remove everything
12. Beer. And cursing. Re-apply mosquito repellent
12. Repeat. Until it works.

[Eric]

subscribed, great stuff!

[jeffnhiscars]

You want to rotate the crank (2 full turns btw) with the tensioner bolts loose

[digger]

have you use the correct mark on the gear for TDC iirc its not the 0 position of the vernier marks there is a separate single mark

[dvallis]

Yes. Aligned faint single diagonal mark on top right side of cylinder head with TDC on cam timing wheel. TDC mark on crank aligns with notch on lower cover.

[peterman]

have you use the correct mark on the gear for TDC iirc its not the 0 position of the vernier marks there is a separate single mark

I think the Vernier marks are on the timing belt cover. Those should be used when checking the O|T mark on the harmonic balancer, correct?

[dvallis]

Timing marks are circled in red below.