M42 build for E36 Compact

[MrPhatBob]

The solid lifters from FCP arrived this week:

They appear to be good quality and are coated in what we think is a Dry Lubricant Coating (DLC).
The standard hydraulic lifters are 62gm
The FCP solid lifters are 50.3gm
Until I measure the lobe clearance I can't weigh the lash caps to get an accurate total weight saving.

They fit in the cam carriers just fine:

And I've found that Toyota 4A-GE lash caps fit my 6mm valves, so they'll be ground to size once the cam is re-profiled.

On the subject of valves I did some weighing of valve plus, spring, cap and collets:
In: 109.6gm
Ex: 109.3gm
As a comparison I weighed the inlet of a Honda Formula 3 engine and that came in at 126.5gm, which is a fair bit heavier - although the valves are a good few mm bigger.

I also started looking at the S50 bodies - this time to see how I was going to modify the throttle shaft, and to check that the centres of the ITBs bearings matched up.

It leaves me with two options: Cut and machine the shaft so that it has the right profile to fit the throttle body.  Or cut the middle of the shaft out and use a drive coupling to join them. The second is the easiest - but the machinist might not let me do it!

[wazzu70]

I thought DLC was Diamond Like Carbon coating to make parts resist wear. PTFE (teflon) coating could be Dry Lubricant Coating too. There are toom many dang TLAs (Three Letter Acronyms) out there

Great info as always! A coupler for the ITB shafts is easiest, but it would be nice to have a single piece shaft!

What engine management are you planning on using?

[MrPhatBob]

I used DFL from Techline a while ago, its also a DLC... TLA overload.  Back when God was a Boy you used to be able to get Parkerized followers and that was it.

As I say its the choice of the machinist at MASS Racing how is a mate of mine - which makes him a very harsh, abusive, critic.  So its down to him what happens with the throttle shaft, and that's fine by me because everything he's told me to do so far has worked.  And he makes me do the work on his machines which pushes me out of my comfort zone (normally I spec what I want and send it off).

I'll be putting a VEMS on this one, it seems silly not to when you consider how long I've been involved with the project

At MASS they specialise in classic, historic and rare race engines, and have a contact who'll make custom copper head gaskets which come in cheaper than Cometic gaskets, this means getting rings machined into the head and block.

[wazzu70]

Somehow I figured VEMS would be the ECU of choice

Im not sure any of my configuration will work for you unfortunately due to the different crank triggers. Please post up the primary trigger settings when you get that far.

[MrPhatBob]

The S50B32 US JE Pistons arrived and were promptly weighed

JE Piston 428.6g
OEM Piston 484.1g
Thats a reduction of 55.6g (1.96oz) per cylinder.

Onto the S50 throttle bodies, the shaft was cut down on the lathe


Then the flat that drives the TPS cut on the mill


And it all bolts together and works nicely


I'm running an electric water pump so a blanking bung was machined out of nylon


Which was sealed with "grey snot", pressed in place, and then held captive with cap heads

[wazzu70]

What waterpump are you looking to use? There is a discussion on bimmerforums about these on racecars. I have also read on the Nissan SR engines the waterpump cavitates at higher RPMs. Not sure if the M42 does the same thing, but an electric pump is a great way to solve the issue!

ITBs look great!

[MrPhatBob]

The exact make has not been decided yet, it will either be a Davies Craig or Bosch unit.  I was undecided as to what to do, as the machinist who did 99% of the work above makes impellers that don't cavitate at high RPM - but a well known race engine builder was up at the dyno with a Ford Zetec engine running a Davies Craig unit, and a brief chat with him convinced me.

[MrPhatBob]

Its been a while since the last update - but thats not to say nothing has been happening...
The ZRP Rods arrived - weighed at 534.5g (OEM weighed in at 547g) 12g saving - totaling in a saving of 68.1g per cylinder when adding the piston mass.

The block was chemically cleaned, so it needed a spot of paint to stop things rusting.

Next up - mains clearancing with Plastigauge - torquing down the caps to 60nm.

And then pulling the caps off to measure the spread - and the results were good! Close enough to 0.050mm on every journal.

So as thats good we need to see how the piston/rod combo works out in the block.

Leveling the piston using the magic tool means I can safely measure the piston to deck distance.

Then repeating the same measurement using the same piston and rod assembly at the far end of the block.

Result @TDC cylinder 1: 0.0476" above deck. cylinder 4: 0.0465" above deck. So I'm going to have to grind the deck flat.
For my metric users out there the piston was 1.32mm proud of the block, which I expected to occur because the compression heights differ in the S50B32 and M42 pistons... And it reminded me why I'd bought the 11.5:1 JE pistons - once machined flat I'm going to be sniffing around the 12:1 compression ratio (if my maths is right - and it seldom is).
Next up I need to check the valve pockets for clearance, so get TDC sorted with the degree wheel.

I didn't photograph measuring the valve depths - because it was hectic, I know, its wrong, but we need to be grown-up and learn to cope with disappointments in life...

Inlet clearance:
12deg ATDC => 4.31mm
20deg ATDC => 6.32mm

Exhaust clearance:
12deg BTDC => 1.50mm
20deg BTDC => 3.47mm

So far so good - its looking like my compression will be close on 12:1 and I can run some aggressive cam profiles.
We were comparing this engine with the Cosworth BDG engine which one of the engine builders used to build at Cos. they made 212bhp from a 1.6litre engine.  Similar bore/stroke combination, exact same rod ratio, similar valve angles, same compression ratio... Its nice because I'd like to make 200bhp from this build, the possibility that I could make it is what drives me...

[jrw21]

Looks good! What compression height did you end up going with on the JE pistons,  stock s50b32 US 31 compression height? Also,  what rod length did you end up chosing?

[MrPhatBob]

Stock S50B32 US piston compression height and stock M42 rod length.

The bench that I'm doing this on has a disassembled M10 engine on it, we noticed that the mains bolts for both engines are exactly the same, as are the rear crank seal carrier and seal.

[jrw21]

I'm shocked to see that your setup was above deck height and by a whopping 1.32mm? How much had you taken off the block already? On my stock block with the same setup (81mm crank, s52 pistons, 140mm rods) I was below deck. However, using the 83.5 crank I was above deck (you can see the picture on page one of my thread.)

The stock m42 pistons are 31.65mm ch
The stock s52 pistons are 31mm ch

So with that being said then the m42 pistons would have been 1.92mm above deck? I must be missing something 

[MrPhatBob]

I am clearly missing something as I put the pistons and rods in to measure how much I needed to remove from the block.

Unless I have somehow stumbled upon an M42 that had a longer stroke crank - I've not measured the throw...

[jrw21]

Check the crank, the m42 crank will have 81 stamped on it and the m44 crank will have 83.5 stamped on it. From the pic you posted it looks like it says 81.

[Warsteiner]

S50B30 US  32.8mm CH/86mm bore

S52B32 US  31.0mm CH/86.4mm bore

S50B30 Euro 31.6mm CH/86mm bore

S50B32 Euro 32.3mm CH/86.4mm bore

Position = (Stroke/2) - rod length - compression height
212.15mm = (81mm/2) + 140mm + 31mm
212.15 = 40.5 + 140 + 31
212.15 = 211.5
This tells you that the piston is down inside the bore by ( -.65mm)

212.15= (83.5/2) + 140 + 31
212.15= 41.75 +140 +31
212.15= 212.75
This tells you that the piston is above the block by ( .60mm)

Maybe you can do a quick measure on your New pistons to see if they are at 31mm CH?? Do the same for the rods and make sure they're 140mm center to center.

Did you already deck the block? How much did you take off?

Cheers,
~Ralph

[wazzu70]

Lots of good info in here.

The pistons he is using are higher compression than stock if I read correctly, which probably accounts for some additional compression height.

This is why you have to measure things! Savesa lot of headaches and guessing later on!