Starting the build S50b30

[h82crash]

I've pulled the engine and about to yank the head. Had coolant in #3 with about 110k on a Bavarian Engine Exchange replacement. Will know soon if I have a cracked head.

I know some of the members here are also on FB Boosted E36 World group. There is a camp over there that say if kept around 400whp, stock compression not only is ok but, preferable. A car is described, having low compression ratios at that power level, as "lazy." Another post I read said "head spacers are a thing of the past with today's tuning."
What say you?

As for tuning, I have a Link G4X ECU and will be tuning myself. Closest dyno is an hour away and has a reputation of blowing shit up.

I am at the point I need to decide what to do. Cut ring and studs only? Spacer? Decompression rods?

Driving style will be just a fun weekend car, some open road pulls, no drifting or drag racing. I'm at 7800' elevation and the car will get down to 5500' on occasion. Best octane around here is 91 and no e85.

Bottom mount GTX3584RS clone.

A few parts to install and a quick mock-up before I cleaned the engine.

[PowerKraut]

1. I would stay on stock CR, with your power goals as well.
2. Lazyness with low CR is somewhat true, but a 3 Liter will be okay, even off boost, when you dont go too low. most seem to stay at 8,5:1. my 3.0 setup (m50 based with 3 liter crank, not done yet tho...) ist at 8,8:1
3. Headspacers are a low budget option. never used one, and never will... but i dont agree with the "modern ECU" statement. What should a modern ECU do better about a physically knock limited setup? If CR is too high, you gotta do something. If its a thicker MLS gasket, headspacer, low CR pistons is up to you and your wallet.
4. You could go studs only @ stock CR for 400whp.. but since you already have to pull the head, i would add some rings (groove-o-matic style)
5. Maybe go with a GT30 sized unit for more mid end.
6. Do some road tuning till its drivable and let an expert finish it properly. driving an hour or more is well worth it.
7. Prepare to waste a lot of moneyz.

Greetings from Germany.

[pbonsalb]

Will this car run on 91 octane Colorado pump gas or E85? How much more boost do you need to run at 7800 with the same turbo to make 400 rwhp than you would run at sea level?

If you could make 400 on 91 at 7800 with stock compression, how do you know now that you would never want more power? Do you have a lot of experience with 400 rwhp E36 do you know you would never get used to it? I once thought 300 rwhp would be all I would ever want. That was in 2006. Then came 400, 500, 600 and 700.

Have you ever driven a well done and well tuned turbo E36 with 9.0:1 CR? Why is a spacer and HG so bad? Many people here have used them to make 400 or 500 or 600 rwhp, though if building a motor and buying pistons and rods, you might as well drop CR through internals although I know of a couple of built motor cars with spacers that make 700-900 rwhp because the builds were originally high compression N/A —the motor in Butters car and the motor in CES Motorsports car.

What turbo kit is that? What are the specs of the turbo?

[h82crash]

I don't know what an e36 with 400 hp turbo feels like. I have only seen 2 other e36s in my town. I do know what 500 hp in a 2200 lb race car feels like and once I took it from 250 to 500 with an engine build/swap, I never felt I needed more power. DIY tuned on a MS2 that I built. I could break traction at will with only the throttle. I also have a turbo SxS weighing 1500 lbs with 170 hp and, although there are commercial upgrades to easily take it to 250, have no desire to tune it for more.

That is why I am asking. Most of what I read says it will be fine off-boost, but some say it will be a dog. trying to figure out what is accurate. I am leaning toward lowering compression through internals, but if a spacer can be as reliable, that is fine too as I don't have to disassemble the rotating assembly. Just the info on this forum basically equates the durability of the M5x/S5x head and gasket to a Christmas ornament in a box of rocks tumbling in a dryer. Not to mention mine has at minimum a blown HG and possible cracked head. I have no idea if my car has ever overheated, I just picked it up a couple of months ago.

It's not a kit. Parts I have been individually sourcing for the past six months. I was going to boost my 325is shitbox until I got this M3. Plan is 2.5 hot side to IC and 3" cold side. All 3" exhaust.

The turbo specs are:
.82 T3 inlet/3" V band exhaust housing
68/62 turbine wheel
67/84 compressor

IC is a 12x24x3. I may cut it shorter in height to fit, but won't decide until I start fitting it.

[h82crash]

Head is off and it's cracked. Also found the block is bored to 87mm. Would you still boost it?

[E30s50dude]

I would, stock bore is 86mm on factory US s50. You would just run 87mm s52 pistons stock or forged for you set up.

Could you double check what size pistons your currently running s52 already maybe?

[h82crash]

I would, stock bore is 86mm on factory US s50. You would just run 87mm s52 pistons stock or forged for you set up.

Could you double check what size pistons your currently running s52 already maybe?

This is a Bavarian Engine Exchange build on an M50 2.5 block. So, no good reason it should be overbore except, maybe, it was the only pistons they had on hand at the time. The pistons fit the bore, and still ran strong even though I was loosing coolant. Probably correct oversize pistons. Paranoia is probably irrational, but my gut wants a problem free head gasket joint. All of the cracked head threads and failed HG stories got me feeling like these are made outta glass. FYI, this head was cracked when I got the car. What are the odds my calipers are off by exactly 1mm?

[E30s50dude]

This is a Bavarian Engine Exchange build on an M50 2.5 block. So, no good reason it should be overbore except, maybe, it was the only pistons they had on hand at the time. The pistons fit the bore, and still ran strong even though I was loosing coolant. Probably correct oversize pistons. Paranoia is probably irrational, but my gut wants a problem free head gasket joint. All of the cracked head threads and failed HG stories got me feeling like these are made outta glass. FYI, this head was cracked when I got the car. What are the odds my calipers are off by exactly 1mm?

If they ran an m50 going from an 84mm bore it would've been easier to just go .5mm or 1mm (an use off the shelf pistons) over unless it was absolutely needed (scored cylinder walls/out of round) and a hone couldn't fix it.
If the cross hatching is still visible I would reuse the short block since this is a mild build. You calipers are probably accurate I didn't know this was an m50 based block.

The heads are prone to cracking when you overheat these motors, usually you'll see a failure with the HG or the head itself. I would just slap another head on from the junkyard, after getting it decked along with the block. At that point you know everything is completely flat giving you the best seal possible.

[h82crash]

Yes, currently looking for a head. Due to my location, closest junkyard with an e36 in it is probably a 12 hour drive. But since they are prone to cracking, most likely all already cracked (which is why they are in the junkyard). Unless the car is collision damaged, I wouldn't bother pulling it off.

[Mklock]

My last 3 cylinder heads are from the junkyard. All perfectly fine.

Now after 20 hours of labor and 100$ for the machine shop you have a nice, refreshed consistant flowing head.

[h82crash]

My last 3 cylinder heads are from the junkyard. All perfectly fine.

This is good. Maybe the odds are in my favor. Still, I'm 500 miles from a decent junkyard.

[pbonsalb]

You will be paying extra to have a known good head shipped to you.

[spyderg0d]

Ive found about 20 good heads from junkyards thay I have installed over the years. However I have pulled probably another 20 that werent any good even though the cars were junked for collision.
I currently have an extra 1 port head (obd1) for myself and an extra 2 port head(obd2) ive been trying to sell for a couple years,. The shipping makes it not worth the sale on used heads. And no one wants to drive to pick them up. Its strange to me how ppl will spend the time to pull heads at the junkyard for the $100, then tjrow it on without having it checked.. Rather than buy a head for $150, no have to pull anything, and just checknit themselves before they buy it.. Ppl are weird..

[h82crash]

If I still lived in San Diego, I would be going down to the Pick your Part. Yes, would have cleaned and checked while sitting down in the dirt, but still skeptical of its condition. I have a friend at a dismantler looking for me. Even considering the new head by AMC.

[h82crash]

Went to fit up the intercooler. Surprised it fit, somewhat. I guess I have a few options. I can hack the crap out of the bumper and brackets so the IC can sit more forward, I can delete the aux fan and the IC fits fine, or I can cut the IC shorter or buy a smaller one that sits just below the bumper, actually hanging from it making mounting easy.

[pbonsalb]

The IC looks big enough to handle your 400 rwhp goal.

[E30s50dude]

What kind of IC are you running?

[h82crash]

Tube and fin 12x24x3. 3" in/out.

[h82crash]

Picked up a replacement head.

[tic55]

im not sure what head you could get for 150, but i dont think i would be skeptical of getting a head from a junkyard if there is any kind of history/story to the vehicle. but im glad you found one! im in the process of building my M3 too, i did the ces spacer combo with studs. also i did all custom stuff too, my intercooler is much much smaller but was able to use punched flat bar, and bent it making a L shape and bolted it to the ac condenser and the intercooler. it works really nice. i also used the bottom mount manifold but i built a pipe to make it a top mount instead of buying a $600+ manifold.

[h82crash]

I got a spare head from the junkyard, as well. $70. I have $500 into the good head and still have to swap the S50 springs over.

After port matching and removing excess material and blending the sharp transitions in the plenum, I had the manifold ceramic coated to keep ambient engine compartment temps down and exhaust pressure up.

[h82crash]

I port matched the head exhaust ports to the manifold and also the turbo inlet to the manifold.



Turbo before:





Turbo after:

[h82crash]

HG/Spacer on backorder. Got a few things done in the mean time. Lapped the valves in the new head, replaced the valve stems and swapped valve springs.

I drilled my own oil pump nut and safety wired it. Also installed heat shield mat in the tunnel and area of the turbo.

[h82crash]

I did some welding.

[h82crash]

It's been a while since I updated. I finally got my cut ring HG and spacer. Put the head on and torqued the ARPs. Cams installed and timed. I started ordering all the bits for my crankcase vent, turbo coolant lines, vacuum/boost fittings. I had to drop the engine in so I could start fitting up the piping. Did the down pipe, wastegate, hot and cold side piping. I did buy a different IC. This one is a 10x20x3 bar and plate core. Welded on some 90 elbows to the intercooler. I get to keep the brake ducts and fog lights. Now that the charge pipes are done, I have to pull it all back apart and yank the engine because I didn't have the turbo mounting studs yet and didn't want to wait. Just wanted to get rolling on pipe fitting.