My E30 Turbo Frankenmotor Restomod

[wworm]

I'm stoked part of my old car is living out the rest of its life in something this crazy lol.

Those fenders turned out so great. Super good call with the e46 graft

[Ludwig]

Yup, i never would have thought e46 fenders would fit the e30 so good!

[efficient]

dang very nice. that driveshaft looks like it will be easy to take out when needed.

[s14brent]

dang. this thing is badass!!

[jph]

On to the engine build. My project plan started as an NA S52 build. I briefly considered a supercharged S52 and finally settled on a turbo S52 for the power plant. I bought an entire E36 M3 automatic convertible to part out and scavenge the components I needed for my build. All in all, I think I roughly broke even on the car but got a complete running S52, engine harness and computer, and an auto E36 M3 driveshaft which I would have needed for the 6-speed had I not gone with the large case diff.

I carefully tore the motor down and everything looked really good considering it had 140K miles. I drove the block and head to VAC Motorsports in Philly and dropped them off for the machine work and cylinder head assembly. I had chosen forged Mahle Motorsports .2mm overbore pistons in a 9:1 compression ratio for this block, along with Molnar 135mm forged rods to pair with the S52 crank. I had VAC balance and polish the crank, bore and hone the block for the Mahle pistons using a torque plate, deck the block, check mains and align hone if required. For the head I brought them a full new set of Supertech stainless intake valves and Inconel exhaust valves along with Supertech valve guides and a set of new OEM valve stem seals. The head received a skim and a 5-angle valve job.

Once I got everything back from VAC I checked every tolerance with a dial bore gauge and a complete set of micrometers. Checking things like cylinder taper, piston to wall clearance, journal sizes and bearing clearances. I clamped the rods in a special connecting rod vise to be able to torque down the rod caps and get accurate journal measurements. Same for the main caps. I went through two sets of rod bearings before getting the correct oil clearance. The mains were good on my first set of bearings purchased so that saved me a couple hundred dollars. I put the entire bottom end together before deciding that for the boost levels I wanted to run (~20 psi) I would be better off with an M52 block due to the larger walls between cylinders due to the smaller bore. I stripped the bottom end back apart and sold everything except the crank to CA Tuned.

I scored the rust bucket M52 that made an appearance in an earlier post in this thread and started from scratch on the bottom end build. This time instead of going back to VAC, I decided to bring the block and new custom JE pistons to Korman Autoworks in North Carolina. Korman was huge in the BMW racing scene in the 80’s and 90’s and they do really top-notch restorations and builds these days. They no longer race as a shop to my knowledge, but they crank out some customer racecars and restos that are killer. That said, I felt confident they would be an excellent choice. Their reputation means the work they do comes at a pretty high cost, but that was fine with me.

I had them do a .5mm overbore on the block to 84.5mm. They also used a torque plate during the boring/honing process and matched the bores to my pistons I left with them. Again Korman checked the mains for spec and determined an align hone would not be needed. Turns out it’s a rare case when one of these iron blocks need an align hone on the mains. I also had them deck the block along with a new front timing chain cover bolted up. Everything was done a month or so later and I drove back down and picked it all up. This would become the bottom end of the Frankenmotor in the car today…

Machined aluminum porn

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

Block fresh back from Korman

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

Specs for the engine components are:
M52 block bored to 84.5mm
Molnar 135mm forged connecting rods with ARP bolts
JE forged pistons in 8.5:1 compression ratio custom spec’d to work with the longer stroke of the S52 crank but the smaller bore of the M52 block
Total Seal piston rings
S52 crank balanced and polished
King Racing Tri-Armor main and rod bearings
ARP main and head studs
S52 head with Supertech 85 lb valve springs, single groove retainers, stainless intake valves, Inconel exhaust valves, bronze valve guides, and OEM valve stem seals
Oil pump is stock housing with new OEM internals throughout
Achilles Motorsports upgraded oil pump sprocket with upgraded gear shaft and bolt (no more nut) and safety wired
S52 cams and trays
Brand new lifters
CES stock thickness cut ring head gasket
Brand new OEM OBD1 magnesium valve cover
Redline synthetic assembly lube for all bearings and cams/lifters
Every engine bolt, chain, sprocket, chain, guides, tensioners, oil squirters, etc were bought new from BMW. Not a single piece of original hardware was reused inside the engine
Also replaced every gasket with new OEM

Now I had the block back and was ready to build the bottom end again. I took careful measurements of the work Korman had done to verify everything was ready to assemble. I also verified the main bearing bores on this block to ensure correct clearance with the King Racing bearings. Then I file fit the piston rings which was a tedious, long process. I’d estimate each cylinder took about an hour and a half for me to fit the rings. The ends of every ring butt up perfectly square which is important for a good ring seal so I made sure to take the time to do this very carefully. I even ordered another cylinder’s worth of rings from Total Seal when I wasn’t 100% happy with the ends of one set I filed. It helped me sleep better at night.

Some measuring tools

E30 Build by Jason H, on Flickr

Before assembling the bottom end I washed the block and crank extremely well with Dawn detergent and hot water. I used a set of engine cleaning brushes to get all the way into every oil and coolant passage to clear any remaining debris or buildup. I washed the block a total of three times using the two-bucket method auto detailers like to do so as not to contaminate the wash water used for the block.

E30 Build by Jason H, on Flickr

VERY IMPORTANT STEP: make sure you either get your block back from machining with the oil galley plugs on the front and back of the block left off or remove them yourself before doing your final wash. There is no way to make sure you do a through job with these plugs installed. Korman put my plugs back in before I picked the block up and I ended up drilling and tapping an M6x1.0 hole in the front block and fashioning a puller out of a socket and long bolt to pull the front plug. Once the front plug was out I used a series of connected 1/4 drive extensions to punch the rear oil plug out the back.

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr


Now we’re ready to assemble the bottom end. I used Total Seal ring seating powder to coat the cylinder walls before assembly. This is good for two reasons: it helps the rings seat fully and quickly by accelerating the micro honing process that occurs during break in and it also shows up as a greenish tint when applied, but only if your bores are 100% clean. Otherwise it will turn a blackish color. I was happy to see mine turn a greenish tint in every cylinder when applied which means I did a good job scrubbing the block!

So the oil squirters go in their holes, bearings go in, then the crank, then the caps. Once the crank was installed and the main caps torqued using the three-step method and ARP Lube I checked end play on the crank snout with a magnetic base and dial gauge and was happy to see it was right in the middle of OEM spec.

E30 Build by Jason H, on Flickr

Then I moved on to setting up the pistons and rods for assembly. I weighed each piston with pin circlips, each piston pin, and each connecting rod with bolts individually to allow me to mix and match rods, pistons, and pins to get the closest balance across the entire set. This was due to the crank being zero balanced by VAC. I was able to play musical parts and end up with a spread of just .8 grams between the lightest and heaviest combination. Pretty damn good if you ask me.

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

I installed the pistons and wrist pins on their corresponding connecting rods using a circlip seating tool to seat the pin retaining circlips. Then each piston got the rings I had filed to each specific bore installed and properly clocked according to Total Seal’s instructions. I used an ARP piston ring funnel to compress the rings on each assembly before placing them in the appropriate cylinder. I have used conventional ring compressors before and they can be a pain in the ass. I won’t use anything but this funnel method from now on. It made dropping everything into the bores a no hassle affair. Anyway, in the go and the rods were carefully fed into the bore to avoid scratching the bore or the rod journal on the crank. Again, tedious but required.

Once these were all seated and the caps installed with the rod bolts snugged down I went through the torque process which required 25 ft-lbs and then I believe it was 55 degrees of turn on each bolt. I set up my torque angle gauge and got them all torqued to spec. I rotated the whole assembly over a few times to check for binding or interference and everything was great.

E30 Build by Jason H, on Flickr

Piston to deck height was perfect, something I was a little concerned about considering the JE pistons had a custom wrist pin height due to the stroker setup they were made for.

E30 Build by Jason H, on Flickr

Then I focused on doing the oil pump overhaul. I thoroughly scrubbed the original pump housing until it looked brand new. I used a light coat of oil on all the components during assembly. Once that was all built up and the Achilles upgraded shaft and rotors were installed I buttoned it up and installed it on the block. I also slid the new timing/oil pump double gear on the crank snout along with the new oil pump and timing chains and new chain guides. Then I bolted up the freshly powder coated front timing cover with new seal installed.

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

E30 Build by Jason H, on Flickr

I had to modify the windage tray that sits beneath the crank before installing it for two reasons: one was to clear a few of the ARP main studs that would have interfered and the second reason was because I had to make a new channel in the tray to allow the oil pickup tube bracket the be flipped around to accommodate the extended length of my pickup tube that Arc Asylum had modified to allow the rear sump E36 pan to be used along with the Arc Asylum modified subframe. Speaking of the oil pickup tube. I sent mine off to Achilles after Arc Asylum had modified it so they could add their pickup bowl reinforcement kit which adds extra support to the bowl to alleviate the bowl separating from the pickup tube issues some have experienced.

E30 Build by Jason H, on Flickr

Wow this is a long-winded post and probably a good place to stop for tonight with the bottom end fully built. The rest of the engine assembly will come in the next post…

[Fasteddie222]

wow!!!!! what a car and built. I love seeing things done the right way. Congrats on an epic built

[K-Bar]

Wow I thought I was detail oriented until I started reading this build, you are in a another dimension! Amazing work man, I don’t know how you sleep at night you must just be buzzing on what you are working on all the time. I love how you weren’t satisfied with your block after it came back from a machine shop and you washed it three more times haha you’re car is insanely clean and perfect in every way. Can’t wait till I build mine a quarter of this nice

[masterofnone]

Hi buddy!

Nice to see how your car came together, very impressive stuff! I’m almost there, engine is in the car just have all the smaller systems to sort out now. Hope all is well.

[jeenyus]

Next level as always. Thanks for keeping us in the loop.

[switlikbob]

This has to be one of the coolest builds I've ever seen.

[THATDONFC]

Are those Hyper Black?

[325isman]

Beautiful e30....the color is great and all the work you put into it is spot on.

[econti]

This is huge!