BMW E30 Engine Swap - Cost Breakdown
A fully restored e30 sells for insane amounts on bringatrailer.com, so we jumped on the bandwagon.
Our e30 came with an M10b18 4 cylinder 1.8 Liter engine punching 100 horsepower.
The head has a single cam with 8 valves powered by a Jetronics fuel injection system. And the best part was it only cost us $1200. Unbelievable right? But if it’s too good to be true it probably is.
The previous owner told us there was a crack in the head, but swapping the head or having a machine shop shave the head wasn’t a big deal for us. But oh boy did we find a surprise…
BMW E30 M10 Hairline Engine Block Cracks
Cracked Engine Block
As we removed the cylinder head, we found a small nick. The damage was tiny enough that a machine shop could take care of it. However after cleaning the top of the engine block we found multiple hairline cracks between the head stud holes.
After more research this seems to be a common place for M10 engines to crack due to poor maintenance. This poor engine looked like the oil wasn’t changed very much.
The cracks in the block isn’t something that we could repaire as it had multiple hairline cracks around every head stud hole and coolant passage. Just like that we needed a new engine.
I was excited (wife wasn’t), but who wouldn’t love to engine swap an e30. There’s so many different options to choose from…
WHAT ENGINES ARE BEST FOR BMW E30?
We started to compile a few swap options along with associated costs. Our main goal was to get the e30 drifting without breaking the bank and we don’t need crazy amounts of HP.
Now there’s a variety of BMW inline 6 cylinder swaps, but you’d need to swap lots of other parts and we wanted the build to stay simple. What’s the fun in just throwing more displacement at the e30?
BMW E30 ENGINE SWAP COST BREAKDOWN
| M10 Swap | M42 Swap | Honda K Swap |
|---|---|---|
| M10b18 | M42b18 | K24A |
| 100 HP | 134 HP | 197 HP |
| Replacement Block $300 |
Engine $400 |
Engine/ECU $500 |
| Head Job $300 |
Transmission $500 |
Getrag 260 $500 |
| Gaskets $200 |
Prop Shaft, Mounts, ECU, Wire loom, Ignition $800 |
K Power E30 Swap Package $5000 |
| Total $700 |
Total $1700 |
Total $6000 |
So we decided to compare 4 cylinder options. Option number one is a slightly updated 4 cylinder M42 engine. Certain e30s came with the M42, so fitment wouldn’t be too bad of an issue.
Another option is the popular Honda K-Swap. I grew up a Honda boy, so this was pretty intriguing… Or we could just find another M10 and perhaps turbo it :)
Engine and transmission parts are used average prices from Facebook market place and the rest are mostly new from different sources or used from eBay. So for double the cost of sticking with an M10 the M42 doesn’t make a whole lot of sense when it just adds a few HP.
We’d love a K Swap, but $6k for the swap kit its not really budget friendly.
So we decided to stick with the M10 and maybe turbo it in the future. With the lower budget, we could also afford a few other things on the list below:
BMW E30 MISC. PARTS LIST
Custom Designed BMW e30 Brake Parts 👉 Chase Bays Brake Booster Delete, Brake Line Relocation, & Clutch Feed Adapter
Stylized door handles 👉 Condor Speed Shop Drilled Door Handles
Beef up your chassis with 👉 Condor Speed Shop Reinforcement Plate Set
OTHER COMMON E30 ISSUES…
BMW E30 Dashboard and Floorboard Rust
Now we just need to find an engine. In the meantime we pulled the head, jacked the car, and dropped the transmission. Then we went to Harbor Freight to find some parts to help us pull the bad engine.
We didn’t have room for a cherry picker, so we found some different parts and made a modified truck crane, mounted it our truck hitch, and pulled the m10 out.
If you decide to pull an engine without an engine stand check out how we built a modified truck crane which we used to pull our engine.
Things were going pretty smooth until we started to pull the interior. As my wife tore out the carpet, we found tons of rust on the passenger side floor boards and firewall. Unfortunately the heat shield and the battery tray hid the worst part of the rust when we initially looked at the car, so this was one more surprise.
But we were already committed to the build, so we started to cut out the rust and patch in new sheet metal with our Eastwood MP140i Multi-process Welder.
We fell a bit behind with all the extra bodywork as we had to learn the in’s and out’s of MIG welding automotive sheet metal. We documented and recorded the whole welding process and even did some flux core welding.
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WATCH HOW TO REPAIR BMW E30 RUST:
BMW E30 RUST REPAIR PROJECT