M10 Engine build

[PeteK]

Hi Guys,

This is not strictly out of an e21, but it's an M10, so I thought it might be of interest.
I finally got the new engine for my e12 finished and out on track over Easter. The build consisted of the following:
- 92mm bore
- Lightened rods
- Lightened crank
- JE Pistons - 12.5:1 compression
- Late e21 style head
- Ported and polished
- Port matched to 48 mm quad throttle body and extractors
- Double valve springs
- Shot peened rockers
- Titanium retainers
- 48 mm intake, 41 mm exhaust valves
- 328 cam
- Light weight flywheel
- 228 mm solid hub 4 puck clutch
- Microtech injection

It all went well until the first run and it turned out the block was a dud! New block machined and then re-assembled. Running on 100 octane fuel I got 150 hp at the wheels. People tell me power at the wheels is about 75% power at the flywheel which makes it 200 hp. I've since found that the best fuel you can get from the bowser isn't quite good enough to stop pinging, so we added a splash of toluene and it fixed it up again.

[Jeroen]

Impressive! Did you do the work yourself? Screams for a detailed build thread!

Must be great fun to drive. As for dyno power loss, depends on the type but the loss is likely to be a bit lower so it is likely there are a few less horses in that engine but even if its 180 (my guesstimate based on 150 at the wheels) it's still a great score!

[Reck]

Nice! Need some pictures and videos.

What was wrong with the first block??

[PeteK]

Turned out there was a crack in the block.

Here's a video of me at Sydney Motorsport Park at the BMW Nationals. If you listen carefully, you can here the pinging. We worked out it was about 30 horsepower down as it only went slightly faster (we were on old rubber and not pushing too much due to the pinging). Once we tuned it up, it went 4 seconds a lap faster!


This is about the only shot I've got of it.

[Reck]

Love that noise! Are you running any sort of exhaust set up?

[Jeroen]

Music!

[PeteK]

Exhaust is 2.5" with a high flow muffler. Extractors are 1.75" into 2" into 2.5" collector custom stainless steel. I did have a straight through muffler but we were taking it to Phillip Island where they have a 75 dB limit. It was way louder than that.