How making an engine lighter can produce more power

Update by Tim Suddard to the BMW 318is project car
Jan 2, 2024 | engine

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With the bottom end in our BMW 318is done, it was time to move into the valvetrain.

The cylinder heads on both the M42 and M44 engines are amazing pieces of engineering. With trick alloy castings, 16 valves and twin overhead cams, there is seemingly not a ton to be gained by messing around here.

Still, never one to be deterred, Metric Mechanic’s Jim …

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Campbelljj New Reader
1/10/19 6:06 p.m.

What rpm will the finished engine turn and what hp and torque does MM expect when broken in. 

irish44j MegaDork
1/10/19 6:24 p.m.

nice to see the M42 getting some love :)

that said, My mild OCD is mildly annoyed at the top picture, since you have the two heads oriented different directions, rather than putting them in the same direction to make a direct comparison easier ;)

irish44j MegaDork
1/10/19 6:26 p.m.
Campbelljj said:

What rpm will the finished engine turn and what hp and torque does MM expect when broken in. 

I'm interested too. I have the Conforti chip in my (stock) M42, with a 7000 redline. The German 318is Cup guys are pretty adamant that the M42 gets valve float above 7200 (and they run a spec 7500rpm chip for that rally series). 

Tim Suddard
Tim Suddard Publisher
2/11/19 11:00 a.m.

We are currently tuning the car at Active Autoworks in Miami. Karl thinks we might see 180 hp at the wheels. He baselined it at 129 hp, but he needed bigger injectors, which have been ordered. A stock 318is makes about 95 hp at the wheels, so we are already way up. I think 150-170 (at the wheels is pretty realistic. 

It will turn over 8000 rpm, once we change the limiter. I will have exact numbers shortly, but I can tell you already, that is smoother, more linear and faster than an M3.

This is the best E30 we have ever built. We already sold our Z4 M Roadster, because we like this car better!

5/10/19 8:40 p.m.

Will this project car be a keeper or up for sale in the near future?  

dean1484 GRM+ Memberand MegaDork
5/10/19 10:08 p.m.

Thank you for this Tim. Great read and great photos!!!!

noddaz GRM+ Memberand SuperDork
5/11/19 6:42 p.m.

Wonderful writeup.  While I think swaps are great (GRM's 350z) I also like GRM working with "out of the standard box" upgrades like this BMW build.  It should run great and be all BMW.  (At least it will look that way.)

David_Sanborn Reader
8/10/20 11:21 a.m.

Ordinarily I'd rather roll on an ant hill than ask this question, but as we know your engine alchemy and voodoo was farmed out to a wizard, and wizards like to be paid.  Some of us might be wondering how many wizard-dollars that the engine voodoo cost?

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