I like!
What are you going to do for engine management?
The intermediate plate that holds the timing chain idler gear had cracked and failed.
Our bottom end (rotating assembly) was still in great shape. If nothing else, we now knew we could save the origin engine.
An M42 engine is an interference fit engine, meaning once the timing chain failed, the valves started bending.
The cams were not damaged and still in very good condition.
With the engine out of our project BMW 318is and partially apart we were able to learn a bit more.
First of great importance: the bottom end (rotating assembly) was unscathed. The oil pick-up screen and oil filter had done their jobs and the bottom end still turned over fine.
Pulling a couple of bearing caps showed no damage to the bearings and not even that much wear.
As for the head, while more than half the valves were bent, the head itself had not been damaged. The cams were also still in good shape.
Theoretically, we could have gotten a used intermediate plate—new ones are no longer available, resurfaced the head, installed some new or used valves, and put the whole thing back together. We probably could have driven another 150,000 miles like that.
Another option would be to just put a used motor in the car and go about our day. Used engines are readily available for between $500 and $1000 depending on mileage and condition.
And of course, with a decent car and a bad engine, the idea of an engine swap popped into our heads.
Installing the S52 or S54 engine ( from the E36- or E46-chassis M3) is a popular swap, but it has been done to death. And in our opinion it changes the light, simple character of the 318is that we love so much.
Time for a dose of reality: These cars are getting valuable. The rest of the car was original, and the original numbers-matching M42 engine we had was still essentially usable. With that in mind, we made our final decision and new plan.
A BMW club buddy reminded us that Metric Mechanic does some amazing things with the M42 engine.
While we had worked with owner Jim Rowe some 25 years ago on a “Big Six” BMW stroker engine, we hadn’t talked to him in years and didn’t realize that he now specialized in playing with M42 engines.
A quick call to Rowe helped us develop what we think is a great plan. First he not only remembered us, but was a huge fan of Grassroots Motorsports and loved the progress we had made with the publication since we had worked together all those years ago.
He was also more than willing to show us and our readers what he had learned about these interesting M42 engines.
His thought was to take our original engine and rebuild it with a lightened, balanced rotating assembly, and better cam profile.
He would bore it and use a crank from an M44 Z3 engine to give us 2.0 liters, instead of our original 1.8.
He would bump the compression up a bit, improve our breathing with his valve train tricks and then finish the whole thing off with a lightened clutch and flywheel assembly.
We could expect a completely rebuilt engine and roughly 40 more horsepower and still retain (cosmetically at least) the original engine with its great drivability and fun-to-drive nature.
So we would have a car that would give an E30 M3 fits, and be all in for $10,000-15,000 with about half that figure being in the engine.
That sounded like an interesting project to write about, especially if we tested it against and E30 M3 when finished. More importantly, that sounded like a car we would love to own and drive every day!
I like!
What are you going to do for engine management?
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Just throwing it out there that the M42 can hold about 8-10psi boost with all stock everything.....and several people have successfully and reliably turbo'd these engines for under $2k, getting close to 200whp reliably.
$7k sounds like an awful lot for 40hp (I would hope MM is giving you guys a deal better than that), which gets you about what you'd get with a $300 M2oB25 or M50 from a junkyard.....Plus, for a magazine build, I highly doubt that MM is going to publicly share all their tips and tricks in any amount of detail.....so what's the upside for your readers?
I like the project, but nice-condition 318is's are hardly collectors models anytime soon. I've bought two rust-free 318is's in pretty good shape in the last few years for ~$2000 each.
irish44j said:Just throwing it out there that the M42 can hold about 8-10psi boost with all stock everything.....and several people have successfully and reliably turbo'd these engines for under $2k, getting close to 200whp reliably.
$7k sounds like an awful lot for 40hp (I would hope MM is giving you guys a deal better than that), which gets you about what you'd get with a $300 M2oB25 or M50 from a junkyard.....Plus, for a magazine build, I highly doubt that MM is going to publicly share all their tips and tricks in any amount of detail.....so what's the upside for your readers?
I like the project, but nice-condition 318is's are hardly collectors models anytime soon. I've bought two rust-free 318is's in pretty good shape in the last few years for ~$2000 each.
The upside is an option you rarely see people take.
I'd just want to add ITB's, huge cams, and jack the compression up enough that it would make sense to run E85.
Be sure to dyno test the car afterwards to confirm just how much horsepower it's gained over stock.
z31maniac said:irish44j said:Just throwing it out there that the M42 can hold about 8-10psi boost with all stock everything.....and several people have successfully and reliably turbo'd these engines for under $2k, getting close to 200whp reliably.
$7k sounds like an awful lot for 40hp (I would hope MM is giving you guys a deal better than that), which gets you about what you'd get with a $300 M2oB25 or M50 from a junkyard.....Plus, for a magazine build, I highly doubt that MM is going to publicly share all their tips and tricks in any amount of detail.....so what's the upside for your readers?
I like the project, but nice-condition 318is's are hardly collectors models anytime soon. I've bought two rust-free 318is's in pretty good shape in the last few years for ~$2000 each.
The upside is an option you rarely see people take.
I'd just want to add ITB's, huge cams, and jack the compression up enough that it would make sense to run E85.
Nobody takes the option, because nobody is going to spend $7k to build a motor to gain 40hp when there are so many better options out there (BMW and non-BMW) for fractions of the price..
Alternately, if the goal is to keep it truly original since 318is's are apparently so rare......well, I'll sell you an original, running, stock M42 for $500 ;)
I've more experience with M42 performance than most E30 guys, and I'd say refresh it and keep it stock or, if seeking any performance, throw the M42 out. NA M42 builds are horrible bang for your buck. Several thousand dollars to make Honda B18C power. That power is fun in a 2,300lb honda but a 318is is between 2,600 and 2,700lbs. Despite having 16 valves and a BMW badge the M42 is positively asthmatic stock (seriously, a 1.8 I4 that stops making power by 6,000rpm? What is this a corolla?) and even a simple upgrade like new cams is an outrageously expensive one.
I'm not a fan of the M42 in general, it is a very flawed engine. Prone to crank walk (half shell thrust bearing wears out), timing case failure, cracked heads, leaks, corrosion around the profile gasket, and expensive in general to rebuild (price out replacement of all timing components and get ready to cringe!)
For context, I had an M42 in my E30 with a good sized turbo on it, eventually I was pushing 18psi of boost with nothing more than head studs and an MLS head gasket. It was fun for the couple of years it lasted, could keep up with a turbo M20 car on 12psi, then it started to leak compression into the cooling system and I ditched it for a turbo M20 instead of putting any more money into the coarse, leaky little 4-banger. I never looked back.
irish44j said:z31maniac said:irish44j said:Just throwing it out there that the M42 can hold about 8-10psi boost with all stock everything.....and several people have successfully and reliably turbo'd these engines for under $2k, getting close to 200whp reliably.
$7k sounds like an awful lot for 40hp (I would hope MM is giving you guys a deal better than that), which gets you about what you'd get with a $300 M2oB25 or M50 from a junkyard.....Plus, for a magazine build, I highly doubt that MM is going to publicly share all their tips and tricks in any amount of detail.....so what's the upside for your readers?
I like the project, but nice-condition 318is's are hardly collectors models anytime soon. I've bought two rust-free 318is's in pretty good shape in the last few years for ~$2000 each.
The upside is an option you rarely see people take.
I'd just want to add ITB's, huge cams, and jack the compression up enough that it would make sense to run E85.
Nobody takes the option, because nobody is going to spend $7k to build a motor to gain 40hp when there are so many better options out there (BMW and non-BMW) for fractions of the price..
Alternately, if the goal is to keep it truly original since 318is's are apparently so rare......well, I'll sell you an original, running, stock M42 for $500 ;)
Yeah an M5x/S5x is the easy button has been done to death.....like even I did that almost a decade ago and that was with everything already VERY well documented. Slap a turbo on is easy and has been done to death.
They are taking a different route which is awesome. A 318is with ~180-200hp sounds about perfect. It will more eagerly rev and everything. I love'd mine with just a chip/exhaust/lightweight flywheel. Another 40hp, would have made it an absolute riot.
To your last part, in most of the country, finding a clean (I have to emphasize this because I don't mess with rusty cars - life is too short), running 318is slicktop is not easy or cheap in the vast majority of the country. Finding an older person that just wants to sell it for a few grand is INCREDIBLY rare.
They're doing it because they're not paying nearly the cost that the rest of us would for that motor. Otherwise, yeah, it makes no sense at all to install a built M42 vs S50/52/54/LSx
The motor change makes a ton of sense if you are trying to write a series of articles that are new.
Boosting has been done to death, and one can find countless articles and web pages telling you how to do it. LS swaps have been done further to death- to the point where some TV shows have even done it into BMW's, and swapping any I6 into that- how hard can that be?
Upgrading the motor to be better is a very different path, kind of old school, too- and it will be interesting to see how it's done. And it will be interesting to see what the hard parts where a back yard mechanic HAS to go to a machine shop to do it. How much work will that crank swap be?
BTW, $7k for 40hp isn't that bad, I paid $5k for the same back almost 20 years ago for my Alfa. And I'm still incredibly happy about it.
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