Lightweight e30, have platform/engine ideas, leaning 318is/N52… talk me out of it

[packratbimmer]

I'm a little nostalgic for the M20, I definitely enjoyed the mechanical character of that engine.

Wouldn't go back to it in a 100 years, I have +110whp with the N52, ZERO leaks, it's lighter and I have a 6-speed, plus my oil pan is higher and more protected. When the engine was running rough INPA told me exactly which coil pack was going bad AND it has really good fuel economy from VVL.

That's my dream build! What are you MPGs if you don't mind my asking?

[hoveringuy]

That's my dream build! What are you MPGs if you don't mind my asking?

I get 26-27 hiway and 20 city. and about 3 1/2 laps per gallon

I have an electric water pump and electric PS plus variable valve lift so not pulling a constant vacuum, plus they have wideband 02 so it keeps the lambda tight.

on the other hand, I have e30 aero...

[AWDBOB]

I get 26-27 hiway and 20 city. and about 3 1/2 laps per gallon

I have an electric water pump and electric PS plus variable valve lift so not pulling a constant vacuum, plus they have wideband 02 so it keeps the lambda tight.

on the other hand, I have e30 aero...

That's what I get in my 2.7l stroked m20, ~175whp

Edit: no a/c. sanden 7hp compressor on it drops down to 23ish highway

[TobyB]

The thing missing from this discussion-

the M42 is disappointing. It doesn't make all that much torque, it doesn't rev to 8500 so it doesn't really make F20C horsepower,
and it has an almost- square bore to stroke ratio, so it doesn't even feel all that peppy. Couple that with a massive dual-
mass flywheel, an E30 that, by 1990, wasn't really very light, and it's just... not all that. Especially by modern standards.
The M42 was a test for 4- valve cylinders and new block features like the 'eco' oil filter,
but it also has that goofy Alfa idler (yes, late E36 parts get rid of that) a timing chain guide
that costs more than 2 or 3 'ran when pulled' engines, an oil pump on the crankshaft (which they never did again)
and relatively low production numbers. It's not a huge surprise that 2024 BMW doesn't give a hoot about them.

If they'd made the S42 available to mere mortals... well, that would be a whole different story....

The M20 torque is fun, kind of like a straight- 6 pickup.
The M54B30 torque is even more significant, and starts earlier and lasts longer. And really, the ONLY
weight advantage of an M42 over the aluminum M54 is that the weight sits 10 cm further back. But there's
100bhp less to push it.
The N52 is almost modern, without most of the problems that BMW designed in thereafter...

The E30 rear suspension, by the way, must be tried to be... appreciated???
A bunch of years ago, having spent decades in E30s and older, I got a beater E36.
The increase in rear grip is... incredible.
For outright handling performance with no other considerations, the E30 chassis is a turd.
There are dozens of better places to start.
Just like the 911, ('wow this is fast. imagine what a fantastic car it would be if the engine was in the right place')
the E30 is flawed by design.
Yes, you can still make it fast.
Yes, it takes more work for less effort than 4 corners of a-arms would give you.
(Miata, wot?)

At the end of the day, the logically 'right' answers don't really apply, and we do what makes us happy.
And that, for each of us, is the right answer. But my right answer might not be the right answer for you.

t
has e30s. has M54B30s. Needs to do it.

[varg]

the M42 is disappointing. It doesn't make all that much torque, it doesn't rev to 8500 so it doesn't really make F20C horsepower,
and it has an almost- square bore to stroke ratio, so it doesn't even feel all that peppy. Couple that with a massive dual-
mass flywheel, an E30 that, by 1990, wasn't really very light, and it's just... not all that. Especially by modern standards.
The M42 was a test for 4- valve cylinders and new block features like the 'eco' oil filter,
but it also has that goofy Alfa idler (yes, late E36 parts get rid of that) a timing chain guide
that costs more than 2 or 3 'ran when pulled' engines, an oil pump on the crankshaft (which they never did again)
and relatively low production numbers. It's not a huge surprise that 2024 BMW doesn't give a hoot about them.

Shame about that crank-driven oil pump that they never did again, it's the one thing the M42 has over every other BMW engine of the era. A pump like that would have made the modified M/S5X engines so much better. Imagine an M5X that doesn't need a hole drilled in the block for an oil pump chain tensioner, an upgraded shaft, and a safety wired/tack welded nut to rev safely, and can instead rev to 7500rpm out of the box if you upgrade the cams to make it worth doing. That would be so nice. Instead we got oil pump shafts that snap and nuts that back off, and two different pumps, one of which has no upgraded parts available for some reason.

The other stuff is what I always come back to when the E30 318is comes up. I read articles and forum posts about my 318is, people say "it loves to rev" or "revvy 4 cylinder" and I think: have you ever actually driven one? Have you ever driven anything else with a 4 cylinder engine? It doesn't love to rev, it's out of steam soon after 6,000rpm. It doesn't love to rev, the throttle response is unremarkable with its massive flywheel. Swapping my 318is and driving back to back within a week of each other, my M20 clutch and flywheel equipped turbo M42 was no more of a rev happy little engine than my turbo M20. A K20 swap is what 318is sounds like when described by an autoblogger, "poor man's M3", except it's better than an S14 because it's lighter and makes more power at a fraction of the cost.

At the end of the day, the logically 'right' answers don't really apply, and we do what makes us happy.
And that, for each of us, is the right answer. But my right answer might not be the right answer for you.

t
has e30s. has M54B30s. Needs to do it.

E30s got popular because they were cheap and an excellent platform for modding. Easy to work on, strong drivetrains with easily available parts, handsome interior, easy on the eyes, pretty light. Once they started being $10,000 cars again they lost some luster imo. They need mods; stock steering sucks, the chassis is so flexible that it makes the doors harder to close when you jack it up, it has poor traction under power if you make power, and the shifter is the worst of any sporty car I've ever driven, even rebuilt with a DSSR. I love my E30 but the car has some drawbacks, which is why I said earlier in the thread to let an E30 be an E30 and appreciate what it is.

Now get on that M54 swap since you have them.

[hoveringuy]

The E30 rear suspension, by the way, must be tried to be... appreciated???
A bunch of years ago, having spent decades in E30s and older, I got a beater E36.
The increase in rear grip is... incredible.
For outright handling performance with no other considerations, the E30 chassis is a turd.
There are dozens of better places to start.
Just like the 911, ('wow this is fast. imagine what a fantastic car it would be if the engine was in the right place')
the E30 is flawed by design.
Yes, you can still make it fast.
Yes, it takes more work for less effort than 4 corners of a-arms would give you.
(Miata, wot?)

.

As an instructor I've gotten to ride in quite a few E36's and the way they plant the rear still amazes me, like the harder you push them the harder they stick...

but I think a lot of it is also that they can run wider tires and larger plus a more modern selection of rubber.

Their aero is markedly better.

The funny thing is, I still keep up with them on my little 225's with trailing arms; it's just not as easy. I need to use 100% of my traction budget on cornering.

[Maxhouse97]

Love the comments/thoughts … keep em coming.

On the flexible chassis comment, see the below link:

https://www.bimmerforums.com/forum/showthread.php?1786165-Torsional-Rigidity-Humor-me

If a basic E30 is so flexible, how did they make the M3 so stiff? I’ve read about the bonded windshield, and some basic braces but it doesn’t seem that substantial. Chassis stiffness is import to me, could a glue in a M3 windshield as well?

Im in Cincinnati.

[Jb325is]

The other stuff is what I always come back to when the E30 318is comes up. I read articles and forum posts about my 318is, people say "it loves to rev" or "revvy 4 cylinder" and I think: have you ever actually driven one? Have you ever driven anything else with a 4 cylinder engine? It doesn't love to rev, it's out of steam soon after 6,000rpm. It doesn't love to rev, the throttle response is unremarkable with its massive flywheel. Swapping my 318is and driving back to back within a week of each other, my M20 clutch and flywheel equipped turbo M42 was no more of a rev happy little engine than my turbo M20. A K20 swap is what 318is sounds like when described by an autoblogger, "poor man's M3", except it's better than an S14 because it's lighter and makes more power at a fraction of the cost.

E30s got popular because they were cheap and an excellent platform for modding. Easy to work on, strong drivetrains with easily available parts, handsome interior, easy on the eyes, pretty light. Once they started being $10,000 cars again they lost some luster imo. They need mods; stock steering sucks, the chassis is so flexible that it makes the doors harder to close when you jack it up, it has poor traction under power if you make power, and the shifter is the worst of any sporty car I've ever driven, even rebuilt with a DSSR. I love my E30 but the car has some drawbacks, which is why I said earlier in the thread to let an E30 be an E30 and appreciate what it is.

Now get on that M54 swap since you have them.

Completely agree with these points. I have the same thoughts whenever I read BaT commentors worshipping 318is' and other stock e30's. I can't understand how someone can drive a stock e30 and then drive any nicely modified e30 and have that sentiment.

As an instructor I've gotten to ride in quite a few E36's and the way they plant the rear still amazes me, like the harder you push them the harder they stick...

but I think a lot of it is also that they can run wider tires and larger plus a more modern selection of rubber.

Their aero is markedly better.

The funny thing is, I still keep up with them on my little 225's with trailing arms; it's just not as easy. I need to use 100% of my traction budget on cornering.

Agreed. Driving an E30 fast on track is edgy, but rewarding. Can't say I've done much of the driving FAST on track thing myself but I do know what it looks like :) Hope my he doesn't mind me sharing this but this is video from Road Altanta a few weeks back- a friend of mine (also a r3v member) driving the car that I built/used to own. This car has ZERO aero, stock M54, some fancy dampers/brakes, and 235/40's 200TW tires on 17x9's

https://www.youtube.com/watch?v=jFuw7EcBoTE

[TobyB]

Shame about that crank-driven oil pump that they never did again, it's the one thing the M42 has over every other BMW engine of the era.

I have also wondered what the 'problem' with the M42 oil pump was. It does increase the amount of crankshaft between #1 crank throw and the harmonic balancer,
so maybe that makes a 6 cylinder crank more fragile? It certainly adds a number of centimeters to engine length, when every mm matters on a straight six.
Lots of V8 engines use the crank mount pump, but most more- recent 4 cylinder and v6 engines
have gone to chains, or even (shudder) wet bombs, (wet belts). hmm- is it a transverse thing?

t

[Northern]

I think that if lightweight is objective 1, and power is objective 2, you end up at K24. The end.


If you want the I6 smoothness, torque curve, or are a purist or find the "K swap the world" trend to be boring, the N52 is it.
AFAIK there's not much aftermarket for these besides tuning.

I love the sound of a built NA M20, but I don't think it has any place in this argument, a 24v is heavy, M54 just isn't a sporty engine, S54 is effectively a pricey N52.

[hoveringuy]

S54 is effectively a pricey N52.

I've compared a lot of dyno plots between my N52 and S54's on the same dyno. The S54 isn't really stronger than my motor until 3500, the DISA intake and variable valve lift really help the low-end (yes, reduced valve lift helps low-rpm power!). The S54 has slightly higher compression, more valve lift and a little more displacement. After 3500 or so the S54 just pulls away and it's ripping by 8000, whereas the N52 is tragically hamstrung by the intake.

With the N54 intake, the N52 is quite a bit more uncorked and keeps pulling past 7500. I was seeing somewhere around 260-265whp without really optimizing the tune. N54 isn't a great intake thought, "it just fits" and is really designed for FI.

Compared to the M54 the N52 is a jewel. Hollow camshafts, CNC machined intake and exhaust tracts whereas the M54 is still rough cast and the parting lines in the exhaust path are galling.

I really wish that the M division had gotten their hands on the N52. You would have seen essentially a factory MILV kit (bumps the valve lift from 9.7mm to 11mm. There are no aftermarket cams for the N52 because you can bump the lift with a simple set of shims!) probably a little higher compression and kick-ass intakes and exhausts.

[Maxhouse97]

RE the torsional rigidity question, still don’t understand how good this makes the E30 look (or how different the M3 is from standard E30).

Bentley Azure - 18,000 Nm/deg
Bugatti EB110 - 19,000 Nm/deg
Bugatti Veyron - 60,000 Nm/deg
Bugatti Veyron Grand Sport - 22,000 Nm/deg
BMW E30 M3 - 23,000 Nm/deg
BMW E36 Touring - 10,900 Nm/deg
BMW E36 Z3 - 5,600 Nm/deg
BMW E46 Sedan (w/o folding seats) - 18,000 Nm/deg
BMW E46 Sedan (w/folding seats) - 13,000 Nm/deg
BMW E46 Wagon (w/folding seats) - 14,000 Nm/deg
BMW E46 Coupe (w/folding seats) - 12,500 Nm/deg
BMW E46 Convertible - 10,500 Nm/deg
BMW E53 X5 (2004) - 23,100 Nm/deg
BMW E90 - 22,500 Nm/deg

[digger]

to me the question of of the OP's budget hasn't been discussed unless i am missing something

[Maxhouse97]

Was looking to spend 10-15k to get a nice car with clean body and interior (I dislike body/interior work) and then limit a swap to $10k total (parts and labor, labor divided between myself and a shop depending on level of difficulty).

[82eye]

Was looking to spend 10-15k to get a nice car with clean body and interior (I dislike body/interior work) and then limit a swap to $10k total (parts and labor, labor divided between myself and a shop depending on level of difficulty).

i can't believe how cheap eveything is in the states. 20k here is kind of a basic paint job with perhaps some minor bodywork. a 15k e30 would need 25k here lol.