ETA vs M42 Daily Hoonmobile

[roguetoaster]

Straight line, m20 will take the cake.

Not if you install a 4.45 differential. Best mod thus far on my 318.

[varg]

M42's are incredibly slow. You can't hold more cornering speed if you don't have the power to get there.

That's what turbos are for.

[Thehemiman]

The OP isn't looking for a track car. The title says "daily" and a m42 is a great daily. It's that simple

[word is bond]

Ask this question in the M20 section and you'll get a completely different response. M42's are incredibly slow. You can't hold more cornering speed if you don't have the power to get there.

Assuming we're comparing an M20b25/M20b27i and not a standard eta motor.

I mean - we're comparing 23+ year old cars. Is either one not slow by modern standards? I mean an M20 is less slow than an M42, but flatout speed isn't why we buy E30s anyway, right? They have different characters. I say buy whichever one suits you better. I daily an M42 and think it's fantastic for that purpose.

[bmwman91]

Overall, if you want a car to hoon in, and by my recokoning that means a car to run up to redline and throw around like a bag in the wind, the M42 wins. You drive it and the overall feeling it gives is that it wants you to drive the piss out of it. No, it is not the fastest E30 but it FEELS like it. The M42 just wants you to beat the fuck out of it***remember the general faults I mentioned above and keep on top of them.

[varg]

remember the general faults I mentioned above and keep on top of them.

I've enjoyed my M42 so far, but I do have to say that I've never owned an engine with so many design issues, minor or major. Go ahead and flame me if you want.
-Valve cover gasket bolts that strip too easily (could've used slightly larger studs)
-Sump bolts that vibrate out (a little thread locker in the factory)
-A critical oil passage is compromised by above flaw
-Odd, non-standard M7 studs
-Timing chain idler sprocket is prone to failure (later design revisions corrected this)
-Profile gasket issue which requires cylinder head removal could've been avoided entirely by making the coolant passage external or outward facing, see Volvo B234F or Toyota 4AG.
-Strange external plastic coolant pipe is prone to failure and difficult to access
-Crank walk due to thrust bearing (this one is a real forehead slapper since it would have been so easy to design in a 360 degree thrust bearing, and I'm hoping my engine isn't going to suffer from this)

That being said, the cylinder head flows really well and it has good performance characteristics, and there are a couple of neat design aspects like the threaded holes in the water pump to push it out, the easy-to-replace timing chain tensioner, and the oil filter canister system.

[bmwman91]

Yeah the M7 studs on the intake manifold are a little odd...and not all socket sets have an 11mm socket in them lol.

Regarding the thrust bearing, the best thing you can do to prolong its life is to NOT press the clutch pedal in when starting the engine. The last thing that bearing needs is hundreds of pounds of force loaded onto it with zero oil pressure. As far as I am aware, you can just pop in a second thrust bearing on the other half and then you have a full 360 degree bearing. Some guys on here have done it, although I don't recall exactly which part they used.

The coolant pipe...lots of people like to save $3 and get the OE one. Apparently it doesn't really fit and is prone to failure, so if/when you have to replace it make sure to use the Genuine BMW part.

The valve cover bolt holes do like to strip lol. Luckily they are pretty easy to repair.

[MX339]

I think you can imagine my opinion on the matter. I must admit though, I haven't driven an M20 car on the street or an M42 car on track.

[varg]

Yeah the M7 studs on the intake manifold are a little odd...and not all socket sets have an 11mm socket in them lol.

The exhaust manifold studs were the bugger. I grabbed a bunch of spares that were laying under the hood of an M20 car at the junkyard before I pulled my head when I got the car, knowing that some of the studs would be ruined, but not realizing that the M42 had M7 studs.

Regarding the thrust bearing, the best thing you can do to prolong its life is to NOT press the clutch pedal in when starting the engine. The last thing that bearing needs is hundreds of pounds of force loaded onto it with zero oil pressure.

I thought someone had removed the clutch safety switch in my car for this purpose but found out later that E30s don't have them.

As far as I am aware, you can just pop in a second thrust bearing on the other half and then you have a full 360 degree bearing. Some guys on here have done it, although I don't recall exactly which part they used.

It looked like some machining needed to be done when I looked it up, either way - I'm not planning on taking this engine out and rebuilding it any time soon.

The coolant pipe...lots of people like to save $3 and get the OE one. Apparently it doesn't really fit and is prone to failure, so if/when you have to replace it make sure to use the Genuine BMW part.

The valve cover bolt holes do like to strip lol. Luckily they are pretty easy to repair.

Yeah, I helicoiled them before the car was on the road. I had some bolts I was going to cut the head off of to make studs, but I can't find them and I have to remove my turbo to remove all of the bolts.

[redlightpete]

How much lighter is an m42 than an m20? I guess the center of gravity is back farther too, but only 3 or 4 inches.

[bmwman91]

You can easily feel the difference when driving the two cars.

The M42 is a big heavy 4 cylinder. Its weight is somewhere between M10 and M20, probably closer to that of the M20. However, having all of that mass behind the front wheels' centers makes a huge difference.

[varg]

The M42 is a big heavy 4 cylinder.

Not really. 427lbs fully dressed with the transmission attached. Lighter than an F20 or 4G63, about the same as an SR20, a little heavier than a 4AGE. Definitely not heavy for a DOHC 4. An M42 with transmission is 70lbs lighter than the M20 with transmission.

[eur04lif3]

Not if you install a 4.45 differential. Best mod thus far on my 318.

Can't say I've done that before. I actually did the opposite, went from a 4.10 to a 3.73. I must say, its great on the highway.

[roguetoaster]

Can't say I've done that before. I actually did the opposite, went from a 4.10 to a 3.73. I must say, its great on the highway.

True, a 3.73 makes it a very daily friendly car, but above a 4.1 makes it a hoot to drive. Admittedly I do find myself looking for a 6th gear on occasion.

[Mr. Tasty]

I hoon all the time in my eta, and all under 3k RPM.