Learn Me: BMW 135i

I've been living with an e30 and a miata as my only cars for several years now and I'm thinking about ditching the e30 and replacing it with an older 135i as a daily driver. I like the idea of making an e36 m3 load of power out of that turbo I6 with just a few bolt-ons but I'm worried about losing that driver's car connection I get with the old e30 and miata.

What are the driving dynamics like? I've read that there's lots of understeer? Can this problem be fixed with front suspension adjustments or moving to a square tire setup? What's the turbolag like? I used to have an old bugeye WRX and I hated the miserable throttle response, are the modern turbo cars really that much better? The car has an open differential, am I going to be roasting one tire out of every turn?

Thanks for any insight you can give.

Someone asked basically the same question two days ago:

Thread from 2 days ago

I have a thorough response there about maintenance, but since you have some specific suspension and handling questions I will answer those:

It doesn't turn in super well, but it's pretty neutral once you get it turned in. With the TC off you can get the back end to kick out under power. you can go up to 225's up front on the stock wheels and you can get -1 degree of camber without camber plates, that helps a lot. Camber plates and going wider up front also help the "neutralness" but the transitions are a bit worse. It's hard to fit more than 245's up front, although some people have fit 255's (you have to go to aftermarket wheels to do 245s or 255s). You can fit 255's on the rear no-sweat.

I recommend doing both sway bars at the same time if you're going to do sway bars. Just doing the front bar isn't great for tight cornering (autocross) - it tends to make it understeer more - it might be OK if it's going to be a track day car, but if it's going to be a track day car then why just do one bar?

If you get new max performance tires, particularly the RE-71R, it puts down power pretty well and you won't be roasting the inside rear. You do need to feather the throttle though. I previously had Dunlop Direzza ZII's (non star-spec) and felt that they put down power a lot worse - to the point where the car was arguably faster with the traction control on in sport mode. With the RE71R's the car is definitely faster with traction control off.

Turbo lag depends on whether you have a '08-'10 or an '11+ the '08-'10 have the N54 twin turbo and the newer cars have the N55 dual scroll. The N55 spools faster and is a more reliable setup but is less tuneable. Remember that even out of boost, you're still dealing with 3 liters of displacement, so off-boost low end torque is still adequate. When other people autocross my car they are more likely to complain that the boost kicking in caught them off guard rather than it being too slow due to the turbo lag.

When Billy Davis (multi-time CSP national champion) drove my car (before it was class prepped for FS) he described it as "an E30 with twice the horsepower".

Anyway, take these responses for what they're worth, I realize that my answers are pretty autocross specific and you're asking about it being a DD. For DD duty I think it's perfectly suitable, although you may also want to consider a 128i. They're a lot less fiddly and still a lot of fun.

In reply to drdisque:

Sorry, didn't see that thread! Thanks for the response, some great information! In regards to what you said in the other thread about the walnut blasting service - is there a reason people get the cars walnut blasted as opposed to just using a brush and solvent?

In terms of 135i vs 128i, part of what makes me want the 135i is how much power it can make with bolt-ons and tuning. I've been driving pretty low-power cars the past few years but before those I had an LS1 trans am with bolt-ons and a WRX with upgraded turbo. I miss having a ton of power, but when I had those cars I realized it was at the sacrifice of being a good driver's car. I gave up the power to get back into a good driver's car and now I'm wondering if it's possible to have my cake and eat it too...

re walnut blasting - it's a much easier way to clean the valves and they can do it without pulling the head off the car. They just blast the media into the ports and then vacuum it out.

Here's a video of walnut media blasting the intake ports of an N54

In reply to drdisque:

Definitely seems easier to do the walnut blasting if you've got the tools, but it seems like I'd have no problem doing it myself with a brush and the shopvac after watching that video. The walnut blasting sounds nice but if I can do it myself in an afternoon and save $500 vs. bringing it in to a shop - I'll do that.

IIRC there was a recall to walnut blast the e30 M3.