Tuesday 2nd December 2014

Bring back the four-cylinder M car: PH blog

If M has a turbocharged future then why not expand the range even further?

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We had a new M3 in at PH last week. Very good it was too, righting many of the E92's wrongs and showing that BMW M's mojo is very much intact.

Not a bad start point...

You know there's a but, don't you? I may sound like a big Jessie here but there were occasions, quite a few, where it just felt too fast. Let me explain before you have my head on a carbon propshaft and stuck in the ground at Bruntingthorpe. The M3 is excellent when you do drive it a bit harder but that's always with one eye on the speedo to ensure 'enthusiastic' doesn't become 'antisocial' and then 'licence losing'. I'm sure it would be a blast on track but that's a small minority of our real driving time.

I think there's a solution. It probably won't attract much interest as it will be slower than all other M models but for fans of driving fun (and that is us, surely?) it should be brilliant. It will also allow BMW to show off its latest developments in turbo and carbon technology.

The slowest M car of any description right now is the M135i. When Harris tested an auto last year it did 0-100mph in 10.9 seconds. That's barmy. New M3s are being clocked under nine seconds.

Now we're talking

They're both turbocharged of course which I'm happy to accept with a less powerful M car. The days of M engines screaming to beyond 8,000rpm are sadly over. But think of the turbocharged alternatives now on offer: the 1.5-litre three-cylinder turbo in the Mini Cooper is at 230hp in the i8 and the 2.0-litre turbo in the 228i makes 240hp. Both offer decent torque and M division could surely work some further magic.

The i projects must have taught BMW a lot about affordable carbon construction too. The i3 remember has a carbon reinforced plastic tub and costs £30K. Could similar technology be employed to make a few panels?

So here's the idea, taking inspiration from BMW's own 1 Series tii concept of 2007 and passing on the 1.5 turbo for a second. A 228i currently weighs 1,460kg and makes 240hp. Induction and exhaust tweaks always work well with turbocharged engines but the focus should really be on response. Perhaps 260hp. Then reduce weight as much as is realistically possible with the aforementioned carbon-plastic panels and perhaps a bit less equipment. Modest wheels and a limited-slip differential would be good too. Could we call it 2 Series tii? There's six grand between a 228i and an M235i as well, which sounds like enough to get quite a bit done.

This looks pretty good as an interior too

Yes, there are hurdles. A six-cylinder engine will always make a better noise than a four-cylinder one for example. But I'm happy to sacrifice that for a lighter, more alert and more involving car. Bringing it back to my original point, I reckon it would be more fun at sensible speeds than the 235i. Indeed I would be tempted to keep it at 240hp (or maybe even less) to force the attention on low mass and how exciting that could be.

And to everyone who says a focused two-door, two-seat coupe won't find buyers, consider this: BMW will currently sell you a 225i xDrive M Sport Active Tourer and ask £31,860 for the privilege. If that can be justified by the company bigwigs then surely there must be room for a few hundred tii coupes to be made?

Matt

[Output Flange]

I get the point here, but I'd maybe come at it from a slightly different angle.

Start of by dictating that the largest permissable tyres are of 225 section, and then work back from there. Have it on 17s so you get a bit of sidewall, and then that will lead to how much usable power you should have, and then what size brakes you need etc etc. Hopefully from all of that you will reach a target weight that is around 1300kg or less.

In my humble opinion, fitting bigger and stickier tyres to new cars is what's making everything get more powerful and heavier, when it doesn't necessarily need to. I appreciate it's not the only driver, but limit grip and the rest will have to follow.

[Leins]

The E36 M3 was originally rumoured to be a 4-cyl Turbo with 240bhp. I wonder if the lack of sales of the Porsche 968 put them off

[Dr S]

Six pot engines are no guarantee for good noise. Drove an M235 cup car in one of this year's VLNs. After 50 yards I understood why it had the nickname "tractor"...

[skyrover]

4 cylinder engines are just plain horrible... sorry, but if I was to spend a heap of cash on a performance car I would rather it did not share it engine configuration with the rest of the shopping trolleys on the road.

[xRIEx]

Output Flange said:

I get the point here, but I'd maybe come at it from a slightly different angle.

Start of by dictating that the largest permissable tyres are of 225 section, and then work back from there. Have it on 17s so you get a bit of sidewall, and then that will lead to how much usable power you should have, and then what size brakes you need etc etc. Hopefully from all of that you will reach a target weight that is around 1300kg or less.

In my humble opinion, fitting bigger and stickier tyres to new cars is what's making everything get more powerful and heavier, when it doesn't necessarily need to. I appreciate it's not the only driver, but limit grip and the rest will have to follow.

From an engineering/mathematical point of view, I'd be really interested to know how much power (or thrust) can be applied through a certain sized tyre contact patch, and how much of the 400+bhp in modern fast saloons is clipped by the electronics keeping it in a straight line.

[3ananaPie]

Personally I only ever found appeal with M cars because of the engine, a smaller turbo four (or 3?) would, if anything, sound even more pathetic than the sixes - At least to my eyes ears anyway. But all of it appears to be the way forward, shame.

[jamespink]

xRIEx said:

Output Flange said:

I get the point here, but I'd maybe come at it from a slightly different angle.

Start of by dictating that the largest permissable tyres are of 225 section, and then work back from there. Have it on 17s so you get a bit of sidewall, and then that will lead to how much usable power you should have, and then what size brakes you need etc etc. Hopefully from all of that you will reach a target weight that is around 1300kg or less.

In my humble opinion, fitting bigger and stickier tyres to new cars is what's making everything get more powerful and heavier, when it doesn't necessarily need to. I appreciate it's not the only driver, but limit grip and the rest will have to follow.

From an engineering/mathematical point of view, I'd be really interested to know how much power (or thrust) can be applied through a certain sized tyre contact patch, and how much of the 400+bhp in modern fast saloons is clipped by the electronics keeping it in a straight line.

Its interesting, I have my E39 M5 on its winter 245 and 255 Continental rubber and its shocking how often the DCT light is on. Both road surface and undulations have a big effect in a straight line (Bilsteins have increased the time the traction is broken) but whilst cornering, the push of the limited diff upsets grip G far more (a spinning NSR would leave the OSR with more grip. Having said that, its really great fun on the edge of the power/grip balance. Not sure how clever I would look with DCT off all the time though...

Edited by jamespink on Tuesday 2nd December 09:45

[bodhi]

Sod the 4 cylinder, just bring back the N52. I wouldn't have thought emissions would present a massive issue for a limited run special, and my 125i will easily break 30 mpg in mixed driving - over 35 on a run, and as a driving tool it knocks the latest 4 cylinder turbos into a cocked hat.

[s m]

The 125i ( old 6cylinder coupe ) had 218bhp with only 205s on from the factory ( 205/50 x 17 )
It had plenty of grip for driving about and enjoying the car

[MikeGoodwin]

Not going to happen though is it. We have the 28i blown 4 banger these days whats wrong with that - not driven one so no idea how it is.

[zeppelin101]

Turbos? Nah.

Supercharger? Interesting.

Eaton's new units are very good in terms of thermal efficiency and you could easily get 250-280hp out of a 2.0l engine without overly stressing anything.

Good power, good economy when bypassed, excellent throttle response (full pressure in <0.5s).

Can't think of many OEMs using them other than Audi (S4) and JLR (both V6 and V8 use TVS chargers).

Still not as good as a turbo in the grand scheme of things, but miles better than the old MP units and knocks socks off any turbo for throttle response.

MikeGoodwin said:

Not going to happen though is it. We have the 28i blown 4 banger these days whats wrong with that - not driven one so no idea how it is.

Average. It's not exactly brimming with character, just "adequate" really. Much like most other engines that deliver a great big dose of torque at ~1300rpm and have peak power just after 5k...

Edited by zeppelin101 on Tuesday 2nd December 10:02

[stevesingo]

skyrover said:

4 cylinder engines are just plain horrible... sorry, but if I was to spend a heap of cash on a performance car I would rather it did not share it engine configuration with the rest of the shopping trolleys on the road.

A LR Tdi is not a great point of reference.

An engine is a means of motive force for a car. It can offer some pleasurable characteristics, but if in the delivery of those characteristics, the engine’s architecture detracts from other desirable characteristics we like in a car as a whole then we should maybe we should ask the question if that engine configuration is correct for the car.

The rest is snobbery.

My wife’s E90 320Si has a 4 cylinder engine with balancer shafts. It is not fast. But it is ideally suited to the car’s chassis. Having driven 6 cylinder petrol E90s, I would say the 320Si has better handling. It doesn’t have a 6cyl howl, but makes a decent noise as it passes 6500rpm and I can enjoy all of the performance more of the time.

Would I prefer a 330i, sometimes yes, a little extra power would be nice, but on my late night commute home, the extra power would be surplus and I would maybe want that slightly better front end response.
Witness what BMW did with the E30M3. They shunned the 6cylinder engine option for a 4cly for the simple reason as a driving tool, the 6cyl detracted from the aim.

[skyrover]

stevesingo said:

A LR Tdi is not a great point of reference.

An engine is a means of motive force for a car. It can offer some pleasurable characteristics, but if in the delivery of those characteristics, the engine’s architecture detracts from other desirable characteristics we like in a car as a whole then we should maybe we should ask the question if that engine configuration is correct for the car.

The rest is snobbery.

Not snobbery at all... it's a simple fact. 99% of 4 cylinder engines are utterly characterless, and no I'm not basing my opinion on an antiquated 4 cylinder tractor engine (which incidentally does actually have a little bit of character )

[FD3Si]

skyrover said:

4 cylinder engines are just plain horrible... sorry, but if I was to spend a heap of cash on a performance car I would rather it did not share it engine configuration with the rest of the shopping trolleys on the road.

You should probably drive a tuned 4 cylinder engine then. Because that's like saying 'I don't want to drive a car with 4 seats, like all the other shopping cars'. Honda's 4 cylinder Type R lumps, Toyota's VVTLis and 4AGE, etc etc.

Didn't BMW try something similar with the E90 320Si homologation special? Everything I've read said they were a right mare to shift, despite being a quite sweet car to drive. Power sells 'sports' cars.

Edited by FD3Si on Tuesday 2nd December 10:25

[rallycross]

To me the joy of a quick 3 series is its 6 cylinder engine, BMW have always been in a class of their own with their fantastic straight 6 engines.

When I had my E30 M3 2.3 I also had a newer model 323i as a daily run-around (2.5 24v) and that 6 cylinder engine was so much nicer than the 4 cylinder engine in my M3.

So I vote for the 6 cylinder forget the 4 cylinder!

[mwstewart]

BMW to me: RWD and 6 Cyl. petrol.

The 4 cylinder engine in the original M3 wasn't that nice...

[Kawasicki]

For the big companies, it's all about published fuel economy/carbon dioxide emissions.

The four cylinder M car will come back, it will probably have a capacity of 2l and deliver around 450 bhp. The sound of the engine will be synthesised, it will go like hell and most people will love it, as it will have the right image, be fast and cheap to lease.

Then, a bit further down the line, everything will be electric anyway, including the M cars, so all talk of cylinders will finish.

Personally I think even an E30 M3 is already waaaaaay too fast/capable to enjoy at speeds that modern (post "Speed Matters" Pistonheads would consider socially responsible. I'd like them to build a modern 318is...but just look at the amount of car enthusiasts who think the GT86 is underpowered. People have become accustomed to performance without revs, so they can no longer accept having to use high revs to extract only nippy performance. The modern fast cars I've driven make a complete mockery of the speed limits...anyways.

[stevesingo]

FD3Si said:

Didn't BMW try something similar with the E90 320Si homologation special? Everything I've read said they were a right mare to shift, despite being a quite sweet car to drive. Power sells 'sports' cars.

It was produced to homologate the engine, specifically the bore stroke/dimensions, valve gear and cam cover.

They were the same price new as a 320i MSport, but with better performance, and crucially worse economy/emissions, hence hard to shift. Great cars.

The opinion of characterless 4cyl I suspect is a result of never having driven a decent 4cyl engine as most 4cyl engines are fitted to shopping trollies, hence they are the same as the motor in your washing machine, performs a motive function.

The S14 (slightly breathed upon) in my E30 M3 has bags of character.

[skyrover]

7

FD3Si said:

You should probably drive a tuned 4 cylinder engine then. Because that's like saying 'I don't want to drive a car with 4 seats, like all the other shopping cars'. Honda's 4 cylinder Type R lumps, Toyota's VVTLis and 4AGE, etc etc.

Honda V-tec's, Toyota VVTi's, driven them all and they did nothing for me... sorry.

I actually prefer Volvo's inline 5 if I want a small engine.

[gumsie]

skyrover said:

4 cylinder engines are just plain horrible... sorry, but if I was to spend a heap of cash on a performance car I would rather it did not share it engine configuration with the rest of the shopping trolleys on the road.

I have to agree. With the exception of the Subaru boxer four I’ve never heard a nice one in all my years.
4 Cylinders - Horrid, just horrid.
5 cylinders, nice.
6 Cylnders, nice.
8 Cylinders, gorgeous.
10 Cylinders, very nice.
12 Cylinders, nice-very nice.

More cylinders tends to mean a nice smooth idle too.