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BMW almost used a turbocharged I-6 in the E39 M5 instead of a V-8

Posted by HawtGarbage918@reddit | cars | View on Reddit | 50 comments

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TunakTun633@reddit

Obviously the V8 makes this car stand out more in today's world, but to make a case for the straight-six: V8 E39s use steering boxes, not racks. The turbocharged car would ha e been sportier.
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sejmroz@reddit

A turbocharged I6 from that era would be a stand out too. Much like the 2JZ.
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guy_incognito784@reddit

BMW, at the time, was very anti-FI. The responsiveness of NA was more natural and they believed it was a low tech way to make power and was unrefined due to turbo lag. Many manufacturers were not like this but initially BMW was pretty stern about sticking to NA. In fact, when BMW went to turbocharged 4 cylinders (F3x gen) and 6 cylinders (LCI E9x with the N54), purists lost their goddamn mind especially dropping the NA I6 for a turbo 4. But given advances in the tech and stricter fuel and emission standards, it's now ubiquitous across the line up and very well regarded. Granted the N54 wasn't the most reliable out there but it laid the foundation that led to the beloved B58.
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ow_windowmaker@reddit

Even so if you look at N55 and also next generation "beloved B58" dyno graphs, from around 5500RPM to 7000RPM it's just a flat line. That's very unfortunate.
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N1NJ4W4RR10R_@reddit

And the barra with the Falcon XR6Ts.
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Supreme-Gucci-137@reddit

If i'm not mistaken, back in the day when turbocharging was rare and expensive it seemed much cooler to have a high horsepower turbo than a big displacement NA block.
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natesully33@reddit

As someone around for the fast/furious era, yup. LS1s were cool but boost was super cool, hence my confusion when I see natural aspiration called out as a feature on cars, haha!
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OldSchoolSpyMain@reddit

Yup. Hence the word "Turbo" being used and overused so much back then.
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c0reM@reddit

Agree, steering has a very 90s feel to it on center with the steering box. That said the V8 is pretty bulletproof because it’s such a low strung engine. A turbo I6 today probably would have aged very poorly.
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bimm3r36@reddit

I think the car works better as a brute anyway though. Plus the steering box is one of those things that journalists liked to complain about but doesn’t really matter in the real world. It’s still very agile on the back roads and perfectly composed as a daily driver.
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phxbimmer@reddit

So many people complain about steering boxes but it really does not make that much of a difference in normal driving. I say this as somebody that has owned a 530i, a 540i, and an M5. If the suspension is in good shape they all drive pretty well.
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Runner303@reddit

Agree with you, but they do suck a bit as they get old and wear. More joints/points of failure, and the boxes themselves wear out and there is no way to rebuild/replace them.
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willtel76@reddit

The previous e34 M5 was an I6 and also had a steering box that was kind of awful. It was one of the main reasons I sold mine.
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bmwblog@reddit

They actually considered a V6 engine
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Deflated_Hive@reddit

Given how fragile their cooling system components were, it was for the best. Then again their V8 valve stems and timing chain guides weren't any better.
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WorkingExercise1316@reddit

Genuine question, why was the decision to use the V8 instead of I6 better?
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UnknownBreadd@reddit

Whilst a V8 has added complexity thanks to having 2 banks, at least you just double something you’re already designing once (essentially). Whereas turbochargers introduce a whole new set of complexities of their own, and now the engine must deal with much higher cylinder pressures and overall hear generation. Not to mention that getting air:fuel ratios right is not as simple as before. The pros typically outweigh the cons in most scenarios when it comes to turbocharging though. As long as it’s engineered right in the first place.
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RiftHunter4@reddit

Don't forget, this was the 90s. Most turbos back then had more lag and ran on vacuum systems, including the wastegate. I imagine that if BMW had used a turbocharged I6, most wouldn't have survived since turbos require proper maintenance, not whatever the 5th owner was doing in 2012.
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Skodakenner@reddit

Wouldnt say that. BMW had quite a bit of experience with turbos back then since they built loads of diesels and a few petrol cars with turbos back then. Also Alpina used a twin turbo i6 in the E34 and that worked really good
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doabarrelroll69@reddit

Yeah, not only did they have experience on production cars with the 2002 Turbo, but there was also their turbo F1 engine
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Skodakenner@reddit

Oh yes the M10 based one wich made so much boost that they couldnt measure it because their test dino maxed out at 5bar
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UnknownBreadd@reddit

Oh yeah back then it would have been even harder than today. What i’m saying is that turbos are only so common today after lots and lots of engineering - but once solved they become pretty good at improving efficiency and gaining power. There are definitely negatives and tradeoffs though. I’m certainly not saying that BMW would have been better off ditching the V8 for the turbo. Like i said, it’s easier to make a good NA V8 than a good turbo engine anyway.
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zzyzx85@reddit

* BMW in the 90s and 00s insisted on NA engines, especially M-cars (IIRC it was Albert Biermann). * the S62 was built from the M62, so I think it was easier to upgrade an existing platform vs. developing a turbocharger system for an inline 6, which didn't exist in BMW's inline 6s at the time.
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BTTWchungus@reddit

Look how shit the N54 was, and that was with even more years of engine development and progress 
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Wide-Gift-7336@reddit

I don’t think turbo technology was there yet in the early 2000s. Even despite some of the V8 issues, I’d argue this is one of the  most reliable M5 generations(The E34 might be a bit more reliable). The E60 had unreliable transmissions, and needed rod bearings as wear items, the F10 loved to blow valve stem seals, and still had timing chain wear issues, and the F90 has been proven to be mostly reliable but turbos always add complexity to a motor. The G90 we shall see but I’m sure it’s a tank(heh).  Think about how unreliable BMWs first turbo I6 attempt was(N54). Nothing that would kill the car but lots of stuff that would stop it from running. Still super costly
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SirLoremIpsum@reddit

I think that's just BMW things. Toyota has reasonably reliable turbos, turbo diesels (Shocking I know) in the 90s. No one says a 1/2JZ unreliable. BMW having to stick different steering on the V8 models compared to the sixes I feel is a minor downside 
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KungFuActionJesus5@reddit

>No one says a 1/2JZ unreliable. Nobody has a stock 2JZ turbo system anymore. Everybody swaps to big singles inmediately. And if you've ever seen the stock intake flow diagram for one you'd probably make that decision too, knowing that your car is from the 90's.
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Wide-Gift-7336@reddit

Yes I like it when my turbo is 5 feet away from my exhaust manifold and my compressor is another 5 feet from the intake manifold /s
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KungFuActionJesus5@reddit

I mean I'm not disputing that the 2JZ is an indestructible block, valvetrain, and internals, but all that complicated state-of-the-art two-stage 90's turbo plumbing? On like 2 models that sold maybe 10,000 units total with that turbo system? That almost everyone who owns one currently seems to have swapped to a big single turbo? Color me skeptical. It's no SBC.
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Wide-Gift-7336@reddit

Oh me neither. Toyota makes reliable stuff, but once it’s been stress tested they won’t change it.  If I ever need to do a turbo engine swap, I’d start off with either a BMW M50 or a 2JZ. But neither of them are gonna run a stock manifold. I’m gonna get the turbo packaged as close to the intake and exhaust manifold as possible. 
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Wide-Gift-7336@reddit

Reliability is one thing, and I don’t think there’s anything bad about their first attempt either(the n54) most of the issues were normal bmw shit , but even early turbo technology had other drawbacks like turbo lag aka uneven power delivery. Most bmw turbo motors do feel turbocharged but they aren’t scary to drive. There’s no crazy surge of torque that plagued early turbo designs, including the 2JZs, just flat power delivery. The turbo charged non M motors usually drop off power early as well, around 5k but I think S motors these days basically make power to redline
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hi_im_bored13@reddit

well the m5 also made like, 100hp more than the tt toyota i6's. sure they could handle more power aftermarket, but they didn't from toyota its quite a bit easier to make a reliable turbodiesel i6 when you don't have to make any power, don't care for performance applications, and can keep the design the same for 30 years
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funked1@reddit

M102 was their first turbo 6 no?
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GimmeChickenBlasters@reddit

lol it's in the article, and it's a very short article
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bschmidt25@reddit

Valve stem seals weren’t an issue on the M62, IIRC. They were a huge problem on the N62. But yeah… those timing chain guides!
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6786_007@reddit

Why can't bmw make plastic that isn't shit. Like every other manufacture has figured out how to make plastic that doesn't turn brittle in just 3 years. In fact every german car is plagued with shitty plastic. My A5 I broke on of the clips for the ignition coil as is tradition. But I still don't get why after decades they can't change it.
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ConfessToMeDaddy@reddit

Well at the end of the day they made the right decision overall
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Wide-Gift-7336@reddit

Valve stems aren’t a known issue on those S62s. That’s more of an issue with the next-next generation S63 motors. Which are also turbo charged.  The timing chain guides are basically a wear item at this point. Gotta do it every 150k miles if you do average servicing(oil change every 7k miles). Maybe 200k or so. 
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dannyphoto@reddit

Neither of those things are issues with the S62 though. Timing chain guides will shit the bed eventually, but usually not until very high mileage.
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cltnthecultist@reddit

I’d still love it regardless, but boy am I glad it had the V8
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Viperlite@reddit

The 4.4L NA V8 in the E39 540i Sport also an enjoyable combo. I really loved mine… until the repair bills went and spoiled the ride.
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bimm3r36@reddit

Ya it would’ve been a neat part of bmw history but also would’ve been a completely different personality. Also possibly not a great competitor to what AMG was producing in the same era, which was probably a big part of their decision to go with the S62 V8
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thefudd@reddit

So glad they didn't. It's the one car out of all that I've owned that I miss them most.
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phxbimmer@reddit

Given how crappy the turbo technology was back then, I’m glad they put in a 5L V8. It sounds great, has great throttle response thanks to the ITB’s, and it’s aged very nicely unlike a lot of late 90’s turbo cars. The S62 feels like a race-inspired motor with instant response and a great sound, you’d lose all of that with turbos.
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hughflungpooh@reddit

I’m sure glad they used the s62. The sound alone is worth trade off in steering. Mine will be on the road again soon.
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deleted_by_reddit@reddit

[removed]
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Ernie_Capadino@reddit

My dad had the first E39 M5 in Utah. It was the dark blue with the blue inserts on the leather. He had the Dinan exhaust package. Our computer room above the garage shook every time he started it. Looking back now I can’t believe he let me take it to prom as a 16yo. Love you, dad!
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ShadyDrunks@reddit

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jwclair@reddit

My father owned one, bought new in 2001. Beautiful car, BMW's finest hour in my opinion. I don't care for the looks of their current cars, so I drive Audi's.
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