BMW M90 3.5 Vs M88 (M1) 6 cyl

Discussion in 'OT Driven' started by 8bit, Feb 22, 2016.

  1. 8bit

    8bit Member

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    I found these power and torque figures for the 1979 2 valve 3.5 and the M1's M88 motor, and can see why BMW didn't bother putting the M88 in the e12.

    M90 3.5 218 hp @ 5,200 rpm 229 lb/ft @ 4,000 9.3:1 CR

    M88 3.5 277 hp @ 6,500 rpm 239 lb/ft @ 5,000 9.0:1 CR

    BMW's 0-100 kph time for the e12 M535i was 7.5 seconds, for the 286 hp 10.5:1 CR e28 M5 it was 6.5 seconds. If they put the low comp M1 engine in the e12 figure a factory time of 7 seconds, and an extra 5 mph on top speed. The use of the M88 would have made the car only marginally faster, but much more expensive. It didn't seem worth it.

    As things stood the e12 M535i was as quick as the Porsche 928 4.4 V8, but only two thirds the price. It was even slightly cheaper than a 924 Turbo;)

    e12 5 series

    [​IMG]
     
    Last edited: Feb 25, 2016
  2. turbodan

    turbodan OT Supporter

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    The 24v big six definitely stomps ass all over the M30/M90. Not just higher peak power and torque but a wider powerband with lots more area under the curve.

    0-60 is just getting started. It just gets embarrassing after that. You can't just write off a 60 HP difference as insignificant. That's huge when you're talking just over 200 to almost 300.
     
  3. 8bit

    8bit Member

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    It's a big difference on paper, but in reality the gain isn't that great, considering the price.

    If you compare magazine tests of the European 635CSI and the Euro M6 it was like 0-60 mph in 6.9 vs 6.4 and top speed was 150 mph vs 140 mph. Also, the e34 Alpina B10 with 260 hp 3.5 2 valve matched the 0-60 time of BMW's e34 M5 3.6 (315 hp), and both could do 155 mph.

    I have noticed too that the big German tuners Alpina, Schnitzer and Hartge all used the 2 valve 3.5 motor. 4 valve per cylinder engines can be peaky in performance. If you recall back to the early '90s the LT1 300 hp Vette wasn't much slower than the King Of The Hill LT5 4 cam C4.;)
     
  4. turbodan

    turbodan OT Supporter

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    You are putting too much emphasis on the 0-60 number. This is like the S52 vs S54 debate in the MZ3. There is no real comparison. Even only half a second at 60 would be multiple carlengths difference.

    You actually have it wrong about generalizing 2 valve VS 4 valve motors. Four valve motors require less aggressive cam timing to produce good power. With better flowing heads and more conservative cams you will find that the baseline torque is higher and the engine produces a much broader power than a comparable 2 valve design. An M30 derivative that makes the same ~275 HP as the M88/S38 will be way more peaky. No bottom, some mid and all top end. Much less area under the curve.

    I have driven M30 powered cars and S38 powered cars. The M30 is all low-mid. Power peaks around 5000 RPM and holds until almost 6000 before falling off. The S38 makes similar torque for the same displacement and hits hard in the midrange. It winds out to 7000 and pulls all the way up. The M30 is a 3500-5500 powerband. The S38 is 4000-6500.

    The M20 is a bit different. Not all of the BMW SOHC motors can't rev out. My turbo B27 made 468rwhp at 6400 RPM and power is literally flat from 5000 until 7000. The M30 needs extensive modification to make the kind of power that most people expect from a car badged as an M535i.
     
  5. 8bit

    8bit Member

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    If you look at in gear acceleration times, where the car is held in a high gear, the multivalve version tends to perform poorer. It takes longer to come on cam. But don't take my word for it, have a look at Chris Harris review of his own e28 M5, he notes and you can see that the car needs a lot of revs to get some action

    Chris Harris on M5

    In contrast the e12 M535i will accelerate enthusiastically in any gear at any revs. Back in 1980 the only other 4 door car that could do 0-60 in 7 seconds and 140 mph was the Mercedes 450 SEL 6.9, not even the V12 Jag could get down to 7 seconds.

    You might recall Porsche did a multivalve version of the 944 called the S back in the '80s, same 2.5 engine size, and if you looked at overall performance it was little better. Multivalve and cam arrangements have their advantages, but aren't the whole picture. Displacement is important in relation to vehicle weight. This is why to this day GM still uses OHV for F body and Vette, so does modern Hemi.:)
     
  6. turbodan

    turbodan OT Supporter

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    I'll gladly wait for actual action as opposed to poking around with the the slow and steady M30 power delivery. You're "asking is it in yet?" and the M30 is already finished.

    I don't know Chris Harris. If he is trying to imply that the SOHC big six outperforms the DOHC motor in a meaningful way he's an idiot. I know I've put some miles on all of these engines and the M30 is boring. The S38 makes more torque, much more power and is more fun to drive. If you like slower, less exciting engines then the trusty, rusty e12 M535 is the car for you.
     
  7. 8bit

    8bit Member

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    If you click on the above hot button link "Chris Harris On M5" you will see him drive his e28 M5 on You Tube. He was from Autocar magazine and is a new host on Top Gear I believe.:)

    The South African e23 745i had the M88 motor too. Once again from all the figures it doesn't get along much better than Alpina's e23 B10 260 hp 7 series of the same era.

    Of course, with a lot of M car owners, they love opening the hood and showing their Motorsport engine, with nice writing on the cam cover. That's priceless.:)
     
  8. turbodan

    turbodan OT Supporter

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    I've put quite a few miles on an S38 in an e24 M6 and I drove an e28 M5 one time. The SOHC big six just doesn't compare.

    The M88 in the SA market e23 was also mated to a four speed automatic transmission. Compare that to an automatic e28 535i with the same gearbox and again, the M88 stomps ass all over it.

    If I remember correctly the Alpina was turbocharged. I have never seen an M30 punch out over 240hp without FI. With boost the M30 makes more power but it still delivers a low-mid powerband that flattens out on the top end. 400rwhp at 20psi is pretty easily doable from an M30B34. For the sake of comparison, a boosted S38B35 runs in the 450rwhp range with only around 8 psi.
     
  9. 8bit

    8bit Member

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    I think you are taking about the US spec 182 hp 3.4 liter M30. The European spec e12 M535i (218 hp) comes very close in performance to the US spec S38 e28 M5. The former doesn't have pollution controls.

    The 1974 GS 530 e12, by German tuner Gerhard Schneider, had a triple carb 3 liter M30 (240 hp) 0-100 kph in low 6 seconds and top speed of almost 150 mph, as tested by Auto Motor und Sport.

    The South African e23 745i (286 hp) was also available with 5 speed manual, and I was comparing that with the e23 B10 (260 hp) 7 series 5 speed manual. Very close cars on speed. The turbocharged Alpinas were denoted B7 and B7S with 300 & 330 hp respectively. Only fitted to the 5 and 6 series though. On the e34 they went bi-turbo with 360 hp M30.

    AC Schnitzer's M30 3.4, as fitted to their e34 package, had 262 hp in the early '90s.
     
  10. turbodan

    turbodan OT Supporter

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    The 182hp M30B34 and 208hp B35 are close enough on the slow spectrum that I believe it is an insignificant difference. Again, you keep saying the performance is close and its really not.

    It also interesting to me that you think the 36 horsepower difference between the high compression european M30 and the 8:0 US M30 is substantial. The difference between an M88 and the early M30 is 68 horsepower and yet you keep trying to tell me the performance difference between these two powerplants is minimal.

    Clearly we aren't getting anywhere. If you have a chance to drive these cars for yourself, please do. I do believe you will notice more than a little more performance out of the DOHC big six. Anyone that tells you otherwise has their head up their ass. Or their shit is broke. There are plenty of S38/M88 motors out there that have been neglected to the point of burned valves.
     
  11. 8bit

    8bit Member

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    I have driven M30 and M88 cars, and tuned examples of the M30. The M88 cars come on strong at the high end, as you have rightly said. This does make them feel very lively because of the change in character once they hit 4-4,500 rpm. Not unlike a VTEC engine going from one cam profile to another, or like a turbo engine from off boost to boost. However, as every magazine report with recorded data has shown, the multivalve version's gain in performance (outright and in gear) is relatively small.

    You need to base your argument on personal experience and objectively recorded data, from the manufacturer and from third party publications. This is why manufacturers and magazines record data, so they have some basis for performance claims. :)
     

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