Metric mechanic 4.0 l

Oldbmwcoupes said:
I believe that part of Jim Rowe’s technique was to also the level of atomization within the combustion chamber- particularly during the later stages of compression. The better atomization allowed for higher compression ratios whole controlling pre-detonation. I’m not convinced that the s38 puts down that much more torque than a tuned m30. Some of the engines I’ve built (b34) have a harder pull though the first two gears (3.73) than my m5/m6 (3.91).

There are an infinite number of theories and arguments about this motor and it’s design. MM claimed 300 hp if I remember correctly. What I do like is that their success was based on empirical studies and lots of hands on cutting/testing/flowing over the years. The intake ports are considerably larger. I believe that the block is b35 or M90 (the only blocks I know of to be stamped with only 3.5 on it (doubt its s38). I’ll try to get some numbers for the sake of it and comparison.

I think the flat top had to be used to keep the compression from going sky high with the strokes crank (wondering if is s38b38 or 3.3li ?). I’ll probably give them a call and get more details to share. My recollection is that they used a different deep I-beam rod as well.

X atlas, I’ll try to get more comparisons in the next few days. I have an Alpina B10 head that I’ll compare it to as well (UK only, naturally aspirated b10, 260hp)
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I'm very interested to see what the ports look like vs a B35 head, since that's the OEM 'gold standard'. I also wonder if you need to port-match the intake manifold to get the most out of it.

You could also compare it to a 'Paul Burke' Head: https://www.mye28.com/viewtopic.php?t=153708

I really like the M30, and always thought it could make more power/torque with the displacement, but the spark plug position isn't ideal since it will limit the effective peak RPM.

M30 Flowbench numbers: https://www.speed-talk.com/forum/viewtopic.php?t=35386
 
x atlas, I’ll get you pics and measurements of each port/head, b34, b35, b10 and metric mech. I’ve wanted to do this comparison myself and the shared info is always a good thing. I was planning on port matching the intake regardless. Also planning on looking at the m90 to 320i intake runner union and flowing that as well. I suspect that I will need to enlarge the butterfly at the intake. I know for a fact that the Alpina b10 had a larger butterfly (by about 3mm) again I’ll have to measure and report.

My experience with m30s is that they really just need head work and a mild cam to make them pull hard. My guess is about 250 hp. I’ve run the m30s I’ve built like this next to the USA m5 and the m30 with a 3.73 always pulls the s38 out of the hole up to second gear. The s38 eventually takes it over. I’ve had this silly drag test done about 30 times with different drivers and cars and the outcome is pretty much always the same. I was surprised the first few times.

My goofy formula is to use a b35 rotating assembly (individually balanced) with a b34 head ported to copy this b10 head. A Schrick 282 cam and b35 valve train. It all bolts together nicely and doesn’t want to stop pulling until a scary 7k. I don’t touch the valve size as I like the slightly higher intake port velocity and I believe that it’s part of keeping the torque in the motor.

I’m excited to see how this 4.0 does with the head work. I’ll also try to find out what cam they used. If I remember, it’s an asymmetrical 282, or something close to that
 
Oldbmwcoupes said:
x atlas, I’ll get you pics and measurements of each port/head, b34, b35, b10 and metric mech. I’ve wanted to do this comparison myself and the shared info is always a good thing. I was planning on port matching the intake regardless. Also planning on looking at the m90 to 320i intake runner union and flowing that as well. I suspect that I will need to enlarge the butterfly at the intake. I know for a fact that the Alpina b10 had a larger butterfly (by about 3mm) again I’ll have to measure and report.

My experience with m30s is that they really just need head work and a mild cam to make them pull hard. My guess is about 250 hp. I’ve run the m30s I’ve built like this next to the USA m5 and the m30 with a 3.73 always pulls the s38 out of the hole up to second gear. The s38 eventually takes it over. I’ve had this silly drag test done about 30 times with different drivers and cars and the outcome is pretty much always the same. I was surprised the first few times.

My goofy formula is to use a b35 rotating assembly (individually balanced) with a b34 head ported to copy this b10 head. A Schrick 282 cam and b35 valve train. It all bolts together nicely and doesn’t want to stop pulling until a scary 7k. I don’t touch the valve size as I like the slightly higher intake port velocity and I believe that it’s part of keeping the torque in the motor.

I’m excited to see how this 4.0 does with the head work. I’ll also try to find out what cam they used. If I remember, it’s an asymmetrical 282, or something close to that
Click to expand...
My experience is more limited, but I too thought that a well thought out m30 would do well against an s38 up until about 4000 rpm.
 
Oldbmwcoupes said:
x atlas, I’ll get you pics and measurements of each port/head, b34, b35, b10 and metric mech. I’ve wanted to do this comparison myself and the shared info is always a good thing. I was planning on port matching the intake regardless. Also planning on looking at the m90 to 320i intake runner union and flowing that as well. I suspect that I will need to enlarge the butterfly at the intake. I know for a fact that the Alpina b10 had a larger butterfly (by about 3mm) again I’ll have to measure and report.

My experience with m30s is that they really just need head work and a mild cam to make them pull hard. My guess is about 250 hp. I’ve run the m30s I’ve built like this next to the USA m5 and the m30 with a 3.73 always pulls the s38 out of the hole up to second gear. The s38 eventually takes it over. I’ve had this silly drag test done about 30 times with different drivers and cars and the outcome is pretty much always the same. I was surprised the first few times.

My goofy formula is to use a b35 rotating assembly (individually balanced) with a b34 head ported to copy this b10 head. A Schrick 282 cam and b35 valve train. It all bolts together nicely and doesn’t want to stop pulling until a scary 7k. I don’t touch the valve size as I like the slightly higher intake port velocity and I believe that it’s part of keeping the torque in the motor.

I’m excited to see how this 4.0 does with the head work. I’ll also try to find out what cam they used. If I remember, it’s an asymmetrical 282, or something close to that
Click to expand...

Thanks, I look forward to the info! Would you see a way to share this info between machine shops so others could duplicate these heads?

Most of the M30 dynos I've been looking at die off around 5k, which most people attribute to 'head design'. However, looking at additional intake options (ITBs with open airbox, Miller 'powerfold') they show significant improvements over 5k, which give significant power improvements.

Powerfold: http://www.millerperformancecars.com/files/Dynos/NA Powerfold Dyno.pdf
ITBs (
93mm bore, 86mm stroke - 3503cc
Forged 93mm Carrillo-pistons with 11.4:1 comp
Camshaft with our own design
13.3mm lift, rated duration 308°, duration 0.05" 264°
RHD 45mm ITB)
: https://www.r3vlimited.com/board/fo...91769-m30-with-rhd-itb-dyno-graph#post9891794

image_153087.jpg
 

I was thinking about this a bit more, and if we want to see what the effect of Surface Turbulence is on the combustion efficiency, we should be able to see a difference in the target ignition timing in the form of more advance vs a standard B35/34 tune, particularly if this build did not incorporate a higher CR than stock. Can you have the tune on the Motronic unit that came with the car downloaded so we can perform a cal compare?​



This was part of my bread and butter back when I was at FCA. Heck, if we wanted to get real fancy we could rig up a knock sensor and run Megasquirt to see differences in the knock behavior.
 
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