m60 cam timing improvement

[JGood]

Interesting info I stumbled across:

http://www.bimmerboard.com/forums/posts/775197

Attempt this upgrade entirely at your own risk. If you adjust the cams the wrong way the pistons will smash the valves.

Below is my own experience, yours may be totally different.

The cam setup in the M60B30/40 are fairly complex to set, and you need prior knowlege of how everything works as well as the ability to fabricate an acceptable degree wheel for this particular setup. (I printed one of the internet and glued it to cardboard backing)

To cut a very long story short, I just did quite a bit of research into camshaft timing, and the effects it can have. I then proceded to "experiment" with the 540, trying out different combinations of inlet Vs. Exhaust camshaft timing.

The M60B40 has fairly agressive cam timimg with quite long durations (valve opening times) and 28 degrees of overlap between the exhaust and inlet, and it is optimised for mid range power. The intake is fairly advanced and the exhaust retarded compared to the later M62B44 and M62B44TU engines. A lot of overlap improves midrange due to scavenging but reduces both idle quality and high rpm power.

I decided to sacrifice a bit of midrange for improved quality idle and low end torque and topend rev power by retarding the intake 14 (crank) degrees and advancing the exhaust 6 (crank degrees)

The result was really awsome , the midrange power dropped very little, the lumpy idle improved to perfection and it revs to the redline very willingly now, producing heaps more power from 4000rpm.

I still cannot beleive the improvement in behavior of the engine with the modified cam timing. This was the best thing I have ever done to this car. It is now much more refined. I think BMW were a litte over enthusiastic when they did this design, giving it too much overlap and emphasis on mid range power as opposed to driveability.

There is no question the low end and topend power improved significantly through this change, and interestingly the valve timing is now almost identical to the M62B44TU engine with a longer exhaust duration

M60B40 Standard timing

IO/IC 14 BTDC / 52 ABDC
EO/EC 48 BBDC / 14 ATDC

Inlet, Exhaust Overlap is 28.00 degrees

Intake Duration 246.00 degrees.

Exhaust Duration 242.00 degrees.

Inlet Cam Centerline 109.00 degrees ATDC.

Exhaust cam Centerline 107.00 degrees BTDC

__________________________________________________ _________

M60B40 modified cam timing

NOW IO/IC 0 BTDC / 66 ABDC
NOW EO/EC 54 BBDC / 8 ATDC

Inlet, Exhaust Overlap is 9.00 degrees

Intake Duration 246.00 degrees.

Exhaust Duration 242.00 degrees.

Inlet Cam Centerline 122.00 degrees ATDC.

Exhaust cam Centerline 113.00 degrees BTDC

The reason I brought this up is because there is a guy overseas with an m60b40 e30 putting out 297whp after doing the timing upgrade and a retune, on an otherwise stock m60b40. His trap speed in the 1/4 mile is 5+mph faster then mine, which is pretty significant. I may attempt this over the winter, figured I'd share in case anyone else is interested.

[nrubenstein]

Before/After dynos please. :)

[senorcarey]

It was my understanding that all of the new timing blocks take this into consideration? In for info...
I also believe that this was the timing that Alpina used and BMW changed over to later.

And wow, 300whp? Was this with a retune on the stock DME or a stand alone?

[iamsam]

If this really works, then the next logical question is: Can you do this to an M60B44 hybrid, and how much power might it end up with, providing the factory ecu can be tuned accordingly?

[nrubenstein]

If this really works, then the next logical question is: Can you do this to an M60B44 hybrid, and how much power might it end up with, providing the factory ecu can be tuned accordingly?

Unless the pistons are stroking higher in the B44 block, there is no reason why it would not work. I would expect it to have the same impact on the running motor,mbut that I can't speak to.

[iamsam]

Unless the pistons are stroking higher in the B44 block, there is no reason why it would not work. I would expect it to have the same impact on the running motor,mbut that I can't speak to.

well B44 pistons have flat tops, while B40 pistons have valve reliefs, so would valve clearance become an issue then?

And my original question more specifically is, if this M60B44 hybrid build bumps you up to ~330 bhp, what would you gain on top of that with the aggressive cam timing?

[bmwmech1]

Bruce and I had talked about this thread a year or so ago and bounced around the ideas in it. That was all we ever did though, was just talk about it. From what we had discussed, it seems as though the changes would be better suited for a street car rather than a full-on race car, since most of the gains were in the low-mid ranges. Maybe Jonsku will weigh-in since I think he does this to his swap cars, as to what the differences feel like, real world...

Garey

[iamsam]

I thought it was mentioned that the gains are past 4k rpm and not in the mid range?

[senorcarey]

well B44 pistons have flat tops, while B40 pistons have valve reliefs, so would valve clearance become an issue then?

And my original question more specifically is, if this M60B44 hybrid build bumps you up to ~330 bhp, what would you gain on top of that with the aggressive cam timing?

Flycut the piston tips for valve relief.

Win-win.

[Jean]

Yeah read about that as well, but I don't want to try that just yet.. We should dyno our different swaps..

1.m60b40
2.m62 with b40 heads
3.above with the timing upgrades

[JGood]

Well, it turns out the guy who did the cam timing change claimed 297 bhp, not 297whp. He actually dyno'd 273whp. I don't know why people use estimated bhp numbers when discussing modded cars, especially when you have a legit whp number to use. And 297bhp from 273whp is like an 8% drivetrain loss, I'm don't think e30's are that efficient. It would be more like 330bhp.

[iamsam]

Yeah read about that as well, but I don't want to try that just yet.. We should dyno our different swaps..

1.m60b40
2.m62 with b40 heads
3.above with the timing upgrades

yes for the love of all that is holy someone please dyno their M60B44 already!

[Jonsku]

Maybe Jonsku will weigh-in since I think he does this to his swap cars, as to what the differences feel like, real world...

I'm using the "Alpina timing", which is the same as in M60's in first E38's. Unfortunately I don't have any specific info on degrees etc so I don't know how it relates to the timing mentioned in the first post.


What comes to "rough idle", I don't agree with that at all. My M60 idles and revs very, very smoothly (you can put a coin standing on the engine and it stays upright all the way to the redline). My engine has original DME that's slightly adjusted in dyno (power gains were slightly under 10%).


I do agree that cam timing in M60's is quite "neutral", and there might well be quite a lot of improvements available "for free". Also more aggressive cams would benefit the otherwise so "mild" engine, similarly to lightweight flywheel (which, of course, doesn't increase power / torque but translates the engine into much more "sportier" direction).


Guess we need a brave soul with M60B44, dyno / mapping shop available and a free day to try out various things :)

Well, it turns out the guy who did the cam timing change claimed 297 bhp, not 297whp. He actually dyno'd 273whp. I don't know why people use estimated bhp numbers when discussing modded cars, especially when you have a legit whp number to use. And 297bhp from 273whp is like an 8% drivetrain loss, I'm don't think e30's are that efficient. It would be more like 330bhp.

Yap, 15% for drivetrain losses would be closer to truth..

[zogs]

can someone explain this to me
M60B40 modified cam timing

NOW IO/IC 0 BTDC / 66 ABDC
NOW EO/EC 54 BBDC / 8 ATDC

what does io/ic eo ec means, I know that inlet and exhaust, but what does o/c

And which is the best timing for m60b40?
How it is possible to set them in right degrees without spec blocks?

[Jon_A]

Is this identical on the B30 as well?