M20 camshaft lift curves

[Devinder]

Dan (turbodan) sent me a couple of cams to measure and I measured my super-eta cam also.

[turbodan]

I think this and the M30 plot should be stickied somewhere. Great information...

[Brad D.]

Very interesting. The eta cam definitely has more lift, but significantly less duration than the stock 325i cam. I guess that makes sense though looking at the super eta's powerband and redline.

[Canuck YYC]

Would someone be kind enough to point me to the M30 cam plot? I'm not having much luck finding it.

[Shawn D.]

Thanks again for the great data, Devinder!

Would someone be kind enough to point me to the M30 cam plot? I'm not having much luck finding it.

Search using Devinder in the "Search for Author" block.

[paul burke]

Good info to post. Are these numbers at the valve with lash?

Paul

[turbodan]

The curves are plotted with zero valve clearance. Zero on the plot corresponds to the rocker arm riding on the base circle. Note the opening and closing ramps.

[Canuck YYC]

Found it thanks. It was off-site - no wonder I spent so much time banging my head.



For future reference

[Brad D.]

Found it thanks. It was off-site - not wonder I spent so much time banging my head.



For future reference

Every time I look at that chart I am reminded how good the m30b35 cam is, and it's stock.

[Rich Euro M5]

Found it thanks. It was off-site - not wonder I spent so much time banging my head.



For future reference

Every time I look at that chart I am reminded how good the m30b35 cam is, and it's stock.

Which is why I have one in my NA M30b34.

Rich

[Canuck YYC]

In the valve event details chart that accompanies the M30 plots, I'm a little confused about the negative numbers. Given that most cams are measured at .050" lift as being the open/close points, I'm using those lines of information. The B32 and B34 lines have IO and EC events listed as negative values. Is this to say that the B34 camshaft IO happens at 5 degrees after TDC?

[paul burke]

b-35 cam with .010 lash measured at valve as installed in head. 217@ .050 405 lift 111.7 centers. These are single pattern cams (intake/ exhaust same pattern) Why are the lobe centers changing at different lifts (see second m-30 page) ??

[eddycooper]

Canuck (fellow Calgarian?),

Looking closely at the graph, I think you are dead on. The yellow horizontal line on the graph is at 0.05" lift (1.27 mm). And sure enough, the B34 cam has the intake opening after TDC. It seems that the Metric Mechanic cam should be the same, so I think there's a typo (ie. the MM cam appears to open at 5.8deg after TDC).

Eddy

In the valve event details chart that accompanies the M30 plots, I'm a little confused about the negative numbers. Given that most cams are measured at .050" lift as being the open/close points, I'm using those lines of information. The B32 and B34 lines have IO and EC events listed as negative values. Is this to say that the B34 camshaft IO happens at 5 degrees after TDC?

[paul burke]

Many BMW cams open after TDC when measured @.050. For comparison you must pay attenion to centers. Example a 210 degree cam installed @ 112 will have an intake opening of 7 after TDC. Advance that same cam to 100 and it will open at 5 before TDC.

Paul

[Canuck YYC]

Many BMW cams open after TDC when measured @.050. For comparison you must pay attenion to centers. Example a 210 degree cam installed @ 112 will have an intake opening of 7 after TDC. Advance that same cam to 100 and it will open at 5 before TDC.

Paul

Indeed, but there's almost 0 overlap no matter how advanced or retarded you install it.. I'm fairly new to BMW specific tuning so I'll readily accept all the knowledge folks are willing to pass me. I've never actually seen a cam with so little overlap before. When I ran the cam specs through the software, it wasn't until the graphic sim popped up that I realized there was almost no effective scavenging during IVO. Didn't seem right but I'm still measuring parts to understand where BMW engineered these things to function.

[Canuck YYC]

Canuck (fellow Calgarian?),

Indeed indeed. That wasn't your sharp black e28 M5 that rumbled by me going north on 4th this evening was it? Nice looking ride whoever it was.

[paul burke]

You are correct about seat to seat overlap being small in comparison. Centers(lobe displacement angles) don't change as these are ploted when cam is ground, therfore overlap will not change no matter where cam is installed.

Paul

[paul burke]

When you start ploting BMW camshafts you must involve the rocker arm, as it 's contact point varies throughout it's travel across the lobe which changes ratio. Any attempt to plot a profile without it will corrupt measurement.
Paul

[Canuck YYC]

Cheers for that - thanks Paul.

[Jimmie G]

Brad I feel the same about the b35 cam and bmw did too that is why they used it in the 745i from 5/83 up. little bit of history from realoem. The 635 dirty motor got the cam next 1/84 then the 535 dirty 12/84. I thought maybe it was a typo in the micro phish but they already had a 635 then and put the new dirty motor in them first. Anyway sorry about the highjerking rant but should we call it an m106 cam? I pulled this cam out of my old m106 head and it has KKK stamed on it did the klan start in germany? Sorry I just had too!

Jimmie

[eddycooper]

Indeed indeed. That wasn't your sharp black e28 M5 that rumbled by me going north on 4th this evening was it? Nice looking ride whoever it was.

Nope, that wouldn't be me but I wish it was! I've got a pair of 535is', one of which is going for its out-of-province inspection tomorrow. I've got my fingers crossed.

Now, back on topic, I have a Cat Cams 284-280 cam and the spec sheet says that the intake opens at 32deg BTDC. Is there any other standard than the 0.05" opening where this 32deg measurement might have been taken (a more European one perhaps)?

Eddy

[paul burke]

European grinders use 1mm or .040 as a checking height. This makes it harder to compare numbers and usually adds aprox. 10 degrees of duration as compared to the numbers you see using .050 as your checking height.

[Canuck YYC]

Nope, that wouldn't be me but I wish it was! I've got a pair of 535is', one of which is going for its out-of-province inspection tomorrow. I've got my fingers crossed.

Now, back on topic, I have a Cat Cams 284-280 cam and the spec sheet says that the intake opens at 32deg BTDC. Is there any other standard than the 0.05" opening where this 32deg measurement might have been taken (a more European one perhaps)?

Eddy

Is the cam installed yet? I have a complete head from a Euro M90 engine that I need to strip and rebuild one of these days. With a little measuring and some creative machining, I can put together a rig to measure that cam via the rocker. I need an excuse to build an iron maiden (to remove the cam) anyway.

[eddycooper]

Is the cam installed yet? I have a complete head from a Euro M90 engine that I need to strip and rebuild one of these days. With a little measuring and some creative machining, I can put together a rig to measure that cam via the rocker. I need an excuse to build an iron maiden (to remove the cam) anyway.

Nope, it's sitting in bubble wrap in my basement. If you'd like to measure it, I'd be all for it. And if you're going to make a jig that can be used to switch a cam without taking off the head, I would definitely be interested in using it!

Eddy

[Jimmie G]

Devinder
Have you had a chance to measure a early 533 cam I have a used one at the shop I could send you if you dont have one. This could settle the question about the duration being 272. When looking at the lobe profiles they are very close to the b35 or euro m30 cam with less lift and different overlap.

Jimmie