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Driveline, Engine & DME Tuning
Talk about driveline improvements, NA tuning and DME tuning your E46 BMW here. This includes diffs, intakes, exhausts, chips, software and OBD tuning.

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Old 03-25-2010, 01:34 AM   #21
///Orient3
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Originally Posted by PEI330Ci View Post
For the OEM calcs, I used 84mm bore.

I measured used gaskets that had already been compressed, and found them to be 0.030" thick. I have a new gasket at the shop I could measure for reference as well. (I'm amazed how much "new" stuff I still have)

Were you measuring the head with the spark plug installed?
I checked, the combustion chamber volume was measured with the spark plug in. I'm not surprised you have so much new stuff left. Hang on to it, and sell it as NOS when the parts are less available, haha.
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Old 03-26-2010, 02:42 PM   #22
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I'll try to find some time tomorrow to CC my combustion chamber on my "Erland made head".

What cast # is on the head you tested?
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Old 03-26-2010, 03:45 PM   #23
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I'll try to find some time tomorrow to CC my combustion chamber on my "Erland made head".

What cast # is on the head you tested?
I'll check...
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Old 03-28-2010, 02:21 AM   #24
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I'll check...
You wouldn't happen to still have one of your CP pins to weigh, would you? I'm looking to compare some pin weights. My original pins supposedly weighed in lighter than the pins that are supposed to arrive on Monday, and I'm curious because your pins would be from a relatively similar time period to my originals.
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Old 03-28-2010, 07:09 AM   #25
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You wouldn't happen to still have one of your CP pins to weigh, would you? I'm looking to compare some pin weights. My original pins supposedly weighed in lighter than the pins that are supposed to arrive on Monday, and I'm curious because your pins would be from a relatively similar time period to my originals.
Numbers for you to work with:

CP piston w/rings = 312g
CP wrist pin = 80g
Rod bearing = 32g
Arrow 135mm rod w/bolts = 503g
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Old 03-28-2010, 01:39 PM   #26
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Numbers for you to work with:

CP piston w/rings = 312g
CP wrist pin = 80g
Rod bearing = 32g
Arrow 135mm rod w/bolts = 503g
Thanks for the numbers. The new ones are supposedly 98g, the originals weighed in at 81g. So the originals were right on with the numbers you had. My original CPs weighed 300g (w/o rings), and the new ones are 288g. I'll throw everything on the scale when I get them tomorrow.

Just an interesting fact: the dome height on the original pistons was .012, the dome height on the new ones is .125.
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Old 03-28-2010, 03:07 PM   #27
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I'm just happy to hear you were taken care of.
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Old 04-23-2010, 12:17 AM   #28
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Ever wanted to design a piston from scratch?

That's the fun I've been having for the past month or so, and let me tell you the M54B30 doesn't make life easy.

Probably the most important spec to look at when designing a piston for an engine is "compression height". This is the measurement from the center of the wrist pin to the crown of the piston. In the case of the M54B30, we need to do a little backwards math to find out what are limitations are in this area.

The distance from the center of the crank to the "deck" of the block is 211mm.

89.6mm crank throws the center of rod journal up 44.8mm.

The connecting rod is 135mm from center to center.

This gives you a "compression height" of 31.2mm from the center of the wrist pin to the deck of the block.

The wrist pin on all M54s (and most other BMW engines) is 22mm. This brings us to 20.2mm of space to work with above the wrist pin on our custom piston design.

So the next step is to figure out the ring package that we want to run. Normally for N/A engines, you'll see top and second rings in the 1mm - 1.2mm area. For FI, it's recommend to run a thicker top ring. So for my "nitrous engine", I've chosen a 1.5mm top ring, and 1.2mm second ring. The oil scraper ring is dependent on a number of variables in the oil system, as well as the stroke of the piston. The more stroke, the more oil there is to shear off the wall and you need somewhere to store this before it bleeds through the breather holes. Luckily, the M54B30 has a modest stroke and moderate amount of oil being cycled onto the piston wall. This means that we don't need to be on the high end of the oil scraper ring scale (5mm for big blocks for example) and can get by with a good 2.5mm ring.

So the combined ring stack is 5.2mm, giving us 15mm of space to place the ring lands. Assuming we are placing the oil ring directly on top of the wrist pin bore, this gives us 3 ring lands to specify

Top Land
Top piston ring
Middle Land
Second piston ring
Bottom Land
Oil scrapper ring

Probably the most critical as far as strength is concerned will be the top land. The more material we can place here on an F/I piston, the better. So this means we want to minimize the land size for the middle and bottom land to give as much as possible to the top land.

On advice from industry experts, I went with a middle land of 3mm, and a bottom land of 2mm. This leaves us with 10mm above the top ring. Sounds like a lot right? Well we still have to design the piston crown, and that's where we have to account for the valves.....

So recounting a bit of math:

Top Land = 10mm
Top piston ring = 1.5mm
Middle Land = 3mm
Second piston ring = 1.2mm
Bottom Land = 2mm
Oil scrapper ring = 2.5mm

Wrist pin radius = 11mm
Connecting rod length = 135mm
Crank stroke radius = 44.8mm

So we've used all of the 211mm of space with the reciprocating assembly.

Some might point out that the head gasket can be adjusted so that we can run the piston above the deck before it will hit the head. This is true, and to be honest, we can get gaskets 3.5mm thick. (0.140") But when you are producing maximum cylinder pressures, do you want to run that pressure against more gasket surface area or a solid cylinder bore? Most top level engine builders when not constrained by deck-height rules, will chose to run the thinnest head gasket possible. So in this case, the piston design will respect a 0.030" head gasket.

If you want to flow lots of air through moderately sized valves, you need to hold them open a long time. The peak lift value isn't as important as the average lift value in cranking degrees. With the custom camshafts I have, this means that the valves are open when the piston reaches TDC at the end of the exhaust stroke and beginning of the intake stroke. With the cams "centered" in the middle of the VANOS adjustment range, this figure is around 4.5mm for both sets of valves. Retarding the exhaust camshaft will increase this value, as well as advancing the intake camshaft. In fact, it's feasible to see lift of nearly 9mm @ TDC at the far end of the VANOS adjustment range for both the intake and exhaust camshafts. This gives you 2 options for designing the valve reliefs:

1.) You mechanically lock the cam position for what you estimate will be the best cam timing position, and design the piston to clear the valves at that position.

2.) You allow the full range of VANOS adjustment, and design the piston to clear this.

A third option is to limit the VANOS range with the ECU, but then Murphy's law is bound to show up with some glitch that ruins the engine.

I went with option #2, and had massive valve reliefs designed into the piston crown. I reasoned that being able to manipulate exhaust cam timing was going to do more to control chamber heat than running the extra material in the crown above the top piston ring. Hopefully, with some of the other tricks I've got planned, it works.

Clearance for the intake valve is 9.62mm @ TDC with a 0.030" head gasket.

Clearance for the intake valve is 8.92mm @ TDC with a 0.030" head gasket.

The result of the valve relief cuts are 2 "low" areas above the top piston ring measuring just 4mm thick across a 5mm area on the intake side, and 5mm thick across a 4mm area on the exhaust side. It's a compromise, but one that I'm willing to accept to maintain mechanically safe clearances in the event of over-reving or ECU failure.

So where does this leave the compression ratio?

11.4:1 with a 0.030" head gasket, which is actually low for nitrous race engines running race fuel.

Someone, at some point, is going to figure out what this piston design means....
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Old 04-23-2010, 02:27 PM   #29
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11.4:1 with a 0.030" head gasket, which is actually low for nitrous race engines running race fuel.

Someone, at some point, is going to figure out what this piston design means....
Lots of nitrous and a completely retuned vanos map?
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Old 04-24-2010, 02:55 AM   #30
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Lots of nitrous and a completely retuned vanos map?
That's part of it....maybe have a look at how much power engines running a 1.5mm top ring have. There aren't many...

I also let a flow rating slip somewhere else that tells a very interesting story if a person works out the #s.
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Old 04-29-2012, 08:29 AM   #31
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Again thanks for all the work youīve done.

if you want, you can add information on the stock valve spring, if never found them anywhere else.

shown is spring force over distance travelled.
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Old 04-29-2012, 07:53 PM   #32
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This is interesting, I read this thread for the first after it got bumped today. I did all the same measurements and ended up with the same numbers.

I also designed custom 11.5/1 flat top pistons and had them made by CP to my specs. I'm building a NA M54 3.0L using the Schrick 264/248 cams. I'm porting the head and installing 1mm oversize Ferrea intake & exhaust valves.

Few few pic's of the work performed to date:


Measuring deck height.


CC'ing chambers using weight method. Distilled water has a specific gravity of 1.




Cleaned parts after tear down.


Checking head warp by sweeping head with indicator on mill table. This is the low point, .0018" of warp, I'm OK with that but I will probably skim it before assembly anyway.


Flow testing head.




Custom "1 off" M54 mechanical throttle body.




CAD model of new piston dome to verify new valve pocket displacements.


Top view of cutom CP slipper piston made to my spec's.


bottom veiw of same.

CP Piston order form.pdf
More head data used for ordering pistons.

All this work happened about 6 months ago, I've been too busy to make any more progress on it. Once I get back into the porting again I'll start a complete build thread. This is eventually going into a 1997 E39 if I ever get time to finish it.
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Old 04-30-2012, 01:10 AM   #33
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nice

is anyone able to measure the clearance between valves (in/ex) and oem piston in tdc? iīve just bought a head and no possibility to measure if the 272 schrick cams arenīt to "big". whats that position called in english? valve overlap (mm, not °) in tdc, maybe?
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Old 04-30-2012, 02:40 AM   #34
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is anyone able to measure the clearance between valves (in/ex) and oem piston in tdc? iīve just bought a head and no possibility to measure if the 272 schrick cams arenīt to "big". whats that position called in english? valve overlap (mm, not °) in tdc, maybe?
I'll check my notes and see if I have anything. Otherwise I may be able to back calculate using the data I have for my custom pistons and measuring the stock piston valve pocket depth. Schrick publishes the lift at overlap for their cams at both VANOs retard & advance positions. That should give me enough data to work with.
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Old 05-01-2012, 03:32 AM   #35
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Quote:
11.4:1 with a 0.030" head gasket, which is actually low for nitrous race engines running race fuel.
I plugged those numbers into my C/R speadsheet and came up with the following.
Piston below deck=.0046"
Piston to head clearence=.0046"+.030"=.0346" tight but do-able.
C/R with flat top piston=13.9/1 before valve subtracting valve pockets.
Valve pocket dispalcement=8.4cc
C/R after subtracting valve pockets=11.6/1

I modeled your piston dome with valve pockets to calc pocket displacement.

Click image for larger version

Name:	valve reliefs.jpg
Views:	139
Size:	29.1 KB
ID:	449615

You probably didn't need to know any of this, but I know myself, it's always nice to have someone else confirm the math.

What are the specs of your cams? Your valve pocket depth is more than twice what I have for my Schrick cams.

Last edited by MotorMan; 05-01-2012 at 03:33 AM.
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Old 05-03-2012, 08:07 PM   #36
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I plugged those numbers into my C/R speadsheet and came up with the following.
Piston below deck=.0046"
Piston to head clearence=.0046"+.030"=.0346" tight but do-able.
C/R with flat top piston=13.9/1 before valve subtracting valve pockets.
Valve pocket dispalcement=8.4cc
C/R after subtracting valve pockets=11.6/1

I modeled your piston dome with valve pockets to calc pocket displacement.

Attachment 449615

You probably didn't need to know any of this, but I know myself, it's always nice to have someone else confirm the math.

What are the specs of your cams? Your valve pocket depth is more than twice what I have for my Schrick cams.
I agree, it's always good to have someone to bounce numbers off of.

I've got my own spreadsheets, but I also use Larry Meaux's software.

Here's the finished piston design, which is even more extreme than you thought:







Valve relief was for really big cams....300/296 custom design from Schrick:



You don't want to oversize the exhaust valve....unless you've got a heat issue and need the extra surface area to dissipate heat back into the head. I had a head ported for 30.5mm and another head ported with 31.5mm valves, and the smaller valve flowed a little bit more up top.
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Old 05-03-2012, 09:21 PM   #37
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Holy crap! What are you building?!
You're running that much duration, plus VANOS?
I can't wait to see what this turns out to be.

I just saw your Cyl head slice and dice job last night, really good stuff. It will help me with decisions on my own head.

Gary
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Old 05-03-2012, 09:24 PM   #38
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I forgot to ask, did you coat your own piston skirts, or is that Swaintech?
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Old 05-08-2012, 09:10 PM   #39
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Holy crap! What are you building?!
You're running that much duration, plus VANOS?
I can't wait to see what this turns out to be.

I just saw your Cyl head slice and dice job last night, really good stuff. It will help me with decisions on my own head.

Gary
I was building a high rev'ing nitrous engine, but my plans changed.

I've since sold those cams to a pro race team, installed the Schrick double valve springs and Ti retainers on my ported street car head, and the solid lifter buckets are still sitting on a shelf at my shop.

The cams were actually designed to be locked into position 104 degrees before and after TDC. The lift profile was so large that in the fixed position, there was more overlap at TDC than with the VANOS fully advanced/retarded with Schrick 264/248 cams.

Quote:
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I forgot to ask, did you coat your own piston skirts, or is that Swaintech?
Those pistons were a custom run done for me by Wossner in Germany. They did the skirts with their own media....not sure where it's sourced from. And....I've got 12 pistons just sitting on the shelf at my shop as well.
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Old 05-08-2012, 09:27 PM   #40
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The cams were actually designed to be locked into position 104 degrees before and after TDC. The lift profile was so large that in the fixed position, there was more overlap at TDC than with the VANOS fully advanced/retarded with Schrick 264/248 cams.
OK that makes a lot more sense, I couldn't imagine running that much duration with the addition VVT.

Quote:
Those pistons were a custom run done for me by Wossner in Germany. They did the skirts with their own media....not sure where it's sourced from.
The reason I asked is that I've had Swaintech coat piston skirts for me in the past and they seemed to have the same approach of not masking off anything but the ring lands. I know the overspray doesn't matter, and it's just me being anal, but I think a professionally coated piston should look professional.

Quote:
I was building a high rev'ing nitrous engine, but my plans changed.
What's the current plan and how far along are you? I've been dieing to get back working on mine but I don't see that happening for a while.

Good luck and keep us posted, I love seeing what other builders are doing with the M54.
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