Where to stop?

kiwibru

Veteran Member
Joined
Sep 21, 1999
Location
Distant island in WA. state
TDI
Golf 2-door, 2k Silver. Red RTDI now gone but not forgotten!
Insurance; Old carpet on the garage floor or a rubberized mat right under that engine stand.
I feel your pain...
 

JFettig

Vendor
Joined
Aug 18, 2010
Location
Blaine, MN
TDI
B5 Passat, 2010 Jetta
zero - none - no valve reliefs in the BEW head gasket. The valves are sunk into the head.
How does the ALH compare to ASZ/ARL/BHW head gaskets?
 

Ben Dur

Veteran Member
Joined
Mar 8, 2010
Location
Pensacola FL
TDI
2000 VW golf tdi
zero - none - no valve reliefs in the BEW head gasket. The valves are sunk into the head.
How does the ALH compare to ASZ/ARL/BHW head gaskets?
ALH 3 hole is the thickest available from what i understand
but im not sure thats the question
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
Check out post 207

The BEW runs a thinner head gasket than the ALH for the same pistion protrusion

Any thoughts as to why?

My first thought was that the valve reliefs in the piston are deeper and that they run a tighter squish for emissions.

I'd be surprised if the rod stretch between the two engines is that much different?

Other thoughts as to the reason for the difference?
 

O.C.TDI

Veteran Member
Joined
Apr 29, 2007
Location
Oregon City, OR
TDI
04 Jetta TDI, 09' JSW TDI, 09' BMW 335d
The BEW is one of a kind. Flat top pistons with a 23cc bowl. The valves are reccessed into the head. They sit about 1/32-1/16" below the surface of the head.

My BHW bowl with valve reliefs cc'd at 25cc including the reliefs. The bowl dimensions measured the same.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
My used 2 hole head gasket measures 0.068" so I'm assuming that the head gasket thicknesses in the Bentley are "compressed".

If the pistons stick out 0.057" (max) and the head gasket is 0.0673" that gives ~0.010" piston to head clearance vs 0.020-0.023 called out in the Bentley.

Valve Reliefs in the ALH pistons are 0.038" and 0.041" in the PD150's so there is 0.003" there - plus I can sink the valves as deep as I want in the head very easily at this point. They're currently 0.030" out.

Rods are within 0.0005" of each other (ALH vs Rosten's) so that's good.

Wristpin to Top of Piston is within 0.0005" between the ALH and PD150 pistons so that's good.

The block was decked "less than 0.010" (pictures of that to come later, but it's interesting) so that's probably the main cause of the issue.

Thermal expansion of the rod and block should be similar, but the piston will grow disproportionately more being aluminum - will it grow 0.010" in length over the operating temp of the piston? I doubt it since it's only ~1.5" from the wristpin to the top of the piston.

I'm trying to talk myself into using a 3 hole head gasket and sinking the valves to 0.010-0.015" protrusion and not having to alter the rods like Matt suggested. Does anyone know the reason for having a 20-23 thousandths piston to head clearance? Is it for valve to piston clearance (which I can fix by adjusting valve protrusion) or is it for something I'm not accounting for above which would allow the piston and head to touch?

I've been trying to rationalize being able to make the reduced pistion to head clearance work without having to do creative machine work (see bold above). Running the pistons very close to the head does not bother me in concept, but discussing it with a friend of mine I decided to run a quick calculation on how much the pistion grows due to temperature.

There is ~1.5" of aluminum between the top of the pistion and the wristpin. Aluminum has a thermal expansion coefficient of ~0.000013 length/length/F so some quick bar napkin math gives us 0.0000195 in/F

I found this on passenger car diesel pistion temperatures and am currently in the 50kW/L area. Per the chart on page 4 (below), assuming that the average piston temp is 300C (572F), gives a ~500F change in pistion temp from room temperature where the piston protrusion measurements were taken.



0.0000195 in/F x 500F = 0.00975" taller piston at operating temps. Given the ~0.0100" piston to head clearance on the one piston mentioned above, that leaves veeerrrryyyy little clearance once things get hot.

This is just ballpark estimations here, but enough to convince me that I really can't put it together and have any expectation that the pistons won't hit the head eventually.

So - this weekend, I'll pull the bottom end apart again, measure everything up to see why there is a ~0.010" difference between pistions.

1) Take Piston & Rod 1 (that measured ~0.046" protrusion) and move it to cylinders 2, 3 & 4 and see what protrusions I get

2) Take Pistion & Rod 4 (that measured ~0.056" protrusion) and move it to cylinders 3, 2 & 1 and see what protrusions I get

3) Depending on what the above measurements come in at, it will hopefully show if there is variability in the piston/rod assembly or the crank throw/deck distance.

4) If it's in the piston/rod assembly, I'll mix/match rods and pistions to determine what parts are short/long

5) If it's in the crank/block then I'll probably turn the crank around and see if it's the crack or the block

Depending on what parts end up varying will determine what I do to attempt to correct it. I'll jump off that bridge when I get there :)
 

TheOtherFuel

Member
Joined
Jul 23, 2011
Location
Chicago
TDI
'80 Westy Rabbit
I'm telling ya, check out the ASV pistons. Give Franko6 a call and he'll get you the exact dimensions, they are shorter than the ALH's and the PD's by a couple thou.
 

Keebler145

Veteran Member
Joined
Jun 29, 2008
Location
Niles, Ohio
TDI
Jetta MKIV 2000, 2003, and MKV 2006 PD DSG
I'm telling ya, check out the ASV pistons. Give Franko6 a call and he'll get you the exact dimensions, they are shorter than the ALH's and the PD's by a couple thou.

The pd150 pistons I think are a stonger piston and he already spent a chunk of change on purchase and coating them. Plus, they are "damaged" so I don't think he'll be returning them :p

I'm sure if you bought him a set of ASV pistons he would use them though :rolleyes:
 

Whitbread

Vendor , w/Business number
Joined
Jan 21, 2007
Location
Johannesburg, MI
TDI
Several
Hey Matt, I talked to the machine shop I deal with regularly and they said another common practice is to press out the small end rod bushing, press in an oversize one, and re bore/hone it to your needed CTC rod dimension. They said there's a racing machine shop in Milwaukee that does it very well. The name is Manitowoc Machine. Give them a ring.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
[EDIT] - Piston Protrusion measurements are inaccurate/not repeatable - see post 243 [/EDIT]

Lost and confused....




I double/triple checked the measurments, both with feeler gauges and a depth micrometer. Checked the block deck for flatness with a straight edge and feeler gauges, etc.

Does anyone see a trend here that I'm missing in my frustration?

The two measurements for each cylinder/piston are "left" and "right" as sitting in the driver seat.

That new car payment isn't looking so bad right now....
 
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TDIJetta99

Top Post Dawg
Joined
May 17, 2005
Location
Port Jervis, New York, USA
TDI
03... Faster than yours =]
are you moving piston/rod assemblies, or keeping the rods in the same cylinders and moving just the pistons? If I were a betting man, I'd say the block was at ever so slight of an angle when it was shaved, causing a little more to be sliced off towards the #4 end... You'll still have a nice perfect straight edge, but it's tilted a little.. That would explain the trend of the pistons sticking out more and more as you go down the line, and the one side always being higher than the other side of the same pistons..
 
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Ben Dur

Veteran Member
Joined
Mar 8, 2010
Location
Pensacola FL
TDI
2000 VW golf tdi
theres some odd variable here.


looks like (head gasket hole chart) vw allows 4/1000 variance
looks like your measurements show 13/1000 variance


it does apear that (looking at cylinder average line) the block is slightly tapered, but there are some odd measurements that dont validate this aswell...
a (imaginary) 4 hole gasket would solve the issue


according to the chart, the gasket is spec at about 21/1000 thicker than protrusion. so it looks like your looking for a 78/1000 gasket. or 2mm.


if a custom can be sourced it may be the best option.
that or have 20/1000 machined off the pistons. but then they arent ceramic coated anymore...


how bout stacking two 1-hole BEW gaskets. never heard of that before... might be a disaster idk. but it would come out to just under 3mm thick giving you 50/1000 clearance or so. would that wreck the compression ratio?

personally id go with a 2mm custom gasket if it can be sourced. gives you OE spec on the tallest piston, and within acceptable CR on the lowest.


but take this post for what it is... its 3am on a saterday/sunday and im 24... think about it
 
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Galactic_Warrior

Veteran Member
Joined
Feb 14, 2002
Location
Milwaukee, WI
TDI
02 Jetta
are you moving piston/rod assemblies, or keeping the rods in the same cylinders and moving just the pistons? If I were a betting man, I'd say the block was at ever so slight of an angle when it was shaved, causing a little more to be sliced off towards the #4 end... You'll still have a nice perfect straight edge, but it's tilted a little.. That would explain the trend of the pistons sticking out more and more as you go down the line, and the one side always being higher than the other side of the same pistons..
I concurr. If you look at the data, the "#4" (right column) side of the piston protrusion is always greater than the "#1" (left column) side with the exception of pistion 4 in #2 cyl and #3 in #3. These could be measurement error too.

Also look at the first deck picture in post #205. It appeared that #1 cyl needed more deck material removed, so another cut was made thus resulting in a lower deck height at the other end (#4) leading to greater piston protrusion.

Althouth a real PITA (timing, coordination and wallet), you might be best off having another cut taken on the block to true it up and then re-bushing the rods.

Probably not what you want to hear.

Just curious, is your decking process a grind or was it dry milled?
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
[EDIT] - Protrusion measurements are inaccurate/not repeatable - See Post 243 [/EDIT]

Rod and Piston assemblies have stayed together so far.

ALH Piston #2 in Cylinder 1 measures 42 and 47
ALH Piston #2 in Cylinder 2 measures 44.5 and 50.5
ALH Piston #2 in Cylinder 3 measures 44 and 49
ALH Piston #2 in Cylinder 4 measures 47 and 52

Chart in Post 229 has been updated with this info now

The block was not ground - I don't know if coolant was used when it was milled or not, but I can find out.

The ammount of protrusion I can correct for in quite a few different ways, the difference between each cylinder and the difference side/side is what I'm more worried about.
 
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silverbox

Veteran Member
Joined
Jul 24, 2005
Location
Halifax Nova Scotia
TDI
jetta wagon 2003 silver
FUB,
Have you figured out what is going on with the piston protrusion?
With all the work you have done, you would expect to be on the road again, better than ever.
Are you considering another block and crank?
 

Whitbread

Vendor , w/Business number
Joined
Jan 21, 2007
Location
Johannesburg, MI
TDI
Several
Use a large set of calipers to measure from top of main journal bore to top of deck at each end of the block. If it's really milled off square that will tell you accurately enough if you measure a .005" difference.

If so, have it re-decked properly and then have your small rod ends recentered. Done. No need for a new block or crank. Sometimes when all tolerances end up at the high end of the spec, adjustments have to be made. Welcome to performance engine building haha.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
I pretty much spent 12+ hours this weekend swapping pistions/rods/bores and taking measurements. Not very exciting and a bit frustrating at times.

I did some rod/piston swapping 3/4 and 1/2 and was able to get the variance to ~0.004" across all 4 with the max protrusion being 0.0515" and most being 0.049-0.050"

For some reason, I have not been able to re-create the 0.057" protrusion that I was able to get last weekend - the most I can get now is 0.054" - no idea why.

Doing some "gauge R&R" I was getting 2-3 thousandths variance each time I measured sometimes and other times was getting within a half thousandth a couple times in a row. Turning the crank and indicating max piston protrusion with a dial indicator each time, making sure that I was always turning the crank the same direction to get to TDC, taking up the ring play, etc and still getting the above variance.

Thinking about it on the way home tonight, I think I have a way that I can reduce the measurement variation more, but will have to try it next weekend.

I used my digital caliper to measure the depth of the piston at BDC between cylinders 1 and 4 and had 0.007" variation between sides of piston #1 at the wristpin with no variation on pistion #4. Pistion 4 was 0.002 shallower than the lower value of pistion #1.

Piston 1 Right: 3.714"
Piston 1 Left: 3.707"
Piston 4 Right: 3.705"
Piston 4 Left: 3.705"

Does anyone make undersized rod and/or crank bearings for the ALH or know where to get them?
 

Ben Dur

Veteran Member
Joined
Mar 8, 2010
Location
Pensacola FL
TDI
2000 VW golf tdi
could have a machinist relief the head. the rings are still 1/3" away from the top of the block and there's enough meat on the head.

they can machine deeper valve reliefs in pistons, why not piston reliefs in the head? (since this is actually %50 of what a head gasket is doing anyways)
 
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