Piston symmetry

CharlieT

Veteran Member
Joined
Dec 10, 2008
Location
Houston, Tx
TDI
Audi TTqTDI, B4V, B5.5V, '12 NMS SEL
Is the only difference between a Cyl#1/2 piston and a Cyl#3/4 piston the valve relief pockets in the top of the piston ??
ie ex/in ex/in then in/ex in/ex
This is for a PD / BHW, but sure it applies to all. Just want to check there are no other wrist pin location differences.

I have oversize intake and exhaust valves, so I need to modify both piston valve reliefs anyway. For some bizarre reason Rockauto only has #1/2 in stock, so I was just going to buy 4 off and modify the valve reliefs as needed.

thx
 

CharlieT

Veteran Member
Joined
Dec 10, 2008
Location
Houston, Tx
TDI
Audi TTqTDI, B4V, B5.5V, '12 NMS SEL
Thx Matt !! I know that visually there is no other difference, and have handled lots of TDI pistons. But I have never measured. I do not totally trust the germans to have not tweaked some other symmetry in the wrist pin/rod/omega bowl, so thought I would ask.
Anyone ever checked this ??
thx
 

CharlieT

Veteran Member
Joined
Dec 10, 2008
Location
Houston, Tx
TDI
Audi TTqTDI, B4V, B5.5V, '12 NMS SEL
dieseleux,

thanks, wasn't planning to rotate, just remachine the valve reliefs.
Pistons are ordered... so here goes.
 

JFettig

Vendor
Joined
Aug 18, 2010
Location
Blaine, MN
TDI
B5 Passat, 2010 Jetta
Bowl is not center in either direction

I only measured one piston so no promices they aren't symmetric
 

mk3pd

Vendor , w/Business number
Joined
Nov 14, 2006
Location
Norway
TDI
Passat Quattro :)
Bowl is not center in either direction

I only measured one piston so no promices they aren't symmetric
I also believe the bowl is sideways located in each direction
Not just offset like all 4 are
But also to the left/right different from 1/2-3/4
 

CharlieT

Veteran Member
Joined
Dec 10, 2008
Location
Houston, Tx
TDI
Audi TTqTDI, B4V, B5.5V, '12 NMS SEL
ah crap.. I guess I am going to have an issue then.
For some reason rockauto are totally sold out of #3/4 pistons, and have been for weeks. I have no idea how they sold more #3/4 than #1/2 oversize pistons ??? seems very odd.
 

JFettig

Vendor
Joined
Aug 18, 2010
Location
Blaine, MN
TDI
B5 Passat, 2010 Jetta
I would take a set if you can get the 3/4 pistons and need someone to take your extras
 

O.C.TDI

Veteran Member
Joined
Apr 29, 2007
Location
Oregon City, OR
TDI
04 Jetta TDI, 09' JSW TDI, 09' BMW 335d
If you of JFettig are interested. I am willing to sell my full set of OEM BHW pistons that I had cut for larder valves and deeper. They are already coated and ready to go.

There are pics and spec toward the end of my build thread.

O.C.
 

CharlieT

Veteran Member
Joined
Dec 10, 2008
Location
Houston, Tx
TDI
Audi TTqTDI, B4V, B5.5V, '12 NMS SEL
Travis, thx, but I need 81.5mm, my block has some minor scratches I want to remove.

Jon, thx, may take you up on that. I have Qty 4 #1/2 81.5mm Nural pistons on order from RockAuto. They still do not seem to have #3/4 available, and don't seem to have a restock date from the emails I got back.
I have photos of some that were received by Nitec, they have a full oil gallery with two ports, identical to Genuine BHWs.

No idea how you can only sell cyl #1/2 of an oversize piston !!! do you think I am only going to rebore 2 cyls !
 

mk3pd

Vendor , w/Business number
Joined
Nov 14, 2006
Location
Norway
TDI
Passat Quattro :)
This is why I never quite understood how Crafter pistons can be used in 4cyl
Because they are not offset
 

CharlieT

Veteran Member
Joined
Dec 10, 2008
Location
Houston, Tx
TDI
Audi TTqTDI, B4V, B5.5V, '12 NMS SEL
This is why I never quite understood how Crafter pistons can be used in 4cyl
Because they are not offset
I learn something new every day.. thx Geir !
I would guess it 'works', but swirl and combustion will be impacted. More smoke, less burn, less hp from same IQ.
Still trying to get a straight answer from Rockauto on the #3/4 pistons..
 

MarkoP

Veteran Member
Joined
Mar 5, 2005
Location
Finland
TDI
2.0 BKD 140hp
Luckily I have one PD head at trunk =)

I measured gasket line being at head ~81mm and that is reference point.
Measured with caliper, so well room for error.

Measured from gasket line to injector hole side, and hole is ~7mm.

From runner side to injector hole: 45mm
From other side to injector hole: 28mm
45mm + 28mm + 7mm = 80mm (approximately one millimeter error somewhere)

From intake valve side bore to injector hole: 38mm
From exhaust valve side bore to injector hole: 35mm
38mm + 35mm + 7mm = 80mm (approximately one millimeter measure error somewhere)

Slight variation due car trunk + dial caliper method, but you should be able to draw where injector center approximately locates and how much there is mismatch.

I can take more precise measurements at weekend if needed.
 

loudspl

Veteran Member
Joined
Apr 22, 2005
Location
Osakis, Minnesota
TDI
02 ASV w/ 02J
Is this lack of bowl offset in the Crafters noticeable?

So, in theory, if BHWs are machined to same CR as Crafters, would the BHWs still be significantly more efficient?

just curious...:)
 

mk3pd

Vendor , w/Business number
Joined
Nov 14, 2006
Location
Norway
TDI
Passat Quattro :)
I have no idea
But the Crafter 5cyl use 5 identical pistons
I know the Crafter use same cam as the older 5cyl TDI
Using the same silly ex-in-ex-in-in-ex-in-ex-in-ex valve pattern aswell
The Crafter has big diameter valve reliefs on both sides and a much bigger/different bowl
Maybe the nozzles has a special spray angle????
 
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