Tdi head stud question

jpderv

Active member
Joined
Aug 20, 2010
Location
n.ireland
TDI
Leon fr tdi 235bhp 365lbft
Hi folks have a small question for you.
At the moment I'm getting head lift pressure in the expansion tank with 2.7bar boost but when it lower the boost to around 2.2/2.3bar everythings alright no pressure in the system.
Pd130 with gtb2265 firad 120s with pd150 headstuds.
If I was to fit ARP head studs now could info back upto 2.7bar without head lift.
 

Mongler98

Top Post Dawg
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Mar 23, 2011
Location
COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
quite a few of us who go to ARP studs have this issue. in reality, the head is probably warped or the gasket is on its way out. i had this issue same as you, so i did a full head job, port polish, valves, seats, decked it from a good shop, undercut valves, helper springs, cam, the works!

I still have this issue and after talking with some folk around here, i highly suspect the head to be warped again due to higher EGT's and a few low coolant overheat events.
you need to check for block flatness against the crank journals, you can do this against the pistons as long as they are not bent at the rods or anything. A properly built set up with normal head studs should take 40PSI before issues come up. im running 32 myself and dont have the $$$ to fix it so i only autocross it as it only acts up when i go for a long pull. short busts and highway driving has no issue.

my advice, dont waste your money on the headstuds, take the head off and have it decked by a good head shop, get a gauge block so you can measure the TDC on each piston and measure it against the surface of the block. You can do a block deck with the engine in place but it takes time and care.
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
Lower the compression while it's apart.

with ARPs torqued to 140ft/lb and ARL pistons mine was lifting at 40 psig, so that's 3800 mbar absolute or 2800 mbar gauge
Even at only 13 deg start of injection timing it was pressurising the cooling system. Completely ignorable, being that it wasn't losing any coolant, but concerning nonetheless.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Just curious, what you would do to lower the compression on the head work? i already have a 3 hole sized (largest) head gasket.
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
Just curious, what you would do to lower the compression on the head work? i already have a 3 hole sized (largest) head gasket.
You do not want to run wider piston/head clearance, this only wastes air where the injector can not reach it. Same with valve reliefs, only make them as large as your camshaft requires, or you're wasting air that could be burned.

Cut the bowl larger to lower compression, on mine I just used an edge-trim router bit to cut the lip off, then used a roundover bit with a 1/8" radius to smooth the edge. No idea where it'll leave the compression ratio. looking at the difference between 19.5 ALH and 18.5 ARL bowl sizes, it looks like maybe they'll end up something like 16-17:1? No matter, what does matter is if it still leaks.
 

Yucca

Veteran Member
Joined
Apr 13, 2007
Location
Finland
TDI
ALH 388bhp, Polo 6R 2.0TDI CR GTC1752VZ
Why the hell do you want 2.7bar boost?

Stock 2260VK can do over 300bhp with 2.2 - 2.4bar boost level. Flow is not same as boost, look EMP gauge to find out right boost level for your setup.
 

BigTurboAlh

Veteran Member
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Jan 8, 2016
Location
Pa
TDI
06 ranger cjaa swap
I used run stock pistons and 35psi blew the the head gasket. I run .120 flycuts and delipped pistons. ARP studs torqued to 140ftlb. I’m at 40psi don’t have the drive pressure gauge hooked up yet it just came in. I’m at 40psi now. I used run stock pistons and 35psi popped head gasket twice. .
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
im pretty brave but not brave enough to re cut the bowls on my tdi. Are there pistons with this done to them already?
 

BigTurboAlh

Veteran Member
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Jan 8, 2016
Location
Pa
TDI
06 ranger cjaa swap
No I had my machine shop do it they came out perfect. They were brand new asv pistons.
 

jpderv

Active member
Joined
Aug 20, 2010
Location
n.ireland
TDI
Leon fr tdi 235bhp 365lbft
Thanks for the help folks seems strange to me you would think that if it pressurised once then no matter what pressure you ran then it wouldn't it all the time.





Why the hell do you want 2.7bar boost?

Stock 2260VK can do over 300bhp with 2.2 - 2.4bar boost level. Flow is not same as boost, look EMP gauge to find out right boost level for your setup.
I highly doubt a gtb2260 would make 300bhp at 2.2bar unless you have some head work and cam perhaps.

The reason I'm running 2.7bar is because I can lol in my case less boost ment less power on the dyno so that's were it's at atthe moment.

EMP seems stable at the moment max 50psi at about 2700rpm then almost matching boost to about 4700/4800rpm.

I wanted to see what would blow the pd130 up after a couple drag events and maybe 40/50miles per week of excited driving nothing has given yet apart from the head.

Before next drag event Il probably get the pistons machined a little should help a bit with cylinder pressure atleast this time the head studs will be done the correct way.

I did change to ARL head studs using the one at a time method perhaps this hasn't helped the situation any although even darkside developments recommend this method so doubtful.
 

Yucca

Veteran Member
Joined
Apr 13, 2007
Location
Finland
TDI
ALH 388bhp, Polo 6R 2.0TDI CR GTC1752VZ
Sure you need good ported head and cam.

I dont know what is good boost level with stock head and cam. It is good to hear that you have also measured EMP.
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
Getting the necessary trapped air mass for a given power output and lambda by volumetric efficiency improvements (e.g. head porting and cam) is almost always preferable over boost from mechanical (PCP, EMP), thermal stress and efficiency standpoint.

A similar analog in the fuelling side is that it is preferable to get the necessary fuel quantity for a given HP / lambda by injection flow rate (hole size and pump pressure) rather than simply extending the injection duration.
 

All Stock

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Oct 6, 2014
Location
Michigan
TDI
AHU
Question is where can we get an H11 or similar ALH stud these days?

A1 who made Whitbreads is no longer in business.

Does anyone know of another motor that has a similar stud that can be made to work for an ALH in H11 or similar?
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
just measured a stock head bolt and they're 110mm under head length, standard M12 pitch
Call up ARP and they'll probably make you some for a hideous price.

On the other hand, I think the limitation is the aluminum head rather than the 8620 studs. There's just too much space between the bolts and the deck isn't thick enough to bridge the gap.

Easy solution on most peoples setup is limiting torque. Tiny turbo and okay nozzles it's easy to make some ridiculous torque figures far too low in the revs to be of any actual utility.
400 ft/lb sounds mean and certainly is a workout for the bits in your bottom end, but when it equates to 110hp, who really cares? Bump the revs up from 1500 to 4000 and that same torque's suddenly 300hp.
 
Last edited:

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
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Canada
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TDI
Poor understanding of properties of materials result in wasted money at best, or no significant improvement.

The metal stretch of a bolt (strain) is related to the stiffness of the material (Young's modulus), applied force, cross sectional area and length - the latter because strain is expressed as a percentage of the total nominal length). If you are dealing with a ferrous-based material, the Young's modulus doesn't vary outside about 210 GPa +/- 5%, regardless whether we're talking plain carbon steel, alloy steel, tool steel or some other exotic grade of steel, therefore not much to be gained there. Ultimate tensile strength (PSI or MPa at breakage) is rather useless in the discussion of bolts, but yield strength is more relevant. The higher the yield strength, the more stress you can apply (and the more strain/stretch by extension) before it stretches permanently longer than the original, unloaded state. But in and of itself, a higher strength bolt does not increase the degree of stiffness or resistance from stretching whatsoever.

SImply installing higher "strength" fasteners of any kind - bolts or studs - with all else being equal (diameter, and torque) will give you a goose-egg zero additional clamping force.

You need either to increase the bolt diameter, along with increasing the tightening torque, but then by doing the latter you can damage the aluminum head.

Installing higher strength fasteners and seeking more clamping force (within what the cylinder head can withstand), while not a bad thing in and of themselves, are very poor Band-Aids for the root of the issue, which is the need to manage peak cylinder pressures (PCPs).
 

All Stock

Veteran Member
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Location
Michigan
TDI
AHU
How to keep PCP in check at 45+ psi in a compound setup without having your own tuning software... When even the right conditions can spike PCPs temporarily enough to warrant a need for something stronger than an ARP 2000.
 

Tero P

Well-known member
Joined
Nov 7, 2012
Location
Finland
TDI
Golf MK4 Estate ASZ 379hp, Passat B5.5 Estate 4motion AVF 365hp
I have pd130 engine with stock compression ratio and pd150 head studs.
Dyno figures says 379hp/600Nm with 3,4bar (49,3psi) boost.
I drove it over 18000km (11000miles) without head lifting problems.
 

All Stock

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Location
Michigan
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I would like to see a dyno chart overlaid with a SOI timing chart that keeps things alive at those levels.

I get not having a typical diesel low rpm power curve in favor for a gas like curve with more power and torque up high and that it is key. But here stateside very few people are doing this at these levels of boost and the correlating amounts of fuel to use it, that has me wondering about being able to get a tune to manage the PCP's.
A few of the brilliant minds here talk about it but no one seems be sharing.

When are talking about the ALH or an AHU/AVG like mine, its 20 year old machines that are not the pinnacle of todays bread and butter for tuners, so why is everything still such guarded in secrecy? Sharing would certainly save some people some expensive parts that are starting to get hard to come by.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
I'm definitely not one of the brilliant minds, but I've dipped my toe in the cylinder pressure monitoring pool. I've got all the stuff to do it, but currently lack the time to dedicate to further the project.

All that I've done is in this thread - FWIW never had a head gasket/bolt issue at those PCPs? Still don't with compounds and 40psi boost (knock on wood). Have 80k miles on the rebuild.

http://forums.tdiclub.com/showthread.php?t=403881

+1 to what TDIMieister said about fasteners - stronger is NOT stiffer
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
How to keep PCP in check at 45+ psi in a compound setup without having your own tuning software... When even the right conditions can spike PCPs temporarily enough to warrant a need for something stronger than an ARP 2000.
Doing your own tuning's the easy part, the dyno time's the kicker.

At this point mine's weak as heck until 2.5-3k RPM, and even above that I was running real weak timing. Erring on the side of caution due to a massive lack of data. That's why I don't share my tune files, they're absolute garbage, incomprehensible even with a stack of notes I took while working them up.

Maybe I'll get together a load cell in an engine mount at some point like FUB did iirc?
That would help with setting timing immensely. Just increase it until torque (at the crankshaft) gains start to taper away, then back it off a degree or two depending on how aggressive of steps you were taking. With high boost and big nozzles even stock timing may well be over advanced, depending on how you scale the fueling into the maps.
 

Tero P

Well-known member
Joined
Nov 7, 2012
Location
Finland
TDI
Golf MK4 Estate ASZ 379hp, Passat B5.5 Estate 4motion AVF 365hp
I would like to see a dyno chart overlaid with a SOI timing chart that keeps things alive at those levels.
Soi was about 20 degrees@3000rpm and 30 degrees@5000rpm.
Chart is not telling the whole truth. It’s hard to have same amount of load on dyno like on road. On road engine woke little bit earlier. In 4.gear 3bar boost@2800-2900rpm and 3.gear 3bar boost @3050-3100rpm
 

Jukums

Well-known member
Joined
Jan 28, 2014
Location
Latvia
TDI
1.9 TDI 1Z TDR.lv
I am using PD150 head bolts and with 3.0-2.7 bar boost and with 23.5 SOI on VP hadn't head lift. CR is lowered - machined pistons and valves.

I have pd130 engine with stock compression ratio and pd150 head studs.
Dyno figures says 379hp/600Nm with 3,4bar (49,3psi) boost.
I drove it over 18000km (11000miles) without head lifting problems.
Which turbo is capable to hold 3.4bar boost ?
 

mk3pd

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Joined
Nov 14, 2006
Location
Norway
TDI
Passat Quattro :)
If block and head is decked properly it will never be a headgasket issue
 

Franko6

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May 7, 2005
Location
Sw Missouri
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Jetta, 99, Silver`
I agree, properly decking both the head and block are MANDATORY. The head warps longitudinal and the block warps transverse. In other words, the head will warp high down the length of the head. The block will warp so that the webs between cylinders are the low point.

Lowering compression with a thicker head gasket is not the way to go. There are a variety of Nural pistons that drop cylinder head pressure, the most dramatic that drops CR to 16.8 are the 81mm Crafter 5 cylinder pistons. The BRM PD 79.5mm pistons drop only to 19:1 and the BHW 81mm pistons are 18.25:1. Unless it's a monster build, the BHW are a reasonable choice. Even the Crafter pistons, in full race situations should have the bowl increased. We stock modified pistons and are improving with coatings for superior piston fit.
 

Jukums

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Joined
Jan 28, 2014
Location
Latvia
TDI
1.9 TDI 1Z TDR.lv
Garrett Gtb3576klnrv (50mm inducer version).
With 3.4bar boost emp was 2.8bar.
That turbo is hard to find for us in Latvia, didn't see any car here, who would have this turbo. So will still trying to get luck with GTB2265-68 hybrid. At least for now with GTB2265 get 357hp on VP with 3bar boost, EMP is 2,5-3bar
 

Votblindub

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NY
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MK4 Jetta Wagon
I'm gonna follow this to learn. The amount of knowledge in this room is awesome!
I'm also wondering about the turbo choice for this application. Instead of a single Gtb3576klnrv, can you do better with maybe a pair of smaller turbos?
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
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Canada
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TDI
Series (compounding, if you will) arrangements of 2 turbo's is where it's at for Diesels. There are multiple issues with parallel turbocharging that has been detailed elsewhere. Therefore, you size the LP (big) turbo for the target max power and put a smaller one in series for quicker transient response, thus having the best of both worlds. You could put something as small as a GT12 or GT14 on the HP side with GTB3576KLNRV on the LP, with appropriate bypassing.
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
You could put something as small as a GT12 or GT14 on the HP side with GTB3576KLNRV on the LP, with appropriate bypassing.
Reuben was doing some work with a sequential-compound gt14(44?) and a big EFR without a bypass valve on the intake side, just a wastegate set up such that once the LP woke up, it was fully open.
He was reporting the HP shaft speed wasn't going too crazy and that it also wasn't nearly as bad of a restriction you'd think it would be.
This was a few months ago, sure wish he'd post more updates on here. :p Does some really interesting stuff.
 
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