to retorque,or not to retorque

[hillfolk'r]

hey,,i was wonderin,,on  the "full race" tdi,,should i at least check the head bolt torque? ive got 900 miles or so on it,,i know its a mls gasket that doesnt require retorque,but would it be a good idea to check it??i been gettin on it a little,,and ihave seen30 psi,,dont wanna "lift" a head,,ive blown enough of em on the old 1.6td,,ive got raceware head studs too,,not junk stock,seein good goost pressures,,but it doesnt need to stay  there long,,hittin like 90 on hiway on ramps,,gotta slow DOWN before entering hiway???hmm,this sucker runs,and imnot even revvin it over 35-3700 or so,,dont even need to rev it,not tryin to,but i dont think ive really had it over 4krpms,dont need to,,it pulls hard,,,,,, im sayin to myself"it wouldnt hurt to check retorque",,,anyone else wanna weigh in on this???

[hillfolk'r]

anyone??this is the part where i hear crickets and stuff,,,,,,,,,

[fspGTD]

My opinion: although not necessary (as the MLS gasket is not supposed to deform), it seems that it wouldn't hurt as long as you have conventional (non-synthetic) motor oil in there.

Reason: Raceware torque specs are for valid only for conventional motor oil lubricating the threads only.  If you run your engine on synthetic oil, some of it might work its way into the head stud/nut threads and due to it's sliperriness, make the torque read artificially low.  Randy Hubbard at Raceware can provide torque specs for synthetic oil thread lubrication on request, it is a lot lower than for conventional oil thread lubrication.

PS - What kind of racing are you doing?

[hillfolk'r]

im stillrunnin plain oil yet,,its only got about 1000miles on it,,maybe ill check it this weekend,,,,wanna tryit at the drags,,just to"see"power,keep it all mostly sleeper,street rice fighter,,,right now the suspension is all stock,,,sorta wanna build a decent dual purpose car out of it,,drag+autox,,  ,i stilllike corners verymuch have you seen that crazy 14mmpump head? :twisted:

[A2TD]

Running 30psi with a stock CR is asking to blow the motor. The motor in stock form was not designed to take that much presure. Just imagine what your peak cylinder pressure is @30psi................... :shock:

[vwmike]

I can't imagine it'd be much worse than the 26-28 psi I push into my tired old 1.6.

[A2TD]

I can't imagine it'd be much worse than the 26-28 psi I push into my tired old 1.6.

your probably not dumping a ton of fuel like he is, as well cylinder pressures in an IDI are alot softer than a TDI.

[vwmike]

your probably not dumping a ton of fuel like he is, as well cylinder pressures in an IDI are alot softer than a TDI.

Tell that to the Suburban that was behind me on the freeway ramp  :wink:

[A2TD]

your probably not dumping a ton of fuel like he is, as well cylinder pressures in an IDI are alot softer than a TDI.

Tell that to the Suburban that was behind me on the freeway ramp  :wink:

LOL, sounds like that turbo is  moving alot of heat.

[vwmike]

Yeah.... I need to get on that intercooler install.  

[nkb]

cylinder pressures in an IDI are alot softer than a TDI.

isn't the cr of a tdi 3 or 4 points lower than a idi like 19.5:1 ? 30psi is probably nothing for the tdi.

[hillfolk'r]

well i got 10k on it now,it still runs+didnt blowup ,like ya thought it would,and im still lettin it go closed wastegate,im pitchin that turdy turbo soon for my hy35 setup,the manifold is coming along ok right now,and my new 4 puck just came in today....
i romp the crap outta it every day,if it didnt blow by now it isnt gonna ...trust me
thats why i got away from the idi engines they can t handle that boost ,i popped 4 or 5 gaskets before i got tired of it   that non mls  headgasket (yea iknow convert it)and tryin to push all that fuel thru that little "whistle" ,thats a lot of heat in that head
im happy with my dollar per hp ratio,ya wanna go fast every day reliabily,ya gotta pay(approximately 5k,but this  hy turbo setup will probably be another 5-600 bux)

[vwmike]

I've heard a lot of people go on about how you don't want to run much boost on a TDI and if you do you should lower the compression ratio. However, I don't think I've ever seen conclusive proof of a failure due to boost/fuel. Can anyone point me to a thread somewhere?

[RabbitGTDguy]

You'd have to do some searching over on fred's...but there are a few instances.
Simon (MKII formerly 1z crazy TDI build from centralvwaudi.com) I guess spent a rod once because of too much boost/fuel. His setup was entirely different though. Larger valve depressions, T4 style TDI pistons from a Eurovan across the pond, etc.

Other failures do to boost/fuel have been more centered around the pistons mainly. Cracks starting much like the cracks in between the valves on IDI heads but forming on the lip of the piston around the combustion chamber "bowl" area. Alot of this though was even confined to earlier pistons from the 1z which are a bit weaker than the later style, AHU, ALH, etc. units.

I went the extra route for the insurance and lowered the CR so I can run whatever I'd like to with the car. Without touching squish volume, removing the lip from the pistons lowered it effectively and has reduced the hot spot on the pistons. I can't confirmed it, but if you ask Kerma over on the TDIclub forums there was some information and evidence showing that with some stock and even upgraded injectors that part of the spray pattern would "hit" the lip of the bowl causing the hot spot and the initial push for cracking.
Machined now...lower CR with the extra insurance of the TBC coating on the top with PC-9 puts me feeling more comfortable and the car still starts excellent and seems smoother in sound than other TDI's I've heard. Not a cure all...just a thought. As far as tuning these goes there isn't alot of "conclusive" stuff. We try, we share... suceed and fail. TDI major tuning and playing around on this side of the pond has only really taken off in the last 5 years or so IMO.
I'm confident in whatever fuel/boost combo I run now and probably can get away with even more advance on the pump if I want to... (just for now, its at 1.05) but I doubt with the robustness of the motors like has been said that 30psi for the TDI is anything to really look at. Its the beauty of the DI side of these motors.

Just my .02...

Joe

[vwmike]

While the modification to the combustion chamber bowls will lower compression a bit but if there is any significance to this modification I beleive that most of it's merit lands in the reduction of stress risers on the piston crown. Losing that hard edge could easily extend piston life in that regard.