Cracks on PD block

[mgbiker]

Hi Guys,
Have anybody experienced the cracks on the block between head bolt hole and water channel on 1.9 TDI PD ARL ? My engine has 400+ps.
My last 2 engine last only couple races and got a blown gasket/ head lift because of these cracks probably - using ARP studs.
I would like to prevent it in my next engine hopefully by upgrafing cooling.
Thanks for any advise.https://ibb.co/zhQxFdM

 

[Mongler98]

then stop using ARP studs. they cause the cracking.
unless your block was bored and honed with a pressure plate with the ARP's inplace, you will damage the block every time.

 

[Booxter]

what is the solution to this problem ?do you have a photo of this plate ?

 

[Rgroves231]

then stop using ARP studs. they cause the cracking.
unless your block was bored and honed with a pressure plate with the ARP's inplace, you will damage the block every time.

Does this also apply to VE ALH?

 

[Mongler98]

Does this also apply to VE ALH?

yes, and basically all TDI and non TDI engines.

 

[p0wer]

Could there be wrong torque on nuts or has studs been tightened into bottom of block thread? Never had or heard these issues with VE blocks.

 

[Mongler98]

Could there be wrong torque on nuts or has studs been tightened into bottom of block thread? Never had or heard these issues with VE blocks.

No. The issue is not with torque. It's that the arps do not give the OEM bolts give a little stretch
Basically your warping the block. Only reason people have minor success with them is on a hail Mary attempt to fix a headgasket without removing the head. 9/10 times the head is already warpped and the engine so far worn that you typically get away with it for a while if your lucky.
Nothing at all wrong with OEM bolts. Only reason to use arp is for extreem conditions or you need to change out things internally very often. Bolts are cheap

 

[mgbiker]

Well I would say over 400 hp is a bit extreme condition but I did not get your point why the ARP bolts are warping the block. Do you mean the OEM bolts will strech and the ARP bolts does not strech - thats why ?

 

[Mongler98]

Well I would say over 400 hp is a bit extreme condition but I did not get your point why the ARP bolts are warping the block. Do you mean the OEM bolts will strech and the ARP bolts does not strech - thats why ?

I must have said this 100's of times...

There are actually some negative results possible. 1) On some of the older blocks, the middle boss is built smaller... that would be all the AHU's and the ALH engines through about 2001. The center boss on the manifold side can crack, ruining your block. DO NOT exceed 125 ft lbs torque... 2) The next issue is that the increased pull further distorts the block. When we are boring any of the TDI blocks, we use a torque plate and have two different torque settings if you are using stock head bolts or ARP studs. The reason is, the block distorts at the location of the bolt hole and pushes the cylinder wall IN toward the piston. At the same time, the point between the bolt holes swells OUT. So, when honing the block, the torque plate holds the block in the position that it will be as if the cylinder head were attached. The distortion is greater with the ARP's, so we torque the plate accordingly for the intended bolt.

Why is this important? The extra loading of the ARP's, replacing a stock head bolt will make the head distort, allowing for the clearances between the cylinder wall and the piston to the point of WEAR LIMIT... .003". And an engine that was not previously burning oil with stock head bolts, is now burning oil.

Unless the engine is built with the intent to use ARP's, it is not our recommendation to use them. I suppose you can reduce the torque value to compensate for the distortion, but that eliminates any reason to have ARP head studs.

 

[Mongler98]

also if your pushing a VE to 400 HP and you do not have the build done properly, any one item can become the weak link. cracking blocks or heads could be from MANY other reasons like crank stress with out a girdle plate, bad casting, so on and so forth. im not an expert, im just regurgitating my mistakes and lessons i have learned and read here. best to get a professionals advice like Frank or perhaps your builder or tuner that you use locally? or is this a DIY garage built engine?

 

[mgbiker]

I have the PD ARL engine with all the proper mods for 400 hp. New block is already bored to 81.5mm, honed and resurfaced, prepared to built up. I'm building these engines almost for 10 years and using ARP studs for 5 years. the previous block did last for 3 drag racing seaseons and over 20k km. the last one cracked after 2 races and 5000km. Is there any picture showing how the torque plate is used?

 

[Franko6]

Torque plates in many shops are a standard for racing application, with the only trick being the amount of torque you expect to apply to the block. We use ARP studs and spacers with our torque plate to imitate the deformity that happens under the stress of head bolt torque. BTW: 81.5mm pistons and the reduced distance between cylinder bores is not worth the small gain you get in CC's. We see these 'to the limit' engines built and my only advice is to stock up on blocks. You are going to need them.

Also, find no justification to using more than the recommended torque for ARP's. The block's center rear boss just can't take it. Over-torqued, the studs just break the block. Anyone want to tongue and groove a cylinder head/ block? Go headgasket-less. Like the Royal Enfield's I learned to love.

If there is any salvation, I think redirecting coolant to the most heat-prone failure areas could help. The fact we are working with a lot of heat out the manifold side and radical cooling/ heating cycles is not conducive to life expectancy. As for our desire to engineer the proper cooling to make that happen... not on my watch. I've already got too many R & D crazy projects that include engine SURVIVABILITY.

All that aside, just have a big bankroll. There were a lot of engines we built that were good for just one pass. It's fun till the money runs out.

 

[turbocharged798]

From the issues that I have seen I used 12.9 allen head bolts from mcmaster on my ALH build rather than ARPs. Worked fantastic.

 

[mgbiker]

I saw the recomended torque for ARP studs is 125ftlb which equals to 170NM. I did 160NM this time, in 4 steps, so hopefully it will help a bit no to crack the block again.

 

[[486]]

huh odd, mine are in there at 150 ft/lb
no torque plate hone because the threaded bosses in the block casting are siamesed to the water jacket not the cylinder wall
nothing like a 400ci gen1 small block where the head bolt is inside the cylinder wall