The ultimate 1.5TD

[VWSmokr]

Hope that's OK, because that's the exact process done to the new 1.6 pistons going into my modded 1.5 block. The machine shop said everything balanced out fine (they mostly build high-revving race VW gasser engines and had never been asked to balance a diesel before!). Oil pump is a later (higher volume) unit listed for Euro-Audi w. hydraulic followers, so it should easily keep up with any extra oil the piston squirters might consume.

Of course I'll thermal coat & polish the (non-TD) piston crowns before assembly; still thinking about doing the anti-friction moly-coating on the piston surfaces & cylinder walls. I have confidence that the Raceware 11mm head studs will do the clamping.

My question in keeping with the broad range of the topic of 1.5L-building, concerns the rod bolts. While the rods have been (by the same performance-oriented machine shop) checked, found to be straight/re-usable, re-bushed/sized, should the rods get new bolts. Is it really worth going to ARP's or Raceware's rod bolts/studs on an engine that is not going racing (given that its fuel efficiency & longevity are of higher priority than raw power), will be intercooled, likely not be pushed beyond 10-12 boost, but may be called on to do some light trailer towing?

TIA, gurus

[jtanguay]

Is it really worth going to ARP's or Raceware's rod bolts/studs on an engine that is not going racing (given that its fuel efficiency & longevity are of higher priority than raw power), will be intercooled, likely not be pushed beyond 10-12 boost, but may be called on to do some light trailer towing?

TIA, gurus

i think some of the older vw engines had re-usable bolts, but the newer ones definitely have stretch bolts.  using the studs will reduce power robbing 'flex', and give you the added peace of mind of knowing it will last.

[MJF]

Doesn´t 1,5 crank have smaller con rod journals than 1,6/1,9?

no, all the journals are 50.6mm according to someones bently manual. im pretty sure i got those measurements from sauerkraut. so basically, all IDI diesels, and i know atleast the first TDi's had rods that were interchangeable with AAZ rods. so they must be 50.6mm also.

Ok, I had to check from book Klik

[saurkraut]

why cant you notch the pistons for the jets? i know of some machine shops that ive spoke with that use 1.6 n/a pistons and just notch them for turbo motors. i seriously think we could notch them and not worry about it. there isnt much load or stress down by the piston skirt. thats where they file off material when balancing them.. so why cant we take a little more off and have ourselves a notch? i think i would take the chance of notching some 1.5 pistons.

Here's a couple of pictures of the oil jet notch in the 1.6TD piston:





As you can see, the notch is reinforced.  It also appears that there is a steel plate just below the notch.


You might get away with notching the 1.5 pistons, but I'm going with the turbo pistons.   Heck, I'm even nervious about pulling .063" off of the crown. :shock:

As far as the piston skirt being a low stess area, I don't know If I'd hang my hat on that.  What I've seen in raceing two stroke engines, good forged Austrian made Elko pistons would develope stress cracks in the skirts directly in line with the piston pin boses.  Right where the oil notch is in the 1.6TD pistons.

Also, I can't pass up the opportunity to use the long 1.9 rods with the short stroke 1.5 crank.  

Just because some machine shops would do it doesn't hold water either. Some of the stuff I've seen them do would curl your hair.  Like some won't measure piston protrusion and will toss in a three hole head gasket and call it a day.

[Rabbit on Roids]

you got it right tho. 2 STROKES!! they turn twice, maybe 3 times what we are going to be turning ours. and they dont have nearly the skirt depth that we do. i think vw pistons are really long for how big they really are. long skirts keep the piston more stable in the bore. less of a chance for piston slap.

as fo me, im going to notch 1.5 pistons and wind the piss out of it.  :twisted:

[MRDART]

I must agree with saurkraut on the piston modding issue...
 During my racing days I have seen plenty of cracked piston skirts although on higher reving engines but the last ones was "only" revving just pass 6000 rpm. Anyway after 10 hours you would see cracks  going straight down on the skirt. This was a 2 stroker 1 cylinder 650 cc  used for sidecarmotocross.
 The normal changing interval was 10 hrs.
 So I would be very careful to not make any sharp edges or even scratch marks on the skirts.
 But as I say this is just my opinion...

[Rabbit on Roids]

ok, well you guys have good points. but that doesnt even come close to swaying me not to notch some pistons. i know its been done. and i know it works. this isnt a hair brained idea i thought up, i heard this straight out of a machinists mouth. he used to rebuild lots of VW diesels. i asked him about a new set of pistons for my td motor and he said he uses n/a pistons and just notches them. cut a n/a piston in half.. i bet anything there is steel in those pistons too, just not visible. why is a simple notch going to cause piston failure? honda CRF450R dirtbikes dont even have any damn piston skirts. there piston is just over an inch tall. and thats from the bottom of the skirt to the top of the crown. and there is hardly any material in there. i know theres no steel reinforcements either. and those engines turn 14,000 rpms. and yes.. they are a 4 stroke. i think you guys are just too cautious. maybe ill build a 1.5/1.6 out of a n/a block first. just to make sure things go alright. and i would still notch the pistons just to see if anything happens. then atleast if i break a piston, its not a good one, and its not gonna be my turbo block either. basically an experimental engine. but i have spoken my piece. and im still going to notch my pistons. you wont need nearly as deep of a notch on a 1.5 piston either. lots less stroke.