Offset race rods on WBX?

[fastback]

I tore down my WBX engine last weekend (due to some failure...)
when pulling the wrist pin i noticed all piston "bore" for the wrist pin had burr's outside the clip's.
so there has been some axial forces on the wristpin clips by the wrispin.
the engine is a 82mm DPR counterweight WBX crank with pauter rod's (working range 4500-8200 RPM
these rod's are NOT offset as the stock rods are .
I need new rods now and should they be offset like the stock ones?

quote Gene Berg:
"Internal snap rings always hold the wrist pin in the piston unless one or more of these problems exist:

1. Bent rod.

2. Case line bored out of parallel to the spigot holes, which is very common with the present rebuild type of line bore equipment.

3. Crank flexing or bending in the middle, pushing the rod sideways with every up and down motion. Travelling down, it pushes the pin forward in the hole; up pushes it the other way. This almost always happens with cast cranks, non-counterweighted cranks and even a high HP engine with a cheap forged crank. This problem was solved with the properly counterweighted and new forged Berg crankshafts over 18 years ago. No other company’s crank meets this rigidity.

4. Endplay too loose, allows the crank to move back and forth too much. This moves rods back and forth, putting end thrust on the wrist pins, and also causes the brass distributor drive gear to wear prematurely.

Common sense should tell us that any one or combination of the above engine problems can cause the keepers to burr up the piston or come out of the piston."

[Piledriver]

The ~650 CHP bus motor?
I would make a WAG that it could be crank flex, something would be expected to have to give a little at those power levels.
We really only have 3 real main bearings

Running all T4 mains? Should help.
That or locate a Berg/Alfing/Oettinger/Okrasa crank.

Mains look OK?

[Steve Arndt]

Marty builds his higher power engines with big wrist pins. The pin would then have a larger bearing area in the boss. I think he uses 0.9 inch or some such size. Pauter uses this larger size also.

[Steve Arndt]

I do agree though, a stiffer crank may be in order. DPR can weld all the journals to T4 size. The full circle option may help as well.

[buildabiggerboxer]

Hi fasty, the stock offset is only very small, 2.5 mm springs to mind, 10c will yea or nea, i dont think its that causing it, i just had a mare with wisecos on an air cooled T1 burred up like yours, their pins fit tight between the circlips so you cant push the pin back a few mm to deburr the hole, 4 hrs getting the pins and clips out!!
is it both sides of the piston? Steve mentioned big pins, ours are stock 24mm wrist pins yes ?
my Okrasa 82mm came with thicker wall 24mm pins,,,,i did wonder why as they are heavy?
rod journal side clearance ok? crank should be ok at 82mm. i only go 7500 with 76mm stockers.
what about the under piston pin bosses side clearance on the con rod eye?

[Steve Arndt]

My Wiseco 22mm pin super squishes are also hard to get the clips out of after use. That was original clips anyway. I tried the heavy duty clips from aircooled.net on rebuild so hopefully they come out nicer.

[fastback]

yeah the "571HP@wheels or 620'ish engine HP " engine took a hell of a beating last trackday

I was participating in a Race and here you can see some video by the car i was having a battle with (race rigged 944 turbo 350 hp)

the statement in the header is not mine but the owner of the video

[fastback]

the type 4 mains is a good tip with the full circle.!
I'll check it with Jose.
I asume the center main is most crusual to get up to type 4 size.
My pauter rods were WBX spec's with the 24mm pins.
The center main bearing had some marks , but this can be from some issues with my drysump system earlier in the season (low oil pressure during cornering ; now fixed)

[Piledriver]

Better to burn out than fade away...

Full circle cranks may reduce windage, but that's about it.
The main advantage they have is they add mass to alter the resonance (as any CW setup does on a boxer crank), but VW already did that on the wasser cranks.

Basically (from memory) the case gets ~BMW or Dodge 2.2/2.4 main shells (steel, like wide rod bearings) in a more or less std T1 case for center and front.

Since we only have 3 real main bearings, all @T4 would probably be the stiffest combination.
Some have even gone larger.

(the T1/T4/WBX snout/pulley end bearing is same as T1, just for any readers who don't know)

I would bet money that it's some combination of crank and/or pin flex at that power level.
...part of the reason I specd'd 24mm pins on my 103mm JEs for my Nickies, also happened to match the 3 crank/rod setups I have on hand I could use them with. Note the Volvo redblocks also run 24mm pins, as do 944s etc.

Running at 150+ HP/hole will break stuff.
Perhaps consider a harder 4K forged alloy for the pistons?
Less wear/distortion, but won't take quite as much abuse.

[syncrogreg]

Fastback, just out of intrest, what went bang? I love the carnage pics, especially when they don't hurt my wallet!

[andy198712]

yeah the "571HP@wheels or 620'ish engine HP " engine took a hell of a beating last trackday

I was participating in a Race and here you can see some video by the car i was having a battle with (race rigged 944 turbo 350 hp)

the statement in the header is not mine but the owner of the video

That thing is ridiculous! the way it pulled away at the end was mental!
shame about the fireworks but best of luck with the rebuild

[fastback]

thx all!
here's some pic's of the result

IMG_20121013_170141 (Small).jpg

IMG_20121013_213549 (Small).jpg

IMG_20121013_230017 (Small).jpg

[fastback]

a few more

IMG_20121013_230201 (Small).jpg

IMG_20121015_155458 (Small).jpg

IMG_20121013_195624 (Small).jpg

[fastback]

head

IMG_20121013_225948 (Small).jpg

[Piledriver]

Hydro lock ?
(may be hard to tell what went first)