Why our rods bend.

[DVST8R]

I already posted over at Tdi club, and since I pretty much suck at the internet and typing and doing all the quote things takes forever for me I will just link it. http://forums.tdiclub.com/showthread.php?p=1642132#post1642132  :wink:

[935racer]

True, but what makes the rod get to the stress point of bending? ---> Peak cylinder pressure, and usually an imbalance of that which is nicely demonstrated by the ***ty manifolds on these engines.

[RabbitJockey]

seems like it's not often discussed, but i see alot of tdis for sale that have a hole in the block.  do the tdis just like throwing rods or whats the dealio

[935racer]

seems like it's not often discussed, but i see alot of tdis for sale that have a hole in the block.  do the tdis just like throwing rods or whats the dealio

   
Timing belt failures seem to bend the rods quite often on the TDI's.

[andy2]

My AAZ with the stock intake manifold bent #2,3 conrods pretty badly and #4 was bent a little and #1 was fine this was mostly due to the stock intake manifold.However with the stock compression ratio and lots of fuel and boost they would'nt have held in there for much longer having a proper intake manifold.We made a better intake manifold,lowered the CR from 22:1 to 18:1 and put the strongest bolt-on rods we could find (BEW).All of these modifications should enable the AAZ with proper tuning,pump and turbo(s) to make over 200 hp.

[Kudagra]

usually an imbalance of that which is nicely demonstrated by the ***ty manifolds on these engines.

so when are you fixing this problem???


p.s.. Ill be able to afford to get a giles pump and pay for my clutch soon.

[935racer]

usually an imbalance of that which is nicely demonstrated by the ***ty manifolds on these engines.

so when are you fixing this problem???


p.s.. Ill be able to afford to get a giles pump and pay for my clutch soon.

Problem has been fixed :twisted:

[subsonic]

A picture is worth a thousand words. A picture of sweet new high speed manifolds might even be worth more..   Time to show and tell.....Please :wink:
Jim

[935racer]

Hmm I don't have any pics of completed intake or exhaust ones but here are some tacked up pics of a mk4-5 and mk1 fitting vnt20 exhaust manifold. I don't have a digital camera anymore so I have to get my friends to come over and take pics, lame I know, I need to get another camera.

[subsonic]

DVST8R,
I followed your link to the other side. Whats up with some of those replys you got?  There was a hint of dinkishness.  You say something about thier sisters on another web site? :lol:

[subsonic]

Jeez freakin looise,  that thar look's SWWWEEEEEEEEETTT :!:   :!:

Every time I see one of your post's I pull out my pencil and start crossing stuff off my list so I can figure out how to get it.
"New shoes? Naa, these Teva's are fine, the snow will melt soon.  I'm saving up for SPEED!!"

[jtanguay]

how much are these going to cost??? $$$$$$$$$$$$$$$$$$$$$$$$  i already need to buy a downpipe... i might need to rob a bank!!!

[Kudagra]

Yes...how much for the Intake/exhaust, downpipe combo???

That will fit in a MK2? Are they just t-3 flanges?

I know its been asked...but whats the best turbo to run with that in your opinion?? For a 70%driver 30%track car?

Im getting money soon that is earmarked for the Jetta. I decided to forego the TIG and just buy parts to get the Jetta running.

[SMOKEYDUB]

i Woild love to pick up a gorgeous intake manifold to fit a 1.9 :twisted:



F@#k I CANT WAIT AHHHHHHHHHHHHHHHHHHHHHHHHH


Jeff

[Dr. Diesel]

This flow imbalance, is it suspected, or actually measured? If there is an imbalance, just how big could it be? These are pressurized, low rpm engines after all...


Why would one cylinder's rod care about what another cylinder's rod is doing? I'm not sure I see how an imbalance in cylinder filling would have anything to do with rods bending. Except that maybe if there is a big difference, with equal filling you'll bend all the rods instead of just some of them.


So have we decided that PD rods are in fact forged steel, and not that PM material?

An easy, common trick for improving rod strength is shot peening. It case hardens the rods. Some of the more shifty-eyed shops have shot peening machines which are more like bead-blast cabinets. These aren't the real deal. Proper (aircraft approved) shot peening requires a very specific stream angle, (to the surface) velocity and shot size to achieve the desired effect. I've been told that there is a measurable difference between the results produced by new and used shot. A rod that has been shot peened looks very different than a stock rod. A smooth, uniform surface. Quite attractive, actually.

Cryogenic hardening is another option. I believe this method draws the material's molecules into a tighter, more crystaline structure, throughout the material, and not just the outer layers like shot peening.

Perhaps you could combine the two after polishing and balancing a set of rods. Cryo harden, then shot peen. So the rod is stronger and case hardened.
I suppose there might be a point where a rod might become brittle if hardened too much. I have no idea whether combining these processes would approach this point.