NefMoto

Yes I know of the "300lbft limit"

But I'm wondering how many of these rod failures have occurred on tunes with a raised rev limiter?

I see the other day on the internet a 1.8t blew a rod on a dyno with less than 300lbft, was believed that the rod kinked at high rpm on a run before going by strange graph reading, the rod then failed on the after run in which it failed and exit'd the engine.

Guess I'm speculating that raised limiters could be half the issue.

But how can you inspect a rod for compression or tensile failure? As normally the rod is destroyed quite badly.

 

http://www.eng-tips.com/viewthread.cfm?qid=333643

I folded a rod on my 1.8t this spring.  My rev limiter was not raised.  My tune kept torque at a "safe" level until after 4,500 to try avoid conrod failure.  I ran this way for a few years and it finally decided to give up one day.
My take, if you are running around 300ft/lbs with stock rods, it's just a matter of time until failure ensues.

Possible to get details on your hardware?

You bet.

550 ev14 injectors,
larger than stock maf,
Full 3" exhaust with high flow cat,
F21 mixed flow Frankenturbo
WMI injection,
larger SMIC

and slammed on racelands bro! (jk)

Now it's all that with the addition of a built bottom end.

I even have logs from that day just before the catastrophic failure showing how it was running very well.. next to no timing pull, no boost overshoot, steady 20-21 psi... etc.   IMO you roll the dice every time you stomp the pedal if you are close to 300 ft/lbs.

Thanks for the details. Funny story. I had a guy ingest water once, we purged the cylinders of the water, and he drove it like that for 50k until he brought it back to do rods. When we removed the rods we noticed every rod was bent (a nice soft radius noticeable to the naked eye). Guy said he didn't notice anything strange.  :)

I bet the lowered compression allowed it to make a ton of timing!

Yea, I tell everyone the same... Oh you want to upgrade the turbo buy rods, you do want to buy rods
keep the stock turbo. I dont like piddle paddling around a limit trying to guess what wont explode.

Anyone can tell me if I have k04-023 stock turbo then if I have boost 1.3 bar - 4500 RPM and 1 bar -6000 RPM my rod were driven near limit? or it is safe?

I've been doing this the past 6 months on 180 bhp rods, and none of them have tried to escape (yet)
But it all depends on engine health :)

my beetle s line was on a k04-023xl 26-27 psi spike hold 20 psi to redline on e85 and it lasted 2 years like that

Engine health does not beat metallurgy.

True, but if engine have been beaten on and have damaged bearings and contact surfaces.
The risk is even higher :)

Want to know why rods bend?

Answer: DETONATION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I'd bet my life that the vast majority of unexpected rod failures are always preceded by detonation. It's probably imperceptible in many cases, but I can promise that it occurs just before a rod lets go.

So long as you don't detonate, I think that you can probably exceed the 300 ft/lb limit for quite some time without damaging the engine. However, if you're right on the ragged edge and start detonating at peak load, your stock rods are gonna let go unexpectedly.

I think it makes a very good case for water/meth on any stressed stock rod setup. But that's just my opinion... 

Ok so I must say my car isn't stressed because I have stock k04-023 turbo and 250HP so I can't reach 300 ft/lb.
My rod bend in normal drive low load and RPM and I logged CF for see does I have detonation and for all RPM's I have 0CF for all 4 cylinders (I use stock ignition map).

You know, everyone is referring to rod life in time, when that really has nothing to do with it. How the hell are we supposed to know how the engine was driven/ treated during that time? Even stating in miles (which is a little better but still) tells not much. I know people with very fast cars that rarely push them at all, and people with no so fast cars beat the living shit to redline 30 times a day every day. My point, saying "it's been fine for xxx amount of time" doesn't mean shit.

Also, the car does not have to det in order to rip rod. Last guy I saw drove super cautious, and said engine stopped when he was light throttle doing 20 mph. We didn't build/ tune it so I have no idea what was on there, or how it was daily driven. It was a 3071-ish turbo on a stock engine I believe. It's a stress vs. time/cycle thing. Once it's had enough it could probably break @ idle. You'd have to be pretty lucky (unlucky?) for time to run out when you're at idle. :)

there is a kid local to me that WAS all about the small frame turbos, he and his buddy swapped a k04-015 (real one) on his 01 b5 a4. the car  was mail order tuned by eurocrustums and semt a rod threw the block on 2 diffrent engines in about 3 months. After that i he contacted me asked my opinion nd i recommended a 30/71 ar .82. After upgraded fuel pump, injectors and turbo install its going on 2 years stock bottom at 20 psi and nothing is hanging out yet.
on one of my project car i had a K04-023xl from china on 27lbs e85 and stock rods. I changed my oil every 2000 miles and knowing id make peak tq at 3k id always wait to over 3000rpm before id floor it. drove that car evreyday redline the shit out of it. huge second gear burn outs, high speed sprints of 160mph+ and it never launched a rod.
I guess what im trying to say is if you keep good fresh oil in the car and work around the weakness you can have a degree if success with the stock rods
 

The faster the crank turns the more inertia it carries with it in the same direction as the rods on the combustion stroke, which in turn takes stress off the rods. The slower the crank is turning the more it stresses the rods because of a lack of inertia. Predetonation is a huge part of why a lot of rods fail. Every time it knocks it strains the rod more than usual and therefor they start bending. The more the rod is bent the easier it is to bend and then snap. A larger turbo not only helps with a later peak torque but also should blow cooler air than a k04 at it's max limit. The engine/turbo will work less to make more boost and therefor run more efficiently. Cooler air = less knock.

Bearing damage from detonation, bearing clearances becoming huge and thus gaining massive oil whip aswell

brotella

I've got nothing to add except to say the brotella might be a new thing.

The rods fail when the normally aspirated ring gaps on these engines close up and grab the block a little. When this startes to happen the rods cannot take the extra pressure. Keep the EGTs down and even across all cyls and you will be able to push much farther. As soon as I get my 2l built, I am going to pull the head off and open up the ring gap to see what these rods will actually take.

Nope.

Somebody watched engine masters on youtube... you will fail. The rods bend if what your saying was the problem they would most
likey rip the wrist pin out of the piston.

So are you saying you've logged EVERY WOT pull you've ever done and noted no timing correction?

My point is, that it can take only one batch of successive detonations, either from bad fuel, oil in your intake from a bad PCV valve, a hot spot from carbon buildup, etc... which can occur without you ever knowing.

Then, the rod and piston are compromised and BOOM, they end up blowing up a day or two later while you're just driving down the road...

Running at component limits is always a lottery... why is anyone surprised if an OEM rod goes?

I've been running a F21 now from 122k to 181k miles, learned and experimented tuning on this motor with no ME7 experience. I nearly blew it up on the first few days due to boost spike from the Frankenturbo's high wastegate setting. After loading the car on the dyno and putting down 344awtq and 309awhp on the quattro/tiptronic at around 3.5k I decided to lower my LDRXN to:
107.42;121.03;127.83;138.05;144.85;151.64;155.07;182.28;189.99;189.99;183.99;177.17;172.06;172.06;172.06;172.06
which put it down into a "safe" zone around 17.5psi I believe, but especially with the horrid automatic trans hardly being able to hang on to the gears while shifting it needed to be set this low. This results in 276 g/s on E85.

Can some of you rod tossers please post your turbo and boost data so we can compare?

Mods here include all the usual junk incl 2.5" pipe large core FMIC, larger EV14s, Franken TIP, ebay DVs, 90mm ebay MAF tuned via MLHFM/KFKHFM, straight pipe 2.5" decat dump exhaust, bosch gauges and 24/7 logging from day 1.

Thanks

I believe your MAF is overscaled.  These things will put out 235 g/s on their very best day.

the new ones with the bilet wheel flow more

...which is what I have. :)  375 g/s is quite optimistic.

What dyno was this on? I can't see those numbers on 1.) AWD power 2.) tiptronic. 3.) That turbo

Maybe E85?

f21? 1.8t? 380lbs crank atleast? i need your info you can just do all my tunes\

These rods fail from rings butting and grabbing the wall, this adds just enough more pressure at high EGTs to fold the rods right up. The rings were gapped this way to meet emissions. The evoX 4b11 has the same issue, and ironically they have the same Mahle pistons and the same ring gap factor. If you keep EGTs down you can go much farther. If you do decide to do drop in rods, use the Mahle specs instead of the foolish VW/Audi ones. Page 21.....   http://www.mahle-aftermarket.com/media/local-media-north-america/pdfs-&-thumbnails/catalogs-and-literature/pistons-and-rings/pr-40-16.pdf

These rods fail from rings butting and grabbing the wall, this adds just enough more pressure at high EGTs to fold the rods right up. The rings were gapped this way to meet emissions. The evoX 4b11 has the same issue, and ironically they have the same Mahle pistons and the same ring gap factor. If you keep EGTs down you can go much farther. If you do decide to do drop in rods, use the Mahle specs instead of the foolish VW/Audi ones. Page 21.....   http://www.mahle-aftermarket.com/media/local-media-north-america/pdfs-&-thumbnails/catalogs-and-literature/pistons-and-rings/pr-40-16.pdf