More and more i think the crank journals don't line up perfectly from the factory.

How many of the rods are bent in the motor? What were the modifications on the car and how did the car blow? Did the customer have clutch vibrations for a while? The thing must have smoked like a chimney prior to blowing.

I am sure the customer will be able to tell you when the car started to act poorly and the events right before it.

3 bent rods, 1 broken. Car had a Cobb AP, Catless turboback exhaust, FMIC and some type of Corksport intake that puts a panel filter where the old TMIC used to go.

Our customer did not have any clutch vibrations that he has told me about. According to him there were no smoking or drive-ability issues before it blew. Unfortunately I was not there when it happened so I don't have any information to say otherwise.

what was the situation when it blew? wot or p-t boost?

lol wow this sounds all too familier. thanks again for you cooperation on this one verocious, it really means alot that we get support from you guys to try and figure this conundrum out

p-t = part throttle just incase it wasent clear




on another note i would highly suggest checking out verocious's site (Welcome to Verocious Motorsports - A Provider of High Performance Automotive Exhaust Components). they have pretty much every exhaust fab/silicone/anything u could ever need for a car project and i ordered all my EWG stuff from them (minus the wg itself which marky mark hooked me up with =D) and got it in one day. if your looking for a weird pipe bend in a crazy diameter or something they prob have it and their website has detailed dwg's of all the radius's and leg lengths and stuff. check it out.

Sorry about that, part throttle at 4000RPMs light acceleration (no boost).

Thanks Verocious, I would like to see the 3 bent rods along with their bearings and what cylinder they are from marked on them. Can you please send them my way? I will provide the address via PM.

You mentioned a CX7 motor - I assume that one has no issues?

No issues that I am aware of. I have not taken this one apart yet so I cannot verify that.

any updates on rod testing lex?

waiting to hear back from the company ... I presume once things get rolling after the holidays we'll hear something back.

awesome glad to see the ball is still rolling

Still very interested to see what they come up with, so hopefully I can fix the problem before I go boom

I had a chat with the company where I sent the rods. These guys make aftermarket rods for Euro cars and they said they are interested in making some for us but it's no a priority for them. Here are their comments on the stock rods we have.

This is of course nothing new. The rods are safe for the 300-350 ft lbs of torque at the wheels according to them given the tune is good and fuel is available. There is always going to be a variation in this due to manufacturing etc.

Torque and boost spike are generally bad and if the rotating assembly is offset it can also cause issues and bending.

Read below for details. As more information becomes available I will post ... and we'll see if I can get another vendor with products for our motors.

And we discussed the piston a little

A little on KR and hydrolock

And now about keeping things safe with a stock motor

In regards to making big power and the ECU

6 - 8 yrs eh?...I guess that makes all of us pioneers then eh...lol...(don't anyone start getting butt-hurt now!)

Thansk Lex for the most informative post on MSF of this week so far!

That's like 52 straight weeks... lol.

So according to this guy, KR isn't our enemy at all. It isn't even a footnote.

KR is a reaction of the ECU to knock. Knock will always be an issue. If you're right at the edge, an episode of severe knock can do some damage.

He is saying that modern ECUs react very quickly to knock to reduce possible damage. That doesn't mean it's a good thing to have it in the first place and KR should be used as a tuning tool and guideline.

Interesting. So for us ATR guys...pulling down load in the high torque areas of 3000-4500 can help save rods.

That's what I've been trying to preach. Take down the torque spike. Unfortunately the K04 is AWESOME at the torque spike and kinda shits the bed in the upper RPM. This is exactly what the guy is saying as well.

This is why I'm a fan of a larger turbo with a linear powerband and 300 ft lbs at redline. That would mean around 380whp and should make all stock block guys happy.

he mentioned something about getting more oil to keep the temps down, would that stop the rings from fuckin up? how could that get upgraded? just bigger oil squirters? i remember seeing pics of the piston rings and there was alot of buildi up on the hot side.

I'd love to see an idiot's guide to saving your rods with reasonable torque and good HP numbers using ATR.

Makes sense that i blew up.. 345 WTQ on a Mustang haha

First of all, use synthetic oil to reduce the ring buildup.

Secondly increasing oil squirter size messes with oil pressure and that messes with bearing wear. So it's not trivial. We all know heat is an issue with our motor and one of the simple ways of dealing with it is water injection. It's not an absolute necessity however, but as you increase boost levels and load on the stock bottom end it's something to think about.

Look at realgib's latest thread showing unprecedented boost control in lower rpms using the throttle plate. He showed it was even possible to limit boost below waste gate spring pressure.

I'm going to be retuning in the spring so I will see what I can do about it then.

I do that too to keep it at 18-19psi in the lower RPMs. It's a bit of a cockblock but gets the job done.

So if I read this information correctly

1) RR claiming you can make 400 whp at 6000 rpm's with 360 wtq at 5500 on a stock block with their turbo kit and AP-tune isn't that bad of an idea.

2) CPE claiming you need to upgrade the internals to achieve 400 whp at 6000 rpm's and 400 wtq at 3750 rpm with their flashes, tune and supporting mods is pretty true as well.

Curious but seems plausible now.

Thank you lex for your informative postings, appreciate it!

1. well, it's not like RR was tuning without any guidance from Cobb, so I think their tune would likely address some of the roadblocks that Cobb has encountered when they're tuning their Cobb MS3.

2. the ever resourceful CP-e would likely have experienced these road blocks as well...and with their capable in-house legal help, I'm sure they cared enough to include a disclaimer against stupid-boosting with stock internals at the power levels they can achieve with their flash.

Thanks Lex, thats definantly the most clear, concise, and informative breakdown of the engine Ive read

Should be mandatory reading for all MS3/6 owners!

Humm...seems like I should plan not to go over 21 PSI since I am already in the 350+ wtq zone...

Now that I got a FMIC, I can probably keep some additional area under the curve beyond 4500 RPMs though...

How many miles have you been at the 350 ft lbs zone and how "often" do you visit that zone during your driving?

Another important issue to remember is that if we are operating above the fatigue limit of the metal it will fail after a certain number of cycles.

oops haha

http://i135.photobucket.com/albums/q...1/sst_dyno.jpg




its ok all is well now, no more torque down low for meeeeeeeeee

That is a strange looking curve. Torque starts to drop after 4500RPM.

I have been at this level for ~8 k miles with several hundred pulls. I probably do 10-15 pulls a week through peak torque.


What I am hoping for at this point is that since some people have demonstrated 380+wtq on stock rods that 350wtq should be good for quite a few cycles. Of course the exact numbers are anyone's guess.

Lex, what is the formula of the relationship between load and cycles to fatigue failure? I seem to recall the number of cycles to failure had a log or exponential factor based upon load.

It is called the S-N curve, and this is a good read: No. 2260: When Metal Grows Tired

Like you've mentioned, there is no exact number. You can only rely on statistics and even then things get foggy because everyone's situation is slightly different.

Assume it takes about 10^7 cycles to reach a point where the metal has been cycled such that if you go above the threshold it will break.

The inconsistency is in the material make-up and how "good" the forging was that day. Parts start to fail at a molecular level that spreads until the rupture is inevitable.

So you can look at a failure in terms of long term stress or ... or as a single event that is above the threshold at that point. If you think of the rod as a spring (which it is) you don't want to pull or push on it such that it deforms. I'd like to be under that curve at all times :)

http://www.uh.edu/engines/sncurvesforsteels.jpg

yea i kno lol that was my fail tune. but peak torque wasent until 4k. as opposed to my near stock dyno where peak torque was like 2800rpm's haha

You know what would be a really interesting calculation - let's assume that you're at peak torque for 20 seconds a drive. So that's having fun, WOT, 20 seconds every time you take your car out.

Now, let's assume that the average RPM that you're at the peak torque is 5000 for simplicity ... and the rod is compression cycled every 2 revolutions.

How long will it take to be "sure" that you're under the curve?

Well 20sec/60sec*(5000/2) = 833

So let's round up and say that the rod sees 1000 compression cycles per drive at peak torque.

That means you will have to drive the car for 10^7/1000 = 10 000 drives.

If you drive it every day of the year like this, it will add up to 27 years.

Hmmm, something tells me NONE of us are under that curve with this car :)

LOL thats funny I did a very similar calculation but decided not to post it,
I cant remember the result now, it was a while ago when you posted the chart that I pulled my calculator out and typed as I calculated.
When I got to the end of the post the number I came up with was so large I decided not to post.

I want to say I came up with 27 hours of WOT at average rpm of 5000 rpm before you would know you were safe.
Or maybe it was 27 x 4 because each rod only gets power stressed once.

Like I said I forgot the result now, but it was a long time till you would know you were safe, and so I didnt even post it. LOL

EDIT:
Just for fun IIRC my calculation went like this:

Lets say peak torque hits at 3500 and you shift at 6500, that gives your average WOT of 5000 rpm.

From the chart Lex posted it looks like at 10^7 cycles you are safe, that is where all the metals in that chart "flat line"

10^7/5000 = 2000 minutes
33 hours.

But each rod is only power cycled once every 4 revs so

33 x 4 = 132 hours of WOT untill you can be reasonably sure you are safe.

Assuming peak torque at 4000 RPM, WOT, you'd need to be there for 83 hours :)

Truthfully, having worked in the industry, this test WAS actually done on the engine - many times - before it was released. It's not so bad on an engine dyno. I bet other things would melt off before the rods broke though.

Doesnt that indicate we must be waaay over the limit, for these rods to be snapping in so few WOT cycles.
OR
There is some other unusual event that is causing them to snap almost immediately.

I think being smart about modding = many years and miles of fun. Anything can blow, even a built engine.