I wish this was my full time job :)

Tension is usually the strongest force on a rod out of all the different cycles.

When its the compression stroke, the exploding combustion helps slow the piston head down and change direction. This takes the load off the road quite a bit.

When it's the intake stroke though, and there's no explosion, That's when the rod alone has to bear the entire force of reversing the piston direction from up to down. This is probably also why our rods let go during shifts, but i'm still confused why it's always low rpm shifts, not high rpm WOT shifts.

I bet i can break one of these rods using my knee, that's how week
they look to me.
Still curious to see the results though, the rods still look cast to me.

The rods break after they have already been bent or twisted. Because they are forged, they are more prone to deforming before outright breaking when overloaded. Once they deform, it doesn't take much for them to further deform or for the piston to snag in the bore regardless of RPM.

It happens during shifts because there is a momentum change and because the crank is moved through the application/release of the clutch further offsetting how forces are applied to the rod. Our rods contact the crank counterweights on either side of the big end.

updates?

I will post them when they are available. In the meantime keep the torque and fueling in check and the shiny side up!

Lex, did you ever get an AP and if so, can you share your map if you made one? With all the knowledge you have shared, I would just like to compare that to the changes you would of made in ATR.

I do have an AP and have great results with it - I can of course share my map and results but I believe most people here wouldn't want to run the settings I am.

This should be in a different thread however.

Thanks :biglaugh:

updates?

Got a little sidetracked on this. I will update when I find something.

In the meantime, I honestly don't think these destructive tests will tells us something we didn't already know.

i think it will personally. i think our rods are much stronger then originally thought

Here's food for thought. Out of the stock rods I have, some are definitely stronger built than others. One is actually a 0.5 mm thicker down the entire shaft with much smoother surface finish. That makes quite a difference.

DJuosteisn i see you viewing this thread go to shoutbox asap

lol, woops. I guess send me a pm if you need.

Now thats a huge deal for more than a few reasons, what is the weight difference between them?

That is not good at all.

Has there been a correlation with build dates and failures? I remember the russians mentioning that they only had rod issues on earlier builds, but not in quite a while. I'll try to find the quote.

Here's one reference to a change in design. This was in regards to whether or not they were having rod issues.

The beefier rod came out of an 07. I have seen 08.5 rods that are back to not being "beefy"

The MS3 and MS6 rods are serialized differently (early versus later builds). The MS6 rods have a 3d bar bode on them probably used for matching weights of rods in each motor.

The MS3 rods only have number/letter markings. I am not sure how to read these serialized numbers but it can be that they are incremental.

I can grab the weight of the rods 06speed6 but I am inclined to think that the rods are matched by weight in a particular engine.

Its too bad that we cant get all 4 rods from an engine.

Regardless, bigger and smaller rods are a big deal...

I wonder if we could get the guys that have had blown engines to weigh their rods in grams and see if its the lighter rods that are breaking.

Generally, production line engines are only static-balanced, matched by weight, some not even that. A GM Malibu V6 likely isn't checked for balance at all, because the engine is mass-produced for low rpm and light loads, typically so, why balance the engine parts to the gram?

Weight is only one factor in strength. Forging tends to produce normalised metal density over the rod more easily than casting, which can be good but, heavier doesn't always mean stronger. The change in reciprocating mass makes a heavier rod put more strain on the rotating assembly than a lighter rod.

Aside from the above, you have the hardening issues that come with forging, since the surface is a machined one, there is often little strengthening of the surface steel through quenching or hammering. This massively affects the potential strength of the rod. Aligning and compressing the grain structure of the steel through work can make a light rod immensely strong. I can't say if these are factors here as I'd need to closely examine the rod and have deep insight into the manufacturing process.

Considering that these rods probably had the same or similar manufacturing processes, I would say weight is a direct indication of strength.

I hope you're not missing my obvious point that a heavier rod NEEDS to be stronger to withstand the added force of it's own increased mass in reciprocation. You can make a lighter rod less strong and be totally fine, due to the decreased recip mass. It's really just a touch more complicated than "heavier = stronger".

do u design engines?

My understanding is that added beef in a non high rpm setup, with the same piston weight, with the same stroke, and with the same metalurgy, will always yield a stronger rod.

Obviously in a cart engine like you are talking about that doesnt apply.

Here is what I mean.

This rod is the "beefy" one.

http://www.mazdaspeedforums.org/foru...g-dsc_0104.jpg

This rod is like all the other ones I have measured (5 others) and it is 0.5mm thinner throughout its entire construction.

http://www.mazdaspeedforums.org/foru...g-dsc_0105.jpg

pull that shit a part lex. i want to know what they can handle

I cant really tell much from those pics except that they appear to have the same finish.

They CAN'T handle detonation. They CAN'T handle boost spikes, low fuel pressure, FFS, uneven meth distribution (the freeze plug idea is terrible), too much timing, too much heat, low oiling.

I can't think of any cars (that were not freak accidents) that have died at anything else but the hands of detonation.

Big pics for full detail

Exhitbit #1. This is what happens when you run meth in the centre of the IM. It only gets to cylinders 2, 3. In this picture you see cylinder 4 which got no meth which has a bent rod (notice the offset spray pattern from the injector on the piston). The piston next to it got all the meth and that's why it's so clean.

http://www.mazdaspeedforums.org/foru...g-dsc_0029.jpg

Exhibit #2. This is the same motor, cylinder #1 that blew. It had a bent rod for a while and it finally broke loose. Cylinder #1 also got little of the meth share.

http://www.mazdaspeedforums.org/foru...g-dsc_0059.jpg

This car was using FFS and experimenting with leaner A/F ratios using meth - except that poor #1, and #4 were not seeing much meth at all!

Pointing out difference in shaft width. Look at the calipers. They are opened and locked the same amount in both pictures.

lex is spraying meth in the intercooler pipe right before the throttle body the best?

Unless you do each runner yes, spray it where the full airstream can come into contact with it.

awesome pics!

yeah that freeze plug idea was terrible i cant believe so many liked the idea.

and yes 18psi thats probably the best idea other than one in each runner etc. if you have the nozzle far enough away from the IM then it should have time to mix pretty evenly thruout the air

Great pics lex, worth the wait for the page to load, lol. Also good info as well.

More food for thought:

From SAE international:

It was found that methanol fuel is more susceptible to pre-ignition compared to gasoline fuel ... Platinum tipped spark plugs were found to be highly susceptible to pre-ignition with methanol fuel.

Pre-ignition and detonation tendency increase with the increase of engine load, compression ratio, inlet air temperature, advancing the ignition timing and lowering the engine speed

The discrepancies in size between the rods is most likely because of the forging process not everything will come out the exact same when forging.

Link to document?

If i recall correctly, methanol has a much higher autoignition temp than gasoline so I would expect it to be less prone under similar circumstances.

bahahah... Im not even going to say anything.

You are correct, gasoline has an autoignition temperature of 280 C whereas methyl alcohol has a temperature of 365 C. There is more to it than this however. I would suspect this to really become an issue when a large percentage of the fueling is done by methanol.

The abstract states:

Here is the link to the paper: Pre-Ignition Phemomena of Methanol Fuel (M85) By the Post-Ignition Technique

I just want to say I appreciate the info shared on the thread.

Here's something else to avoid. This car blew as it was being loaded (foot to floor) from a low RPM. Bent rod but not through the block. It happened right as KR hit 6.0.

http://i47.photobucket.com/albums/f1...2746/boom2.jpg