Greetings, working on my 2.9 stroker M50 swap.

[matt]

Having read most of this thread, I think it a shame that two of the most knowlegable guys I have ever seen having a discussion on this topic need to fight about it.

Mike and I aren't fighting...

[StereoInstaller1]

Having read most of this thread, I think it a shame that two of the most knowlegable guys I have ever seen having a discussion on this topic need to fight about it.

Ultimately, I bet we find the both of you in near total agreement...but pissed off nonetheless.

Would you two please find some way to discuss this gracefully? I would really like to know more about your topic, but less about the asshole either of you can be.

Luke

[SchnellerVert]

Give it a rest guys. When it's built lets see your numbers, otherwise this will be a pissing match to you meet in person.

[techno550]

Fine the sleeves that are currently in it, you ass.

Right, the sleeves. of course. my bad. I thought you knew what you were talking about and I was trying to be helpful.

This is still about 2k cheaper than a rebuilt S50 could be purchased.

why rebuilt? A moderately freshened S50 is cheap, and even then the freshening is optional in most cases. If the engine had 200k or less, the leakdown was OK, and the bearings looked good, I wouldn't touch it. Nothing wrong with running a good used engine.

[triggrhaapi]

Fine the sleeves that are currently in it, you ass.

This is still about 2k cheaper than a rebuilt S50 could be purchased.

[techno550]

For bending forces, go look at a craftsman breaker bar. (the beam kind, not the round ones.)

The block should have plenty of room for going to an 86mm bore. The blocks are rarely ever the problem...

so how much less is it to build this hybrid 3L than just buying a 3L?

[triggrhaapi]

Well back on topic again, my machine shop came back telling me that my block is tapered so I have to go with new pistons. I'm going to have a sonic penetration test run to see if it's feasable to bore to 86mm and use S50 pistons, effectively making the transformation into an S50 from an M50 complete. In the mean time, I bought a set of S50 pistons I found cheap. If I can't use them I'll sell them, but if I need them, I got a helluva deal.

[triggrhaapi]

And we care what the rod does when the rest of the motor lets go... why?


The most common "bent rod" cause is detonation. too much spark lead or hot spots in the cylinder or just too much compression for the air/fuel/fuel load/volume. If you can make that happen early enough, you can do what basically equates to hydrolocking the motor. bent rods ensue.

Alright, and what kind of force bends the rod? And why would you want the design of a rod to bend that way in a progressive manner and absorb energy? What would cause it to break and not bend? And back to the original argument, why would an S50 rod be able to handle that event better than an M50 NV rod?

[techno550]

Then I will waste more of my damn time arguing with some guy who doesn't think that there is any lateral force acting on a rod when the engine fails, which could in no manner have anything to do with why it bends instead of breaking.

And we care what the rod does when the rest of the motor lets go... why?

You've already said that rods bending instead of breaking is good. What could possibly apply the kind of force that would cause it to bend? Explain that to me and I'll write you a goddamn doctorate thesis if you want.

The most common "bent rod" cause is detonation. too much spark lead or hot spots in the cylinder or just too much compression for the air/fuel/fuel load/volume. If you can make that happen early enough, you can do what basically equates to hydrolocking the motor. bent rods ensue.

[bmdubya84]

[euroshark]

lol

Fun thread!

[triggrhaapi]

write out the equations for modeling the forces seen by a connecting rod.

do so without mentioning certain cars that use an H versus an I, or what can/cannot work.

Ok sure, I'll write you a damn dissertation. What is this, a college class? You keep putting the burden of proof on me, when this is my thread, and you're the one who keeps ignoring what I say. I'll make you a deal, I will spend all that extra time doing it when I'm done building my engine using my M50NV rods and it's all running and working just fine like we all know it will. Then I will waste more of my damn time arguing with some guy who doesn't think that there is any lateral force acting on a rod when the engine fails, which could in no manner have anything to do with why it bends instead of breaking. You've already said that rods bending instead of breaking is good. What could possibly apply the kind of force that would cause it to bend? Explain that to me and I'll write you a goddamn doctorate thesis if you want.

[techno550]

write out the equations for modeling the forces seen by a connecting rod.

do so without mentioning certain cars that use an H versus an I, or what can/cannot work.

[triggrhaapi]

http://www.legendrods.com/hbeamrods.htm

Oh my god, so you are not going to believe this. Somebody started making forged H beam rods last night. Seemingly in an attempt to prove you wrong. This will not stand, my friend. I am a man of justice, I will tell them to machine them from billet like any decent american would.

[triggrhaapi]

Thats a translation? what language does he speak?

Lets look at H beam versus I beam here for a sec...

H beam: easy to machine from billet. made popular ~4 decades ago by carillo. Still popular mostly because its an obvious change from stock. Usually long thin ribs that are much longer in the plane of the rod. The ribs being deeper increase the stiffness in plane, but they are also generally so thin that they want to flex at the outside edges allowing the beam to bend.

I-beam: easier to forge. Typical OE construction for rods. It allows for more in-plane flex and is generally more forgiving because of that.

Both are approximately equal in tensile strength.

H beam rods are more popular in applications where no detonation will occur. I beam is more popular in applications where detonation may occur as they are more forgiving. At least thats how it works in engeering race cars world. The street car side of things loosely follows this as its "engineering" is largely based on occasional observation of what race cars do... and not always looking at a comparable race car setup.

We can go as deep into this topic as you'd like.

Yes, you're so right, Carillo made those because you can machine them, they don't make other rod designs as well, you're right.

and you're right, a four cylinder engine under 44psi boost in no way will ever have to deal with detonation. And neither will a honda Civic DX, which is why honda totally used H beam rods on that motor, because detonation will never occur there.