All of our rods are designed by me here in the US and the finishing work is done in our shop in Michigan. We have never hid from the fact that we have some of the work done in China and label the plastic bag the rods are packed in as such. Just for the record, there are some people that think there are companies getting a forging from China and doing the machining here so here are some facts. If you buy raw forgings in quantity, you can get them for $15-$25 each depending on material. Even if you were to get forgings off shore for free (which is not possible), the labor would be the same and it would not reduce the price from $1,400 for a set of 8 rods made here to $550 (or less).
H beam vs. I beam rods
- Thread starter Alky V6
- Start date
All of our rods are designed by me here in the US and the finishing work is done in our shop in Michigan. We have never hid from the fact that we have some of the work done in China and label the plastic bag the rods are packed in as such. Just for the record, there are some people that think there are companies getting a forging from China and doing the machining here so here are some facts. If you buy raw forgings in quantity, you can get them for $15-$25 each depending on material. Even if you were to get forgings off shore for free (which is not possible), the labor would be the same and it would not reduce the price from $1,400 for a set of 8 rods made here to $550 (or less).
BTW, we do not use the same factories in China as most of the others and we do not look for the low cost providers. We only use companies that are capable of and willing to produce high quality parts that are made to our strict tolerances and specifications. It does cost us more for parts but if you compare our next to the others, you will see a distinct difference.
Tom
The Radius Kid
Active Member
- Joined
- Jan 26, 2002
That's what I like,intelligent dialogue.
Glad you talked to Mike.
He is an insightful guy and a gentleman.
He does scare me sometimes though.
I'm looking at the pic's presented so far and I see a common problem:
Parallel beam sides.
I don't know if you remember your wave theory from physics class,but you have the start,the peak,the crossover point,the trough and the end at zero.
It's known that metals do tend to have a resonance "Q" or natural vibration.
Put a series of sensors along the beam of a set of rods with parallel sides and you will find peaks and troughs around 1/4 & 3/4 marks along the length of the parallel sections,when the natural resonance is excited.
The higher the inpulse applied,the greater the excitement or motion.
Looking at where Mike's rod failed in the pic',I would say it was at the 1/4 point of the most highly stressed end of the rod.
Shouldn't be hard to excite that resonance somewhere in the RPM band.
Couple that with the extreme loads .......
Two things might have saved that rod [and Mike's wallet]:
1.Greater broad face width on the big end [to withstand the swinging motion].
2.Non parallel sides to minimize any standing waves [lower Q].
I realize the wave issue may not sink in with most people,but the issue has it's roots in structural designs such as buildings and bridges,especially in earthquake zones....think Tacoma bridge.
Structural reinforcement doesn't work too well when it's wobbling around like a drunken sailor.
The Chevy V6 crank pin centerline is offset to the cylinder bore centerline by .100".
For comparison, the off-center Buick block puts the crank pin centerline to cylinder bore centerline at .127".
From what I understand, any off-setting would create a bending force on the rod.
For comparison, the off-center Buick block puts the crank pin centerline to cylinder bore centerline at .127".
From what I understand, any off-setting would create a bending force on the rod.
I noticed in Robert's picture of his bent rod that there is no offset built into the rod in an attempt to center the small end in the piston. With an offset crankpin situation, that seems very odd to me.
Donnie,I have been talking with Oliver about a rods for my on center engine and they want to put 0.20 offset in them.If they did that to Roberts I wonder if you could tell it by looking at that picture?Aren't the on centers supposed to be "on center"?Or are they a little off one way or the other?
There is still some offset of the centerlines with the Buick on-center block. Someone can correct me if I'm wrong, I believe the on-center blocks only correct for about half of the off-center blocks offset. This makes the offset of the on-center blocks better than the Chevy V6, but still not a perfect on-center alignment.
edit: I think you mean .020", don't you?
I wonder, when an on-center rod is used in an offset centerlines situation, and the rod bends the way Robert's rod bent, which direction does the small end bend too?
I'm going to make a guess and say that the beam would bend in a manner that would move the small end further off-center to the cylinder bore.
I'm going to make a guess and say that the beam would bend in a manner that would move the small end further off-center to the cylinder bore.
In an offset situation, I would think that anything that would help keep the piston and rod in perpendicular alignment with the crankshaft would be a good thing to do. Such as generously skirted pistons, low piston to wall clearance, low rod big end side clearance, low rod bearing clearance, tight clearanced or pressed piston pins, slight rod off-setting to put the small end more centered in the piston.
In a high output situation, the wrist pin should not be ignored. As hp levels increase, so should the pin diameter. This would help prevent any problems transferred to the rod by the wrist pin.
I'm presently using a .927" OD, thick walled, coated Ti wrist pin. The last time I had the engine apart, some of the pins were showing a slight bend to them. Not enough to make disassembly or assembly a problem, but I figured next time I PM the motor it will be time to increase the wrist pin outer diameter.
I'm presently using a .927" OD, thick walled, coated Ti wrist pin. The last time I had the engine apart, some of the pins were showing a slight bend to them. Not enough to make disassembly or assembly a problem, but I figured next time I PM the motor it will be time to increase the wrist pin outer diameter.
I have to slightly disagree with some of that. I rod needs to have enough mass and strength to withstand its use by itself. Trying to keep it from bending with other parts and tight clearances is not a good idea. The following pictures are from a mock up I did to order my MGP aluminum rods. This on on an oddfire crank with .940 wide rods so it cannot be totally compared to even fire crank , but you can get a good idea!! The rod in pics has zero offset!! Mike
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The Radius Kid
Active Member
- Joined
- Jan 26, 2002
Don't go there Don.
Get them out and use some good Steel pins.
They're showing signs of fatigue NOW and Titanium does not forgive too much,if at all.
Remember guys:the pin carries the load that's applied to the rod that applies the load to the crank journal,etc.
That's a LOT of stress for a little piece of metal.
The Radius Kid
Active Member
- Joined
- Jan 26, 2002
Correct Mike.
The motive force applied by the piston must be transfered with minimal losses - because it floats between two points.
Too much monkey motion and the HP can by lost as well as a higher likelyhood of failure...as you found out with your Titanium rods.
As with everything mechanical,there's always an optimal balance point.
It's the crazy racers who always try to stretch the limits. :smile:
Here are some more pics of the mockup with an aluminum rod. You can see the clearance of various areas. Please note the closeness of the bottom of the piston and the crankshaft counterweight!! In my earlier post I gave my opinion that the rod beam folded or buckled and this shortened the rod , which pulled the piston down into the path of the swinging counterweight thus impacting the piston and fracturing the bottom of the piston and tearing the piston boss out of the bottom of that piston!! Hope this clears up my view point!! Mike
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Sorry. I didn't include the odd-fire crank in my statement. My statement about the offset with an on-center block and an even fire crank still holds true.I have to slightly disagree with some of that. I rod needs to have enough mass and strength to withstand its use by itself. Trying to keep it from bending with other parts and tight clearances is not a good idea. The following pictures are from a mock up I did to order my MGP aluminum rods. This on on an oddfire crank with .940 wide rods so it cannot be totally compared to even fire crank , but you can get a good idea!! The rod in pics has zero offset!! Mike
When I mentioned tight clearances, I should have specified the lower limit of an acceptable range. I would not run more clearance than is needed with an offset crankpin.
I've been using a Ti pin since the start of the v.3.0 build. BUT, I do understand the risk. The suppliers of the pins even voiced their concern. I do plan to go with a larger OD thickwalled steel pin next PMing.
What does rod to camshaft look like? Are you moving the camshaft?Here are some more pics of the mockup with an aluminum rod. You can see the clearance of various areas. Please note the closeness of the bottom of the piston and the crankshaft counterweight!! In my earlier post I gave my opinion that the rod beam folded or buckled and this shortened the rod , which pulled the piston down into the path of the swinging counterweight thus impacting the piston and fracturing the bottom of the piston and tearing the piston boss out of the bottom of that piston!! Hope this clears up my view point!! Mike
When I was working on the v.3.0 combination I did a CAD of the crank and camshaft locations and built a digital rod. The idea at the time was to use an aluminum rod. The room wasn't there for the extra bulk of an aluminum rod. Are you trying to get the strength by simply going as wide as you can, even with the camshaft problem? I'm wondering if going wider is as strong? I would guess it isn't.
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