H beam vs. I beam rods

[SS/GN]

What HP are the rods you are looking at made to withstand?In N/A the H beam seems to be favoured.Why The I beam in forced inductionThanks great info

Kevin

 

[K1tom]

I am going to try and keep this in as simple terms as I can as some people will loose interest in this thread if it is too complicated.

Referring to the "Manual of Steel Construction" most engineers refer to it as "The Green Book"..... it has tables for the properties of many structural shapes..... including I-beams. Two particular properties listed in the tables that engineers refer to..... to "pick" a particular beam size based on a load.....are "moment of inertia" and "section modulus" These values directly relate to the beams particular strength in a particular direction..... i.e. your hypothetical situation on the I-beam on the sawhorses above. There are separate values for relative strengths about the "x-x" axis and the "y-y" axis.

A general note: In the green book.... the "s" beam is what most people call an "i-beam". From this point forward... I'm going to refer to the beam as an I-beam so as to hopefully not confuse anyone.... I hope.

If you break an I-beam down into it's basic parts that make up a shape..... there are two "flanges" and one "web"..... with the web separating the two flanges. I-beams are significantly stronger if turned right for the given load..... in the case of the sawhorse example..... you would want one flange laying flat on the sawhorse.... and the web sticking up vertically... with the top flange parallel to the bottom flange..... make sense?

Anyway.... to give you some idea of the relative strengths of i-beams in general if you want to compare the "values" of section modulus or moments of inertia.... you can easily see how much stronger the i-beams are if loaded correctly....

Looking at a small 4" x 7.7 I-beam.... (7.7# per foot).... the moment of inertia in the "strong axis" which would be loaded like above with one flange laying flat on the sawhorse.... is 6.08 in^4. But if you loaded it on the weak axis.... the moment of inertia is only .764 in^4.

This should give you some sort of "feel" for how much stronger an I-beam is in one direction vs. loading it in the other direction.

In the case of the "twist" that I mentioned in my post above.... I would think you would find after some lengthy engineering analysis....that the "h-beam" rods are weaker when the load moves from loading one axis to another.... i.e. a twisting load....

One observation is that when you compare the two different rods and how they are installed in a motor.... the i-beams have their "flanges" turned 90° from the way the h-beam rods are when installed in the motor. How does that come into play? I am not real sure without some 3-d modeling..... which I don't have time to do at the moment...

I hope I didn't loose anyone...

This is a good way of looking at the issue but since the piston / wrist pin is pushing on the end of the beam and not pushing on the side of the beam as if it were on a pair of sawhorses, it is not really applicable. With an I-beam rod, you have two parallel members with a thin web between them. On the power stroke, the cylinder pressure is trying to drive the wrist pin right through the center of the rod with only the thin web supporting the load. When this happens, the web will crush and the two side beams will split out like a banana peel.

 

[Kip]

This is a good way of looking at the issue but since the piston / wrist pin is pushing on the end of the beam and not pushing on the side of the beam as if it were on a pair of sawhorses, it is not really applicable. With an I-beam rod, you have two parallel members with a thin web between them. On the power stroke, the cylinder pressure is trying to drive the wrist pin right through the center of the rod with only the thin web supporting the load. When this happens, the web will crush and the two side beams will split out like a banana peel.

Hi Tom. thanks for adding to the discussion. You may want to add what your background with performance rods is for those who have no idea who you are.


Take care, Kip

 

[Alky V6]

What I'm curious about is what sort of load is put on the rod if the wrist pin is pinched or drags and doesn't rotate freely in the small end of the rod or the pin bore of the piston.

If abnormal combustion pressure causes this pinching of the pin at near TDC and the crank throw continues rotating through its normal path, what sort of stresses would the rod go through?

 

[Alky V6]

Let me try to describe this better. If I had a tight fitting wrist pin in the end of a rod and clamped the wrist pin in a vise, and then took the big end of the rod and attempted to rotate the rod about the wrist pin, what sort of stresses are we putting on the rod?
I believe we would be putting a bending force on the beam of the rod.
If this is true, and we are putting a bending force on the beam of the rod, then what beam orientation is the strongest to resist this bending deflection of the beam?

 

[Alky V6]

Let's add to this.
An engine rotating at 6000 rpm. At TDC, cylinder pressures become such that the pin drags and momentarily causes this slight bending force to be imparted on the beam of the rod. This would be occurring at 100 times per second. Or maybe not so regularly, but erratically.
Comparing this to another sort of occurrence that is commonly seen. A driveshaft with a tight U-joint. It's not uncommon to see a tight U-joint on a driveshaft set up a vibration in the shaft. Even a vibration that resembles a harmonic vibration.
I wonder if a vibration couldn't be set up in the beam of a con rod if the above situation were occurring? Add to the momentary drag on the wrist pin happening 100 times per second, all the other forces that are occurring with the rotating/reciprocating assembly. We know the crank is twisting and vibratiing. The crank damper is busy trying to control that, but what about the rods? The harmonics from the crankshaft also must be transferred to the rods adding to the mix of forces that are being put on them that we do clearly understand.

 

[Alky V6]

Could a frequency of these forces be met where it sets the beam of the rod to wobbling like a piece of spaghetti? Twisting and bending? And which axis would the bending typically be greatest?

An engine builder once told me of an experiment where someone put a strobe light on the bottom end so that they could observe what was occurring to the bottom end during high speed. Similar to the type of videos that you can see on youtube of the valvetrain. He told me that it would scare the heck out of you to see how components in the bottom end were moving around at speed and load. Frankly, I really don't think I'd be surprised.

 

[its2qik]

I have these rods (Dyer's Rods) in my twin turbo Mustang - 1-800-TOP-RODS

I was turned on to them from a friend who runs them in his 10.5 Outlaw Firebird that makes 2000rwhp. You can see the build up here - http://www.stenodperformance.com/gallery/thumbnails.php?album=65

Nice thing about them is they are made of 300m material which I'm told is some really strong stuff.

You guys might want to check them out and see if they can do something for a Buick engine.

 

[K1tom]

Hi Tom. thanks for adding to the discussion. You may want to add what your background with performance rods is for those who have no idea who you are.


Take care, Kip

Hi Kip,

We have known each other for several years now but for those who do not know me, I am an engineer and have been designing connecting rods and crankshafts for just under 30 years. I was one of two people who started the Oliver Racing Parts Company in 1981 and along with designing all of the rods they ever made, I also ran the day to day operation as well as writing every CNC program they ever used to make a connecting rod or crankshaft. In 2005 I left Oliver to start K1 Technologies with the goal of bringing to market high quality rods and cranks at an affordable price. At the end of 2006, we were purchased by Dover Corporation which is a huge company that also owned Carrillo, JE Pistons and Wiseco Pistons and I was retained to continue running the company. In 2008 they sold Carrillo and kept K1.

This I-beam, H-beam debate has been going on since the early 1960's when Fred Carrillo made his first rods. The fact of the matter is, while most people look at and group all H-beam rods into the same group, all rod beams handle loads differently and some are much stronger than others. While our rods are lighter than a lot of the others on the market, because of the way they are designed, they are much stronger than the other brands.

Just for the record, Oliver rods are not a conventional I-beam and handle the loads differently. I no longer have anything to do with Oliver but I will tell you they do make a good rod but not everyone needs or can afford them. For these people, we have K1. I hope this does not sound like an advertisement as my goal is to discuss the differences in rods and not to promote one product over another.

Tom Molnar

 

[Mike Licht]

I would listen to Tom, he tought me more about rods in a short time than in all the years I have been playing with engines. He is also the reason we only use his stuff in our kits and projects, thanks Tom
Mike

 

[BlownV6]

I would definitely NOT LISTEN TO TOM!!! At least I would take any advice he may give , with a large grain of salt!! I can tell you from first hand experience , he is clueless as to what a high HP Buick v6 needs as far as rod design!!! Period , end of discussion!!! At least in my opinion!! Mike

 

[Alky V6]

Thanks so much for participating, Tom.
Since you now run a company that is competing with Oliver, I can understand if you don't want to give out too much information. I'm going to step out on a limb here and just hope you might answer a few questions.

Can you elaborate a little on the parabolic beam?
We don't see the parabolic beam on other rods. Is it a patented design?

In the context of this thread where we're investigating which steel rod design is better suited for a max effort turbocharged V6, let's add, on alcohol and nitrous, can you give some information as to how the different designs would work in this type of application?

On a side note. Tom, do you remember Murl Bruton?

 

[Alky V6]

I would definitely NOT LISTEN TO TOM!!! At least I would take any advice he may give , with a large grain of salt!! I can tell you from first hand experience , he is clueless as to what a high HP Buick v6 needs as far as rod design!!! Period , end of discussion!!! At least in my opinion!! Mike

Take it easy, Mike. We're all here to share and learn. It's not every day we get a con rod designer to participate in a simple forum thread. Take it down a few notches.
Can you add your experiences with rods that you've found to be successful for your project? I think we can skip which designs you don't like.

 

[BlownV6]

Take it easy, Mike. We're all here to share and learn. It's not every day we get a con rod designer to participate in a simple forum thread. Take it down a few notches.
Can you add your experiences with rods that you've found to be successful for your project? I think we can skip which designs you don't like.

No need for me to take it down a notch. Im simply stating my opinion about his design and or engineering standards as they relate to a high HP Buick V6.
Mike

 

[Mike Licht]

Mike your blown V6 the outer limits of Buick engines. I know nothing about what it needs but my first thought is alumunum. As far as 99% of the members here the K1 rod is great, they have a proven track record of holding up, some is some very fast cars. The guy that designed them and Oliver rods which many other very fast V6 guys use is here trying to help, we understand your opinon but lets not blow the guy out of the forum. There is enough suppliers who want nothing to do with us because of this type of thing.
Mike

 

[BlownV6]

Mike your blown V6 the outer limits of Buick engines. I know nothing about what it needs but my first thought is alumunum. As far as 99% of the members here the K1 rod is great, they have a proven track record of holding up, some is some very fast cars. The guy that designed them and Oliver rods which many other very fast V6 guys use is here trying to help, we understand your opinon but lets not blow the guy out of the forum. There is enough suppliers who want nothing to do with us because of this type of thing.
Mike

I just started another thread "K1 Rods How much HP" in this section. I will try to keep myself contained here, but It will be intresting to hear from others that some experience with them as to what they will withstand!! Nothing personell Mike!! Mike

 

[K1tom]

I just started another thread "K1 Rods How much HP" in this section. I will try to keep myself contained here, but It will be intresting to hear from others that some experience with them as to what they will withstand!! Nothing personell Mike!! Mike

Mike,

I do not know who you are or your background anymore than you know mine. Because of this, I would not set out on a personal assault as you have done here. The fact of the matter is, I have designed and built rods for some very extreme engines for highly respected people like Dan Strezo, Kenny Dutweiler and many others and if this is what someone needs, we can make them but for most applications our off the shelf rods perform excellent and are priced at a point where most people can afford them.

For those of you that do not have a closed mind and are not afraid to learn, I will try to answer your questions either here or you can call me at my office direct.

Tom

 

[cruzn57]

there are ALOT of us here

who are very interested in this discussion.
I'm delighted to have some one as qualified as Tom Molnar contribute!
I feel we (the buick crowd) have unique demands on Buick V6 connecting rods, if we aren't trying to pull em apart, were trying to squash them into oblivion!
and as Donnie has said all the other stresses involved.
Who knows, maybe something will come of this disscussion?

Mike( BlownV6) your dislike of K1 ( or Tom or what ever) is noted, but please don't make this personel.
were here to learn, and maybe gain some insite into what rods go thru in their use.

Merry Christmas to All!

 

[Alky V6]

I have these rods (Dyer's Rods) in my twin turbo Mustang - 1-800-TOP-RODS

I was turned on to them from a friend who runs them in his 10.5 Outlaw Firebird that makes 2000rwhp. You can see the build up here - Stenod Performance Photo Gallery - Tom's "Money Shot" Drag Radial Formula

Nice thing about them is they are made of 300m material which I'm told is some really strong stuff.

You guys might want to check them out and see if they can do something for a Buick engine.

Very cool documentation on the build. Is it finished?

 

[its2qik]

Very cool documentation on the build. Is it finished?

Yes. Tom's car made it to the last LSx shootout down in Florida at the end of the year (late Oct, I think?). First time to the track, first pass out of the trailer I believe the car was in the 7s

I think they are running a 114mm turbo!