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K1 Technologies A Class Act !
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Even though a lot of manufactures rate rods by power, it is nearly impossible to put an accurate power rating on a connecting rod. Power is produced from the expanding gasses in the combustion chamber pushing down on the piston which in turn pushes down on the connecting rods. While there are certain situations which could lead to failed rods due to compressive loads, rods generally don't fail because of power loads. If a rod broke due to power, they would experience severe bending to the point of permanent deformation prior to breaking. When you see a broken connecting rod where there is no seizure of the bearing or failure of the piston/pin/cylinder wall, look closely and you will see that the rod was actually pulled in two. This high tension pulling load on the rod takes place at TDC on the exhaust stroke and is caused by the piston trying to continue up the cylinder walls and through the cylinder head and the crankshaft trying to pull it back down. The heavier the piston, longer the stroke and the higher the RPM, the more pulling load is placed on the rod. For an example of this, look at a dyno sheet. You will see that as the RPM is taken past peak power the power falls off, however, quite often a rod will break when it is over revved. This is also the reason a rod will break under deceleration or when down shifting. You certainly are not making much power when the throttle is closed.
EightSecV6
MDBL
- Joined
- Jul 18, 2001
- Messages
- 2,514
that's too bad...What do you suggest that will hold up?
Rods
Scott,
I have built several 1200 + HP engines with K1 rods , I wouldn't have given
any consideration to them if I thought there were issues. I have also sold some custom length sets to Buick vendors for big HP build ups. I have had
discussions at length with Tom of K1 about this negetive post. These are
his thoughts :
I have some information regarding these rods. K1 Buick connecting rods have a beam cross section of .357 square inches. That means with 170,000 p.s.i. tensile steel, the beam will see ultimate yield at 60,690 pounds of tension load. Fatigue life consists of two things; load and cycles. The higher the load, the less cycles the part will run before it sees a fatigue failure. From an engineering stand point, using a steel part (I emphasize steel because alloys such as aluminum do not have these same low load fatigue properties), if the load is below 50% of ultimate (30,345 pounds of load) the part will normally run over 10 million cycles which is considered infinite. Loads above 50% will not break the part but it will shorten the cycle life. In the case of a engine with a piston, wrist pin and ring pack of 692 grams, 3.625" stroke 6.00" rod and 7,500 RPM, the rod will see about 8,000 pounds of tension load at TDC on the exhaust stroke. Since most rods break due to tension, the K1 rod has over a 3:1 safety factor.
Compression loads are another factor. An engine with a bore of 3.83", has a piston with an area of 11.5209 square inches. At a peak combustion pressure of 2,000 p.s.i., you will produce a maximum of 23,042 pounds of compressive load on the rod. Keep in mind that a Pro Stock drag race engine produces something in the range of 1,300 p.s.i. cylinder pressure so this 2,000 p.s.i. number may not be realistic. Very high compressive loads in an engine with too light of a rod will produce bending or buckling. This is where the material is stressed to the point where it will take a permanent set. With the tensile strength and beam cross section of a K1 rod, the beam is capable of handing even the severe loads of a turbocharged engine.
What all of this means is, under normal conditions, the K1 Buick rod is capable of handing very high loads for a very long time. Some other variables that also enter into this and can cause rod failures are things that are completely out of our control such as detonation, hydraulic lock or a bad tune up. I may not be an expert, but during my 26+ years of designing connecting rods, I have learned a few things about what it takes to make a rod live in certain environments including some of very high 1200+ horsepower applications you have built using connecting rods that I have designed. If you consider the fact that K1 builds connecting rods for a lot of different applications and there have been no reported failures, I do not think anyone can make a blanket statement that our rods will not work in a engine that makes over 1200 horsepower.
Scott,
I have built several 1200 + HP engines with K1 rods , I wouldn't have given
any consideration to them if I thought there were issues. I have also sold some custom length sets to Buick vendors for big HP build ups. I have had
discussions at length with Tom of K1 about this negetive post. These are
his thoughts :
I have some information regarding these rods. K1 Buick connecting rods have a beam cross section of .357 square inches. That means with 170,000 p.s.i. tensile steel, the beam will see ultimate yield at 60,690 pounds of tension load. Fatigue life consists of two things; load and cycles. The higher the load, the less cycles the part will run before it sees a fatigue failure. From an engineering stand point, using a steel part (I emphasize steel because alloys such as aluminum do not have these same low load fatigue properties), if the load is below 50% of ultimate (30,345 pounds of load) the part will normally run over 10 million cycles which is considered infinite. Loads above 50% will not break the part but it will shorten the cycle life. In the case of a engine with a piston, wrist pin and ring pack of 692 grams, 3.625" stroke 6.00" rod and 7,500 RPM, the rod will see about 8,000 pounds of tension load at TDC on the exhaust stroke. Since most rods break due to tension, the K1 rod has over a 3:1 safety factor.
Compression loads are another factor. An engine with a bore of 3.83", has a piston with an area of 11.5209 square inches. At a peak combustion pressure of 2,000 p.s.i., you will produce a maximum of 23,042 pounds of compressive load on the rod. Keep in mind that a Pro Stock drag race engine produces something in the range of 1,300 p.s.i. cylinder pressure so this 2,000 p.s.i. number may not be realistic. Very high compressive loads in an engine with too light of a rod will produce bending or buckling. This is where the material is stressed to the point where it will take a permanent set. With the tensile strength and beam cross section of a K1 rod, the beam is capable of handing even the severe loads of a turbocharged engine.
What all of this means is, under normal conditions, the K1 Buick rod is capable of handing very high loads for a very long time. Some other variables that also enter into this and can cause rod failures are things that are completely out of our control such as detonation, hydraulic lock or a bad tune up. I may not be an expert, but during my 26+ years of designing connecting rods, I have learned a few things about what it takes to make a rod live in certain environments including some of very high 1200+ horsepower applications you have built using connecting rods that I have designed. If you consider the fact that K1 builds connecting rods for a lot of different applications and there have been no reported failures, I do not think anyone can make a blanket statement that our rods will not work in a engine that makes over 1200 horsepower.
Cranks
Scott,
I also don't believe that the eagle crank would have any problems. The only
drawback is they only come in stock stroke. We do have stroker cranks
available to us from offshore suppliers . We have seen engines in excess of
900 HP using these parts. I think that a good import crank has a better
chance of survival than a used BMS crank of unknown history.
Scott,
I also don't believe that the eagle crank would have any problems. The only
drawback is they only come in stock stroke. We do have stroker cranks
available to us from offshore suppliers . We have seen engines in excess of
900 HP using these parts. I think that a good import crank has a better
chance of survival than a used BMS crank of unknown history.
EightSecV6
MDBL
- Joined
- Jul 18, 2001
- Messages
- 2,514
In extreme applications I prefer to use an Oliver or Carrillo rod (American made). If it is a drag race only engine, it is tough to beat a GRP aluminum rod. I have successfully used K1 rods in engines making 700+ HP and never had an issue but I have also never heard of anyone using them for a V6 that had plans of making 200hp/cyl either.Just my opinion, not a negative post BUT if someone wanted to build a 1200 hp V6 running at 7500 rpm, K1 would not be the rod of choice and an Eagle would not be the crank.
Wasn't the orginal plan to make this much power but, I guess I'll be the guinea pig
Scott Wile
EightSecV6
MDBL
- Joined
- Jul 18, 2001
- Messages
- 2,514
Wasn't the orginal plan to make this much power but, I guess I'll be the guinea pig
Scott Wile
Go for it man! You will never know unless you try!!!!
