Because Honda cranks are already next to perfect once they leave the factory...
Rod Bearing
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caboose
USDM to the bone
In terms of knife edge? IIRC, it's all rough casting, so the end was filleted/rounded.
Some cranks that I've seen knife edged have been so sharp that you could probably eat steak with it, lol. They also ground off all of the casting finish and polished it.
caboose
USDM to the bone
caboose said:
That is my question.
And I am learning... I just prefer to know why the honda crank is coated or why you can't knife edge, versus people saying "because if you don't it will break" or "because it's not a chevy" lol.
Anyone with eyes can tell you if somethings broken... the key is trying to find out WHY it broke in the first place.
Yes, in terms of doing a knife edge. Honda has the counter-weights a certain size and weight for a reason.
What you don't understand is how advanced Honda is. You don't realize how advanced they are compared to most of the other automakers in the industry and even machine shops that build high horsepower race engines.
Most other factory cranks can be taken to a machine shop and machined better. Honda cranks can't because Honda already does it...
caboose
USDM to the bone
Oh, trust me, I have experience with Honda Engineering... there's a reason that their cars are so much better.
Im my understanding the theory always was that I-4s are internally balanced (you always have one piston that's exactly 180* out of rotation), so as long as your rods/pistons all weighed the same, and your counterweights all weighed the same, they will balance themselves.
1sikef
New Member
this forum really blew up didn't it i mean i'm with blanco he seems to have a knowledge advantage over caboose, i have had friends that had there motors built by people who turned the crank and they had nothing but problems with spun rod bearings and throwing rods, one in an ls, one was a d-series and the other was a b16, so im going with blanco on that topic, i mean it doesnt mean every time someone gets there crank turned it fucks up, in some cases it will work fine but about 90% of the time turning it causes problems
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wow i work on domesticrap at work all day and do thing that work great and when i come home and work on my car there are many things that i would never do to my honda like grind the crank/run aftermarket bearings/ well any of the conventional shit that people do. by the way i know of a race team with a 20k plus all motor k series powered insight and they still refresh there engines with OE honda bearings if the crank gets fubared they throw it away
BertMcGert
New Member
Im my understanding the theory always was that I-4s are internally balanced (you always have one piston that's exactly 180* out of rotation), so as long as your rods/pistons all weighed the same, and your counterweights all weighed the same, they will balance themselves.
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This is a common misconception of building a 4 cyclinder engine when coming from the v-8 world, I know this from experience. Another glaring misconception most v-8 guys have is about the major point of this discussion bearing tolerances and coatings,treatings, ect,ect........... An extremely large portion of late 60's to 2008 v8s have a factory redline of 5000-6000 rpms. A large amount of 4cylinders have a factory redline of at least 800 rpms higher than this, if not much higher. When you are dealing with the forces of rotational stress which expand exponentially with each rpm, the clearances and friction coeffecients become super-critical. Thus using the OEM Honda parts that are uncountable multi-millions of dollars and decades into research and development VS a machine shop or independent race builder that says "this worked good", is a good idea.
BTW im not an engineer or sumthin Im just a former auto-tech that happens to know a few things about engine dynamics.
__________________
This is a common misconception of building a 4 cyclinder engine when coming from the v-8 world, I know this from experience. Another glaring misconception most v-8 guys have is about the major point of this discussion bearing tolerances and coatings,treatings, ect,ect........... An extremely large portion of late 60's to 2008 v8s have a factory redline of 5000-6000 rpms. A large amount of 4cylinders have a factory redline of at least 800 rpms higher than this, if not much higher. When you are dealing with the forces of rotational stress which expand exponentially with each rpm, the clearances and friction coeffecients become super-critical. Thus using the OEM Honda parts that are uncountable multi-millions of dollars and decades into research and development VS a machine shop or independent race builder that says "this worked good", is a good idea.
BTW im not an engineer or sumthin Im just a former auto-tech that happens to know a few things about engine dynamics.
The reason Honda has so many different sizes of OEM bearings is to assure that the correct oil clearance is achieved. Many manufacturers do this and it is for quality control. Crankshafts are mass produced and have variation in tolerences in an assembly line situation. By having these different bearings the engine assembler can compensate and get a perfect fit. In a machine shop the machinist has the burden to provide proper oil clearance. A good machine shop will rough grind the crank, install the rod bearings in the rod and torque the cap to factory specs. They will then measure the inside diameter of the rod bearing and determine how much must be polished off the induvidual rod journal to achieve the factory or customer desired finished oil clearance. That is what a good machine shop will do, many however just turn the crank to a specific size and give it back. You should always mic your crank, rods and mains to assure they are right. Plastigauge is for Chevy farm trucks not high revving high performance motors. This extra step takes time but it takes less time then pulling the motor back out. As for the rod on the spun bearing, I have never seen one not damaged and most machine shops only charge 10 to 20 dollars to resize. If it is out of round and not resized the new bearing will just spin again as there isn't adequate clamping force or bearing "crush". And never throw a new bearing on spun journal, it won't last at all.
Still surprised nobody said anything about this post.
caboose
USDM to the bone
His reasoning behind it is that nothing was really changing. The crank was fine to begin with. Plastigauge would have shown that the clearances were ok or close to ok. Even if they were shown to be out of tolerance, I would have probably run it anyways and just to see what happened.
caboose
USDM to the bone
Ok, for clarification, Blanco's way is defiantly the right way if your going "by the book" so to say. I'm just trying to explain what you can get by with. Replacement motors are very cheap for my car, so if I was going to rebuild it, it wouldn't have been very economical to go all out.
The only thing that I was trying to do was to get my car back on the road for the least amount of money possible. IMO the rebuild was a huge sucess, the car runs much much better than ever before, and I have no regrets on any of the work that I did on it, even after this tread. I would trust the car to drive me anywhere. (Note: I did NOT have any machine work done to the crank... or any part of the motor.)
caboose
USDM to the bone
Reid, J (1987).The Effect of Surface Hardness on Friction. Wear. Volume 118 Issue 1, 125.
I'm sure you are right on the Honda engine Blanco as it is a much better engineered engine than most other makes. I hate to see guys sink money in cheap rebuilds and O'Reilly cranks with "fitted" bearings only to have them fail. I was speaking generically as I don't build Honda engines. The machine work on these engines is specialized and should only be left up to Honda specific shops even if that costs more or takes more time, ie shipping the parts off. I worked on Porsches' for years and they are very similar in construction. Thanks and it's nice to find a site with so many knowledgeable people.
George777
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