Now I understand some blocks are terribly damaged, they are in fact scrap however I have seen a couple blocks of late where the main bearing has spun and taken some block material with it. So if you have a candidate and you are prepared to take on an interesting project read on.

Our engines are a little old tech, that is not being demeaning at all but it was made a long time ago and material technology has improved and as such this has allowed some improvements. What is commonplace in Nascar and I mean every single engine they have smaller main bearings than what we have. The standard is about 2" where as ours are almost 3" (70 mm) like wise the big ends the only journal they are now using is the BMW journal or 1.85" I have a 1.888" journal or Honda styled journal.

The advantage is lower weight and lower friction, if you look up Jon Kaase and below is a few links, you will see he goes to this trouble with good engines. i don't know exactly how much trouble it will be but if a kit was made it could be worthwhile. Also I would do the bushing in grey cast iron like the GT3 get. They use the cast iron because of the lower expansion rate.

http://www.popularhotrodding.com/eng.../photo_06.html

A write on his engine, notice the manifold filling with epoxy, and notice how small the ports are as they were designed by Jon as high speed ports.

http://www.jonkaaseracingengines.com...-emc-2003.html

I think we could use the Chevy bearings, don't know about the thrust bearing setup but that could be investigated or maybe somebody on the board might now. Throw it open for discussion.

Greg

 

I think it's a fantastic plan if you could pull it together. Just a good set of rod bearings costs enough money to make me want to call moldex. The smaller diameter would have a lower shearing rate on the oil which would lower it's temperature slightly and covering less surface area would require slightly less volume from the oil pump (in other words make the oil pump "look" bigger).

 

By Entropy-engineering
Yes one of the advantages is use less oil, you could in theory at least run the early smaller oil pump. The smaller pump will consume less power and as stated before the smaller circumference also requires less power to drive them due to less friction, it will also spin up quicker.

The smaller journals on the big ends and mains are considerably smaller and the mains bushed with cast iron may allow tighter tolerances than what would be possible with aluminium. I suspect that is the reason the GT3s have this system.

Greg

 

I've seen an article in something like Hot Rod before where a block had inserts made. I remember the insert was "pinned" with a metal dowel and then align honed. That brings up my question; are you concerned with the block growing any around the insert and letting it rotate or move? At least you could move down to perhaps more conventional bearing designs and sizes.

 

Quote from the article: "Next was to bush down the main bearing size to 2.499-inch. This in an absolutely terrible job, and the only thing keeping me going at this point was the picture of Joe Sherman, the man to beat, on last year's cover."

 

So to take this a bit further I contacted a top crank maker who makes very high end cranks and does custom one off work too, I explained the situation of our cranks, i.e both the originals and aftermarket cranks and told him of some of the issues that have arisen with high power engines such as cracked blocks.

I explained there was various opinions as to the cause of the failures, some say the outright power, some opine that there is a inherent balance issue with 6 cwt cranks, other issues may be just too high a mass of metal to contain at high revs.

That was one part of the conversation, the other part was when I asked what he thought about my idea of smaller journals in general for this engine (he was given bore spacing, power revs weights etc) he said that he wouldn't like to see a 2" main journal but was very comfortable with 2.3" to 2.5" he said it would just depend on what bearings you could find to suit this application, which I was already aware of. The thrust bearing probably being the most difficult to source.

He said and I have already stated there is no question there is gains to be had
with smaller journals, both mains and rods. Their cranks would weigh around 20 lbs lighter for our application compared to OEM Or with a 3.75" stroke no more than 43 lbs and cranks like mine around 40 lbs.

In terms of the mains, I said what if you had 2" mains and 800 hp, he said doesn't scare me on a crank point of view (He said the price will scare you!) but had concerns with the block rigidity, he said the more rigid the crank the less strain on the block, he also said that the weight of the crank doesn't have to imply strength and stiffness.

The design would need to be determined, there was a process for this. FEA and other issues considered and at the time I just wondered if some other crank makers were keeping up with the latest technology. He was keen to help and I thought a very open in sharing his knowledge, he said an order for 3 cranks would be economical proposition for all parties.

This will only appeal to racers with manual gearboxes, the autos would get little or no benefit, I was just trying to think of future developments, I have set heads which flow quite well and I am just fiddling with them for fun but with a 15% increase in airflow which should be possible the heads can support 800 + hp. To create the demand for that type of airflow you need revs, I don't think you can do it with displacement, if you did, you will have way too much torque down low.

In fact with the airflow I have now you can get 800 hp but it goes without saying you need everything else to be in place which is easy to type but much more difficult to put into place. Here's an example, you can click on the link to the flow of the heads on the second page, the heads I have beat these pretty easy but you need the revs to take advantage of the airflow. A cheap program like Pipemax will detail basic requirements. Sorry the last part of this post went a bit off track but that was the thinking behind the idea.

http://www.speedtalk.com/forum/viewt...r+235+tony+joe

Greg

 

Guess I shouldn't reply when I'm half asleep (restating the first post). If crank mass is much of a concern have you considered much undercutting the crank throws (I'm assuming with your knowledge of motors you're well past that). As far as block strength, have you looked at epoxy filling the bottom of the stock bores with aluminum flocks inside? I know it's been mentioned here before. Full sleeved motors I don't know about. I remember Lennart and Birgitta Bergqvist won engine masters in 2005 with a motor that had ridiculously small counterweights the crank grinder felt unsure about making. I think it had tungsten inserts to help bring the balance back closer. Perhaps harmonics are relevant to the block cracking? There used to be a big thread about Fabio (I kid you not) having his Supra built by a formula one engine builder that reduced his counterweights to practically nothing with undercutting and it survives nicely from what I've read (apples and oranges comparison?). I understand he removed something like 15 to 20 pounds. Here's a vid of it... http://www.youtube.com/watch?v=-MnrH7Z9NFs The only reason I bring that car up is because how much development the engine has enjoyed. Do you have much of an opinion about under balancing crankshafts?

 

Greg -- Did you proceed any further with these inserts? Best, Tuomo

 

All the blocks I've seen with thrust bearing failure either have a huge crack migrating up to the water jackets or have a small crack that is going to do the same thing. That silicon impregnated aluminum is some of the most brittle crap on earth.

 

Tuomo nothing as yet, been working on other stuff, I think given the work load of things I would like to do I need to be choosey. As such one of the reasons I put it out there was to just inform others of the possibilities.

Cheers Greg

 

Short of the cracks Greg BBRD speaks of, I cannot understand why TBF damaged blocks can not be repaired with the installation of a "saddle", made of the proper material and properly engineered for installation into a correctly machined previously damaged, block.

Perhaps it is because no one has actually tried.

 

I have 2 blocks in my possession , one early and late , they have TBF (failed due to oil pressure loss ) that would be ok for modification. Both are without any cracks and both from autos .

 

I have done one North american block like that.
It was a 455 that was line bore'd, inserts were screwed into the mains, line bore'd again to the proper size for a 425 steel crank main bearing. I would shift at 7200 rpm.
7 inch rods on that monster.
it tore the mains out and detonated when a 1st to 2nd sift broke a trans planetary and I saw the tach go past 9000 rpm
$9000 worth of machine work alone up in smoke