Reply With QuoteI have a Linished BT crank here.
What do you want me to get pics etc of?
You have a good point. I do not have two of these cranks to compare. But I am sure someone reading may. We need some photos, weights, markings, hardness tests etc...
Then we need photos of a failed 4A crank, and ask what went wrong etc...
Then we need some solid info on knife edgeing and balancing or whatever you want to do.
This is starting to get exciting. I am liking your 11,000rpm engine already! (But Formula Atlantic went to 12,000rpm?)
I have a Linished BT crank here.
What do you want me to get pics etc of?
Thats good to hear jonny.
Starni if we could have a measurement in weight, aswell as some pics of the crank in a birds eye view, journal corners, counter weights, and the balancing of each would be good.
I'll see if i can find a ze crank, better yet see if i can get the one i will be using.
As for testing hardness, I would be unsure how to check it, any ideas?
its not possible at all to adapt stuff from a gen 3 3sgte, they come from the factory with everything balanced, bigger diam,
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are you suggesting looking at 3sg parts or what, i'm a little confused to how that relates?
Edit: Atlantics spin to 12,000rpm jonny
Last edited by Gunner; 8th February 2009 at 10:22 PM.
it would be possible to fit a 3s crank into a 4age wouldnt it? a little bit of a machine here and there, could be cheaper way out.
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I'm not sure if we need to know hardness. It was just an idea. My local engine machine shop has a handheld hardness tester, and they test all my alloy heads that I bring in.
Maybe we would confirm that some cranks look a little different due the the casting etc if we look hard. But it is still going to be hard to tell which is stronger. How did you find that GZE cranks are stronger? I would like to see the picture of the failed 20valve crank. The crank often outlasts both the conrods and the block. But we know 4A cranks in general can snap at the front near the keyway.
I doubt you'd get a 3s crank in a 4a block.
Im just going off what I have seen engines do, though with cast parts you can never be too sure on quality. I was under the impression that the failure that occurs in the nose of 4a cranks is all to do with too much stress on the keyway itself. I personally have never seen a 4a crank fail, but i have had to cut harmonic balancers of 4a's after a slightly loose keyway has ripped itself and the crank to shreds.
I do believe that a 20v crank will be somewhat lighter than an early ze crank, and mainly due to cost effectiveness by toyota.
Last edited by Gunner; 8th February 2009 at 10:48 PM.
i have looked at the bottom end of a 4age very little, but i just assumed the strength in a gte 3s would be a fair bit higher than a 4a, but the size couldnt be a world of difference, even length,
the difference in bore 81mm 4age? vs 86mm for 3s would mean that you would just need to make some spacer for where the connecting rod mounts, and if you machined a little off either end it would still be stronger? My knowledge with this sort of stuff is limited just trying to think out the box,
also in regards to comparison in strength between between 20v and ze and ge etc, wouldnt there be less to do with actual dimensions such as thickness etc and more to do with the metallurgy. ive heard stories about bmw f1 engines from the 80s, deliberately using old blocks and components that have done high k's so that everything is settled.
my belief with things like this is that sometimes its better to have a combo of a crank and bore that have spent a lifetime together, than try to get various components from different places that fit. This sort of theory sort of came about to me through years of rebuilding 2 stroke motocross bike engines.
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