It's to have the least amount of material to hold the tungsten. Their ideal theoretical crank would be nothing but bearing journals connected by the thinnest spans with a heavy weight at the furthest distance possible accross from the rod journal.

 

BPG
We draw in inventor. Then Cory ( CNC Master of the Universe) imports the model into a post processor to generate the tool path.
He was using Bob Cam But that will change now with the 5-axis stuff.

Mike
I havn't a clue how to design a single plane crank. But if you can design it I will take a go at building it.
How are my rotor hats comming?. Rotors finally showed up here.
Thanks
Sean

 

They do sound great.

 

Racing is a given! Winning, well thats another story

 

Today at the Autoclub speedway (Fontana) infield road course a fellow showed up with his Grey F car a mid engine 4xx something it sounded great as I chased him for several laps. The sound as he pulled away in the straights then I would close up under braking and the twisty bits....hear him pull away again....and again :0 The old very brown 1980 sounded pretty good TOO ! 198 hp at the rear wheels but he was reving his a lot higher.

 

Please don't go down the flat crank track, the power difference is very little when the 90 degree engines are optimized. Studies have shown this at our level and Nascar level of revs to be of little or no benefit. To properly optimize our engine you just need a 4-2-1 system of which I have designed and mocked and will be welded up in the next six months.

Advantages of this style of system are well known, i.e tuneability and broadness of power.





Here's a nice crank to copy, the makers of it say that our stroker cranks are at least 20 pounds overweight. That may not btw make them stronger.


Why not buy one crank from them and then copy it? Have you got a set up for the grinding and the nitriding? Because the processes to make a crank are very involved and not just a matter of cutting it out. The heat treatment process aligns the metals structure much in the same way a forging does. I don't have the time to go into all the details as it is nearly midnight here and the wife might punch me in the nutts if I keep typing.

4340 is the most common and best I think to start with that as I understand it the other material really jump up from there and when you start driving you don't do it in a Rolls Royce.

Good Luck

Greg

 

Get the extra power from the exhaust and dry sump system, I am also modeling up one of those also. As to the exhaust note, you guys would have heard a Nascar, what do you think compared with the conventional 4 to 1 exhaust? Also the lighter the components are the better it will last, less stress. I did a piece on the future direction of crank design.

https://rennlist.com/forums/928-foru...nd-oiling.html

Toyota just released details of their still born 2010 engine, amongst other things they said that roller bearing in the mains saved 20 hp.

In respect of the smaller 928 crank in terms of the rods and mains, it is generally accepted and was tested by Car Craft or Hod Rod that honda sized journals saved around 7 hp at 7,000 or so RPM and add in the mains, I would say around 20 hp is there altogether, just guesstimates. I would and have only used a 8 cwt crank for stability in the 928 block which can be a bit fragile.

Greg

 

Marriage is like a deck of cards
In the beginning all you need is two hearts and a diamond
By the end you'll wish you had a f****ng club and a spade.

 

By all means, go flat crank if you want to build a 4 liter engine...

I don't know anything about crankshaft design, but I think the best crankshaft would have very heavy counterweights close to the crank centerline and the worst crankshaft would have very light counterweights far from the centerline.

Again, completely ignorant comment: Sure the counterweights will cover a broad section to get enouguh weight in at a short enough radius. The rounded edges (i.e., the oval shape on the outside) is probably for deflecting the oil in the least harmful way. Otherwise, they could have filled in those corners and gotten more mass on the circle.

There's also the question about how large the center counterweights should be. They do help a bit if they are on the other side of the throw for the same reason as the counterweights in flat-plane cranks help. They don't help much with the most significant balance issue of cross-plane V8s, the off-center counterweights are much more effective for that. Someone with good modeling software can figure this stuff out, I can't.

 

This is what the Roush/Yates NASCAR engines use:
Buy one of these & get a the benefit of a whole lot
of R&D to learn from

http://www.roushyatesparts.com/Roush...p/b001000u.htm

 

Risking making *** as I am not a crankshaft expert, I would say that the crankshaft in the link is significantly behind the one in the speedtalk.com link and photos. For example, the oiling holes in the journal enter at an angle, unnecessarily disrupting the oil film.

 

Not to try to derail the thread,

But Greg, with your headers I see you have 1&3, 2&4, 5&7, 6&8 paired. From my research it would have been better to pair 1&4, 2&3, 5&8, 6&7.

 

Hi Colin but I don't have 1 & 3, 2 & 4 paired I have 1 & 2 and 3 & 4 paired and to my knowledge with reference to the other bank and the exhaust experts on Speedtalk where I double checked this design, this is the optimum. If you could clarify I will check it out as no welding has been done as yet.

Firing Order

1,3,7,2,6,5,4,8.

As to the crank of Roushy Yates, that crank is 7 pounds heavier than the one I have. Heavy metal makes cranks lighter. If you can afford it, use it, no disadvantage except cost.

Greg

 

For any one who might be interested here is a model of a single plane 928 Crank 3.75" stroke.

 

Why larger counterweights in the ends if it's a single plane crank?