Making your own crank shaft

Does anyone have any technical information on current / after market cranks. Or any cranks come to that.

I'm researching this realistically.

Would be from a casting position, with post-cast finishing machining processes.

As well as upgraded gear sets for transmission, I'm looking at what internal items I could manufacture with casting using super alloys.

Really surprised no one's at least had some idea on this. Thought I'd have ideas flooding in.

99% of aftermarket performance cranks are machined from a billet or a forging, not a casting. In the UK Farndon Engineering did my Skyline RB26DETT crank. In the US SCAT are popular. Farndon's used to do the stroker cranks for HKS, not sure who do them for HKS now. Many cranks and rods are now re-badged frm China. Some are OK, some are not. I know of a good Chinese supplier for cranks and rods for many Jap and German engines, and had a crank and rod X-Rayed and the material checked out.

99% of aftermarket performance cranks are machined from a billet or a forging, not a casting. In the UK Farndon Engineering did my Skyline RB26DETT crank. In the US SCAT are popular. Farndon's used to do the stroker cranks for HKS, not sure who do them for HKS now. Many cranks and rods are now re-badged frm China. Some are OK, some are not. I know of a good Chinese supplier for cranks and rods for many Jap and German engines, and had a crank and rod X-Rayed and the material checked out.

Thanks for the reply Chris.

I've been reading a lot of the cast cranks are compared against forged and billet but don't have the material taken into consideration. I've found most cranks seem to be iron based material, whereas forgings and billets are usually steel.

I'll look up the companies you've listed and see if I can find any further information regarding the materials.

Thanks Chris

I really am trying to investigate this further. The market seems to be victim to only being able to find parts for what we can search for. I'm a strong believer we have the ability to develop new parts ourselves. I'd love to be involved in a market share and introduction of such items to the communities. At that high level, I'd probably consider other engines as well (to make sense business wise). I have the availability of a world-class casting facility, I just need to have a business case and be scientific enough to justify making such items at a profit.

In a perfect world, I'd be trialing my own crank shaft made from superalloy.

Not sure alloy of any kind would ever be the right material for a crankshaft, simply because its too light, you would need to counter weight it for it to function correctly, as the weight of the con rods and pistons would not be counterbalanced during dynamic operation, so I would imagine that its counter productive to to do that when perfectly good steels/iron are easy to achieve the counterbalance without having to use heavy metal to offset the alloy.

Superalloy is much different to the common lightweight-alloy in terms of it's density and weight. You'd be surprised how similar it is in terms of weight compared to steel. It's not light weight that's for sure.

There are upto and sometimes more than 10 components to superalloys used in aerospace, with various combinations for different properties (as is obvious). At this time I don't think weight should be a problem. Of course though, top tip noted and I'll definitely compare this so thanks for the heads up!

Not trying to sound negative but the reason theres not many companys making cranks for our cars is because the stock crank is very good, the only time people change them is when fitting stroker kits.

I am not sure why you feel a casting would be superior to a billet, with uniform grain and zero inclusions, or a forging with optimised grain flow and no or few inclusions? A casting is cheap, not very wasteful of materials and quick to machine, but has little to offer for a con rod or a crankshaft save cost.

Not sure alloy of any kind would ever be the right material for a crankshaft, simply because its too light, you would need to counter weight it for it to function correctly, as the weight of the con rods and pistons would not be counterbalanced during dynamic operation, so I would imagine that its counter productive to to do that when perfectly good steels/iron are easy to achieve the counterbalance without having to use heavy metal to offset the alloy.

All steels are a blend of alloys giving them different properties, they're made up from different components such with main ingredients being Iron & Carbon, then they get small amounts of Chromium, Manganese, Molybdenum, Vanadium, etc etc depending on what properties you want your Steel alloy to have

The same goes for Aluminium which will also be blended with other components thus making it an Aluminium alloy of which there are also dozens to choose from

http://www.gcsescience.com/ex32.htm

http://www.thefreedictionary.com/Alloy+steel

Some info on machining and materials, easy reading:

All steels are a blend of alloys giving them different properties, they're made up from different components such with main ingredients being Iron & Carbon, then they get small amounts of Chromium, Manganese, Molybdenum, Vanadium, etc etc depending on what properties you want your Steel alloy to have

 

The same goes for Aluminium which will also be blended with other components thus making it an Aluminium alloy of which there are also dozens to choose from

Maybe I miss read then, and obviously was not being pedant enough ,I was under the impression that he was referring to aluminum alloy, rather than a steel alloy, hence my comments about it having the weight to be effective,

He said superalloy.

I'll take the soup please, as it's lunch time.

Not really sure what benefits the "super alloys" would hold. the straight six is not an ideal engine for high RPM, the market does not demand it, nor would a lengthy crank be suitable for miniaturisation of pins and cheeks, as a long crank needs very good stiffness to avoid torsional issues.

Going even longer than the stock stroke precludes very high revs as the loading becomes excessive, as does piston speeds. The only place I see claims of high RPM (9000 RPM +) are in drag race engines, that only need to survive for seconds at a time. Being that most 2JZ performance engines are turbo charged, there's little need for high RPM, and associated crankshaft optimisation. Whereas a 4 cylinder 1.6 race engine may have been expected to regularly and sustainably turn 10, 500 RPM plus in the 1980's, and indeed thanks to a short stiff crank, a short stroke and big bore, they achieved this as a matter of course. The Toyota 4A-GE based Formula Atlantic engine in one of my sports prototypes revs to 10,500 plus, on a billet steel crank, with no great pretensions to exotic origin. just an EN40 steel billet. It's US origins show in it being micro polished, but this is probably 90% BS in this application. Whilst the main cap suffered a fatigue crack (the engine had a good few hours on it), the crank survived. Top images are of a stock 4A-GE turbo crank. Bottom the billet, micro polished Formula Atlantic crank.

http://www.newbury-house.com/atlantic/atlantic.html

Sounds highly stressed, and it is:

The stock one might be spot on, but I'm looking to see if I can cross my career with the industry, and not only create an improved product for a lower cost but also consider other engines.

Pistons and cranks must be manufactured somewhere. Higher production companies sub contract to casting and forging facilities, I'm investigating the potential to look at this. I'm just using the Supra as a main engine for my preliminary research.

I'm not looking to try and make an upgrade for the Supra and leave it at that. My cost model would consider this (if worth it), but it would be an industry wide consideration.

Billet and forging may have optimised grain structure, in my industry I'm able to create single grain parts, and have no grain structure at all, something billets and forgings can't compete with.

Perhaps just manufacturing stock products and not high performances ones may be an option. I'm trying to consider the industry not just have a single goal in aim with a high RPM stroker or even the 2JZ, that's just my datum for research.