ZRP Forged Conrods

[227bhp]

It is you're right, it's so the exiting oil gets squirted up at the pistons to cool them down and lube the small end bush.

[Boosted LS1]

Some rods will come with 4 slots instead of 2. They splash oil all over the place, especially the bores. Some may have a drilling from the big end to the little end for pressure fed oiling.

[99hjhm]

Swiftune are using a big end that looks like the top of a castellated nut in their Mini engines, don't seem to have any issues with them. Almost went with it on a set of custom rods for a different application by same manufacturer but decided against it.

[stevieturbo]

99hjhm said:

Swiftune are using a big end that looks like the top of a castellated nut in their Mini engines, don't seem to have any issues with them. Almost went with it on a set of custom rods for a different application by same manufacturer but decided against it.

Maybe partly because of the large offset in use ?

https://swiftune.com/parts-shop/con-rods/swiftune-...

[Boosted LS1]

^ Crikey, that looks gash. Does a stock mini rod have that offset? I'm assuming it's a 4 cylinder banger, 1 rod per journal etc. With those huge slots I'd expect the rod end to bleed out but obviously not. Maybe the oil pumps set at 100 psi :-)

Or have they widened the journal to get more bearing width?

Edited by Boosted LS1 on Saturday 24th February 17:00

[stevieturbo]

Boosted LS1 said:

^ Crikey, that looks gash. Does a stock mini rod have that offset? I'm assuming it's a 4 cylinder banger, 1 rod per journal etc. With those huge slots I'd expect the rod end to bleed out but obviously not. Maybe the oil pumps set at 100 psi :-)

Or have they widened the journal to get more bearing width?

Edited by Boosted LS1 on Saturday 24th February 17:00

Because of the 3 journal crank, yes A-Series rods do carry an offset...I guess it's better than having a bend in the middle of the rod lol

Or more recently Swiftune developed a "fake" 5 bearing crank for them which allows the use of a thinner and straight rod without the offset.
Although strangely I cant find it on their website, although MED now list this kit. Pretty cool

http://www.med-engineering.co.uk/med-multi-web-cra...

[Boosted LS1]

^ and is all this the way to get performance? Life used to be so much simpler, lol.

[99hjhm]

As said above the offset is where they stretched the A-series from 998 which doesn't have offset rods. Offset big ends work totally fine, offset little ends don't.

The oil pressure is kept by the bearing, so it doesn't matter how much bleeds out the sides, infact most modern (late 90's?) use piston guided rods so more end float on the crank which reduces friction, probably some other advantages which I'm not aware of. I'm sure some of the castellated rods I have seen actually had deeper slots, maybe wrong.

This is worth looking at when comparing Mini cranks....

http://www.shengineering.co.uk/content/mini-cranks...

Notice how much is left surrounding the little ends, these apparently hold together fine at 9k all day long (Youtube Mike Jordan Austin A40 Goodwood), has them balanced by the same company we use which probably helps as Trevor Wilkinson does know a thing or two about crankshafts. Taking way the shoulder on the little end improves the counter balance which is a flaw of a standard Mini crank.

The fake main bearing idea is nothing new, seen Aston Martin 6 cylinder, 4 main bearing engines with aftermarket crankshafts dating to the 1980's with the same idea, probably pioneered by Gordon Allen. My thought is it adds a lot of weight to the assembly, mini main bearings are pretty tiny and there are still only three of them. The same Aston crankshafts now are based on the original design and are far superior and far lighter mainly due to computer aided counter balance design and analysis. Not to mention excellent manufacturing by the likes of Arrow.