A-Series big end weight comparisons - what's best?

Friday tech and today a look at the various crankshaft/conrod big end journal dimensions and the huge differences it can make on a competition engine...
www.med-engineering.co.uk

[@jameseastwood4984]

I appreciate the time you've taken to put these films together. Very informative.

[@quintalyurts8192]

Very, very interesting.

[@truckatadders]

Factor in a lightened flywheel & clutch ass & a lighter front pulley & that's a huge weight saving 👌🏻👌🏻

[@levigwinup7612]

So im still learning but would a "perfectly" balanced crank with a connecting rod and piston stop at any position on a set of Parallels instead of dropping straight down? Has anyone had to add weight to the counter balance?

[@oldschool1993]

Another way to illustrate this is- 1200 grams = 2.65 pounds of rotating weight- spinning at 8000 rpm = 21,200 pounds of weight the motor is moving in 1 minute. In a 30 minute race that would be 636,000 pounds less weight that your motor is moving compared to a stock rod and crank.

[@LoneStarMini]

if the crankshaft is milled down to 2.65 (Cooper S), then would a thicker shell/bearing be required? If this is true, then the added weight of the thicker shell must be included in the weight comparison.. very interesting.. wonderful videos..

[@MEDEngineeringTechVideos]

No, as you would then run a Cooper S type conrod to suit, with the smaller big end journal.

[@LoneStarMini]

@@MEDEngineeringTechVideos ah.. makes sense. I’m guessing then that the the over con rod arm length is slightly different then… learning all this as I go…

[@mmvc1998]

Can you also use this for a road engine? And would it then be drivable?

[@MEDEngineeringTechVideos]

The multiweb?

[@mmvc1998]

@@MEDEngineeringTechVideos Both the pistons and the multiweb yes

[@MEDEngineeringTechVideos]

@@mmvc1998 Yes, there are a number of these in use on the road. They make a very smooth revving engine.

[@mmvc1998]

@@MEDEngineeringTechVideos Good to hear! Thanks for the quick response!

[@user-cq2it4hc6e]

@@MEDEngineeringTechVideos Hello. Are these parts available individually or do they require quantities? Are they manufactured on demand or for specific types of engines?

[@duffield55aj]

What RPM are those cranks and rods red lining at?

[@MEDEngineeringTechVideos]

It's usually limited by the camshaft and head characteristics. Standard cranks we don't recommend going over 7000rpm on a regular basis, these will just keep going.

[@duffield55aj]

@@MEDEngineeringTechVideos I use to manufacture and fit a steel centre main. Had a standard one break.

[@MEDEngineeringTechVideos]

@@duffield55aj yes they can flex quite a lot at higher rpm

[@currentbatches6205]

1:33 - You lose the overlap between the rod and main journals; care to comment on that compromise?

[@stevevacopoulos2422]

Unspun weight ? Crank is a rotating assembly including the big end half of the rod small end 1/2 is considered reciprocal.

[@jimsmith1856]

Steve needs a fucking big joint.