crankshaft weights
Turbo Mini Forums

A golf ball goes further because of the dimples due to the rotation of the ball which makes a pressure differential between the top and the bottom lifting the ball like a wing. I don't see how this would apply to a crank.

Jean

http://www.jbperf.com/

Clever

I seriously doubt it!

if your looking at this sort of thing paul, i think it would be easiest to put a vac pump on the sump

Just out of interest, what affect would this have on the seals?
Also, I've always read that the a-series likes to "breath" a lot, just curious.

you need to reverse your seals if yu fit a vac pump. but only if you actually crate a vacume, if you simple reduce postive pressure you should be ok

Team www.sheepspeed.com Racing

Is a vac pump just something that connects to the breather system to in essence aid the engines breathing ability? (reduce crankcare pressure)

Sort of the opposite of forced induction for the breather system?

Less crankcase pressure, less inertial losses?

Air has mass, if there is no air there is no mass and anything moving in this vacuum absorbes less energy, which is why if you were to throw a ball in space, it would travel theoreticaly indefinately until it hit something

I understand why you want to reduce the crankcase pressure, i just wasnt sure if that was how a Vac pump worked?

If it does manage to create a vacuum then surely you would have to use a dry sump system?

Am i talking total shite? twas a heavy night!

its as you suspect james, except it will only be a partial vacum, some modern stuff run electric vac pumps (emminsions control pumps) or smog pumps, ut the traditional way is to have a vane pump running of a belt and blowing the sucked out air into the exhaust.

infact in other contries ther were minis with this setup, I belive they had head castings with holes to inject into the exhaust ports.

No, the "smog heads" forced upon us in the mid 70s had a belt driven air pump and ports to inject air into the exhaust ports just behind the valves. Awful idea.

Reducing crankcase pressure is a good thing, but running a vane pump would surely give a nett power loss?

Removed x2 post.,...

Edited by Hedgemonkey on 21st Jul, 2009.

Bugger off, I'm getting there.

The system I'm familiar with is a non return valve hooked up to the inlet manifold (sucks on overrun) and then a small pipe inserted into the exhaust pointing downstream. Resulting pressure drop creates a fair old suck. Oil catcher in line with the inlet pipe for obvious reasons and anti-flashback valve in the exhaust....

Nice touch as with running temp around 80, a vac will cause moisture to boil and get sucked out as well. Making your castrol R last longer. :)

Bugger off, I'm getting there.

thats a goot point stu i forgot about the boilinpont of water lowering in a vac.

iirc in an absolut vaum water boils at room temp,

I'd say that the benefits of having an evacusump are not primarily less windage. The lack of blowby moisture (since it will all have boiled off) will mean that you don't need detergent in your oil to avoid emulsions. So, if you have no water in the oil, you have nothing in the oil that water soluble compounds (like acids) can hang on to. This means you can run proper uncompromised oil, without the worry that you will dissolve your bearings.

If you ask me, you can run proper oil and proper bearings, which means you can push it that much harder without shagging your expensive components.

I have convinced myself that the evacusump is perhaps one of the greatest performance additions that are thinkable.....

....which doesn'ty stop my pile of bits being a pile in the shed and my mini being something I walk past and can't really be arsed to fix.....need to get a grip.

Bugger off, I'm getting there.

So did you ever run this crank Carl or is it still in the Airing cupboard?

If something is worth doing, it's worth doing half of.

not yet,

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

Fastcarl always loved seeing your stuff and the interesting things you come up with. This one... i don't know. I have been doing a bit of research on cranks for another project and there are a lot of theories out there but little evidence. so i thought i would get a baseline and model a stock crank in solidworks I then modeled a stock vtec crank and looked at the rotational center of mass. the mini crank is way out of balance in the center of mass and actually would need a lot of weight added to the counterweight to get more rpms it is common knowledge that the more counterweight a crank has the kinder to the bearings it is. since a high powered mini has bearing reliability problems anyway... The non counterweight crank probably will be a short lived engine. and shake pretty good while it is alive. Aaron

Racecar spelled backwards is Racecar

i had a thought about these heads on a turbo, i have one,
my thought was use the 'injetcor' hole's plumbed into an air container of some kind, then release the 'air' down the ports to spin the turbo up.....for an anti lag kind system,

and then i wondered how much 'air' you'd need to spin it up....lol

Bit of thread resurrection again.

Just weighed 2 x STD CAM6581 cranks and my Force Racing crank which is a CAM6232 that has been wedged, bladed, backdrilled, OD turned down to 125mm, Ground 10/10 and hardened.

1st 6581 11.7kg's
2nd 6581 11.9kg's

Force Racing crank 9.9kg's

A fair weight saving in my opinion.

If something is worth doing, it's worth doing half of.

My MED wedged and bladed crank weighs 10.6kg even after a 0.020" regrind. Its still heavy by the looks of it! Pile of shit!

I don't think thats bad TBH Colin. Mines been backdrilled and had the OD turned down extra to yours so this could account for the further weight reduction.

With your working relationship with Mr Austin perhaps you could get a new one done by him

If something is worth doing, it's worth doing half of.

Hum, I'll weigh My SC crank while its out.

It depends where the weight is though

I seriously doubt it!

My Force Racing crank which is a CAM6232 that has been wedged, back drilled, OD turned down to 125mm, cross-drilled big ends and hand clean up. No journal re-grind or hardening yet. Weighs in at 10.9KG.

Edited by Sprocket on 9th Jan, 2011.