Any suggestion on who to modify my K Head?
Turbo Mini Forums

Osb, I’m going to throw in a consideration into this mix.

Obviously the pistons rings create friction on the cylinder walls, more as you increase the stroke.

by upping the stroke to 86mm you will create a 5.54 percent increase in friction due to surface area effectively being scrubbed.

However my changing from 1380 to 1460 you’re only increasing the capacity 5.479 percent.

personally i think its detrimental to a high performance engine, the increase in revs possible from a shorter stoke for performance reasons out weighs that of going long stoke by the torque generated.


Don’t you think you will have enough torque to deal with? Revs are more controllable then torque.

Edited by Sam on 8th Oct, 2008.

Yeah your dead right. Me and my old man were discussing this before i was even going to 1430 let alone 1460.

This is why i was considering the 970 crank. The thing is, i just dont think the 970 will give anywhere near the amount of power/torque in a sensible rev range compared to the bigger cc's. I know that the 970s can take 10'000+rpm but i dont think it would under that much strain and boost.

plus its only supported in 3 places.

what about a shortened stroke 1275 crank?

78mm crank, what i want to do but it was more practicle to retain the 81.3mm stroke.

Again, i'm increasing the revs and thats exactly what ive tried to avoid from the word go to get the power.

more boost then.

i cant see you getting the power your after unless your prepared to get it to rev to 9+ grand also.

Sorry Sam, what i meant to say was reduce the ammount of rev needed.

Never mind osb, i read it in correctly anyhow.

In my opinion the most logical way to go would be revs or boost, idealy both.

is it worth machineing the life out of the crank for 5 percent extra torque?

The crank hasn't been machined the life out of though. Its been made to 86mm originaly.

As for the torque, because its 5% bigger it doesnt neccersarily mean i get 5% more. Being that its turbod and fuel is beeing forced into that 5% extra capacity with each stroke, it may result in it making 7-8% more power/torque across the rev range....i might be wrong though

Edited by Oldskoolbaby on 8th Oct, 2008.

where pray tell me did you get this once off custom crank which has been made to 86mm ??

1300 pounds for a steel crank from med.

not too bad, but rather you then I.

Got it from Morspeed. Its brand new though and never used. It a forged EN40B crank and similar to Swiftune cranks and cost 1500 squid

Oldie - How about you do what no-one has done before, and play with some seriously high boost figures?

Keep the bottom end simple and strong, and take a look at the area you can investigate - ways of getting more than 30psi without surging the crap out of your compressor.
Just a thought

Lol Ok, sounds like a plan

again just outo of idle intrest what are the bearing journal diameters on the big end's

Cooper S size.

I think you will find it has been

well unless you need to machine the block caseing to fit, surely it would have been?.

made weaker then a normall crank, because it has to stay within the same size constraints realisticly. so some bits will be thinner.

much like off setting a crank, its just been made up into an offset.

I think youll find its just like the second one down on this page. http://www.swiftune.com/Product/469/mini-e...crankshaft.aspx

Its not possible to regrind a standard crank to 86mm.

Not quite sure what your getting at Sam relating to the block? Why would it be weaker than any other S crank?

they they must make it bigger, meaning more roateteing mass.

i mean make clearence in block caseing for the crank to rotate

you can get thoes cranks for 1000 pounds brand new =/ from mini speed

Edited by Paul R on 9th Oct, 2008.

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

That crank you have give a link to came from the same place as the cranks MED, Morspeed and a cupple of other A series tuners supplyit is a modifyed forging from the orignal Rover dies it starts it life as a STD stroke crank and is reground to the desired stroke that is why it has S diameter jornals nearly all the steel cranks on the market come from the one guy he also produces nearly all the race valves People in the know will know exactly the guy Im talking about.
you crank with out question is ground from a std stroke to the stroke you say,
and for you information it is possable to regrind standard cranks to 86mm as long as you are happy to use 0.010 under size big end bearings,
regards,
Paul.

Edited by PaulH on 9th Oct, 2008.

playfull = expensive......your be more than happy with a realible (as minis can ever be) 200bhp and have much more road, track, drag time and less garage time.

"Cars are a lifetime of pain"

Last time I checked the crank it had standard S big ends though. Im not saying your wrong by anymeans as Im not 200% of its original origines anyway.

ministef1 your 100% right and I cant stress this enough. **It wont be running to its max all the time**

Ill be happy with 150bhp in a mini as they are quick as hell anyway.

ive been digging around, anyone know what happened with this?