LSD for road use. Pistons, thanks
Turbo Mini Forums

Going to be running a Eaton M45 at 12PSI and expect to have traction troubles with a 3.2 FD. I have read that some of you turbo boys run LSD's on the road. I thought this was a bad idea driving wise but heavy steering doesn't bother me. I have my suspension totally set up and want to not get wheelspin as much on hard cornering/accelleration. It is my fun hack and not a serious car. I will be using a Salisbury as that is what I can get my hand on. What pre load do you run........Any takers? Also, for running massive power loads, is a SC or Semi SC crownwheel a good idea? I might consider running more boost but first things first.

Also does anyone know where I can find NOS pistons? I am looking for some 8:1 jobs.

Stu

Bugger off, I'm getting there.

Is this a Vmax kit then ?

NOS pistons? What are they???

I've never bothered with a semi, or sc FD, better things to spend my money on...

Mark or Jon will advise on the Salsbury...

nos - new old stock????

probably wrong!

And on the 7th day........... God created turbochargers!

dave , you have first hand knowledge of the salibury.lol.
there a bit heavy , mines at 80lbs , can be "interesting" on the road until your used to it .

Everyone knows that instructions only have to be read if the thing doesn't work....

Jon advises a Quaife but uses a salisbury.

A 3.2 is a reletively tall diff so traction should be fine i would have thought.

I have got wind that the LC metros had 8:1 pistons and were after oversize pistons giving the same ratio. I expect that the oversized option was not just 9.4:1. I will find out about this.

The 3.2 will be for 10" wheels and so will be more lively. I can get a salisbury for £150 and so will go with that.

Thanks for your input. S

I was interested in the cast old stock pistons as I reckon that they are up to the job. Forged ones are harder and the ring lands more 'powderable' I hear. It's hopefully going to be as non-wearing as possible, hence thoughts of SC final drives. I know a good engineering shop and they should be able to whack one out in any ratio.

Bugger off, I'm getting there.

woah!!! not too sure about your piston theory. im pretty sure that the turbo pistons were of a lot higher quality than the lowerr range ones. whilst your theory is good, i think you may well be asking for trouble. im sure someone with a lot more knowledge of this sort of thing will post shortly.

And on the 7th day........... God created turbochargers!

I heard that they are OK but they disintegrate spectacularly when detonated. I think they are OK if you make damn sure you don't get detonation. I am going to attempt not to. (Exhaust gas analyser for setup.........hopefully). I'm only going to run about 12 PSI.

More research needed.

thanks. s

Bugger off, I'm getting there.

i dont think piston rings are available for original pistons any more not sure but something to find out about

no longer a series, but still 1.3 turbo.

Try Minispares for there mega pistons, tested and good. Same rings as Omegas so easily available. They did a turbo version to with an 11.?? dish.

machining a standard piston is an option.

There is lots of choice, you just need to know where to look.

unless you ring Carl Austin who will happilly machine a standard one down to fit.

don't think a 3.2 will fit the LSD - a little too small...

UuuuuuuuHHmmm i am not sure!

Curious, according to a mate, when buggering about with BIG power figures, they favoured seriously low FD's. If I remember rightly, the huge mid range torque of 8 ports and blower engines caused some sort of failure. I am sure this was either the crownwheel or the diff housing. I will go and have a chat with this old mini racer bloke I know. He was saying that on his car the weber came right into the cabin and he would have flames shooting past him when it backfired. Also, one guy had a passenger door mounted radiator with a huge kenlowe inside. Forget ashtrays, this guy let go of his fag and it went through the fan :) This was mid 60's. Awesome bloke to talk to.

Anyway, enough talk of fancy final drives. I will have to run a 3.44 and "speeder upper" drop gears. By the way, what are gears machined from. Originally and ST, aftermarket?

s

s

Bugger off, I'm getting there.

I have ran a 3.44 semi helical FD for years and with XX amount of power and XX amount of torque i have had no problems.

A Minispares item.

XX = enough.

as above , never had any probs

Everyone knows that instructions only have to be read if the thing doesn't work....

hi
those low comp pistons will (probably) have a huge slot around the oil control ring area so wont take kindly to high revs or lots of power
the 21253 piston machined to lower comp is about he cheapest performance piston for turbo /sc
the power band being more progressive with the m45 @12 will be less prone to wheelspin than a turbo at 12psi (the turbo will get 12 psi at 4000 rpm where as the geared s/c will be at about 7 at 4000 ,geared to 12 at 7500?)

Ok, thanks for your inputs so far.

So, before I realise I have to get some very expensive pistons (bearing in mind I am not building a totally mental engine) I will look into what I can find on the cheap.

So, I read a bit and realise that 8.4cc dishes are the same and compression heights vary ( that was news to me ) for different CR's. So I will go down the scrapyard and pop a LC piston out and have a look. Before I go hacking one up to see what I am left with, what do you lot think a viable new dish size is?

What is the depth of the dish? I know very little about pistons as I haven't really payed much attention to them in the past.

Lets turn this thread to "what dishes you can machine into your pistons" (and hope the chuck is big enough).
s

Bugger off, I'm getting there.

Seriosly, why are you bothering with stock pistons? The only stock piston i'd use is the turbo one... (12.5cc)
Is £200 too much to spend for piece of mind - that way you're getting new pistons, pins, rings and piece of mind...

Dave, I expect that I will be getting it wrong a few times despite the best maths and advice!! I reckon a couple of meltdowns will be unavoidable. Being a feet first idiot often, I am gradually learning from my mistakes and will use a couple of donks to try ideas out on like modded valves, etc. I expect that I will be scrapping a few first. It would be idiotic to step into the unknown with an expensive gearbox, etc. I will find out the truth about pistons and proceed accordingly. On principle, I don't want to be melting anything expensive. The expensive ones are inevitable really as I imagine I am going to want 180hp once I get it going.

Bugger off, I'm getting there.

we`d all love 180 brake .

Everyone knows that instructions only have to be read if the thing doesn't work....

You won't ever melt a piston if you do things right... The only time i melted a set was when my bleed valve fell off on a 1/4 run...

A set of ARP rod bolts, MiniSpares Mega pistons (basically the Metro turbo piston) and you'll not have any problems there...

Stick 'putty pistons' in there and that's asking for trouble... A low CR of 8.5:1 or less, and the chances of melting a piston are low, provided it's set up...