Andy Royles old 1460 minus?
Turbo Mini Forums

Im guessing that stroking a crank to 86mm is going to cost around £150?

You cant stroke a crank to 86mm, it has to be a billet or forged. you can stroke to (I think 84.something) to achieve 1425cc

Paul

I seriously doubt it!

Stroked cranks, are 84 or 84.3mm depending on who you buy from. Aparently.

You will laso have to factor in the cost of either H beam cooper S rods or standard cooper S rods, but i suspect you would need to get either of those modified to fit the crank journal widths.

Oh right, so thats where the large expense would come in, i think im just going to stick to 1380.

Thanks for all the help guys.

As Paul said, they are not really worth the extra money, more of a bragging rights motor

74mm pistons and 84mm crank will give 1445cc

Edited by Sprocket on 30th Nov, 2008.

74mm pistons, walls would be getting abit thin lol.

Does that mean to stroke a crank to 91mm it would also have to be of the billet variety? (just curious)

Why would you want to stroke the engine to 91mm anyway, you've been reading Vizards book

86mm cranks need block clearance mods, just think what you have to do with a 91mm stroke, for a start the pistons will pop out the top of the block, and the combustion chamber will be difficult to get the right size to get the compression ration back down from the dangerous levels it would be at, and pretty much be a low reving slug

Big is not always better, hense my first ctatement

Edited by Sprocket on 30th Nov, 2008.

hahaha yeah also been reading mini performance manual. I wouldnt have thought the engine would last amazingly long anyway.

Thanks very much for all the information guys, all been absorbed, and helped me to make some final decisions. 1380 it is.

On 30th Nov, 2008 Sprocket said:
Why would you want to stroke the engine to 91mm anyway, you've been reading Vizards book

86mm cranks need block clearance mods, just think what you have to do with a 91mm stroke, for a start the pistons will pop out the top of the block, and the combustion chamber will be difficult to get the right size to get the compression ration back down from the dangerous levels it would be at, and pretty much be a low reving slug

Big is not always better, hense my first ctatement

But would it be worthwhile overboring to 73.5mm, with a fully worked 84.3mm crank as this is cheaper than the same but in 81.3mm from MED. That way block mods arn't required, but still obtaining a 1425cc motor.

If you can lay your hands on a GT crank and S con rods, would it pay off with a turbo motor? Running 15psi would you see a good increase in hp and less turbo lag???

I suppose the issue would be achieving a suitable CR?

Chris.

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A 84mm crank isnt cheaper than a 81. Stroking a crank is going to cost an extra £100ish, then you need S or steel rods for the journal size.
Compression ratio is an issue, particularly if you turbo it.

Paul

I seriously doubt it!

A dogs bollocks 84.3mm crankshaft costs 340 quid from MED.

A dogs bollocks 81.3mm crankshaft costs 360 quid from MED.

As I said on condition you have a GT crank? Therefore if you already have the right parts (i.e. S rods and GT crank) then it is actually cheaper.

Chris.

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The GT did not have S rods...

????

Im not saying it does.

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I know, but I am saying it does not :)

Im not assuming anything.

All im saying is, if they are willing to, they can source them seperatly or even together from the same seller.

It was only very recently that someone on this forum was actually selling a 1275 GT crank AND S rods, good nick and not for that much money.

Chris.

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Im not being a smart arse James H, il be the first to admit that im a rookie when it comes to tinkering with engines.

Just had a question thats all

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hehe, i didnt mean you fella. i was just sayin you were simply asking if that crank/rod combo would be a cheap solution. didnt need the whole who has them laying around comment.

was a bit of light hearted banter, not aimed at you by any means.

No worries then

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I seriously doubt it!

Paul, on the MED website.

http://www.med-engineering.co.uk/home.php

Infact the price has gone down... to 331.50! Jesus MED should offer me a job... free advertisement!

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Sorry but the fully worked 81.3mm stroke crank is bladed, the 84.3mm one isnt

lol i do actually have a gt crank sat on shelf in my workshop doing sod all, if only i could say the same about the rods.