6 replies to this topic

[bully]

hi im after building a short stroke screamer for autograss racing with 1300cc class limit,

I want to know how to obtain such an engine without buying expensive cranks

 

like 850 crank in a 998 bored out to the max (what is the max it can go)

 

bit of a bodge but making t bearing shell shims to fit the 850 crank in a 1275 block

 

I have a 850, 998 1275 1293 1380 and 1400 engine at my disposal im currently running a 1293

 

what are youre thoughts?

 

thanks

[Cooperman]

If the class limit is 1300 cc then that is what you need to win (no substitute for capacity).

So if you overbore th,say, 73.5 mm, then use a standard crank with the big end journals offset to give the shorter stroke, with the journal diameters ending up as a Cooper 'S' big end and use Cooper 'S' rods you will have the correct capacity.

Balance everything, use Omega pistons (or similar quality high revving ones).

Fit an ultra-light flywheel and a really 'hot' cam, ultra low FDR and custom-curved distributor.

[bully]

What size would the stroke be and who would do it med? Do know how much it would cost
Hot cam? I'm using a 296 scatter cam in my 1293 but the swiftune sw10 was better as for fd I'm using a 4.1 on minispares lsd? Thanks

[Cooperman]

You will need to do the calculations, but the Cooper 'S' has big end journals of 1.625" whereas the normal A-Series crank had 1.75" big-ends.

[mini13]

with 73.5mm pistons your looking at a 76.55mm stroke on the crank,

 

the shortest you can get to with a reground crank is around 78mm so you'd be looking at a billet crank whcih is £££

 

http://www.minispare...|Back to search

[Cooperman]

I didn't do the maths and had forgotten that to use a standard crank offset ground to get a shorter stroke 1300 the maximum overbore is not 73.6. I might do the sums later to calculate the bore size for this, but not at this moment.

[David Reid]

If this is for class 5 your capacity limit is 1420cc.
to be honest I don't think you will ever make a 5 port a series competitive, I run a 160bhp vauxhall and have only just got to the point I can win club meetings. This my car (mini pickup)