A friend of mine wants to make the bottom end of his s2 low comp but wants to do it on the cheap. i advised going the hole hog with rods etc but he seems to think if he just changes the pistons and rings then he will get away with that without making the engine weaker... is this correct or is there more he has to do???

thanks in advance for your answers guys!!!

 

One can always take max ~1mm away of the ~7mm thick piston crown in a lathe keeping in mind that it's better not to dish the piston all the way to the edge. The pistons should of course be balanced afterwards, and of course it's better to just replace everything but that obviously isn't what he wanted.

 

I use to run a 1.6 ERST on low comp pistons with standard rods on a re-ground crank at 23psi.
S.

 

the rods will be the weak link they can only take around 260 bhp what power is he after ?

 

If he wants to do it on the cheap you'd be better off getting a decomp plate. Works a treat. I was running 18 psi all day long without problems.

If done properly these are a way of going low comp.

Cheers
Dave

 

cheers guys for the info

my mate only wants about 220 and is running efi like i am, i thought he mite get away without doing low comp for that bhp but supposiddly no?

 

You should be fine without lowering the CR, if you are EFI.
S.

 

Easily. 8.3:1 is very low comp to begin with.

 

Thanks SAS

what would he need roughly to run that power.

i think at present he has standard bottom end
stage 3 head
stage 3 turbo
chip
air filter
Efi
3 inch exhaust
kent 34
2.5 bar map sensor


oh and hes not sure what injjectors either he wants to go for

 

He will need a front mount intercooler.
A set of Bosch 803's (dark greens) injectors.
Uprated clutch.

 

you cant run 803 on efi only on cossie mangment

 

jonny make sure your m8 but new shells in as well


if you do things on the cheap it will end in tears

 

yeah i know that from experience with my old car mate!!

thanks for the tips guys!!