at what point would you need to fit oversized pistons ? is 0.5mm gonna do anything, or does it just make for a fresh snug fit after 15 years of thrashin out your old block ? ( after re-bore of course )
If its had 15 yrs and prob 100k of thrashing
then you may as well go for a rebore 0.5mm is the norm although i have gone 1mm due to scoring of the bores.
It will basically make that part of the engine like new again (execpt for corrosion in the bore walls which cant be helped)
while on pistons... flat, unfinished pistons, can these be machined to set spec or do you need to know what cam / crank / con rods are to be used ? how or who would spec your unfinished piston to a finished piston ? again, brings me to the "is it worth doin it diy?"
Yes pictons can be machined to a set c/r (i bought accralite ones and had burton machine them down)
And yes you would be better knowing your final spec before you have a sit load lopped off the top of em
con rods... what point would these need to be steel ? what kinda power would / could the STD units fail givin that they are of sound condition.
Circa 250 Bhp (i would allways replace the old rods with new std ones at least!)
would an aim of 230-250bhp need all this bottom end work, or is it a lil too over spec'd ? or is it better to over spec and increase the reliability side ?
Allways good to have a nice bottom end so more power can be achieved with out taking the engine to bit every 10 miles
also, while Im here... what makes for good torque figures in a 1600 ( or close as ) CVH ?
A shit load of boost and a propperly speced engine!
IMO DIY is good for the CVH engine, obviously there are thing you arent going to do yourself like balance/regrind/polish the crank.. however the actual putting together of it is childsplay. (were you any good with lego ?
)
For a 250 Bhp CVH my basic spec would be this. (using mainly off the shelf parts)
rebore (if necessary) 1600 block.
New forged pistons and rings (id go with accralite personally cant fault them in mine) with 7.6:1 compression ratio
Fully balanced bottom end with reground/polished crank and suitable Heavy duty bearings
Standard main bolts
A.R.P Big end bolts
Either new STD con rods (on limit) or steel h section rods
'Stage 3' hybrid turbo (.48exh .55 comp) although prob very near its limit @ 250Bhp
'Stage 3' big valve head Ported and polished IMO is only good for arround 220bhp MAX
Piper 285t cam
5th injector
and probably arround 25Psi
there are of course incidentals such as plugs (arround £100
) zorst, filter, hoses etc and finally a suitable chip (turbosystems will remap your ignition ECU for arround £175)
Anyway hope that helps if you want anymore help give us a shout
CheeRS
Phil