k10 questions

[superls]

hi all,

need to find out a couple of little things before starting my latest project.

does anyone know the stock valve duration and lift.

can anyone suggest any durations and lift which better suite a turbo car, such as the figaro valve duration and lift, (if different from the non turbo ma)

ive read a couple of things mentioning that when turbo'ing reduce the compression ratio. ive hered of spacers used between the head and block, 2 headgaskets, and obviously custom pistons. but as i have a couple of spare sets of pistons and metal working machinary could i not just take some off the top of the piston?

also how is the compression ratio calculated?

what is the c/r of the figaro as a comparison?

cheers i think that is all for know, thanks in advance superls.

 

[frank]

superls

i,ve seen the fig engine c/r listed as 8:1, and personally i would open up the combustion chambers to drop your c/r, then check they are equal, and (for example) 10% bigger with a perspex cover with a hole in the middle over the chamber, then measure how much thin oil is needed to fill the chamber.
i posted a wiki page the other week with the cam specs (st etc) but i cant find the damn thing now:doh: (i think forced induction cams just need very little overlap)

 

[ollyc98]

I think comp ratio is 10.3:1 but I've had so many cars that might be for another one lol

 

[superls]

superls

i,ve seen the fig engine c/r listed as 8:1, and personally i would open up the combustion chambers to drop your c/r, then check they are equal, and (for example) 10% bigger with a perspex cover with a hole in the middle over the chamber, then measure how much thin oil is needed to fill the chamber.
i posted a wiki page the other week with the cam specs (st etc) but i cant find the damn thing now:doh: (i think forced induction cams just need very little overlap)

is that a slight overlap on the inlet and outlet valv on the same cylinder? or something totally different?

surley its easier to mke the pistons have a flatter top then to machining the cylinder head? how would you open up the combustion chambers? what advantages over taking a bit off the piston does it achieve?

 

[frank]

superls

yeh, n/a,s use overlap (exh closing overlaping the inlet opening) to scavenge the spent gasses from the combustion chamber, but a turbo would blow too much fresh charge out with the spent gasses.
i think you would risk a melted top ring if you machined the piston crown, and opening up an ally combustion chamber should be a doddle (have a look at makrakin08,s head)

 

[superls]

frank, just looked at his head and it doesnt look like theres been alot taken out, will that much really make any differance at all?

having not examined the pistons maybe i could take a little but of material out of the 'dish' to avoid going too close to the top ring?

 

[frank]

frank, just looked at his head and it doesnt look like theres been alot taken out, will that much really make any differance at all?

having not examined the pistons maybe i could take a little but of material out of the 'dish' to avoid going too close to the top ring?

superls, they,ve gouged a fair bit from around the inlet valve, looks like about 10% (4cc ?) extra volume to me
and personaly, i would section a scrap piston to see how much meat there is, before deepening the dish :glance:

 

[superls]

superls, they,ve gouged a fair bit from around the inlet valve, looks like about 10% (4cc ?) extra volume to me
and personaly, i would section a scrap piston to see how much meat there is, before deepening the dish :glance:

that would be good if i had 1 spare i have got 4 spares out of (well still in) an old engine, so cant afford to chop 1 up really, good idea though if i could get hold of a spare.

i do have a set of ma10 pistons though but dont really want to touch them.