Will this be a problem? :(

[Mathias]

Ok so i've posted my progress thread on a few other forums, and its been pointed out to me that there may be a problem with my spec :(

Baically when i bought my forged pistons, wossner confirmed that the low comp ones that i'd need for my vtr 8v turbo'd engine would be the same part number as the 16 ones, so i went with those and fitted them, but if you look in the picture below the pistons have the cut out for valves on both sides as they would for a 16v head, will this cause problems in my 8 valve engine, somebody has pointed out that there may be a problem with valve clearance at top dead centre?

http://i290.photobucket.com/albums/ll271/WIDE-VTR-TURBO/saxo/Picture006.jpg

[DaN90]

Do the 8v ones have cut outs in them??

[raunchz]

Suppose it all depends on where the valve in the 8v head sits on the piston in relation to where a 16v valve would sit.

I would imagine the 8v would need a different valve cut-out in the piston to a 16v head due to the space for 2 valves per cylinder vs 4 valves per cylinder. I can't say for sure as have never compared them, but common sense would tell me the valves need different sized valve-cut outs in a different location on the piston for 8valve heads.

If you're not running an aggressive camshaft then should be fine, otherwise it could be a problem timing the camshaft up for 'optimum' power etc. due to limited clearances, as I suppose you effectively have standard 8v pistons with regards to valve clearances?

[Sophia_Bush]

IIRC VTR pistons are flat top either that or it had a slight dish/dome what I would do since the engine is together is turn the engine over my hand slowly Andy.

[Mathias]

Wild camshaft already fitted :(

Think it'll have to be stripped again, or as gav says turn over slowly by hand :(

[raunchz]

Wild camshaft already fitted :(

Think it'll have to be stripped again, or as gav says turn over slowly by hand :(

Looking at them you effectively have standard vtr pistons with regards to valve clearances? So if the camshaft can't be run on standard pistons then you will need some 8v low comp pistons with different cut-outs, or get 8valve cut-outs machined into those pistons? Sure Colin (eeyore) could do that?

How wild is wild ?

[DaN90]

If i can remeber correctly the ph1 block has flat pistons and the ph2 block has domed pistons. I would however check it out first mate because when you do eventually run it up you will want to be sure that the clearance will be enough espesh with a spec like your engine.

[Mathias]

piper 285 already fitted, have emailed colin to ask him just waiting for a reply, hoping i wont have to change pistons, cams etc

[raunchz]

piper 285 already fitted, have emailed colin to ask him just waiting for a reply, hoping i wont have to change pistons, cams etc

don't people fit Piper BP285's on standard pistons? If so then i'm sure you'll be fine.

I'm running the 16v version of those cams on standard 16v pistons and its fine so fingers crossed the 8v equivalent will be fine also !

[Mathias]

well thats what i thought, yes they do run those cams on standard pistons, so i think i'll be fine too! hope so anyway, but best to check before i bend all 8 valves

[oadamo]

the easy way to find out is put the bottom end to tdc, then put some plasticine on the pistons fit the head and turn the cams over by hand to see if it hits. be carful doing this tho.
adam

[Mathias]

anyone else know if they'll be ok or not?