OK, question for anyone. What is with the cutout (shave) on the back side of my piston? Do they all have them or just the shelf ones? Here is a pic of what I am talking about.

 

Here is a pic of the pistons though. It looks a little different then the 9.0 comp pistons. No cutouts for the valve. My are the 8.6 comp ones. Very nice overall.

 

8.6?!?! Ewwwww!

 

Possibly balancing to get the piston weights closer to each other. Do they all have the same mark or do they each have a different sized shave?

 

Mine look the same (same 8.6 as yours), I just assumed the shaved area was a result of the factory balanceing process?

 

Spaz...mine have the same cutout on the underside of my piston, and mine are 9.0:1. I spoke to Arias, and they said that is the spot where the machine holds the piston during the CNC machining process. It's doesnt effect anytything on the piston..and is normal.

I bet becuase the 9.0:1 have slightly higher tops, they put those valve cutouts there for safety....at least that is my guess.

 

Makes sense.

FYI , I noted that the 8.5s (CPs) offered by SGP have cutouts and the ARIAS 8.5/8.6 does not. My assumption is that CP added extra clearance for very aggressive cam lift profiles. I'm not so concerned ,since I only plan on OEM or mild street grind and any good builder will "clay" the crowns and check for clearance.

I'd be curious to know the weight specs between the ARIAS and CPs though?

 

This may sound dumb...with with the performance cams, I though they just increase the duration that the valve is open, and not the actual distance that the valve opens.

Either way, you are correct...any engine builder will check check valve clearances, and will make adjustments as necessary. They also leave extra clearance for rod stretch.

 

cams are duration and lift, but you don't want a raddical lift on a FI car you could end up floating the valves. I would venture on the JWT or nismo cams for a good daily driven FI car. thanks for the reply on the cutout. Thought it would be something like that.

Spaz

 

the weight of the piston and pin is 350 grams, if anyone know on the SGP ones please chime in

 

the most agressive cams lengthen duration and increase lift as well. For instance, the stock lift on a 350Z cam is 9.9 mm (at least from what I have been able to find. This could be a bit off.). The Tomei 268 cam increases the maximum lift to 10.5mm. The JWT cam has a maximum lift of 10.9 mm.

 

Agreed.....the Tomei 264's are only 10.2 mm and like you said the 268's jump to 10.5mm

 

I'm kinda waiting to see what Crane releases. One of their new profiles is suppose to be FI oriented. If I don't get info by the holidays , I'll probably settle for the JWT S1 profile and a 5 angle job.

 

Nice Rolex.

 

Any problems with the technosquare reflash on your z cause its a 2004? I heard that some of the production dates in 04 can't be reflashed at this time. ???

 

Tadashi is finazling the programs for the new 2004 ECU. The early model 2004's are OK, since they use the older ECU. I believe an Oct 03 production date or earlier is fine, even if the car is a 2004 model.

 

That's what a good valve spring upgrade kit like a Ferrea double spring and titanium retainer setup is for.
Usually going with more lift and a bit more duration is the best way to go on a forced induction car. The lift gets you the power without sacrificing low end torque like duration will.