Hey!

I bought on eBay 4 accralite forged pistons rectified at NMS with the inscrition "0.15" on each one and about 7,8:1 comp ratio(announced).

I've assumed that the inscrition was about the measures that they took off (3,81mm short) but I've made some calculations about the comp ratio (using the same method/info that is on Burton site) and the result was about 7,14:1 comp ratio...

Since I've made the verification with the dim's that are there and the result was correct (for origin dim's, I assume that the calc is well done) I wonder if this comp ratio is a little bit low or perfectly possible...or the "0.15" may be other info and the pistons have a diferent rectification smaller than the 0.15"=3.81mm?

These where the origin parameters for the origin ratio:
Bore=79,96mm
Stroke=79,52mm
CC=1597,24mm³
comp volume=55,45mm³
comp ratio=8,20:1
These where the new parameters for my situation:
Bore=81,50mm
Stroke=79,52mm
CC=1659.36mm³
comp volume=57,61mm³
comp ratio=7,14:1
(even correcting the comp volume do get 8,30:1 comp ratio, it still gives me 7,24:1 comp ratio with the my stuff...)

If some one can check this out for me so I wont do nothing wrong and blow up my engine...

Other doubt's:

What is the boost limit I can get with these conditions (comp ratio at 7,14:1 or the announced 7,80:1)...these are my other mod's:

- Balanced and lightweightened cranckshaft and flywheel;
- AP Racing 4 paddle clutch;
- THS Performance forged conrods;
- OddKids Creations stage3 big valve head;
- NewMan Cam's complete kit (double cam springs, fastroad CVH turbo cam, solid lifters);
- Cometic head gasket;
- ARP head bolts;
- GarrettT34 stage 3 turbo;
- Mongoose 3,5" exhaust line;
- DTAfast ECU s200;
- and the Accralite forged pistons, of course xD.

I've made 0,7bar boost running and I want to know what new boost can I get to remap it...

Regard's

 

any help?