JB_97ws6TA

iTrader: (6)

I am shopping for pistons for my 383 build and while doing some searching around some people were adamantly advising against using dish pistons for NA builds. It seems that out of a true dish piston that would be more purpose built for boost and you wouldn't get the same (or hardly any) squish out of those pistons but what are people's thoughts about an inverted dome piston in a NA build?

97Z28SS

iTrader: (5)

It really depends on what the size is of your combustion chambers and your static compression goals, however most people use flat top pistons which will give 11.5:1 - 12:1 static compression with stock size combustion chambers. So bottom line is say no to dished pistons for a na build unless you plan to run boost later.

JB_97ws6TA

iTrader: (6)

heads are 54 cc and to get the quench in where I want it -16cc piston gives me 8.93:1 DCR with my baby cam and ~11.0:1 SCR. I was just wondering if there was any other reason to not run dish pistons in a street/strip NA build...

96capricemgr

iTrader: (1)

Run higher compression and a properly sized cam.

JB_97ws6TA

iTrader: (6)

I have to pass emissions so the cam I have is about as big as I can go, what would be your ideal DCR? I have been told no more than 9.5:1 DCR

tonskiguy

iTrader: (3)

Been there, done that, big waste of money and disapointment. Pulled the engine back out after 1500 miles and changed out to flat tops. Much better. I will make you a killer deal on a set of slightly used -16cc SRP's if you want them.

JB_97ws6TA

iTrader: (6)

What was your compression ratio, cam size, and quench distance out of curiosity. I can't really use a flat top and the head that I want while having a decent compression ratio and proper quench distance.

94Z28rag

iTrader: (10)

I went with flat tops and a lot of compression. Don't fight what works.

BLK,97,T/A,M-6

Cam lift doesnt affect emissions as much as duration, that kills your emissions. And unfortunately for us it is the big duration numbers and hi rpm's that make NA cars power. If emissions is neccesary, keep the duration down and the compression up.

I would take a low lift, and hi duration cam long before a low duration hi lift cam. like a 236/240 @ 050 and .500/.514.. But this cam wouldnt pass emmisions even if the sniffer was unplugged.

BLK,97,T/A,M-6

And btw: any good engine builder will tell you to use flat top pistons at all cost. They provide better overall fuel atomization. Infact, they would even tell you on a boost motor, To buy heads with a large combustion chamber to get your CR down, and use flat tops. Unless you already have the heads, then keep them and use dish. But basicaly, dish should only be used kinda as a last resort. The difference isnt big enough to warant selling heads, to buy new ones just so you can run flat tops, but avoid dish if possible.

duh

iTrader: (16)

exactly what has been said, a dish piston is a crutch for an N/A motor. Flat tops or domes are the only way to go. Otherwise it's like starting a race with a bullet hole in your foot.

Ray@Nitrous Outlet

maybe thats why my car is so slow...-18cc dish piston...and an eagle crank

FASTFATBOY

iTrader: (23)

Use a reverse dome piston, not a dish.

JB_97ws6TA

iTrader: (6)

Yeah that is what I had intended, I was just sloppy with the terminology but that is what I ordered was some -16cc inverted dome pistons. The inverted dome still has plenty of meat outside of the combustion chamber itself so you still get squish as opposed to a true dish piston that lacks a "quench pad" as I heard it referred to earlier.

BLK,97,T/A,M-6

I'm not knocking your build, BUT ideally, you want to lose the compression in the CC not the piston. Im sure the laughing gas more than makes up for it.

Ray@Nitrous Outlet

I agree....I was just being a little sarcastic, my pistons are actually inverted domes, that were originally spec'd for a set of LT1 castings that were milled to a 48cc combustion chamber. The new AFR heads dropped my compression quite a bit, but I will readjust it when I replace the pistons.