Im looking at a set of mazda 323 gtx pistons. They have a nice dish and would be good for a high boost turbo build for my '92 1.6l. Does anyone know if these are the same bore or not as the miata na 1.6l motor? Also does anyone know how the wrist pin height compares to the pin height of a stock miat na 1.6l? Basically i'm trying to figure out what the in hole measurement these 323 gtx pistons will have compared to the stock na 1.6l measurement to determine if i have to do any decking.

Anthony

 

http://cgi.ebay.com/ebaymotors/mazda...98167862QQrdZ1

Same bore , lower compression (gtx block is the same as the miata..)
The oil pan and the intake are different, also the oilpunp (dipstick hole)

The gtx head is slightly different as it has 2 water lines @ the back...
All difference has to do with the miata is an in line engine...

 

I believe you mean longitudinal engine... aka mounted front to rear rather than side to side.

 

so...rod length, piston pin height, deck height, and in hole measurement are all the same on a 323gtx engine. That's saying that the gtx motor achieved 8:1 compared to our almost 10:1 compression in the 1.6 na's by just dishing the piston. Is the dish really that deep in these gtx pistons.

P.S. that is the exact set i was looking at on ebay

 

question. Why?

Pistons are dont seem to be the problem on miatas. Plus there is always a trade off. All things equal a turbo running at a lower pressure setting with higher comp pistons well be equal to the same car running lower comp pistons and higer boost

 

Well well...the pistons themselves arent the problem in stock na 1.6l agreed, but the compression ratio that they yield call for some extreme measures to safeguard your butt against knock at higher boost levels. Lower static compression = higher attainable boost levels + excellent detonation resistance + more horsepower than a high compression engine of same displacement. So, the extra insurance against knock at high boost levels afforded by these pistons will save the pistons themselves from being fried and also the weak link of high boost 1.6's "the connecting rods". Predetonation in a high psi boosted 1.6 with stock rods spells certain disaster.
The reason i'm so worried about wrist pin height and in hole measurment of the gtx pistons is b/c i'm too impatient to wait to measure the things and i'm anticipating decking etc. to keep in hole measurement reasonably close to stock measurement for an effective squish area.

Anthony

 

I would agree except that I know many people that run high comp motors with
after market ecus with no problems. I use to think that way a long time ago.

also High boost means what to you??? what psi on a turbo flowing what cfm's

 

my point exactly. aftermarkt ecu, knock sensors, timing retard curves are all ways to control detonation but, low compression pistons are an ever present mechanical solution to reducing knock in a high boosted motor. combine a solid foundation of within reason lower compression pistons and nice ecu and you can have no fear of detonation unless you have rediculous carbon buildup well......i'm only putting together a diy kit at the moment with a t25. aiming for 8-9psi for now. its always nice to get parts in line when its time to take it to the next level. regardless....this post is getting off topic. i was just wondering if anyone had some meas. on the gtx pistons. They're kind of a lost cause anyway....if i were to spend money on new pistons im probably not going to be getting stock bore used pistons. would atleast go with a little oversize. know what i mean. later.

Anthony

 

Bore & Stroke 83mm x 85mm

 

Taken from http://www.protegefaq.net/ thanks edwyn

 

thats for the BP pistons. the 88-89 323gtx pistons are the same size as stock miata b6 pistions.

 

just a tad off topic but i've been told that if i order pistons for the 323 gtx, i would be sent a miata piston.

 

yes, GTX pistons are no longer made

 

were the gtx models rare a bit? can they be found pretty easy?

 

you would be better off using the 9:1 auto pistons from a miata. thats my plan with my GT. belfab rods + 9:1 comp auto pistons + either a t3/t04e or a 16G, my goal is make atleast 190 - 200 whp below 10 psi, that way leaving enough room with the turbo so i never should feel the need to upgrade it after that.

 

wery, even here in europe/balkan

 

I used to have a set of GTX pistons. They are 7.9:1 CR with the same bore as a 1.6L. They have valve reliefs and are just cast hypereutectic pistons like in the B6ZE 90-93 1.6L. I wouldnt really want to use them, the CR is TOO low for off boost performance.