I have a 1992 FD3S S6 from Japan but the motor was swapped. The motor is from a 1996-2002, S7 or S8 FD3S. I was wondering if anyone knew if there was a difference between the S6(1991-1995), S7(1996-1998), and S8(1999-2002) when it comes to the engine. It's time for a rebuild and I'm just curious if the rebuild kit for the common S6 would work for all FD3S models, S7 and S8. Thank you!

If anyone can also identify what motor it is from, that would be a great help as well!

The ECU Reads:
C N3F1A
N3F1 18 881A
079700-7511
12V
DENSO
007511E

 

The main short block is the same, some VERY minor differences but a rebuild parts will work for all FD's, 92-02.

External parts have differences and there are some differences JDM - USDM.

Dale

 

the N3F1 ecu is from the 96-98 cars, which is good the newer stuff is better

 

Went searching for Silver and found Gold. Thank you both for the rapid responses.

I'm also planning on doing a Half-Bridgeport too. More of a standard build question, but what are the proper clearances of the side seals and corner seals for a Half Bridge, as well as the recommended Apex seals. All the threads I've seen just say you can use any Apex seals you like, and dont say anything about what is better or not. Not planning for crazy power, just love the lopey idle. Thank you again!

 

Going with a bridge will reduce engine life, you can also get a dopey idle from a large street port. Also while it sounds cool it gets REALLY annoying after a while.

That said, there's nothing different in apex seal choice or clearances when building a bridge or a street port engine. There's a lot of great aftermarket apex seals out there, search around and see what you like and what fits your budget.

Side seal clearance is typically .003" on a turbo engine. Some like a little tighter than that but that's a good spot to be in.

Dale

 

i wouldn't do anything different for a half bridge, measure everything. with a bridge you need to make sure all the seals will stay in place all the way around, its easy to have a seal fall into the port...

seal choice is more about the clearances, you need to measure length, width and height, and curvature, especially with aftermarket seals. i used to try and get 0.002" for side seals, but 0.003" is fine.

 

Hi, I have a similar question. I have a car in from a guy in, its a S8 spec RZ, with the kevlar recaro seats and the N3G1 turbo pack. Now it lost compression on the front rotor and upon opening the engine it had 3 piece seals in there, like normally found in FC engines. It had exsessive sealant at places so it was definately opened before but now the question is did they switch back to 3 pc seals in the S8 or did someone rebuilt it in the past with wrong seals?

 

all the FD's had 3 piece seals, and Mazda switched when the Rx8 came out in 2003. there are also aftermarket 3 piece seals in Japan, they seal better.

 

That is a bad idea. As Dale said, it will reduce engine life -- appreciably -- for little power gain and a monster street port will get you the same lopey idle.

 

really? I thought FD’s ran 2 pc seals stock wise w pn: N351-11-C00C

 

from the 99+ catalog...

 

Crazy. Why did they then come up w the 2 pc seal if even the last production 2mm non renesis motor used 3 pc as stock? To me the 3 pc seems like a good idea for sealing but a rather fragile setup in terms of violent pressure waves in the chamber from knock or worse pre ignpition.

 

i don't know, it would be interesting to find out. they switched when the Rx8 started production (if you look you can find threads, the 3 piece seals ran out and the 2 piece seals didn't show up for a while)
the Rx8 is a 2 piece, so maybe it was a cost thing?
the high power stuff in Japan is mostly running stock 2 piece seals cut into 3 piece seals....

 

OP you need to clearly define your goals and use case. How much street vs track driving, what is your preferred powerband, what turbo were you considering, etc.

 

+1 on the 3pc seals on the late models. Openned the original engine (15 or so years ago) and i was surprised

 

For the RX-8 I think the main goal was to reduce friction and there a lighter seal package is your friend. With the reduced height it would not be possible to run 3 pc seals. Also because it being NA a weaker seal with less height formed no issue in terms of groove wear.

 

yes, the 3 piece to 2 piece switch was done at the same time, so after the FD production was complete

 

That all sounds right, I remember getting 3pc seals from Mazda in the early 00's.

I've never seen anything one way or the other as to which is better.

Dale

 

the changes to the REW are really minor, but
for 1996, the front cover o ring is eliminated, front iron changes to an N3F1 Casting
for 1999 the metering orifices (orifi?) are made smaller. this can be ID'd because the old ones have a flat head screw driver cut in them, the new ones don't.
also in 1999 the rear irons get new numbers, but i think its just that the oil pressure port is plugged

in 2003, after production of the car stops, the 2 piece seals show up, and the rotor housings get the new fangled QC date stamp things under the spark plugs



these new parts supersede the old parts, so the only front iron available after 1996 is the new one, the only rotor housing available after 1999 is the new one, etc
other than that, there are no changes to the actual engines.

 

3 piece seals were being sold in Japan by a few tuners there as some sort of secret sauce some time back, believe they were wire cut. Seem to remember a couple guys locally claiming they could walk on water too. Haven't noticed them recently, maybe still out there?

 

matey was selling them, haven't seen a post for them in a while.

 

yep, they are 2 piece seal cut apart, and then clearance is set for big power