Dished or domed pistons for Mazda 323 dohc fe3n - Mazda MX-6 Forum
 
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post #1 of 3 (permalink) Old 11-11-08, 9:31 Thread Starter
 
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Dished or domed pistons for Mazda 323 dohc fe3n

RANDY STOCKER WHere are you?

I am seeking some technical information that I hope one or some of your members would be able to advise on. The information sought is however for a 1993 Mazda 323, 200i, DOHC 16 valve FE3N engine. I would dearly appreciate if you could pass on this request for information to your members.

I opened my son-in-law's engine in order to do repair work to it. As the vehicle was starting to smoke, the worst case expected was to re-bore and replace pistons. The bore's were fine with damage to number 1 and number 3 pistons. On trying to source aftermarket pistons, I found confusing information on the replacement units. Although the aftermarket data lists the number 60121 in different data books, the piston itself actually differs from the piston removed.

On comparing the two pistons, I found that the common replacement unit had a slight dome as opposed to a slightly dished pistons removed from the engine. Now this engine had previously been opened and re-bored to 0,50 mm oversize. On further inspection, I found that the piston from the engine had a KIA insignia on the inside. I have also learnt that Mazda had sold this base engine specs to KIA for fitment into their Sportage models from '98 onwards. The Kia units however operated at a lower compression ratio and were somewhat de-tuned compared with the original Mazda FE3 engines.

I would dearly like to find out which is the correct piston to bring the vehicle to it's original performance spec(giving the correct compression ratio), or alternatively, if the dished piston is the 'proper' piston to fit; what would happen if I now fitted the domed piston increasing the compression even more. Is their a conflict? Will the piston knock up against the cylinder head or valves? Will this increased compression ratio have a negative or detrimental effect?

Can anybody shed some light on the issue?

Thanks in advance.

Kind regards.

Ierfaan


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post #2 of 3 (permalink) Old 11-12-08, 0:46

 
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The FE3 was sold in various parts of the world with either 10:1 comp or 9.2:1 comp.....I dont know which models were available in South Africa....

The Kia ( I think) was around 9:1....

clearance should not be an issue with either, higher compression is better, but it will require 95RON or better fuel.....if you dont want to use that or its too hard to get....maybe use the kia pistons....

depends whether you are after better performance or just something that runs.

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post #3 of 3 (permalink) Old 1-4-09, 13:56
 
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Quote:
Originally Posted by iere View Post
RANDY STOCKER WHere are you?

I am seeking some technical information that I hope one or some of your members would be able to advise on. The information sought is however for a 1993 Mazda 323, 200i, DOHC 16 valve FE3N engine. I would dearly appreciate if you could pass on this request for information to your members.

I opened my son-in-law's engine in order to do repair work to it. As the vehicle was starting to smoke, the worst case expected was to re-bore and replace pistons. The bore's were fine with damage to number 1 and number 3 pistons. On trying to source aftermarket pistons, I found confusing information on the replacement units. Although the aftermarket data lists the number 60121 in different data books, the piston itself actually differs from the piston removed.

On comparing the two pistons, I found that the common replacement unit had a slight dome as opposed to a slightly dished pistons removed from the engine. Now this engine had previously been opened and re-bored to 0,50 mm oversize. On further inspection, I found that the piston from the engine had a KIA insignia on the inside. I have also learnt that Mazda had sold this base engine specs to KIA for fitment into their Sportage models from '98 onwards. The Kia units however operated at a lower compression ratio and were somewhat de-tuned compared with the original Mazda FE3 engines.

I would dearly like to find out which is the correct piston to bring the vehicle to it's original performance spec(giving the correct compression ratio), or alternatively, if the dished piston is the 'proper' piston to fit; what would happen if I now fitted the domed piston increasing the compression even more. Is their a conflict? Will the piston knock up against the cylinder head or valves? Will this increased compression ratio have a negative or detrimental effect?

Can anybody shed some light on the issue?

Thanks in advance.

Kind regards.

Ierfaan


Ierfaan Williams
Tel. +27 21 9598170
Fax .+27 21 9598004
Cell. 083 649 6617
Email: [email protected]
use the domed pistons... you will not have a compression problem.. here in sa the motors came standard at 10:1 you will not have a problem with detonation.... clearances wont be a problem either i am running domed pistons with cams with 2mm more lift than standard....pistons should cost you about grand....
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