FS-ZE piston question

[Lukas007]

I've bought a set of -ZE pistons from Corksport, but after comparing them (on the picture, not in real) to the stock FS ones, they look exactly the same, and also very different than the piston presented on Corksport page in 626 Other Engine category ... I just want to be sure that I recieved a correct product, so if you could confirm that they are/aren't -ZE I would be greatfull.

Picture (old ones are stock FS pistons)



Picture of FS-ZE piston on CS page

Greetings
Lukas

 

[Maxx Mazda]

ZE pistons arent dished like the stock ones.

 

[Lukas007]

So the new piston that was sent to me by Corksport, presented on the left side of the comparision picture, isn't FS-ZE, it is just stock FS, right ??

 

[Maxx Mazda]

It is a ZE piston.

 

[Lukas007]

Now I don't understand. You've said that -ZE pistons aren't dished like the FS ones ... but those that I recieved from CS ARE dished and shaped like stock FS ones ...

This is the piston that I recieved ... it is shaped just like the stock FS, nothing close to the piston presented on CS page ...

 

[Maxx Mazda]

They're not dished like the FS pistons, but they still have a dish to them, just not as deep. You can clearly see it, I don't know what you're having difficulty with. That is a FS-ZE piston. Post up the part number on the box. Did you order the 10.4:1 ZE pistons or the 10.7:1?

10.4:1 part number:
FPY2-11-SA0B normal size
FPY2-11-SB0B .025 oversize
FPY2-11-SBXB .050 oversize

10.7:1 part number:
FSY4-11-SA0 normal size
FSY4-11-SB0 .025 oversize
FSY4-11-SBX .050 oversize

 

[Lukas007]

OK. Thanks for clarifying the whole situation. I just thought that the -ZE pistons should look exactly the same as the ones presented on the CS page. By the part number my pistons are stock bore 10.4 : 1. Thanks again.

 

[Maxx Mazda]

OK. Thanks for clarifying the whole situation. I just thought that the -ZE pistons should look exactly the same as the ones presented on the CS page. By the part number my pistons are stock bore 10.4 : 1. Thanks again.

That's just a computer generated generic image, probably not representative of the actual product. In fact, I'm sure it says that on the site. What ECU are you going to run with the new pistons?

 

[Lukas007]

Stock e-spec FP ECU with ECU Master DET II piggy back. Also everything depends on how the powerband will be like ... I was thinking about moving the rev. limiter higher (to 7500rmp) but I'm not sure if my fuel pump and injectors will compensate a lot more air at higher rpm's ... also messing with the limiter is impossible on standard DET II unit, I would have to switch to the newest DET III and make a standalone fuel maps, then there would be a possibility of moving the rev limiter higher.

 

[HKPRO5]

sub

 

[Maxx Mazda]

Don't bother raising the rev limiter. The stroke on the fs is already so long that you'll end up with astronomical piston speeds. I took mine to 8500 on the dyno and it was pointless. Power tapers off well before that, around 6500RPM

 

[Lukas007]

Good to know, thanks

One more thing is bothering me ... will the stock fuel pump and injectors handle the setup with both bigger camshafts and higher compression pistons ... I saw that e-spec FP has got higher flow rated injectors than stock 93-97 FS, but I couldn't find any info whether FS-ZE had or hadn't different injectors, or even different fuel pump.

 

[Maxx Mazda]

Fuel requirements increase with how much air you add to the engine. Being naturally aspirated, you're not adding any. Stock pump and injectors are more than adequate.

 

[Lukas007]

Ok, next week I'm going to fold everything together, while all the parts I need should be in my hands until the end of this week, so OEM piston ring set, all gaskets, new Exedy Clutch, and the most important - FS engine block. Also I have one more question, how do I should treat the engine after installing new pistons, with new rings in the used engine block ?? How do I should drive for first 1000-2000km ??

 

[Maxx Mazda]

Well you'll need to have the block honed, maybe bored if it's scratched deeply. In which case you should have ordered overbore pistons. You always start with the block first, and have it measured, so you can order proper sized pistons.

 

[Lukas007]

Engine I've bought is in a very good shape, so I didn't bored or even honed it. Stock sized pistons and OEM rings fit without any issues. For the first 100 miles no signs of oil consumption, we'll see in future. You can find the resoults in my topic.

Greetings
Lukas

 

[Maxx Mazda]

What the hell machine shop did you use that didn't at least hone the block? You ALWAYS have to hone the block when installing new rings, it's not for fit, it's for break in. Those rings are never going to seat now being dropped into glazed cylinders, and that engine WILL end up burning alot of oil, it's only a matter of a few thousand miles.

Ball hones are like $15. You couldn't buy one? Seriously?

 

[Maxx Mazda]

Taken from Total Seal's website:

[FONT=Verdana, Arial, Helvetica, sans-serif]QUESTION: [/FONT][FONT=Arial, Helvetica, sans-serif]Do Total Seal rings require special cylinder honing? [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]ANSWER: [/FONT][FONT=Arial, Helvetica, sans-serif]No, Total Seal rings do not require special cylinder honing. But they like all piston rings do require proper cylinder honing. One of the most common causes of ring sealing issues today is improper cylinder honing. It’s not uncommon to see engine blocks and cylinder sleeves ranging in hardness from approximately 150 to over 300 on the brinell scale. Yet it is very common to see these all of these being honed using the exact same process. The end results vary dramatically. These results are measured with a tool known as a surface roughness tester. The results are measured as Ra, Rz, Rpk, Rk, and Rvk and vary depending on the specific application. Basically these numbers are telling us to how rough the cylinder is and how well it can retain oil. An overly rough cylinder will prematurely wear the rings while an overly smooth cylinder may never seat the rings and can lead to cylinder burnishing. Cross hatch angles can also vary depending on the application, These angles determine the critical ring rotation speed, generally a 45 cross hatch angle will do a very good job. Though some O.E. applications do vary from this, if your not sure check before you proceed. To steep of a cross hatch angle can cause the rings to pump oil, rotate to quickly leading to accelerated ring and ring groove wear. To flat of a angle can cause a chattering affect as the ring passes over the valley preventing the ring from receiving proper lubrication again leading to excessive ring wear.[/FONT]

 

[shootz]

Thanks for the info Maxx, very informative!

 

[Lukas007]

I have some comparision photos that I took when I was rebuilding the engine. On the first one you can see the difference between stock FS and FS-ZE 10.4 pistion. Second one is comparing stock FS and FP (e-spec 1.8 version 105BHP). Intresting thing is, that both FS and FP have the same compression ratio, same head (so same combustion chamber) but differently shaped pistions. Bore is the same, so to increase compression of FS engine, you have to use FP pistons (you'll get sth like 9.7:1), and if you want to get lower compression, just put FS pistions in FP block.

About honing and oil consumption. You were right Maxx Mazda - after like 5000km of break-in time engine was burning like 2l of oil for each 100km. Thats why I bought oversized -ZE pistions, and rebuilded the whole engine like it should be. Now its all perfect.

Greetings
Lukas