Gen 1 vs Gen 2 piston and rod differences

[Lex]

If some of you still remember, there was a time when zoom zoom boom occurred often and I did some in-depth investigations of the parts the were part of the carnage.

There has been speculation that the Gen 2 rods were stronger since the Gen 2 cars didn't suffer from as much initial boom as the Gen 1s and the speed6s.

Well, I got my hands on a Gen 2 piston and rod from a car that blew (thanks @Ckmazdaspeed3) so I had a chance to bust out the calipers and compare these.

Here's what I found:

- The rods are identical between the Gen 1, Gen 2 and MS6 cars.
- The wrist pins have thicker walls on the Gen 1 and MS6 cars. I doubt this affects much as I don't see too many people breaking the very stout wrist pins. Other things will go first.
- As it has already been mentioned on the forums, the pistons are different for the Gen 2 cars.

The Gen 2 piston has been designed to improve combustion and direct the fuel spray upwards and AWAY from the cylinder wall. Cylinder wall wetting and washing is a common issue with these cars and they addressed this with the Gen 2 piston. We see a lot of the older cars lose compression and this may have something to do with it. Otherwise, the ringlands, oil passages, coatings, piston skirt design, etc appear identical.

Also the Gen 2's have modified ECU tables which are also responsible for averting the boom. The MS6s are the most likely to blow not just because they are the oldest but also because the AWD drivetrain loads the motor more and the Gen 1/MS6 ECU calibrations were just too aggressive for how the motors heatsoaked.

We've learned a lot and the aftermarket tunes address these issues in the Gen 1/MS6 cars. IMO unless the damage was already done, with a proper tune, a Gen 1/MS6 car is just as unlikely to blow as a Gen 2.

So, what have we learned from here:

1. The rods are identical for all years and for a stock application they have proven plenty strong.

2. The Gen 2 pistons have a better design that prevents fuel wash down and improves combustion. If rebuilding a motor, consider a piston design similar to what is used in the Gen 2 cars - otherwise, with a proper tune, all speed motors have similar strength internals.

On to the pictures. Gen 1 piston and rod are on the left and Gen 2 are on the right.

[Dmurray06]

That's some good info. Thx @Lex

[Midnitehours]

is there any significant weight differences between the two?

I'd assume the gen 2 combo with smaller wrist pin and bowl in piston is lighter

[Lex]

Originally Posted by Midnitehours is there any significant weight differences between the two? I'd assume the gen 2 combo with smaller wrist pin and bowl in piston is lighter

Good question - have not weighed them. I don't have a scale accurate enough. I will keep this in mind and see if I can get some numbers.

[Tomas]

I have gen 2 pistons ready for my build and digital scale.
Will post weight tomorrow.

[GLORIFIEDBOZO]

I had @phate look up some part numbers for me recently and I knew the part number for the rods was the same and that they had changed pistons for the gen2's, but wasn't sure the difference. Thank you kind sir the comparison and pics.

[TRSpeed]

Thx Lex!

Sent from my DROID4 using Tapatalk

[Mizzle]

How do they maintain the compression ratio with that bowl?

[Lex]

Originally Posted by Mizzle How do they maintain the compression ratio with that bowl?

The area outside the bowl is somewhat raised.

[Mizzle]

Could the new piston be mixed with the thicker pin?

[Midnitehours]

Originally Posted by Mizzle Could the new piston be mixed with the thicker pin?

wouldn't you want to avoid that though? As stated in Lex's post it's unlikely to snap either of them.

lighter rotating mass = better.

unless you were thinking of upgrading the piston and re-using the pins

[Mizzle]

Originally Posted by Midnitehours unless you were thinking of upgrading the piston and re-using the pins

this.

[Tomas]

that.

[Mizzle]

and like this and uh

[Mchart]

My assumption was that a lot of zoombooming was due to the logic of the Gen1 ECU as well. On Gen1 cars when the HPFP was maxed out boost wouldn't drop and things would just keep going until blowing. Where as the Gen2 logic pulls boost among other things to save the engine. The decreased BAT's of the hoodscop on Gen2 vehicles I would assume would help a bit as well.

[Ckmazdaspeed3]

Iirc there was a 15 gram difference between gendone and genpu, but for some reason i thought thepu was heavier. I should have written it down. I used a digital kitchen scale and i weighed all 4 gendone sets and 3 genpu sets because 15 grams was such a small amount. Again, i could be remembering it wrong, but i am pretty sure.

Also, not that it means anything at all, but the k1 rods were 100g ligheter than the stock rods.

The one thing that sucks for me is that i didnt know the significance of the piston design, so i used traditional wisecos, but the cpe pistons are wisecos w the genpu design

[Ckmazdaspeed3]

Ok, just found a text that i sent about the piston weight, so i guess this is without the rods and wrist pins. All 4 gendone pistons weighed 378-380, while the 2 genpu that i weighed were 388 and 390g.

[Tomas]

Ok. no need for me to whip out the batscale.
FYI the wrist pins of the genpoopie pistons I meassure weighed 177.8 grams.

I was thinking about having titanium wrist pins with cassidium or DLC coating made for the build but its probably not worth the 30% weight reduction at $85 a pop.

[Mizzle]

meh, $85 ea. isn't much if the coating reduces friction enough for even a tenth of a mpg

[pzr2874]

Lex, not being a dick but explain why MS6's would have a bigger boom issue due to AWD... There isn't a load difference on the engine... It's the tranny/axles/gears

Unless you mean load/bog from a launch with too sticky of a tire

Good post

[Mizzle]

Originally Posted by pzr2874 Unless you mean load/bog from a launch with too sticky of a tire

.

[Lex]

Originally Posted by pzr2874 Lex, not being a dick but explain why MS6's would have a bigger boom issue due to AWD... There isn't a load difference on the engine... It's the tranny/axles/gears Unless you mean load/bog from a launch with too sticky of a tire Good post

Let me put it in terms of physics. When there is greater resistance to a change in momentum, the forces within the engine are greater in an attempt generate that change.

This is the same principle as when running the car in 1st gear WOT versus 4th gear WOT. In 4th gear you will reach higher boost and torque numbers. Simply because in 4th the vehicle has a higher resistance to acceleration.

A heavier car such as the MS6 will generate more boost and load sooner in any gear than a comparable lighter car (MS3). This translates into higher temperatures and cylinder pressures.

[06Speed6]

Originally Posted by Tomas Ok. no need for me to whip out the batscale. FYI the wrist pins of the genpoopie pistons I meassure weighed 177.8 grams. I was thinking about having titanium wrist pins with cassidium or DLC coating made for the build but its probably not worth the 30% weight reduction at $85 a pop.

Off topic but titanium work hardens and the wrist pins would be race only and need to be swapped after every race.

[Tomas]

Originally Posted by 06Speed6 Off topic but titanium work hardens and the wrist pins would be race only and need to be swapped after every race.

Keeping it off topic and thread jacking that depends what you call titanium work. TiAL6Va4, or grade 5 titanium, does not harden after heat cycling that I know of. Most uses of Ti are in alloys. Pure titanium is only used for high corrosive environments or some surgical tools.

[06Speed6]

Work hardening is embrittlement from flexing. All aluminum and ti alloys work harden to my knowledge.

I also dont believe that any ti alloy weakens from heat cycling.

@Lex can you measure the ring grooves and the top ring land? They look different

[Mizzle]

Let's really derail this thread.

Google video search "Emily Browning Sleeping Beauty"

You're welcome.

[karl-hungus]

so the genpu pistons have smiles on them? makes sense.

[mason]

are the cpe pistons designed like the genpus? the cpe magnum ones

[Rokusek]

Thank you good sir!

[fredricktsang]

Originally Posted by karl-hungus so the genpu pistons have smiles on them? makes sense.

It's a happy car inside and out!!!

good info btw. hopefully this shows that genpus are less likely to go boom. I don't want that to happen to my genpu any time soon (fingers crossed)

[Lex]

Originally Posted by 06Speed6 Work hardening is embrittlement from flexing. All aluminum and ti alloys work harden to my knowledge. I also dont believe that any ti alloy weakens from heat cycling. @Lex can you measure the ring grooves and the top ring land? They look different

@06Speed6
Ring lands and grooves have identical heights - just checked

[pzr2874]

Are the pistons compatible?
@Lex

[06Speed6]

Yes

7 more char

[lito37]

Sorry I now this is a old post but if the pic on the right is the gen2 the pin looks larger?

On the pistong the edge is tiker on the gen2 making the difference on compression

Lex thanks for the info and pic great jop

[Jeff23spl]

Good job Lex

I'm trying to check for part # and price but when i look for 2007 pistons, there seem to be 2 different part # for California and Federal??? is any of you has seen any difference in between ? (And what is the real difference from both if there is one)
2007 Mazda 3 Parts - Discount factory (OEM) Mazda parts and accessories at Park Mazda OEM Parts

And since the wrist pin is different, interchanging pistons is probably not easy but is the crank journal is the same size or rod bearing ?

[aviator79]

Originally Posted by lito37 Sorry I now this is a old post but if the pic on the right is the gen2 the pin looks larger? On the pistong the edge is tiker on the gen2 making the difference on compression Lex thanks for the info and pic great jop

That's what I am seeing. @Lex; did you make your note wrong on the pin being larger on MS6/gen1 where as picsures clearly show thicker pin walls on Gen2 with small ID on pin.

And if the rods are the same (which they are) then obv OD of pin same. I assume this has been figured out in other posts.

Genpu
Rod L33L11210A (SAME as MS6)
2011 Mazda 3 PISTON, CRANKSHAFT & FLYWHEEL (2300CC)
ROD, CONNECTING for 2011 Mazda 3. #L33L11210A

piston (4 req) L3Y411SA0
PISTON SET. PISTON, CRANKSHAFT & FLYWHEEL (2300CC) for 2011 Mazda 3. #L3Y411SA0

ring set L3Y411SC0 (SAME as MS6)
RING SET, PISTON for 2011 Mazda 3. #L3Y411SC0



MS6
Rod L33L11210A (SAME as GENPU)
2006 MazdaSpeed6 PISTON, CRANKSHAFT & FLYWHEEL
ROD, CONNECTING for 2006 MazdaSpeed6. #L33L11210A

piston (4 req) L3Y011SA0
PISTON SET for 2006 MazdaSpeed6. #L3Y011SA0

ring set L3Y411SC0 (SAME as GENPU)
RING SET, PISTON for 2006 MazdaSpeed6. #L3Y411SC0


So 4 pistons is the only difference between long blocks for
MS6
L3M6-02-300M
https://onlinemazdaparts.com/parts/i...&siteid=214264

Genpu
L3Y6-02-300H
https://onlinemazdaparts.com/parts/i...&siteid=214264

Cost is $700 difference thru MSM ($910 thru onlinemazdaparts.com).

Cost of pistons $300 shipped here
Mazda-Parts.com :: Original parts for your Mazda

Sort of bullshit but assume that is how they ensure they can sell all the gen1 blocks.

[Jeff23spl]

curiously there is also a different short bloc part # for a CX7 2007 but i checked every part # and they are all the same as a speed 2007 but few$ and numbers difference...

I was looking to make sure one could use a cx7 bloc for a rebuild base without any surprise like non forged parts or lower cams design etc...But everything looks the same...

As you said it looks like the same exept pistons between 06-09 and 10-13

I just wonder if some older bad part # could just have been replaced by the new upgraded one when ordering it separetely VS a complete old short bloc that could have been assembled few years ago with older parts at that time? Old VVT for exemple ?

[aviator79]

Ya I was just trying to find part number for 2010 CX7 but had no luck. It should have gen2. But what I did find is short block for genpu is less than MS6/gen1 and CX7 is way more:

ENGINE / ENGINE / ENGINE / SHORT BLOCK
L3ZA02200C - SHORT block
CX-7; To 3/9/11
Includes: Block, Pistons, Rings, Connecting Rod & Crankshaft.
MSRP Core ? Online Price
$3,401.23 $0.00 $3,314.55


ENGINE / ENGINE / ENGINE / SHORT BLOCK
L3ZB02200C - SHORT block
MazdaSpeed3
Includes: Block, Pistons, Rings, Connecting Rod & Crankshaft.
MSRP Core ? Online Price
$2,401.20 $0.00 $2,340.00

ENGINE / ENGINE / ENGINE / SHORT BLOCK
L3YH02200G - SHORT block
MazdaSpeed6
Includes: Block, Pistons, Rings, Connecting Rod & Crankshaft.
MSRP Core ? Online Price
$0.00 $0.00 $2,665.00

[Jeff23spl]

2007 CX7:
L3YZ02200F - SHORT BLOCK
CX-7
Includes: Block, Pistons, Rings, Connecting Rod & Crankshaft.
MSRP Core ? Online Price
$2,534.60 $0.00 $2,470.00

Yea it's funny that 2010+ engine for speed3 is less when it should be better than gen1 and on the opposite side, the CX7 engine cost more for a gen2. It's

Then you can try to enter the part number on google and you will find it for sale at lower price...

[aviator79]

I was looking for 2010 CX-7 long block part number.