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Modifications >> 3.0L Duratec

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PuckPuck
CEG'er

Reged: 12/12/00
Posts: 317
Loc: Windsor, Ontario, Canada
Re: Piston durability new
#320029 (Re: warmonger) 06/17/03 02:19 PM

Originally posted by warmonger:
Originally posted by PuckPuck:
Ok I just came back from my brother in-law's mold making shop

My piston has a dome center, so all measurements are not from the dome but from the top of the outer rim... we layed the piston upside down on 2 machined blocks on a flat marble work surface... pulled out some funky guage that sits flat on the table and zeroed it on top of one of the machined blocks... because he's a mold maker he measured everything 3 times to ensure accuracy...

top of first ring .158
top of second ring .368
top of oil ring .606
top of piston pin hole .769
piston pin diameter .828 (using telescoping guage)

do the math and i'm sure you can figure it all out




"Mold"?? Does he make Cheese, or penicillin perhaps?
Lol I'm just having fun.






I'm French Canadian... therefore I am allowed to mispell words, and have my own flavor of funky english grammar oh and i'm sure you figured out he's a MOULD maker

Now onto serious issues. I know how many of you praise the extra 1.2 points of compression, however now if money is tight and you can't afford a new set of pistons for your 99 block being converted to a 3L, you may want to think about running a lower compression by opening up the combustion chamber (only slightly more $$ in machine work). I have always felt that 11.2:1 is a decent jump on stock internals for an engine designed to run 10:1 or lower. Sure you'll lose a little HP for running the lower compression, but at least you won't have a 150lbs paperweight.

I'm still interested in knowing if we can say that all blown pistons were in the front bank... then the next question is WHY? Maybe the water pump has something to do with it, now i'm not sure but, that is the only big difference from front to rear.

--------------------
2000 Cougar V6 MTX
2001 3.0L Swap w/ PnP Heads - It ran, it boomed, it RUNS AGAIN
Nearly all suspension mods
Big ass stereo
...and more...
See Her Here

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Dan Nixon
Hard-core CEG'er

Reged: 06/09/00
Posts: 1469
Loc: Virginia
Re: Piston durability new
#320103 (Re: warmonger) 06/17/03 03:30 PM

Originally posted by warmonger:
Ok.
We have buckshots engine that shows clear signs of detonation from the melted edges of the pistons.






Didn't Buckshot have forged pistons??

--------------------
1999 Amazon Green SVT Contour (#554/2760)

"People demand freedom of speech as a compensation for the freedom of thought which they seldom use."
-Soren Kierkegaard (as posted by Jato)

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kinger
Veteran CEG'er

Reged: 08/15/01
Posts: 976
Loc: Clear Lake, IA
Re: Piston durability new
#320155 (Re: Dan Nixon) 06/17/03 04:20 PM

Originally posted by Dan Nixon:
Originally posted by warmonger:
Ok.
We have buckshots engine that shows clear signs of detonation from the melted edges of the pistons.






Didn't Buckshot have forged pistons??




Nope stock, but he had forged rods.

--------------------
I offer PnP Heads for all durtec's details at PnPheads.com or jesse@pnpheads.com for details.


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warmonger
Hard-core CEG'er

Reged: 08/16/01
Posts: 5810
Loc: Ozark, AL
Re: Piston durability new
#320603 (Re: PuckPuck) 06/17/03 10:31 PM

Originally posted by PuckPuck:
Now onto serious issues. I know how many of you praise the extra 1.2 points of compression, however now if money is tight and you can't afford a new set of pistons for your 99 block being converted to a 3L, you may want to think about running a lower compression by opening up the combustion chamber (only slightly more $$ in machine work)




Oh my! Now that is an interesting proposition, wish I'd heard of this before.?.? Makes me want to pull my heads off right now. lol

Originally posted by PuckPuck:

I'm still interested in knowing if we can say that all blown pistons were in the front bank... then the next question is WHY? Maybe the water pump has something to do with it, now i'm not sure but, that is the only big difference from front to rear.




So far they are all front-bank pistons. Why, I have no idea yet though I have mulled over it for a while.


--------------------
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black

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RaraAdministrator
"Absolut Rara."

Reged: 09/09/00
Posts: 3223
Loc: Westland, MI
Re: Piston durability new
#321263 (Re: warmonger) 06/18/03 01:57 PM

I still contend that most if not all of these failures have been detonation induced.

buckshot and burrita's failures involved melted areas on the pistons, this is indicitive of excess heat (duh), which may be due to the knock sensor retarding timing from excessive low level detonation. The others, where the ring lands are broken, may not have had time to melt anything, and a good, but quick bit of detonation may have been enough to cause it.
Remember, that the ring lands are typically the weakest area of a piston, and especially on a hypereutectic cast piston. These are the areas most sensitive to detonation damage.

Granted, this is just educated speculation, but I don't think there is any reason to freak out thinking these pistons are junk or anything, they are just not designed to handle the detonation that a lot of you guys are flirting with on these high compression duratecs, whether that high compression is purely static, or is dynamic (ie NA or forced induction)
If you want to make a durable motor, you have to do your homework all the way through and not just at random points.

1) When you start planning the motor, think logically about what you plan to do with it, and choose an appropriate CR, including dynamic CR (dynamic CR= static CR+ CR related to added boost) Perhaps an 11.2:1 static CR really isn't a good idea in a daily driver that runs on pump gas . . .

2) When putting your motor together, make sure you understand how the parts are interacting. One thing that has concerned me (I have no idea how well founded these concerns are though) is using 2.5L heads on a 3L block, because I have no idea what you are doing to the "squish band" because of the difference in the cylinder bore on the 3L and the 2.5L that the combustion chamber on the head is designed for. An improper squish band, as well as any hot spots induced in the combustion chamber can have a huge affect on how and when detonation occurs. As for me, I honestly don't know jack about the details of the squish band, and I wouldn't touch it myself without several very long conversations with both piston and head engineers/manufacturers/designers.

3) You can do all of your assembly and porting and other hard part work exactly right, but if you bugger the tune, you are screwed just as quickly. I think we all know Rick's (buckshot) first failure was most definately caused by a bad tune (or a tune not done yet ) just becuase Rick got a bit impatient before he could get the tune done.
Fuel and timing maps are of the utmost importance both for making optimal power and keeping your car running safely and reliably. OEMs spend thousands of hours perfecting the tune for power, driveability, durability, and emissions for every single possible powertrain combination they offer; do you really think that a simple one shot deal with an SAFC on your local backroad with a very inexperienced engine tuner (you, or most everyone you know) is enough to ensure that you have things set up safely and for optimum power?
Take the time to do it right; there are so many alternative routes to arrive at a proper tune, there really is no excuse for not doing it right. And if I hear "money" as an excuse from anyone, I will beat you about the head neck and chest with a wideband O2 sensor. It will cost you a lot more money in the long run to not do it right the first time. Ask Rick how much his one little incident of impatience has cost him . . .

There is so much more, but this is the gist of it. Now go do your own homework, the info is out there, you just have to look for it, and learn how to discern the good from the bad.

Geez, why do my technical posts always turn into books???

--------------------
Balance is the Key.

rarasvt@comcast.net

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quickSVT
CEG'er

Reged: 05/21/02
Posts: 388
Loc: tampa, florida
Re: Piston durability new
#321866 (Re: Rara) 06/18/03 10:57 PM

very well put...i plan on tuning mine to the T.....if i can just get around to droping it in....its been in the spare bedroom for months now just waiting..

--------------------
2000 t-red SVT
****too quick for civics****
i have a few tricks up my sleeve

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warmonger
Hard-core CEG'er

Reged: 08/16/01
Posts: 5810
Loc: Ozark, AL
Re: Piston durability new
#321950 (Re: Rara) 06/19/03 12:14 AM

Thats all very well and good, and some of it is common knowledge on here.

I did tons of homework on my motor and I think in both N/A and F/I modes it has shown itself to be a winner.
I don't know as much about engines as you guys do, but I will say that I'm trying to get to the bottom of an obvious problem. Its ok to say we're running on the edge, but that doesn't explain why its always front bank #2 and #4 pistons that are getting blown, even if it is through detonation.

I'm ok with you saying that the pistons ring lands being broken are caused by light detonation, it explains it and its the best theory by far.
I would like to point out that detonation IS causing a compressive load by the way since the pressure from the charge burning is coming on before the piston goes through TDC.
I can easily see from my temp readings that I was spiking temps of 190+ F when I cracked my pistons before, and detonation is probably what caused it. Ok.
But why always front bank?
YOu also have to see that with the thinner ring land supporting the second compression ring on the earlier pistons that it has to be the weaker link, AND that may be why they are more 'light-detonation' sensitive.
This is the gist of why I will say to use later model pistons.

tom


--------------------
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black

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Y2K-SVT
CEG'er

Reged: 08/16/00
Posts: 82
Loc: TAMPA, FL, USA
Re: Piston durability new
#331580 (Re: warmonger) 06/27/03 08:24 PM

i would probably say that the newer pistons might be even more prone to this problem then less so.... having a higher ring pack (aka rings higher up on the piston) puts less beef between the combustion process and the rings. manufacturers use this to up the compression and to clean up emissions. that space between the top of the pistons and the top of the rings is notorious to have unburned fuel and hydrocarbons that can escape during the exaust stroke.

now if the newer pistons are a better casting with higher quality control then it may be a wash but i still belive the fact that the ring lands are thinner might agrivate this issue more then anything. it maybe the fast that less 2000 cars have a turbo that this isnt showing up

--------------------
-Y2K SVT- BORN 1/03/2000
DIED 02/29/2004

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Y2K-SVT
CEG'er

Reged: 08/16/00
Posts: 82
Loc: TAMPA, FL, USA
Re: Piston durability new
#331602 (Re: warmonger) 06/27/03 08:34 PM

cont from my last post...

the primary ring is going to observe the most punishment in a detonation type event. where exactly are the breaking? is it at the top, or between the ring lands? what do the cooling passages look like around the block? ive never had mine apart (or never studied pics close enough) to see what they look like, how big are the cooling passages around the 2 and 4 cylinder? are they smaller or more obstructive the the rest? also how hard would it be to add piston oil squirters to our cars? as this would take a significant amount of heat out of the pistons. (i know that 3.0 and 3.5 non turbo nissans can be upgraded, however the turbo cars came with them, so that may be why)... i dont know what about those two cylinders running lean as the are closer to the throttle body? (just talking out my ass, to see what can be dreamed up). also what was the mixture like (12:1, 13:1)?

--------------------
-Y2K SVT- BORN 1/03/2000
DIED 02/29/2004

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warmonger
Hard-core CEG'er

Reged: 08/16/01
Posts: 5810
Loc: Ozark, AL
Re: Piston durability new
#331642 (Re: Y2K-SVT) 06/27/03 08:53 PM

You've misunderstood the issue.

The ring is a little closer to the combustion, but it isn't the rings that are breaking, it is the metal support, the ring land for the rings that is cracking.
Typically in cases where there is no melting of the aluminum present, the support for the lower compression ring is the part that is breaking. This particular support is half the thickness on the mid 99 and earlier pistons. In late 99 and up, this area was doubled in thickness by shifting the two rings upward by a couple of milimeters.
This is why under whatever loads and/or detonation that are breaking the lands is more prevalent on the earlier pistons.

As far as the two front bank pistons going out, they are the two that are furthest from the TB.

--------------------
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black

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