So... thought I would share. Pics are worth a thousand words
#21
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Originally Posted by Sharif@Forged
Remember its 17psi with two turbochargers worth of airflow. If you calculate the mass air rates of both APS turbochargers at that boost level, it would be the equivalent of a single GT35xx running at about 30psi boost pressure.
Certainly, tuning could have something to do with, but IMHO, you need a stronger pistons that is better at the limit, which gives you a larger margin for error....particularly when the car has left the shop, and now is in the hands of the customer, with all the variability that can come with that.
Certainly, tuning could have something to do with, but IMHO, you need a stronger pistons that is better at the limit, which gives you a larger margin for error....particularly when the car has left the shop, and now is in the hands of the customer, with all the variability that can come with that.
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Originally Posted by Sharif@Forged
Remember its 17psi with two turbochargers worth of airflow. If you calculate the mass air rates of both APS turbochargers at that boost level, it would be the equivalent of a single GT35xx running at about 30psi boost pressure. Arias recommends a max of 20psi boost pressure on the standard duty piston (single turbo), but it really should be calculated in terms of airflow, rather than pressure.
Certainly, tuning could have something to do with, but IMHO, you need a stronger piston that is better at the limit, which gives you a larger margin for error....particularly when the car has left the shop, and now is in the hands of the customer, with all the variability that can come with that.
Certainly, tuning could have something to do with, but IMHO, you need a stronger piston that is better at the limit, which gives you a larger margin for error....particularly when the car has left the shop, and now is in the hands of the customer, with all the variability that can come with that.
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Originally Posted by MRC Motorsports
17 psi is 17 psi to the motor no matter how you look at it
I dont care if he buys Arias ED's, Wiseco, CP or whatever. He posted a picture of an Arias standard duty piston, and I mentioned the reason we introduced the Arias ED piston.
I didnt tune this engine or build it so, I have no interest in it either way. Just pointing some things out for discussion.
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Originally Posted by Sharif@Forged
This is 100% incorrect. 17psi psi through a tiny turbocharger is much less mass of air than 17psi through a GT35. This is turbochargering 101, Julian.
I dont care if he buys Arias ED's, Wiseco, CP or whatever. He posted a picture of an Arias standard duty piston, and I mentioned the reason we introduced the Arias ED piston.
I didnt tune this engine or build it so, I have no interest in it either way. Just pointing some things out for discussion.
I dont care if he buys Arias ED's, Wiseco, CP or whatever. He posted a picture of an Arias standard duty piston, and I mentioned the reason we introduced the Arias ED piston.
I didnt tune this engine or build it so, I have no interest in it either way. Just pointing some things out for discussion.
Im just pointing out the fact that there are other pistons out there that have seen much more boost pressure than any Arias Extreme or Standard has and have done just fine...In Fact Performance motorsports when they were around made 1300-1500whp on CP pistons....So has Carl Stevens from Extreme Motorwerks..
All I am pointing out is that I dont think his piston failed cause it was not an arias Extreme, otherwise you would have 100's of other people posting pictures of broken CP,Ross,Weisco Ect..Pistons..This is clearly not the case.
There are possibly other factors at play..Material defect,Nitrous,EGT's, Engine temps, detonation,timing,ect....
Originally Posted by Sharif@Forged
This is 100% incorrect. 17psi psi through a tiny turbocharger is much less mass of air than 17psi through a GT35. This is turbochargering 101, Julian.
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^^I agree with that^^
Arias recommends a max of 20psi (single turbo) on their VQ35 shelf piston, which is a high silicon content piston. A lot of piston manufacturers use low or zero silicon content pistons, and even Arias uses zero/low silicon in some of their shelf pistons (Honda and 4G63 come to mind), and those designs will hold up to much more abuse.
We are still waiting for soemone to post a pic of a cracked Arias ED ring land.....havent seen it yet, which means that we must be doing something right.
Arias recommends a max of 20psi (single turbo) on their VQ35 shelf piston, which is a high silicon content piston. A lot of piston manufacturers use low or zero silicon content pistons, and even Arias uses zero/low silicon in some of their shelf pistons (Honda and 4G63 come to mind), and those designs will hold up to much more abuse.
We are still waiting for soemone to post a pic of a cracked Arias ED ring land.....havent seen it yet, which means that we must be doing something right.
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I usually ignore most spelling/grammar stuff on here, but that one always drives me crazy for some reason. Sorry for the random post. But I feel better.
good luck with the re-build.
moot: no longer applicable because already resolved / answered
I usually ignore most spelling/grammar stuff on here, but that one always drives me crazy for some reason. Sorry for the random post. But I feel better.
good luck with the re-build.
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Originally Posted by Sharif@Forged
This is 100% incorrect. 17psi psi through a tiny turbocharger is much less mass of air than 17psi through a GT35. This is turbochargering 101, Julian.
So with that said, I'm not claiming to be an expert, but pressure is pressure. Where it comes from doesn't mean a thing. If 17psi is coming from huge quad turbos, the result at the intake where it matters will be 17 psi. If one large turbo was spinning much faster and producing 17psi by itself, it's still putting 17psi at that same point in the intake. The volume of your intake plenum hasn't changed, so there's the exact same mass of air at that intake plenum from 4 large turbos generating 17psi as the single turbo spinning faster producing 17psi at the same point in the intake.
17psi is 17psi. (unless one air charge is colder than the other
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An engine does not consume pressure, it consumes a mass (weight) of air. Try blowing 5psi though a straw with your mouth....pretty easy...right? Try doing this with a fire hose...not going to happen. It's the mass of air that determines power potential, not pressure. This is the reason that most turbocharger companies have moved away from CFM (Cubic feet per minute), and moved to lb/min. Its the mass or weight of the air that matters in these types of calculations.
Another simple example is from the STI and Evo world. Their stock turbochargers tend to loose efficiency past 20-23psi. If you run the turbochargers at 30psi, you do not achieve anymore peak power, and they are not flowing a larger mass of air...yes..more pressure...but no more mass air. If you run a GT35 at 20psi, you will get MUCH more power than running the stock turbocharger at 20psi.
I am sure Gurgen will chime and describe it better than I can...I am tired...and its Sunday...LOL.
Another simple example is from the STI and Evo world. Their stock turbochargers tend to loose efficiency past 20-23psi. If you run the turbochargers at 30psi, you do not achieve anymore peak power, and they are not flowing a larger mass of air...yes..more pressure...but no more mass air. If you run a GT35 at 20psi, you will get MUCH more power than running the stock turbocharger at 20psi.
I am sure Gurgen will chime and describe it better than I can...I am tired...and its Sunday...LOL.
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Cylinder pressure is what cracks ring lands. Not pressure in the intake manifold, not CFM, not pounds per minute of air. Cylinder pressure is a result of mass flow rate in conjunction with timing and compression.
As sharif said, with respect to turbocharging mass flow is what matters. The number of molecules of oxygen in any parcel of air is the only thing that is of any consequence. You can heat that air up and it will take up more volume (higher CFM) and exert more pressure (higher boost pressure) and still make no more power because the number oxygen molecules available to be reacted has not increased. This is what happens when we run a less efficient turbocharger than ideal. You heat the air up which causes higher boost pressures, higher volumetric flow rates, and yet no discerable power increase.
As sharif said, with respect to turbocharging mass flow is what matters. The number of molecules of oxygen in any parcel of air is the only thing that is of any consequence. You can heat that air up and it will take up more volume (higher CFM) and exert more pressure (higher boost pressure) and still make no more power because the number oxygen molecules available to be reacted has not increased. This is what happens when we run a less efficient turbocharger than ideal. You heat the air up which causes higher boost pressures, higher volumetric flow rates, and yet no discerable power increase.
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Originally Posted by Sharif@Forged
An engine does not consume pressure, it consumes a mass (weight) of air. Try blowing 5psi though a straw with your mouth....pretty easy...right? Try doing this with a fire hose...not going to happen. It's the mass of air that determines power potential, not pressure. This is the reason that most turbocharger companies have moved away from CFM (Cubic feet per minute), and moved to lb/min. Its the mass or weight of the air that matters in these types of calculations.
Another simple example is from the STI and Evo world. Their stock turbochargers tend to loose efficiency past 20-23psi. If you run the turbochargers at 30psi, you do not achieve anymore peak power, and they are not flowing a larger mass of air...yes..more pressure...but no more mass air. If you run a GT35 at 20psi, you will get MUCH more power than running the stock turbocharger at 20psi.
I am sure Gurgen will chime and describe it better than I can...I am tired...and its Sunday...LOL.
Another simple example is from the STI and Evo world. Their stock turbochargers tend to loose efficiency past 20-23psi. If you run the turbochargers at 30psi, you do not achieve anymore peak power, and they are not flowing a larger mass of air...yes..more pressure...but no more mass air. If you run a GT35 at 20psi, you will get MUCH more power than running the stock turbocharger at 20psi.
I am sure Gurgen will chime and describe it better than I can...I am tired...and its Sunday...LOL.
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EGT's have raised due to whatever reason. be is blow by? oiling down? too agressive timing? extended periods of boost? I dont see much/amy scuffing on the skirts, so id have to assume they were clearenced properly. i know JE (hi-silicon content) would blame this fuel octane. But in the end, it all comes back to the tune. 17psi is very capable on street gas.
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Originally Posted by MRC Motorsports
Oh and based on this comment , you contradict yourself from the previous post..Remember, he was running tiny little GT25's as supplied on the APS Standard kit...Therefore your point is mute..
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OMG, I am sounding a lot like Peter from APS.
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Originally Posted by Sharif@Forged
I am not contradicting myself, becuase there are TWO of those tiny GT25's....roughly the same as one large GT40xx. Each APS turbocharger flows roughly 40lb/min worth of air at 2 bar pressure ratio (14.7psi relative pressure)...so times two is 80lb/min worth of air..thats a LOT of airflow, for just "just" 15psi. ![thumbup](https://my350z.com/forum/images/smilies/biggthumpup.gif)
OMG, I am sounding a lot like Peter from APS.![Smilie](https://my350z.com/forum/images/smilies/smile.gif)
![thumbup](https://my350z.com/forum/images/smilies/biggthumpup.gif)
OMG, I am sounding a lot like Peter from APS.
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PS you need to follow with a CHEERS mate..
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I have the same problem with my engine.
I have standard 8:5 arias pistons with pauter rods running a GT35R at 10-12psi.
I had the piston go in cylinder 3 only, the others were fine with a little damage to the head.
I would sometimes get random cylinder misfires and sometime I would get cylinder 3 only. I would change the spark plug and it would go away thinking it was the plug.
I talked to arias and they said that maybe I have a faulty injector or bad coil pack for that cylinder and that I should check it out. What do you guys think?
Well here are pics of my piston with obvious detonation.
I have standard 8:5 arias pistons with pauter rods running a GT35R at 10-12psi.
I had the piston go in cylinder 3 only, the others were fine with a little damage to the head.
I would sometimes get random cylinder misfires and sometime I would get cylinder 3 only. I would change the spark plug and it would go away thinking it was the plug.
I talked to arias and they said that maybe I have a faulty injector or bad coil pack for that cylinder and that I should check it out. What do you guys think?
Well here are pics of my piston with obvious detonation.
Last edited by denchan350gt; 07-02-2007 at 12:35 AM.