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do I have to tell the shop all this, or should they be competent enough to figure this out on their own?
I will tell them I'm boosting it so they can leave a little slack on the top ring when they file it on. . .I'm just afraid that I'll get this done, everything will be fine, then I make the trek over to Arizona this summer, dyno the hell out of her, and BOOOOOOM, right at 14psi it all goes to hell (I'm assuming 14psi would be safe to run with forged rings and rods. . .)
Suneil
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14 psi on what turbo though???
It is not the psi level but the airflow at said psi level. Just a psi rating means little to nothing without airflow numbers.
14psi on a T3 40 trim would barely get you moving but 14psi on a T66 would likely pop the stock head bolts... 
Either way forged pistons & rods will easily support 14psi on a T3/4 60-1 trim and that would be my guess as to what you are running (if you are building a 3L too) Otherwise I'd guess it's a 54-1 with a 2.5L
Heck the stock rods are stronger the anyone believes and will take more abuse then the stock pistons and the revised pistons should support a max of 450 crank HP or so. (400+ is already a known given thanks to TOM)
For instance I think a full oval port 3L at ~9.7CR (~$1200 if you can do the labor) should do nicely and safely with a T3/4 60-1 trim and large turbine wheel at 8-10psi (330-360FWHP/TQ) 
That's already far beyond the level of power this platform can handle in the first few gears.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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The total seal rings have a chrome steel top ring which I was told by total seal to be safe at 15psi.
2001 Lincoln LS8
1994 Lexus GS300
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Originally posted by DemonSVT:
14 psi on what turbo though???
It is not the psi level but the airflow at said psi level. Just a psi rating means little to nothing without airflow numbers.
14psi on a T3 40 trim would barely get you moving but 14psi on a T66 would likely pop the stock head bolts...
interesting point, and I think I might have a problem because I'm rebuilding my 2.5L and going with a t3/4 trim option through SF. . .so, I'm assuming that it should be a decently packaged upgrade since the t28 runs out of breath beyond 10psi, or so I've been told. . .
I guess I'm opting for the t3/4 upgrade because I want to push more air than the t28 is capable of, and that's what the logic was behind the forged rods (I could sustain higher air flow, more boost, on a larger turbo, without the deleterious risks associated with increasing combustion chamber temp's). . .as for the 3L upgrade, I didn't want to spend the extra $2k to get it done right, because NO ONE here is capable in that realm (nor am I!)
I'm rambling. . .but since this has become kind of a cool tech forum on upsizing turbo's on 2.5L engines, out of curiousity, how do you calculate the INEFFICIENT point where the heat from compression reduces power put to wheels. . .like in my case, with a 2.5L t3/t4, nothing beyond 15psi as Keyser said?
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dude, I hope the t-28 doesn't run out at 10 psi! If so I guess I'll be putting that on my mazda sooner than I thought 
2004 Evolution VIII cams-exhaust-tune
315whp 12.7@109
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Originally posted by BStoneMega:
dude, I hope the t-28 doesn't run out at 10 psi! If so I guess I'll be putting that on my mazda sooner than I thought
That's very old and dyno tested news...
The T28 is already beyond it's efficiency range pushing 270-280FWHP. (~10 psi)
Even straight race fuel (to stop the super heated air from the compressor so far out of it's efficiency range from causing detonation) only managed about 290FWHP. (~12psi IIRC) You can see that race fuel and a few more psi netted next to no real gains. That is the "just pushing hot air" syndrome of being far beyond it's safe efficiency range.
The T28 is a "power under the curve" turbo. It's was sized and chosen to make a nice fat usable curve from 3000-6500rpm. SF picked out a great turbo for an "overall" package.
This is also why when certain "Cougar" turbo folks decided on their own to raise the boost they shelled their engine. They were not running high enough octane fuel to quell the detonation of the super heated intake charge since they moved the turbo well out of it's safe efficiency range.
Turbos are all designed to be run in a specific range of operations (via trim, A/R, housing size, even piping size) and it's cfm to psi relationship is also dependant on the size of the engine & it's volumetric efficiency. (to put it basically)
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Originally posted by ssmumich00:
..... I hope I can sell my CSVT pistons and rods (which I KNOW are in great shape since I've had a DMD on forever) to recoup the lost money. . .
Pardon my ignorance but how can you use used pistons ?? Isn't that like buying old shoes ? I mean, I know the tolerances on modern engines are pretty tight and that there is likely very little difference in cylinder diameter between cars but won't your pistons and cylinders have "worn" together and putting pistons from one engine into a different engine cause a problem ??
Or is that why we have piston rings ?? !!
TIA for educating an ignoramus.
Bless our servicemen & women overseas.
L.Cpl Ian Malone, 1st Battalion Irish Guards, R.I.P.
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My turbo of choice is .57 trim compressor with a .63 AR for the turbine housing. IIRC it pushes 49lbs per minute compared to the 31lbs from the T28.
2001 Lincoln LS8
1994 Lexus GS300
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Originally posted by ssmumich00:
I'm rambling. . .but since this has become kind of a cool tech forum on upsizing turbo's on 2.5L engines, out of curiousity, how do you calculate the INEFFICIENT point where the heat from compression reduces power put to wheels. . .like in my case, with a 2.5L t3/t4, nothing beyond 15psi as Keyser said?
Well that all depends of your power goals, shape of the curve you want and how fast you want to get to maximum boost.
It is easy to plot a specific engine combination on a compressor map and see where your desired boost level (per rpm) puts you in it's efficiency range.
Depending on the factors I listed in my previous post certain turbo's offer more surge area (needed running a T3/4 on a 2.5L), faster spool up (really a moot point - see later), high boost capability, low boost efficiency, etc, etc...
You can play with trim and A/R sizing to get a proper medium.
For instance Tom is using a T3/4 60-1 trim (on his 3L, NOT 2.5L) with larger turbine wheel. (.83 A/R IIRC) He generates full boost around 3500rpm which is easily soon enough and has plenty of room to grow on the top end.
IMO the worst thing you could do is use a large compressor like a 60-1 trim and then castrate it with a small turbine wheel. (still talking 3L as the 60-1 is too "large" for a 2.5L - I.E. surge)
You end up with the worst of both combinations.
Poor low boost airflow, slightly sooner spool time (but in real world driving that's completely moot and you'll need a dual stage boost controller anyway because of traction), but then no top end airflow because the exhaust compressor is already over spinning because it is so damn small. Don't even think about high boost. (Serious heat air)
That leaves you with a turbo that under performs at both ends.
So what are you "goals"???
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Originally posted by Keyser:
My turbo of choice is .57 trim compressor with a .63 AR for the turbine housing. IIRC it pushes 49lbs per minute compared to the 31lbs from the T28.
Damn you posting between my soap box speeches.
I was getting there.
Yes the 57-1 has a very nice increased surge area.
The moderate A/R turbine will help the smaller 2.5L spool the compressor faster. Remember the 2.5L is ~20% smaller in volume then a 3L.  This directly relates to the amount of exhaust gasses "powering" the turbo.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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