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Old 06-13-2009, 10:54 AM   #1
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Default Why 10psi?

Why do I see many of the members here running 10psi when it would appear that they have everything the need for a still very safe 12psi. ie. IC, MSPNP, big injectors.
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Old 06-13-2009, 12:27 PM   #2
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Because alot of people on this forum use their cars for daily driving purposes and don't want to risk any thing, i.e. mechanical failure or driving error

Even at 10psi, our cars can be a handfull.
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Old 06-13-2009, 01:28 PM   #3
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10 psi on my car is 260 rwhp. that's why.
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Old 06-13-2009, 01:39 PM   #4
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Don't think is PSI so much... as each turbo really has different air outputs.

Think in power levels.

That being said... I run 10.x psi because it's the spring that was in my used Tial wastegate... and so far its fun so I'm just running it.
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Old 06-13-2009, 01:42 PM   #5
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I daily drive mine. It's my only vehicle at the moment. I also beat the crap out of it so I'm always fixing something. It is a work in progress.
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Old 06-13-2009, 01:44 PM   #6
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240rwhp at 10.5psi here. Daily driver. I've bumped it up to 13 since dynoing the car. It's a whole lot more to handle at 13psi than 10. Gotta be a whole lot more aware of what I'm doing. It'll bite you.
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Old 06-13-2009, 02:15 PM   #7
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Limited by turbo.

The little IHI RHB5 has incredible spool characteristics, but for the volumetric flow rates of even the 1.6L at redline this turbo falls off the deep end of efficiency past 10psi.

I could turn it up (to 11...these go to 11), but IATs would surely go up, and the rotating assembly would be at the top speed line of the compressor flow map.


10psi is nice though. It's certainly fast enough on the road. I walk G35s, Mustang GTs and dust F-bodies. I hung with a GTO yesterday despite some ignition problems over 5500rpm (had paper plates, guy obviously couldn't drive). This is probably a wee bit over 200hp on my setup (I envy y8s), which keeps me in safe territory for the rest of the drivetrain. I still have an open 6" diff and stock 5spd.

We do build for headroom for a reason though. If I ever get a torsen the next step will be a compressor swap. Nothing else in my setup would have to be upgraded.
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Old 06-14-2009, 10:25 AM   #8
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Quote:
Originally Posted by y8s View Post
10 psi on my car is 260 rwhp. that's why.
on a *** dyno.
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Old 06-14-2009, 11:19 AM   #9
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Quote:
Originally Posted by hustler View Post
on a *** dyno.
I've never heard of these before. How do they differ from other types of dynos?

Thanks for the responses guys.
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Old 06-14-2009, 11:46 AM   #10
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Quote:
Originally Posted by hustler View Post
on a *** dyno.
dyno dynamics. with their mystery correction factor.
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Old 06-14-2009, 01:57 PM   #11
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I don't run 10 psi because my puny little Greddy needs more than that to make the power I want.
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Old 06-14-2009, 03:52 PM   #12
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What PSI are you running through the greddy for 247hp? I still really need to get mine dyno'd, I vary between 6 and 10psi depending on how how well the rest of the setup is working, I really need MS.
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Old 06-14-2009, 03:56 PM   #13
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14-15
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Old 06-14-2009, 04:16 PM   #14
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The greddy is not so puny compared to some of the turbos guys use in miatas.

I run 10 psi because I wanted headroom and reliability... and because my original plan had been a goal of 8 psi - the 10 psi I have now make sthe car quite quick... but the reality is, with every component I put together for this setup, given a motor that could handle it and the right turbo I could do 20, so I think I'm going to bump up to 13 or 14 soon... even though it's the stock motor, some guys are doing 16-18 on the stock motor so.. why not?
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Old 06-14-2009, 04:22 PM   #15
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My greddy runs about 12 psi and is the shittiest feeling turbo car I've ever been in. I need moar spark tuning.
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Old 06-14-2009, 05:19 PM   #16
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12psi on my T25 and I still doubt i'm breaking 170whp. I also need some spark tuning :( However, at 12psi its a major handful at autox.
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Old 06-14-2009, 06:29 PM   #17
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Quote:
Originally Posted by 1redcanuck View Post
Why do I see many of the members here running 10psi when it would appear that they have everything the need for a still very safe 12psi. ie. IC, MSPNP, big injectors.
why 10psi? why not?
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Old 06-15-2009, 02:07 PM   #18
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I'm running about 11 right now, and I want to run 12, but I need to get some spark tuning done, and get a new manifold.
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Old 06-15-2009, 02:22 PM   #19
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Old 06-15-2009, 02:53 PM   #20
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220rwhp @ 13psi using my Greddy, but I need spark tuning for moar powar.

10 psi feels good, 13 better - when you have an EBC, Link ECU and 550 injectors more boost is simply a case of dialing in higher numbers.
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