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Discussion Starter #1
I'm wondering how much boost i should push on my new fuel system, it's the phr stage one with dual walbros.
I have a precision billet 6765dbb .81a/r and tuned with a geforce ecu (timing,fuel,8k redline) and a safc2

I'm going to be on straight 93oct. and don't know how much boost i can push without having knock on only 93oct.

Any input is welcome :)
 

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i heard anything above 22psi or 23psi you need e85? i dont know if this is true
 

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i heard anything above 22psi or 23psi you need e85? i dont know if this is true
The new Billets flow more air then similar Turbos so 22-23 PSI i believe would blow your shit up in a hurry but im just going off of what i "think" i know. :fruit:
 

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Asking here is almost like taking a poll of wild guesses. There are a lot of variables that can get you in serious trouble. Why not monitor knock and a/f and base it on that? Even just looking at a wideband won't be enough since knock/detonation can easily occur at safe a/f's if the boost is too high for the octane, timing, compression, other setup details.
 

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Why not tune it for E85? depending on your injector size u can go crazy with E85. If you run 93pump then tune it as high as there is no knock or detonation, as soon as you see that there is turn your boost down about 2psi. In the real world I would say that 1.5bar or 21/22psi should be the max on pump gas and no extra additive fuels, im running 22psi with methanol injection to be safe.
 

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IIRC the PHR stage 1 fuel system only includes ~750cc injectors, which means the injectors are too small to gain any power on E85 vs pump gas, since you need to dump so much more E85 vs gasoline for a given HP level.

Considering that you're on a Gforce ECU/SAFC setup, I suspect you'll find the sweet spot around 17-18psi on 93 octane. It's possible that you might be able to push more, but without knowing how your Gforce's timing maps were tuned it's impossible to say.

But like Nick said, you're basically taking a poll of wild guesses and monitoring A/F's and knock would be the only way to know for sure. Monitoring knock accurately can be a dicey business, so it might be best to simply play it safe around 17psi and run good gas when you want to play crazy.
Once you go standalone and have accurate timing control, a skilled tuner could probably push for more power/boost on pump gas.
 

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I would not go any higher than 18 psi with that setup on 93 octane. If you want to run more boost you will need race gas.
 

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Asking here is almost like taking a poll of wild guesses. There are a lot of variables that can get you in serious trouble. Why not monitor knock and a/f and base it on that? Even just looking at a wideband won't be enough since knock/detonation can easily occur at safe a/f's if the boost is too high for the octane, timing, compression, other setup details.
Correct answer here.
 

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Discussion Starter #9 (Edited)
i would love to do e85, but i don't think it would be to driveable/tuneable without going standalone.
I have some 11 available at $8per gallon, what would be the max for that?
 

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Asking here is almost like taking a poll of wild guesses. There are a lot of variables that can get you in serious trouble. Why not monitor knock and a/f and base it on that? Even just looking at a wideband won't be enough since knock/detonation can easily occur at safe a/f's if the boost is too high for the octane, timing, compression, other setup details.
I would not go any higher than 18 psi with that setup on 93 octane. If you want to run more boost you will need race gas.
^^^Bingo^^^
 

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i would let your tuner decide. if thats you i would play it safe.

if it were me i probably would stay at or below 18psi. probably around 18psi.
but if i were tuning it i would probably get a knock meter.

and i would also get meth injection, because i have it and its awesome. ;)

my car is tuned on 92 octane and i run 94octane to be safe. and i run 24 psi daily. might turn it up a lil to around 28-29 psi.
we'll see what john reed does tho, i can only speculate.

just play it safe man. who cares about that extra few HP per psi
 

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Monitor A/F ratio, EGT, and knock. That's the only way to really know.

Monitor injector duty cycle to not exceed 80% either so you're not overdriving your injectors to make the desired power.

Run the highest octane possible. This will allow you to maximize your power because it will raise the knock threshold. For all practical reasons, this is usually limited to commercially available premium pump gasoline with an octane rating of anywhere from 91 to 96.
 

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i would say max is around 19-20psi. Anything over that is asking for trouble. I would just stick with 18-19psi just to be on the safe side...for your setup. For a 61-63mm..you can probably push it too 21-22psi. But I still wouldn't..Stick with a 18-19psi tune...and then E85, or race gas afterwards..why risk det on your motor..for a couple of bux. That's what I'm going to have done on my car..a 19psi tune.
 

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Asking here is almost like taking a poll of wild guesses. There are a lot of variables that can get you in serious trouble. Why not monitor knock and a/f and base it on that? Even just looking at a wideband won't be enough since knock/detonation can easily occur at safe a/f's if the boost is too high for the octane, timing, compression, other setup details.
How exactly is a person supposed to monitor knock though?

Also, A/F should be monitored in each individual cylinder to make sure that one doesn't run lean.

Unfortunately, implementing both of these appears to be impractical for a street car.

For a race car, however, nothing is impractical.
 
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