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How Much Boost???

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Old Feb 20, 2008 | 12:55 PM
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How Much Boost???

I am curious how much boost a stock 7.3l will handle? I have heard and read around 14-16 PSI. Now if u put the head studs in will it handle more. I believe the engine was assembled with factory hypertuantic pistons which can handle around 1250-1300 degrees in heat. So is it possible to put 20 PSI of boost along as your get your temperature down? I am not talking about continuosly...Just if your needed when pulling or want get moving in a hurry. I have '93 ford 4x4 I am fixing to start working on and want to upgrade it to a turbo. Also were are u guys getting your studs kicks from for the heads? regardless how much boost I use i am going to install the stud kit
 
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Old Feb 20, 2008 | 01:12 PM
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15 is supposed to be the max on a stock engine.

I may go up to 12, but probably not higher.

You have to reduce the compression ratio to run more boost. Stock is 21:1 I think.
 
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Old Feb 20, 2008 | 07:07 PM
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Your right 21:1 is the compression ratio. But I am just curious why a person could not run 20psi? Unless that would create to much cylinder pressure? I believe the new powerstrokes are either 18:1 or 16:1 ? not forsure. But if their able to put around 40psi. why can't we run up to 20. You figure if you keep the heat down it would be possible. I am just thinking out load here.
 
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Old Feb 21, 2008 | 01:15 AM
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it's because the engine is not designed to handle all that air, not enough fuel, and not enough cylinder. it won't burn completely, like not enough spark. when you go to the pulls and you hear "chuff-chuff-chuff-chuff" as the truck stops, thats because theres so much air going into the engine, it almost stops the engine, usually that causes the turbo to blow or you pop a head gasket or a rod etc...
 
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Old Feb 21, 2008 | 10:27 AM
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I was kinda thinking that but was not forsure. I wander if u lower the compression down to around 18:1 if u could. But I know pre-chamber designs are limited. To bad no one has come up with a direct injection head yet!. Will the 6.9l head bolt kit work on a 7.3l? All I see for head stud kist are 6.9l or 7.3l powerstrock. what about 7.3l IDI? someone point me in the right direction here please. I have been working on my drag truck for so long i kinda miss working on my diesel. So now that truck is up and running good time to work on the truck that hauls it around(or pulls it)
 
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Old Feb 21, 2008 | 10:59 AM
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Originally Posted by polcat
Your right 21:1 is the compression ratio. But I am just curious why a person could not run 20psi? Unless that would create to much cylinder pressure? I believe the new powerstrokes are either 18:1 or 16:1 ? not forsure. But if their able to put around 40psi. why can't we run up to 20. You figure if you keep the heat down it would be possible. I am just thinking out load here.
Well, yeah...21:1 plus 20 psi would create some SERIOUS cylinder pressure.

It would also be a very hot burn.

I'm not really sure how PSD's can run so much boost, but I think they have a bit beefier design and probably better pistons.
 
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Old Feb 21, 2008 | 12:35 PM
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20 psi is doable with head studs and some extra care on the intake and exhaust gaskets. Look through previous posts by Dave S and you'll find all the info you need. You may need to mill some off the pistons for 20 psi, although I'm not sure... If you want more power, first open up the exhaust and intake (not hot under-hood air though).

Power strokes have a lower compression ratio to start with than the IDIs.
 
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Old Feb 21, 2008 | 10:34 PM
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As far as the intake I have modified my air cleaner to have dual inlets that lead up to the grill. And the exhuast, it has been opened up real good. I run 37" tires on it and it wants to spin them in 2nd gear. Engine has lots of power. I am just wanting to s do some mods. on it. Everyone is running Turbos now so I figured it is time to upgrade. I am just curius and I need to reserch a little more is how is the Powerstrokes able to make more power. But like I said before you are limited to the combustion because of the pre-chamber design. The burn is not as efficiant as a direct injection engine.
 
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