Head stud and transfer case questions

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Suzuki450ltr

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Sep 17, 2015
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I have two questions I've found mixed answers. I have 425 studs and I've read you should only go to 75 psi of boost and some say they Are pushing around 100 psi of boost. My question is it ok to run 100 psi of boost on 425s or is there something I should do before running 100 psi of boost like fire rings or o rings some say torque the studs down more? Also is there any parts in the transfer case I might break? Any billet parts I should put in the transfer case or is it good stock?
 
I have 425's running well over 100psi drive pressure, and torqued to 150ft/lbs multiple times. Never had an issue.

I would definitely run orings just because.

Tcase should be good to go. What are you doing with the truck? That really determines your limits.
 
madmikeismad said:
I have 425's running well over 100psi drive pressure, and torqued to 150ft/lbs multiple times. Never had an issue.

I would definitely run orings just because.

Tcase should be good to go. What are you doing with the truck? That really determines your limits.
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its a street and race truck. do you have o ringed heads? and is your boost and drive pressure 1:1? I've had my drive pressure to 90 psi I'm just worried about boost pressure going over 70 psi.
 
Head is ringed. Boost is 100psi, that's all the gauge goes to, same for drive pressure when I had it hooked up. I can almost guarantee you drive pressure is at least 1.3:1 though LOL
 
Your drive pressure is harder on head gaskets than "boost".
 
BRE said:
Your drive pressure is harder on head gaskets than "boost".
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i dont think boost or drive pressure is hard on the head gasket. when your piston is compressing all that air and fuel, its putting thousands of pounds of pressure in the cylinder. so that 100+ psi of drive pressure or boost is nothing to the gasket.
 
Suzuki450ltr said:
its a street and race truck. do you have o ringed heads? and is your boost and drive pressure 1:1? I've had my drive pressure to 90 psi I'm just worried about boost pressure going over 70 psi.
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ktm450rider said:
i dont think boost or drive pressure is hard on the head gasket. when your piston is compressing all that air and fuel, its putting thousands of pounds of pressure in the cylinder. so that 100+ psi of drive pressure or boost is nothing to the gasket.
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Is this the same person?

And lifting the head and blowing past the head gasket is what you're trying to save by using studs.
 
madmikeismad said:
Head is ringed. Boost is 100psi, that's all the gauge goes to, same for drive pressure when I had it hooked up. I can almost guarantee you drive pressure is at least 1.3:1 though LOL
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Ok thanks. I wanted to see if I could use 425s without fire rings at 100psi.
 
ktm450rider said:
i dont think boost or drive pressure is hard on the head gasket. when your piston is compressing all that air and fuel, its putting thousands of pounds of pressure in the cylinder. so that 100+ psi of drive pressure or boost is nothing to the gasket.
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From what I've read egts and high drive pressure are the worst on head gaskets. I'm not sure the cylinder pressure is the worst on head gaskets.
 
I would use 625 studs for what you are trying to do,more clamp load and no stretch.
 
Suzuki450ltr said:
From what I've read egts and high drive pressure are the worst on head gaskets. I'm not sure the cylinder pressure is the worst on head gaskets.
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high egt's may be worse on a head gasket, but i dont know and have never heard of that. but there is no way that drive pressure is worse on a head gasket. drive pressure has only a fraction of the pressure pushing on the head gasket compared to the compression stroke.
 
ktm450rider said:
high egt's may be worse on a head gasket, but i dont know and have never heard of that. but there is no way that drive pressure is worse on a head gasket. drive pressure has only a fraction of the pressure pushing on the head gasket compared to the compression stroke.
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It all figured into cylinder pressure. I don't see how you think drive pressure doesn't equate into head gasket failure.
 
BRE said:
It all figured into cylinder pressure. I don't see how you think drive pressure doesn't equate into head gasket failure.
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I dont see DP affecting the head gasket due to what i have said previously. DP is a fraction of the pressure that the compression stroke makes. A metaphor-You take metal target made for shooting bullets (compression pressure) at it and you throw rocks (DP) at it. The rocks are not gonna affect the target.
 
ktm450rider said:
I dont see DP affecting the head gasket due to what i have said previously. DP is a fraction of the pressure that the compression stroke makes. A metaphor-You take metal target made for shooting bullets (compression pressure) at it and you throw rocks (DP) at it. The rocks are not gonna affect the target.
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Drive pressure effects cylinder pressure!
What's gonna blow a headgasket quicker... Hx35 at 50psi or 62mm at 50psi?
 
any pressure will change overall cylinder pressure. 100psi added to anything is a lot. Lets say cylinder pressure is 600psi at the moment after combustion (just a number, I don't know what it would actually be). You add another 100psi of boost or drive, thats another 16.6%. Plus whatever expansion takes places with that extra air and heat produced. Thats pretty significant to me.
 
This went from a simple question to an argument really quick lol. Hx35 at 50 psi will blow a head gasket i had a buddy so it to his truck.
 
Suzuki450ltr said:
This went from a simple question to an argument really quick lol. Hx35 at 50 psi will blow a head gasket i had a buddy so it to his truck.
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It's not an argument... Or at least I'm not arguing. Just simply stating what little I know to either try and teach you, or you teach me.
 
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