Headstuds nessesary?
Postmaster
Joined: Dec 2004
Posts: 2,941
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From: Maple Valley, WA
What's with the 20psi on stock headbolts? I know I haven't been around much lately, but when I first got my IDI, everyone said 15psi would put the heads through the hood. I'm familiar with the nothing but hot air past 12psi argument(on the regular turbo arrangements), but the inability to handle the pressure always seemed to go hand in hand. Has something changed? Not intending to step on any toes here, just curious if the IDI world has learned a new trick.
Posting Guru
Joined: Dec 2012
Posts: 1,065
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From: western washington
you will chase your tail, more fuel, tiny bit more boost, more psi more heat, more heat prechamber less expansion less efficient, more fuel, 
if you run the numbers, more boost from that turbo means more heat, IMO start with the IC, then play with the pump and turbo. or get taller gears, put in a cam, mount a hx40 and a trans brake, 8inch stack thru the hood and practice the tree. go racing
its just cost money
if you run the numbers, more boost from that turbo means more heat, IMO start with the IC, then play with the pump and turbo. or get taller gears, put in a cam, mount a hx40 and a trans brake, 8inch stack thru the hood and practice the tree. go racing its just cost money
Lead Driver
Joined: Apr 2008
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I agree with racin on most accounts. Would i run 20psi on a 6.9 DD.. probably not unless i was looking for an excuse. I was running around 22 on my 7.3 and didnt even know it, no problems. Im understanding that just because a map shows "this" its more of a loose interpretation of a good starting point. Regardless, i dont think anyone has fully tapped out an 093/088 like racin was saying. No one has hit the wall of turbo explosion, wont clear the fuel, undrivable EGTs, or simply the fact that you cannot get anymore power from it period. A ****ty turbo and a great IC is not an ideal situation, nor is a great turbo and no IC... basically, if it works it works... if it dont..... well it dont. Example plot out a 7.3 on a hx35 map. it will tell you its OFF THE MAP at 2500 rpms and 15psi... by no small amount either. Yet i was running 22psi and pulling it to 3800. Also, thats kinda what i was getting at with studs, theyre a great idea, but might as well wait until you need them, or pull the engine for some reason, no sense really in pulling it just to stud it. I would suggest doing a cam at the same time.
Postmaster
Joined: Mar 2013
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From: Over There
I can only add a little bit to this.
IMO tires are a great way to make up for low gears, when it comes to MPG width is a bigger factor then diameter. Narrow is better for MPG, tall can do a lot for overall ratio.
Aftercooler, older term, used more for water cooling, used more in the commercial heavy duty trucking/equipment world.
IMO tires are a great way to make up for low gears, when it comes to MPG width is a bigger factor then diameter. Narrow is better for MPG, tall can do a lot for overall ratio.
Aftercooler, older term, used more for water cooling, used more in the commercial heavy duty trucking/equipment world.
Postmaster
Joined: Dec 2004
Posts: 2,941
Likes: 30
From: Maple Valley, WA
I agree with racin on most accounts. Would i run 20psi on a 6.9 DD.. probably not unless i was looking for an excuse. I was running around 22 on my 7.3 and didnt even know it, no problems. Im understanding that just because a map shows "this" its more of a loose interpretation of a good starting point. Regardless, i dont think anyone has fully tapped out an 093/088 like racin was saying. No one has hit the wall of turbo explosion, wont clear the fuel, undrivable EGTs, or simply the fact that you cannot get anymore power from it period. A ****ty turbo and a great IC is not an ideal situation, nor is a great turbo and no IC... basically, if it works it works... if it dont..... well it dont. Example plot out a 7.3 on a hx35 map. it will tell you its OFF THE MAP at 2500 rpms and 15psi... by no small amount either. Yet i was running 22psi and pulling it to 3800. Also, thats kinda what i was getting at with studs, theyre a great idea, but might as well wait until you need them, or pull the engine for some reason, no sense really in pulling it just to stud it. I would suggest doing a cam at the same time.
Logistics Pro
Joined: Apr 2005
Posts: 4,221
Likes: 17
hopefully it'd go the other way and create a cold air intake with water injection....
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Lead Driver
Joined: Dec 2002
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From: Kuna ID
That's nice to know I haven't been running on the ragged edge these last few years at 12psi. 
As far as head studs, I know it's probably not the best way to go about it but I recall a couple people installing them without removing the heads. They removed one bolt and replaced it with a stud, did them all one at a time. Last I heard they had several thousand miles without any issues but I don't recall if they were running higher than usual boost pressures.
As far as head studs, I know it's probably not the best way to go about it but I recall a couple people installing them without removing the heads. They removed one bolt and replaced it with a stud, did them all one at a time. Last I heard they had several thousand miles without any issues but I don't recall if they were running higher than usual boost pressures.
New User
Joined: Oct 2013
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Oh okay, I appreciate it. Wouldn't happen to know much about the 6.9 idi would you? Okay so I'm new to the whole forum thing, not really good with performance on diesels, especially around the 6.9 idi era. I have a 85 f250 6.9 idi, was leaking from every where, so I pulled the engine, trans, and transfer case. Now that engine is out, I really want to beef it up. I was reading on a forum that is you put a turbo on a 6.9 idi that you would have to install beefed up connecting rods? Please help me with this. Again I'm not sure if this is the right area, but I seen y'all we're discussing 6.9 idi performance upgrades
Thanks, Ryan
Thanks, Ryan
Elder User
Joined: Dec 2011
Posts: 751
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From: Kodiak, Alaska
Oh okay, I appreciate it. Wouldn't happen to know much about the 6.9 idi would you? Okay so I'm new to the whole forum thing, not really good with performance on diesels, especially around the 6.9 idi era. I have a 85 f250 6.9 idi, was leaking from every where, so I pulled the engine, trans, and transfer case. Now that engine is out, I really want to beef it up. I was reading on a forum that is you put a turbo on a 6.9 idi that you would have to install beefed up connecting rods? Please help me with this. Again I'm not sure if this is the right area, but I seen y'all we're discussing 6.9 idi performance upgrades
Thanks, Ryan
Thanks, Ryan
Logistics Pro
Joined: Apr 2005
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