will my 6.9 handle 20lbs of boost with head studs? also wanted to know if I can swap the bolts out for the studs one at a time so I dont have to pull the heads?

 

1. yes

But getting 20 PSI might be a challenge unless you get a bigger turbo and fuel injector pump and or injectors. Intake an exhaust gaskets will be at their limit though.

2. no

You run the risk of cracking the head if you remove one bolt at a time and its impossible to install the rear most bolts that are against the firewall without removing the head. If you are about to go up to 20 PSI, its better to have fresh gaskets in there anyway.

 

no and no...

From what I've heard and read for your engine to take 20lbs of boost you'd probably have to do some internal engine mods first. A stock engine even with studs probably wouldn't last too long before the head gaskets or something else blew...

And to install a head stud kit you'll have to remove the head's... Removing a bolt at a time would probably warp or crack the head... those bolts should be removed in reverse procedure to the torquing sequence ... in steps. hope that helps...

EDIT: ok david is probably right as he's more knowledgeable than me... but I think that 20 lbs of boost is at the very limit. I would lower my compression before trying for that kind of boost... but that's just my opinion...

 

and a big hello from the mainland david... hows thing's on the big island?

 

The head studs are nearly 3 times the strength of the OEM bolts and clamp harder per ft/lb of torque applied because of lower friction when tightening them down(if instructions are followed properly).

 

Not bad, but would be nice to either see some snow or the sun. All this wet grey in between weather is getting me down.

 

haha yea... I'd rather see some snow... need to test my new transfer case...lol

 

Yeah I need to test my drifting skills LOL Never had much chance for driving mine in snow. Mine is 2wd, but seems to do well with the few chances I did have (with proper tires of course). What can I say, I guess I never out grew the snow.

If I can try and steer this back on topic, I do have a larger compressor on order and hope that I will eventually hit 20 PSI with my engine. I'm topping out at 10 PSI now with some smoke so even with my stock fuel system there is room for more boost. Hoping for 12-15 without IP upgrades. When I do replace my injector pump it will be with an upgrade since local shops charge the same for a stock pump anyway.

 

I've read up allot on this here at FTE and other sites and people are allways talking about lowering there compression... you don't have any worries there david?.... the ip's across the line are super cheap compaired to local prices... that is till our dollar took a nose dive...lol

 

Worries about compression? no, in reality your 7.3 probably has comparable compression to my engine. The 6.9 has 22.5:1 and the 7.3 is 21.1. As it is the engine will start without glow plugs in the hot summer sun. Plugged in overnight and its running before the first full turn, again with no plugs, but it never really gets very cold around here.

I know what you mean about prices over the line. Local shop was $700 plus core. For that price I could get an upgrade that several members on OBN swear by. I really liked buying from the states because of better pricing back when the dollar was worth a dollar. Fuel prices are in free fall though. My dad looked at the latest cardlock bill and the average price was nearly $0.80/liter for diesel

 

I just was under the impression that 20lbs of boost was the outer limit with out shaved pistons...the problem being that the high compression of our idi's combined with 20+lbs of boost made it difficult to keep the head gaskets in one piece... even with head studs... I know people have even toyed with thicker gaskets to lower there compression...with no luck I might add.

 

I would agree that 20 is probably the limit for stock pistons even with studs. So I wouldn't try for much more than 20 without more drastic internal mods.

 

I used ARP studs from Summit Racing in my engine.

The directions say to install the studs and run them to torque setting listed in the listed steps.
Then remove them again in steps and torque pattern.
Repeat step one a minimum of 5 times.

So that means torquing the heads down and removing the studs five times before you are ready to install them for good.

If you do not have the engine out where you can get to it you will be a tired puppy before you get everything done.

If you install the head gaskets correctly, like absolutely no oil contamination on the block or heads and you torque the heads down correctly, I have confidence you can run 20 PSI with just head studs.

22.5 to 1 compression with 20 pounds boost will put you a little over 53 to 1 for an effective compression ratio, just 1.5 pounds behind a Power Stroke running 30 PSI boost.

I do mean the head gaskets are going to have to be installed perfectly to run that much boost, but I do believe it is possible.


Almost forgot, head studs come in different grades.
Mine are 220,000 pound yield strength, the highest grade.

Lowest grade is 180,000 pound strength and may not be up to the task.
Middle grade 200,000 would be iffy.

 

Sadly, I have the 200 000 studs in mine. I've been told they are all that grade now.

 

thanx for all the input guys. ive been wondering about the yield strengths too. all the ones on ebay are 200,000, hopefully I can find the 220,000 psi studs.
just need to get the wife to approve of the big plans... hx40w, intercooler and of course the head studs... then we will see if the pump will feed the beast.

thoughts?