6.9 high pressure turbos
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6.9 high pressure turbos
Hello everyone my friend is about to get a 85 6.9 and he wants to add some performance to it. One of the many the many things he wants to do is add twin holset turbos. I think that would be about 60 psi if he put on a head stud kit from dps would it work?
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Joined: Sep 2006
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From: North Van, B.C. Canada
it would work on a powerstroke, something that can handle that much boost.
but on these idi's... first ive never heard of a twin turbo set up on an idi.
second with the higher compression on them, 60 psi would be somewhere near imposible.
the highest boost numbers ive seen and a 6.9 or 7.3 idi are mid 20's (daves)
and thats after extensive work to his 6.9.
in my opinion if your friend wants a performance diesel, get something that would be easier to get that much more power out of.
but on these idi's... first ive never heard of a twin turbo set up on an idi.
second with the higher compression on them, 60 psi would be somewhere near imposible.
the highest boost numbers ive seen and a 6.9 or 7.3 idi are mid 20's (daves)
and thats after extensive work to his 6.9.
in my opinion if your friend wants a performance diesel, get something that would be easier to get that much more power out of.
Lead Driver
Joined: Nov 2003
Posts: 6,900
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From: Campbell River, B.C.
Simply fitting the turbos (and related piping) would be a challenge. If you drop the compression ratio, you could probably run some high numbers like that, but to drop that much compression will cause cold start and serious economy issues.
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i told him that that was probably too much psi for that high of a compression, not to mentioned they were never designed for a turbo. However i have a 93 7.3 and was considering a single holset, I'm not as ambitous, i think that with a head stud kit it might work but i dont want to tear it up ill probably have the moter out wwhen i do this but I'm not doing a rebuild, yet.
Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
Milled pistons to lower compression and head studs will let you run about 30 PSI boost.
To go over that you are looking a O ringed heads and block as well as a couple other mods.
With milled pistons and head studs, at 25 PSI boost my effective compression ratio is higher than a Power Stroke running 30 PSI.
To go over that you are looking a O ringed heads and block as well as a couple other mods.
With milled pistons and head studs, at 25 PSI boost my effective compression ratio is higher than a Power Stroke running 30 PSI.
Posting Guru
Joined: Sep 2007
Posts: 2,207
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From: Las vegas
Ok first off wich holsets are you talking about? they make them in many different verieties and alot of them would not put out much boost with the exaust flow of theres engines. 60psi on the stock 21.5 to 1 cr would be an insanly high efective compresion ratio. But If you guys like the trucks, have money and would like to make a preformace truck it is definatly possible. Get head studs heads with built in firerings milled down pistons, and a custom IP and injectors. I'd also replace the rods and use ARP rod bolts if availible and have the governor set at 4000 rpm with some heavy duty valve springs.
Twins are possible I've seen a powerstroke with three turbos you could definately fit two on one of these but a single turbo could also be made to put out high boost #.
So how fast can you aford to go?
Twins are possible I've seen a powerstroke with three turbos you could definately fit two on one of these but a single turbo could also be made to put out high boost #.
So how fast can you aford to go?
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Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
22.5 to 1 base compression ratio with 60 PSI boost would have an effective compression ratio of 114.33 to 1.
A Power Stroke engine with an 18 to 1 compression ratio would only be 91.46 to 1 with 60 PSI boost.
Right now my compression ratio is 20.25 to 1, with 25 PSI boost my effective compression ratio is 54.68 to 1.
At 30 PSI that increases my effective compression ratio to 61.57 to 1.
A Power Stroke running 30 PSI has an effective compression ratio of 54.73 to 1.
There is a limit as to how low you can go with the compression ratio of an IDI, starting will be a big issue at 18 to 1 or lower.
A Power Stroke engine with an 18 to 1 compression ratio would only be 91.46 to 1 with 60 PSI boost.
Right now my compression ratio is 20.25 to 1, with 25 PSI boost my effective compression ratio is 54.68 to 1.
At 30 PSI that increases my effective compression ratio to 61.57 to 1.
A Power Stroke running 30 PSI has an effective compression ratio of 54.73 to 1.
There is a limit as to how low you can go with the compression ratio of an IDI, starting will be a big issue at 18 to 1 or lower.
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Senior User
Joined: Apr 2007
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From: Conway, AR
I doubt it would hold together long at 60 psi, even with studs, and as far as studs, go with the ARP head studs, There has been a rash of failures lately on the DPS head studs and the guy has yet to respond to a single one of the people who spent hundreds of their hard earned dollars with him on his defective studs, He's left them all holding the bag.
There is also an ARP option for 7.3 head studs .
There is also an ARP option for 7.3 head studs .
Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
You will never make it to 30 PSI with just head studs and stock pistons very many times.
And you will also blow the valley pan at the intake to head junction.
23 PSI is all that gasket can take in stock form.
Been there done that before.
And you will also blow the valley pan at the intake to head junction.
23 PSI is all that gasket can take in stock form.
Been there done that before.