6.9 build questions

[mudduck]

soon i will be starting a build on my old mudtruck , its going more in the truggy/trail truck direction rather than just mud .this is what it used to be

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the truck is now stripped to bare frame, it was a gasser. im repowering it with a 86 6.9. i know theres really not a lot we can do with these motors on a small budget but here are my plans as of now.

1.moose pump
2.custom ground cam
3.either mister's or bb injectors
4.i would like to do some headwork , i thought i saw on here that you can run 7.3 heads on a 6.9 if you get the block drilled out for the larger 7.3 head bolts?i also thought i have seen something about usin powerstroke valves.
5. some type of aftermarket fuel pump , not sure which brand yet
6.twin turbos on custom made headers, and intercooled. im not doing twin turbos to make a huge amount of boost , more for quicker spooling and almost no exhaust to get in the way . it is a offroad only rig and will have hood stacks off the turbos.
7. remote mount oil cooler.

what i was wondering was is there any other differences between the 6.9 and 7.3 heads and if studded on the 7.3 heads how much boost could i safely push? also is there any reason why i shouldn't run a remote mount oil cooler on these motors? if there are any other things that could be added to my list that is somewhat on the cheap feel free to suggest it.

the rig will also be on 2.5 tons , one link suspension , a 2wd t19 trans runnin to a divorced 205 w/ pto for my winch and grooved 48 inch ags if it matters for the build of the motor.

 

[6.9poweredscout]

moose pump, 6.9 heads, studs, a touch of timing, remove GP's and get a grid heater, run about 20 psi and hope for the best. should be good for a while!

-Jon

 

[mudduck]

would a grid heater even be needed ? searching the site a little ive seen some people saying they are still starting fine with out them. also what would be best to plug the holes where the glow plugs were?

 

[6.9poweredscout]

my truck always needs a little GP help even when it's 90 degrees out on the first start, i figure it'd help. i heard of people just chopping off the GP tips and putting them back in.

-Jon

 

[Worstenemy453]

a T19 for something like this. I would go to a ZF-5 i guess.

Sounds good. Just make sure you shield those turbos from getting water in them.

 

[mudduck]

i have a zf in my 91 turbo'd idi and i love it but i don't need the extra gear for this thing as its lucky if it would ever see 50 mph, and the old cast iron np 435 that was in the rig before has never done me wrong besides the motor breaking the stock bellhousing to peices in the middle of a deep hole.and the t19 is almost identical to the 435. i would also do what i could to keep the turbos from suckin up water and dirt.

and that would be great to get rid of the glow plugs as long as it wouldn't have any trouble with starting . the less wiring the better

 

[6.9poweredscout]

i have a zf in my 91 turbo'd idi and i love it but i don't need the extra gear for this thing as its lucky if it would ever see 50 mph, and the old cast iron np 435 that was in the rig before has never done me wrong besides the motor breaking the stock bellhousing to peices in the middle of a deep hole.and the t19 is almost identical to the 435. i would also do what i could to keep the turbos from suckin up water and dirt.

and that would be great to get rid of the glow plugs as long as it wouldn't have any trouble with starting . the less wiring the better

I think a 435 will bolt to a 4 speed bellhousing. I still think you'll need a grid heater to get a little heat in the cyls to help startup.

-Jon

 

[dyoung14]

Your gonna need glow plugs, or use the block heater, or either it or come up with a intake heater, i havent seen many idi that would crank with nothing, i have seen a couple but not many,

If it was me honestly you dont need alot of boost for a mudd/trail truck, i wouldnt lower compression i would stay either the same or go higher and the reason i say that is your gonna be ridding slow in the trails and stuff so a stock compression or slightly higher compression with a turbo is gonna make for fast spool and some amazing low end torque,

My vote is stock compression, head studs, atleast a turbo pump, moose stuuf if you can afford it, a cam grind, either a wastegated ATS turbo or the factory ford version with a better downpipe and set it to 10-15PSI and have fun with that thing

 

[mudduck]

i am plannin on keepin the stock compression ratio. i think that most of my questions are for the top end of the motor , mainly the heads . would i gain anything from swapping to 7.3 heads ? i would like to get as much headwork done as possible on this thing as i think thats where i would get more power gains on the cheap.

im gonna be studdin the heads either way , but how much more could i boost it by runnin the 1/2" studs instead of 7/16" studs? my 91 7.3 has hit 18 psi with an all stock motor besides the bein turbo'd.i would like this 6.9 to see numbers of 20 psi , maybe more if someone could confirm that it could handle it.

the moose pump and injectors will probly be the last thing i do on the motor as my 91 7.3 badly needs a moose also but i think im gonna run bb's on that , so ill probly send both pumps in at the same time .

 

[dyoung14]

i am plannin on keepin the stock compression ratio. i think that most of my questions are for the top end of the motor , mainly the heads . would i gain anything from swapping to 7.3 heads ? i would like to get as much headwork done as possible on this thing as i think thats where i would get more power gains on the cheap.

im gonna be studdin the heads either way , but how much more could i boost it by runnin the 1/2" studs instead of 7/16" studs? my 91 7.3 has hit 18 psi with an all stock motor besides the bein turbo'd.i would like this 6.9 to see numbers of 20 psi , maybe more if someone could confirm that it could handle it.

the moose pump and injectors will probly be the last thing i do on the motor as my 91 7.3 badly needs a moose also but i think im gonna run bb's on that , so ill probly send both pumps in at the same time .

You cannot tap a 6.9 for 1/2 studs, if you want 1/2 then you need a 7.3 block, and there is no sense in using a 7.3 head on a 6.9,

i ran 20 psi for a couple months never had a problem, first time i hit 28psi i blew the gasket, so with studs you might hold 20 psi for awhile but really its anyones guess as to how long it will hold it, because there is not many people who push the limits of there trucks, and there is some peoples trucks that blow a gasket at a much lower psi, so its anyones guess

 

[mudduck]

i thought id seen a 6.9 build with 1/2" studs? maybe i misread i don't know. i guess ill see how far mine will make it then , 6.9's are cheap around here so it would be easily replaceable if it blows up.

 

[mudduck]

also ive heard of a 6.5 gm that had been rigged for dual ip's, is this possible ? maybe with a custom made ip cover? from what ive read up on here the rotary ip is one of the main problems for the idi's to make some real dyno numbers. if there was a way to rig up dual ip's would it solve that problem or just over fuel the engine ? could a good set of moose injectors hold up to them? how would the timing work with them?

 

[Knuckledragger]

You can use 7.3 heads on a 6.9 if you want, but there is no need to change the bolt size unless you want to give it a try. I have not yet made a side by side comparison of the blocks, but feel that it is possible to redrill and tap the 6.9 to 1/2-13 threads. 1/2-20 threads in the block would be better yet. I'm just not sure it is necessary unless you plan on running a lot of boost. You would probably be better off getting a set of turbo rods for the engine.

 

[seawalkersee]

435 will bolt up to the bell housing. I have proof in the garage.

SWS

 

[6.9poweredscout]

435 will bolt up to the bell housing. I have proof in the garage.

SWS

thought so....

-Jon