Navistar 6.9L boost limits.

[Andertusa]

Navistar 6.9L boost limits?

I have an '84 Ford F350 super duty extended frame dually with the 10.5 Sterling, 4 speed stick, and a 6.9 Navistar in it. I want to 'hot rod' the engine, and build the truck as a 'mini semi', and I was wondering what the MAXIMUM boost I could ram into this beast before I risk catastrophic damage. I don't care too much about long-term longevity as the truck may only see 3,000 miles a year and is more for 'fun and show'. I was thinking of two turbos from Cummins 4BT engines, running with a heavy dual inter-cooler set-up.

 

[OLDBULL8]

Read this, then you know what you've got to start out with.
http://www.dieselpowermag.com/tech/ford/0703dp_international_diesel_engine/

 

[Andertusa]

Read this, then you know what you've got to start out with.
http://www.dieselpowermag.com/tech/ford/0703dp_international_diesel_engine/

Interesting website, but it doesn't really talk about boosting it; the weakest point I can really see seems to be the five bolts per cylinder, you want as many as you can get for unning much boost. Though, I was only thinking something around 20-22 lbs boost.

 

[drinkypoo]

The biggest problem is that the engine has very high static compression, 21.5:1 IIRC. It doesn't hurt the 7.3 that it has bigger bolts, though.

allegedly if you change the cam you can run more boost, but I have no details

 

[Andertusa]

The biggest problem is that the engine has very high static compression, 21.5:1 IIRC. It doesn't hurt the 7.3 that it has bigger bolts, though.

allegedly if you change the cam you can run more boost, but I have no details

Interesting. See, I'm sorta new to this whole diesel love thing, I Have the 84 F350 Diesel; and couple of projects I wanna 'diesel-up, like a ;56 GMC 450 and a 51 Ford F-6, and a 79 Suburban I'd love to see with a tweaked 3208.

 

[drinkypoo]

Well, personally I would only swap two diesels. Mercedes OM617.951A (or B) and I think it's the 94-98 cummins that comes with the inline injection pump with one pump per cylinder. People swap their fords TO cummins, I wouldn't use an IDI anywhere I didn't have to. And I say that as an owner of a 1992 7.3 with an ATS 088. The DB-2 injection pump is poop and an inline fits in a light truck MUCH better. And I find the appeal of the IDI is low parts cost and high reliability so I wouldn't mess with it too much, but maybe that's just me

 

[chris142]

An inline cummins would be more correct. Semis have not used a v8 in decades...you could always use a small screamin deamon though

 

[88 Ford]

Here are a few threads you need to visit. These engines are extremely underrated compared to what most believe. There are quite a few guys over on FTE running 20+psi. And even some over 25psi.

http://www.ford-trucks.com/forums/1115258-project-smogie-racinndrummins-idi-build.html

http://www.ford-trucks.com/forums/1231342-just-another-impossible-build.html

http://www.ford-trucks.com/forums/1226979-my-6-9l-idi-build.html

Also here is a performance site you need to see as well.

http://idiperformance.com/

 

[Andertusa]

Thanks for the info guys. I wasn't thinking too wild and crazy, but something similar to what was in the first link '88 Ford' contributed seems pretty close, though I don't want a box, and mine isn't a 4x4 and I'm not interested in 'harvesting' parts from another truck the way they discussed. The engine stuff looked 'right on' though.

 

[jaluhn83]

I'm consistently hitting 19-20 psi max and well over 10 frequently. Now, that's with 0.015" decked and ceramic coated pistons and head studs. ~20k miles on the rig so far with no evidence of issues.

On the other hand, you're never going to get near what a more modern engine can do as far a ultimate power. You're also talking about putting a lot of effort and money into something that doesn't really seem worth it to me. To each their own though.

 

[Andertusa]

The project isn't really about making sense, it's a labor of love; like most hot rodders. I'm sorta aiming to hit 350 HP and 450 TQ, I'm currently thinking of a twin turbo set-up. I have the technical metal skill to fab whatever I can't find(within reason)Brackets, tubes, plumbing lines and that is pretty easy, I'm even thinking of maybe running a multiple inter~cooler set-up.

 

[88 Ford]

I disagree about not getting near what a modern engine can. That has already been done by both Justins. Now RacinNdrummin has even more fuel. He will easily hit over 400HP. With enough fuel it is easier to attain that.

 

[88 Ford]

The project isn't really about making sense, it's a labor of love; like most hot rodders. I'm sorta aiming to hit 350 HP and 450 TQ, I'm currently thinking of a twin turbo set-up. I have the technical metal skill to fab whatever I can't find(within reason)Brackets, tubes, plumbing lines and that is pretty easy, I'm even thinking of maybe running a multiple inter~cooler set-up.

If you're at 350HP you will be around 700lb-ft. Diesels tend to be double the torque to horsepower. Are you building parallel twins or compounds? Also an intercooler is pretty much a necessity. With higher boost levels you will have high egts if you don't.

 

[Andertusa]

Well, I've never undertaken any 'turbo' project before, so I have no real experience to bandy about, but what I've sorta been mulling over in my noodle the last few days has been BOTH, a compound AND parallel turbo set-up. Maybe twins in parallel and then one slightly larger one taking the exhaust inputs from the parallels.

 

[drinkypoo]

I disagree about not getting near what a modern engine can. That has already been done by both Justins. Now RacinNdrummin has even more fuel. He will easily hit over 400HP. With enough fuel it is easier to attain that.

That's quite good, but it's nowhere near what you can get out of a modern engine. Still a labor of love kind of project. Nothing wrong with it, it doesn't need to be justified