Porting idi heads

[Frstdiesel]

Hey guys, I'm doing a freshen up job on my 90k miles 1984 F250.
I have a couple questions.
1. I haven't found much info on porting 6.9 heads. For example what areas need to be cleaned up or not even mess with them.
2. What's the going rate to have an IP rebuilt?

Purpose for this truck is to tow with a couple times a year, not a daily driver. Has the T19 4 speed.
Probably will not tow over 7500 lbs.
Thanks

 

[Thewespaul]

If you’ve never ported heads before I wouldn’t start on an idi. When I port these heads I don’t change much, and I do so very conservatively, these heads flow very well in stock form for their application.

 

[Frstdiesel]

Ok thanks.
I have ported a set of Ford 400 heads and gasket matched a few sets of the bow tie heads.

 

[Hydro-idi]

Like mentioned, porting these heads won’t do much good imo. They flow quite well in stock form, and doing so won’t net you a power gain. Only thing that does a damn bit of good in regards to hp is a turbo on these old engines.

 

[Frstdiesel]

Ok, I'm good then as this has an old Banks setup on it.

 

[hce]

Never see any mention of the the cam is less then .400 lift. So porting would only be effective if it improves flow at low lift. Not impossible but need a different approach and really need a flow bench.

 

[IDIBRONCO]

All of this being said, if you want to port your heads, go right ahead and do it. The intake side barely needs to be touched to gasket match, while the exhaust side needs to opened up quite a bit. Since the fuel doesn't come in with the air, you can polish the intake side as smooth as you want. I mostly gasket match on mine, but I try to do some extra reshaping on the exhaust ports. I figure that any gain is a good gain. Also, once it's done, it's done. There is nothing else required to keep what gains you get. Since you've done a few sets of heads before, I wouldn't be afraid to tackle your 6.9 heads. The first pair of heads I ported was on a 6.9.

 

[Macrobb]

If you want more power, get a set of headstuds installed. Then, you can crank the fuel and make a bunch more power.
A N/A IDI is limited by air; once you get the turbo on there, you need more fuel to make more power. All the porting in the world will make no difference when the fuel is metered in seperately.

 

[Thewespaul]

Yes. Polishing is really only effective on our diesels, and the castings can be pretty chewy. I only polish the intake, I port and polish the exhaust and I cleanup around the valves and on a few of the short turns. It’s free and personally it’s a relaxing task to do on a weekend night. Yes you can just add more boost to make more power, but that’s not always the answer.

 

[Frstdiesel]

Thanks guys.
I have a set of head studs waiting.

 

[Macrobb]

Yes you can just add more boost to make more power, but that’s not always the answer.

Nitrous, then? Sounds good!

 

[Thewespaul]

Been there done that

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[Frstdiesel]

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The Banks set-up I have dates back to the mid 80s.
Is there a way to increase boost on those?
Not sure how much boost they put out originally but from what I have been reading I probably wouldn't go higher than 15.

 

[Thewespaul]

There is no wastegate on that generation of banks turbos so your only adjustment is going to be the fuel screw on the side of the pump, don’t touch it until you get a pyro in first.

 

[Macrobb]

The Banks set-up I have dates back to the mid 80s.
Is there a way to increase boost on those?
Not sure how much boost they put out originally but from what I have been reading I probably wouldn't go higher than 15.

With a 6.9, 6-ish is safe, though I've heard of people pushing 14.
With studs, 15-20 is safe.

12 PSI is basically equivalent to being able to double the power of the motor, assuming you are adding fuel. You increase boost by... adding more fuel(up to a limit). Basically, once you don't have a problem of the heads lifting on you and blowing gaskets, you just crank the pump up and get an EGT gauge. You can then crank the pump down as needed.

Also, when we talk about "cranking the pump up", or the "fuel screw", it's not like a gasser where you change the mixture. It's simply a fuel limiter, which limits the amount of fuel per cylinder/revolution at wide open throttle. It won't affect 'part load' fuel, because, effectively, the injection pump will always be running the "leanest" mixture that outputs the power you request using the accelerator pedal. If you only attempt to maintain speed(with, say, 1/4 pedal), the pump throttles back fuel as needed to maintain that speed. Add a load(up a hill)? The pump will increase fuel. Down a hill? It'll decrease fuel. Now, there are limits to how much it does this, which is why you can't just use the pedal as a cruise control, but it's 80% like that(Note: The reason it works like this and not as a constant RPM governor is due to the springs inside. With the right springs, it would maintain a constant RPM under 0 to full load at a given throttle position).