Trying to understand idi air flow

[rustygold]

I have been thinking about idi air flow vs all the new powerstroke air flow. The idi has more flow the the 7.3ps and 6.0ps. So mu questions is why does the 7.3 and 6.0 make more power then the 7.3idi. Is it the pre combustion camber where the power lost is at or is it the intake? Just trying to figure it out I do understand you can have the same gen sbc and hp and torque is all slightly different from the two, but that's not two different motors.

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[IDIoit]

pre cups is a big factor.
the IDI's have a separate intake runner to the intake valve., where the PSD's have a open plentum in the head.
they push more air more freely. and boost a hell of a lot more.
I believe getting rid of the stock intake would help tremendously.
I actually have a split intake I plan to run on my 41.
but it still uses some of the cast aluminum intake.
I will be contacting @freebird and have him cut me some stainless intake flanges, soon as I get on this pig.
hes already made me some 3/8" ss exhaust flanges, and im anxious to get them together.

my goal is to grenade a block

 

[rustygold]

So having the pre cup the port in some air and rest goes to the cylinder right? But you say the n
Intake manifold is restrictive for the motor so if you had bigger intake with the right flow and velocity you would be a perfect match for this motor.

I haven't tore into one yet but I like ro have knowledge to make things better.

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[IDIoit]

another way to look at it is, boost is boost. when you have a charged intake of say 20 psi, does it really matter much?
Im no scientist, nor am I very smrt.

but you can open up the intake runners, make new manifolds, and do a lot of other work. but your only real restriction is the valve itself, valve lift, and valve duration.

 

[79jasper]

I would say more to do with being direct injected.

Intake design has no bearing. Look at the 6.0 intake.

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[rustygold]

Ok I can see it being direct injected because of the flame front and how it's move around the cylinder. On the idi it has to go move out of a little whole then around maybe it's the air to fuel mixture.

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[79jasper]

Oh yeah, I left out flowing way more fuel. Lol

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[rustygold]

So I wonder how this would work out. If I could cast heads it would be awesome need to get a set made for an idi but direct inject getting rid of the pre cups. This would probably cost more the 10k to get the psd on a common rail injection system.

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[icanfixall]

In our idi engines no air flows from the intake directly into the precups. When the intake valve closes most of tha air in the cylinder is compressed into the precup. Thats the volume of a cylinder about 4.110 bore by 4.110 stroke. The squish area between the head and the piston top is around 402 thousands. When compressing all this air you ctrate heat. That heat is what ignited the diesel fuel when its injected into the hot precup. BTW that precup is not really contacting the sides of the head. There is a slight gap so heat can't transfer easily. Only the ring that seats in the head is contacting anything. Diesel requires around 940 degrees to ignite. So you must make at least that much temp for good ignition.
Piston tops have a Ricardo cup bowl in them. Many think it is a valve recession but it clearly is not that at all. But it looks like that.
Our pistons come up out of the heads by as much as 31 thousands in stock form. The only reason they do not hit the head is the thickness of the compressed head gasket which I have measured at about 76 thousands.
Now if you run a turbo you have pressure stacking up on the bottom side of the intake valve. When that valve opens it fills the cylinder with I believe the same pressure because we have so much reserve volume in the intake manifold. This makes an increditable extra amount of compressable air for combustion. That's why we can turn up the fuel. We have more air to burn it now. Be careful adding much more boost too. you can over ride the intake valve springs easily.
Headers sure would be nice with a turbo but will be a very custom fab job. Running free flowing no muffler 4 inch back from the 3 inch down pipe gets the heat and makes more hp too. Running a better cam helps.

 

[F350camper]

Besides the VE stuff thats already been mentioned, the only other way to make more HP is to burn more fuel. Which means (typically) more boost, which means being safely able to handle burning more fuel and having more boost. Another common way to burn more fuel is more RPM, which means being safely able to handle more RPM etc etc.

 

[jaluhn83]

Direct injection is inherently more efficient, as is higher pressure injection. The computer control also allows finer control to get the proper amount of fuel at the right time for the optimal burn.

Net air flow is displacement times boost - 6.0 @15 psi of boost is essentially the same as 12L NA (very very generalized concept - point is a 6. point whatever with much more boost than an idi is flowing much more effective air than the idi even though the idi displacement is larger.)

 

[76ford466]

Im going to throw my 2 cents in on this. Im saying the in direct injection is the worst hindrance. From a performance standpoint. It wastes heat which is power, these motors are harder to cool than a powerstroke. Notice the radiator size difference. Where ever your heat is going there goes lost power. The exhaust manifolds are actually pretty free flowing in my opinion and so is the intake and heads. But the fuel system is a terrible limiter. Not that decent power cant be made but, it cant flow enough fuel at higher rpm where hp is made to really carry the power curve and keep the larger ports happy. If you have a turbo that can light off early and low in the rpm range to burn the fuel the db2 pump can put out then its going to choke at higher rpm. There goes hp. Or a bigger charger to clean up the fuel at higher rpm then you cant use the fuel at 1400. Also the fuel injectors have a big by large opening so as to flow the fuel fast at a lower pressure. compared to most any other direct injected modern diesel, which doesn't atomize the fuel like say a 20,000 psi common rail with 5 or so tiny openings.

 

[rustygold]

So the injection pump is a down side then pre cups are a big deal on power lose because the flame front out of a small hole. I built alot of chevy and flame front it's important.

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[mbolton1990]

Figured I'd mention Justin Anderson (owner of R&D IDI Performance) hared on his Facebook where his IDI Bronco build put down 725 ft/lbs on the roller today.

Have hope good gents.

 

[typ4]

Nice head cutaway. .