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IDI Head Flow numbers, Stock Vs. Ported

 
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Old 02-22-2015, 08:17 PM
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IDI Head Flow numbers, Stock Vs. Ported

Ok, so awhile ago I had a stock IDI head flow tested, and the thread is located here:


https://www.ford-trucks.com/forums/1...w-numbers.html




I ported a set of heads for my 6.9 build last year, but found out that they were cracked after way to many hours of porting went into them. They came out pretty good if I do say so myself, at least in the sense of traditional porting techniques and advice:





Originally Posted by RacinNdrummin View Post
They are as follows...

All measured at 28" of water column


Intake

.100" - 69cfm
.200" - 128cfm
.300" - 175cfm
.400" - 184cfm
.500" - 187cfm

Exhaust

.100" - 45cfm
.200" - 82cfm
.300" - 119cfm
.400" - 147cfm
.500" - 163cfm

...

Well I had one of the heads flow tested, and the results were quite surprising for me.


The test resulted in the following:



Intake

.100" - 62cfm
.200" - 112cfm
.300" - 160cfm
.400" - 186cfm
.500" - 206cfm

Exhaust

.100" - 54cfm
.200" - 96cfm
.300" - 130cfm
.400" - 159cfm
.500" - 173cfm



This was on the same machine, under the same atmospheric conditions. The exhaust was an excellent gain across the board, but I lost more ground on the intake than I gained.


This shows that intake porting needs to be more strategic than exhaust porting, and until I get some time on a flow bench, I don't know where the head could be optimized on the intake.


These heads also didn't have a valve job, so the impact of the angles isn't reflected either.


However, at the end of the day, if anything, this proves that you probably shouldn't screw around with porting IDI heads unless you have some way of measuring results of specific adjustments. The exhaust port is definitely more forgiving, and even rudimentary porting tech seems to work well, but the intake really isn't worth touching.
 
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Old 02-22-2015, 10:08 PM
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That's some interesting info! Too bad the numbers on the intake side dropped. It would have been nice to get some extra flow all the way through...
 
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Old 02-22-2015, 10:28 PM
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That's cool stuff man, I don't really understand all of it..but its cool
 
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Old 02-22-2015, 11:55 PM
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Originally Posted by southtexasidi View Post
That's cool stuff man, I don't really understand all of it..but its cool

Well essentially, I lost more flow on the bottom 3/5th's of the range than I did on the top... Guess where the most time the valve is open at is?... The worst part is that I "tried" to do tricks that traditionally resulted in more low lift flow, like de-shrouding, and short-side pocket work. I was really optimistic about this port job, even so much as to talk to my machinist about pinning the cracks if the test was good.... It wasn't.


Ill get around to testing the intake port part by part sometime.... as of right now, this is the status quo.
 
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Old 02-23-2015, 12:50 AM
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The ports are too big by those numbers. A rifled cut and minor blending/smoothing might show big gains, as would a remodeled port floor to increase charge velocity at lower lifts. I bet if you started about 1/4" thick at the edge of the head, tapering back to metal right at the radius it would flow some fairly respectable numbers. As it sits, the air is just tumbling through at lower lifts and not swirling to go through the valve.
 
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Old 02-23-2015, 07:19 AM
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I always thought that on a forced induction engine that bigger cams and porting had minimal return on investment. A slight increase in boost would give the same effect.
 
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Old 02-24-2015, 03:49 PM
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What if you leave the intake alone and just clean up the exhaust? Wont that help it breathe a lot better across the board?
 
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Old 02-24-2015, 04:18 PM
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Originally Posted by Ford_Six View Post
The ports are too big by those numbers. A rifled cut and minor blending/smoothing might show big gains, as would a remodeled port floor to increase charge velocity at lower lifts. I bet if you started about 1/4" thick at the edge of the head, tapering back to metal right at the radius it would flow some fairly respectable numbers. As it sits, the air is just tumbling through at lower lifts and not swirling to go through the valve.

Fwiw, I didn't do any enlarging to the port, just guide boss work and blending the seat into the port, with a light scuffing and cartridge roll blend. The port is very small in terms of cross section, so Im sure velocity isn't an issue. I don't doubt the floor mods, for a head like this with the valve angles we have, Im sure that would be a huge gain.... I just don't know how confident id be with the epoxy in an engine that sees such drastic heat cycles as a diesel.
 
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Old 02-24-2015, 04:20 PM
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Originally Posted by bashby View Post
I always thought that on a forced induction engine that bigger cams and porting had minimal return on investment. A slight increase in boost would give the same effect.
No and Yes.


Forced induction is simply just increasing pressure of the airflow that's already there. So lets say we increase flow 10%, that 10% is going to be compounded by pressure ratio, making gains on a forced induction engine even more pronounced. However, the benefit the forced induction engine has is the ease of cranking up the power by just increasing boost... Just depends how much give you have in the efficiency of your setup.
 
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Old 02-24-2015, 04:24 PM
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Originally Posted by Gettysburg150 View Post
What if you leave the intake alone and just clean up the exhaust? Wont that help it breathe a lot better across the board?
Proabably the best idea as of now... I wouldn't recommend going in a hogging things out, but if you have some porting experience, and know how to blend things in nicely, I don't think youll hurt the exhaust, only help it. This will be especially true on turbos that have the bigger exhaust housings or hot sides, your drive pressure is only going to be lower, netting more gain by a higher flow exhaust, and that extra flow is going to mean quicker spool. I don't think it will result in much on the tighter, smaller turbos.
 
 
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