Questions about Porting heads

[IDIoit]

looking for info on porting heads for the IDI is something id love to comprehend.

ive done alot of research on porting pontiac gasser heads, but diesels are a different kinda animal!
ive been told that when doing so, there really is no need to flow test them, due to the lack of atomized fuel.

but something tells me that getting all of the ports the same is still very important.
i hope some of you that have done this could help us out, im sure alot of people here are interested in this
low buck way to gain a bit more power.

its obvious that we need to do this prior to having valves and seats ground.
do you guys just blend the mouth to throat transition?
what grit do you do final polishing with?
i have 3 more gas engines to build before i embark on my next IDI build.

thanks in advance guys!

 

[laserjock]

Ping Gary. I saw him post pics of his port job not too long ago. I've thought about it but with forced induction, I'm not sure there is much too be gained. Still, gasket matching couldn't hurt I suppose. NA I'm sure it would make a difference.

 

[BDCarrillo]

Laserjock nailed it... benefits may be had with N/A, but they largely disappear with forced induction.

To match flow you need a test rig capable of measuring the cfm output at each port. Port volume also affects performance... at our low RPMs keeping the volume low will keep air velocity up. IE, no point hogging out the intake ports.

A polish on the exhaust side wouldn't hurt... fewer nooks and crannies for carbon to cling.

 

[marmot]

It seems that with no danger of condensing fuel you should be able to port match em and polish them up without affecting performance much...which is why I personally would never do a porting job on a diesel. I have done it with gas cars and have had heads flow matched but this is a whole different ball of wax. I am sure there would be a small benifit even in turbo applications but I doubt it would be very much.

 

[riotwarrior]

Any head has irregularities in them from casting....cleaning th overall port up and a good blend of the short turn radius and bowl shape is ok...haggin out large amounts is not a great thing. These heads flow quite well as is, and it's just getting the most for a little bit of work. As there is no fuel on intake side they can be a good polish with very little problem. There will still be a layer of air at the surfase that moves slower than the middle and that's normal all we are doing is removing friction from that movement.JM2CW

 

[PwrSmoke]

Yeah, it's quite a lot of work and if you pay someone to do it, it's very costly because it's quite a lot of work. Benefits are negligible in a turbo and middling with a NA. Benefits there but not in comparison to the cost/effort.

 

[TahoeTom]

Justin at R&D Performance posted some data on FTE on a set of heads he ported. He actually made the intake worse than stock, but gained some on the exhaust.
http://www.ford-trucks.com/forums/1363960-idi-head-flow-numbers-stock-vs-ported.html

 

[riotwarrior]

Yes I remember Justin's posting and we ...him and I had extensive disscussions on this matter.

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


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


There you go, Ill let you guys draw your own conclusions before I weigh in...




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:

You must be registered for see images attach

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


They are as follows...


All measured at 28" of water column




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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One thing that's seen in the image he shows, is the extensive porting and unshrouding he had done around the valves. I would like to have seen how the factory's head design works with porting in direct comparrison to this mod he did.

The flow gained is at very high lift of valve so I'm guess he opened up the ports too much losing velocity and CFM at lower lift but gaining at high lift...this is theory of course.

Maintaining a factory profile with minimal change except maybe gasket match..is really all one should do unless you have a flow bench.

Just saying no bench no proof...and well worth the time to do basic cleanup...maybe it is...maybe it isnt.

JM2CW

 

[BDCarrillo]

Looking at those stock numbers I'm amazed! For a factory casting with relatively small valves, they flow pretty darn good. The GT40 heads on my Mustang flow almost exactly the same, but feed 2/3 the engine at up to twice the RPM.

Makes me wonder how balanced the intake manifold runners are...

 

[icanfixall]

I'm sure some have been waiting and watching for me to weigh in on this posting idea. I disagree with most of whats been posted here about porting does little for a turbo engine. What I do completely agree with is the exhaust port work. I learned what needs to be done on the exhaust but explaining it will not tell those of you that want to attempt this. It takes a special burr to clean out the particular area of the exhaust port. Also care MUST be taken porting the exhaust. There is lots that must be removed from the non cooled side of the port. Blending the port to the exhaust manifold log is important too. Try to imagine what the pressurized air is doing in the intake and the exhaust ports.First off with a turbo you have X amount of intake pressure loading up on the back side of the intake valve. Now as that valve cracks open the inrush of air is dragging past the ruff walls of the intake. So simpley clean up and match the intake ports for increased flow into the cylinder is going to help no matter how you look at it. No need to hog out anything really. A mirror finish is nice but if you have no experiance doing it then stick with 300 grit finish. Remember all the turbo pressure flows better in a smooth bore port and it fills the cylinder as the piston sucks it down on the down stroke. The cylinder is going to be filled with the turbo boost pressure so if you see 10 lbs on the boost gauge then the cylinder now has 10 lbs in it as the valve closes. Now getting the hot gas out of the engine thru a port that has the wrong radius turns in it.. Not happy expanding gas really. My exhaust ports continue to open up as they get closer to the manifold. I also ported my exhaust manifold logs. I mostly cleaned up the crappy casting flaws so the flow was easier. Remember that the exhaust is under a pressure too because its driving the hot side of the turbo. My final porting was done to the precup chambers in the heads. I made a custom ball end mill to my specs that did 2 things. First it cleaned up the ragged casting and milling down in the offshore heads. They looked like a monkey with a broken grinding wheel cut them out drunk. Anyway I also cut them 60 thousands deeper so the injectors are now set in the cups the original amount they were designed for best burn. Some might recall that after a certain date ALL idi heads had the injectors pulled up out of the precups 60 thousands for epa reasons. the claim was it burned cleaner doing this.. Probably did but the effect on hp was horrible. Of course one could easily just used an end mills on a bridgeport mills and sunk the injector seats another 60 thousands and been ok. But cleaning up the chambers and sinking the same 60 thous was a 2 for really. When I did my first set of heads I was at work where I had several million dollars worth of grinders and burrs plus all the 3M sanding rolls anyone could ever use. Here at home I have one Makita grinder tool that has a 25,000 rpm shaft. I do plenty of burr changes here but in the place I worked, the shop. I had probably 6 different air grinders of all shapes and sizes hung on my tool box with different burrs and sanding rolls ready to go. I even had them plugged into an air manifold so all I did was choose one and start working on what I was doing. In a home shop its much slower work but whos in a hurry really. Would I recommend anyone doing this work.. Not really. Its plenty of work really so much so that a person gets bored with it. For me I choose to only port the off shore import heads. Reason is they are built better than the oem heads. Reading how someone ported a 6.9 head and after having lots of hours into it only to find out the head was cracked..... WTFH... Do you not think first to mag the heads BEFORE working or repairing them like doing a valve job ob a sinking ship....

 

[IDIoit]

Anyway I also cut them 60 thousands deeper so the injectors are now set in the cups the original amount they were designed for best burn. Some might recall that after a certain date ALL idi heads had the injectors pulled up out of the precups 60 thousands for epa reasons. the claim was it burned cleaner doing this.. Probably did but the effect on hp was horrible. Of course one could easily just used an end mills on a bridgeport mills and sunk the injector seats another 60 thousands and been ok. But cleaning up the chambers and sinking the same 60 thous was a 2 for really.

hmmmmm do you recall the production date?
im guessing this happened during the 6.9 era, so all 7.3's have the adjustment?
great info Gary, and yes we were all waiting on you! but honey do's come first, right?
thank you!
this is all just research to make this truck run as good as it can when i finally build my next engine.

 

[The Warden]

hmmmmm do you recall the production date?
im guessing this happened during the 6.9 era, so all 7.3's have the adjustment?

If Gary's talking about what I think he's talking about, this happened very early in the 6.9L run...starting with block #59209, which corresponds to early to midway through the 1984 model year. My truck was built in August '83 as a 1984 model year, and still has the early engine, FWIW...

You must be registered for see images attach

 

[icanfixall]

When this raising the injectors 60 thou the hard lines were also shortened the same amount. This shortening the hard lines may be a cause of some of them being stinkers to get threaded on the injectors. I seriously don't think any of us here can measure the length of a hard line to determine if we have a mixed bang of lines on our engines. Buying new eliminates this long and short issue if in fact it really happens.

 

[marmot]

Thats great information! thanks guys for sharing it

 

[IDIoit]

When this raising the injectors 60 thou the hard lines were also shortened the same amount. This shortening the hard lines may be a cause of some of them being stinkers to get threaded on the injectors. I seriously don't think any of us here can measure the length of a hard line to determine if we have a mixed bang of lines on our engines. Buying new eliminates this long and short issue if in fact it really happens.

60 thou is basically nothing!
i can tell you first hand, going from the 7.3 hard lines (which have the pulse bulb, or wtfever it is) to the 6.9 lines with that bulb out of there gave me no trouble.
altho i did install a better IP and injectors.
as long as the lines are the same?
one can easy manipulate 060 out of the injector hard lines.