porting heads

[topgunn]

How big can ports be opened to? Have gaskets that are 1&13/16ths, the other is 2". The only close spot is by head bolt holes.
Icanfixall, how big did you open yours?

 

[GenLightening]

I don't think there's a magic number. You'd have to use a flow bench and decide what rpm you want to be the most efficient at. Then you add in the port design, and any issues, to come to the best route. I just port matched mine and cleaned up the castings. I also cleaned up the intake where the screen mounts. It's pretty square and I made it flow better. May not actually do much, but it looks a lot better!

 

[icanfixall]

I'm not sure what you are posting but here is what I did. Sounds simple but thats just how it sounds. All my gaskets for the intake and exhaust are from Felpro. I simply matched the opening to those. On all exhaust manifolds there is an alignment bolt hole. Use that to align the gasket to the head exhaust port. I found a sprayon layout die that work great. The name is Dykem. I didn't use the paint on stuff cause its kinda ruff to get it on the way I like. Now use the gasket to scribe a line as to how large the port can possibily be made. You can leave this exhaust port just about 1/64 smaller that the exhaust manifold. No reason for a lip that the flow will be hitting. The intake is just the same way. Its going to be close at a few intake bolts so be careful as to what you cut away. Mostly what you are trying to do is clean up the ruff machining the factory gave you. Look down into the valve pockets. Kinda ruff isn't it. There is a tuff area of the intakes that you wont be able to reach. The exhaust ports are the most important. Get them smooth and the hot gas will flow out faster. We can actually make all the ports a mirror finish. Thats something that will kill a gasser because fuel wil bead up on the smooth surfaces. All we do is push air into the motor. No fuel flows in but it is injected late. The small curve in the exhaust port needs to be smoothed out. If you looking in from the exhaust manifold its on the bottom. Feel it. Now round it out. I use a large double cut burr for this. Its tapered both directions. I can get the part number later. The finich work needs to be done with some special 3M type burrs. I can get the part numbers for thos too. Sanding rolls and cones really help. 3M makes the best but Harbor Freight sells a chainese kit too. Its not as well made as 3M but it will work in a pinch. Let me know if this helps or more is required. Figure about 20 hours per head too.....

 

[GenLightening]

Oh, keep in mind the direction of flow when working on the areas around the valve seats. The intakes can use some work. Not so much on the exhaust, you can do it anyway but it will be a lot of work that won't make much difference.

 

[icanfixall]

Doug.. Any "cleaning and port matching" will add to flow. We don't turn high enough rpms to require a flow bench plus most of us are running a turbo. If these motors were turning 8000 rpm or higher then yes, flow testing is needed. So adding 12 lbs on the intake valve before it opens is adding lots of air above na motors. Now ad the dynamics of heat and expansion to the exhaust. Opening them up will cause better flow out of the head. A 20% plus flow can easily be had. Talk with Barnett Performance about their porting options. They open the intake first. Then step 2 they open the intake and only part of the exhaust.... Then stage 3 they open the intake and all of the exhaust. I've been doing all the stage 3 work on these motors for years.. These heads are really ruff machined so any work will increase flow in and out. Remember both the intake and exhaust are both under pressure. If you look at the boost gauge it never drops when a valve opens. Thats telling me there is way more volume that any one intake valve can suck up.

 

[GenLightening]

All true. But it's real easy to make a head unusable by going too far without a plan and just going in and hogging it out. Best to imagine the flow of air and smooth things out accordingly. And the intake porting will be different than the exhaust will be due to the direction of flow. On my heads, I did more work in the intake valve seat area than the exhaust because it wasn't really needed. Not like I'll be racing my truck.....probably!

 

[seawalkersee]

Well...sorta. I only disagree with Icanfixall on the exhaust part of this. If you hog out the exhaust of these heads, you are going to put the quench point moved freom the head to the manifold. The driver's side ESPICALLY is very restrictive when you look at the bend at the rear outlet. It is very small and I think there should be a larger manifold or header used if you go all the way to a "gasket port" on the exhaust side.

SWS

 

[seawalkersee]

Here is some of my videos. I just figured out how to do this since for some reason, I can not upload them to supermotors.

http://www.youtube.com/watch?v=IVYUd7LDt3E

http://www.youtube.com/watch?v=YmFOu9TDOHA

AND in my previous post I used the term "quench point". Not sure why since I saw it today, but the term I wanted was pinch point. If you go too big, with 2 cyls firing, you run the risk of the exhaust gas expanding in the head/manifold only to pinch it there since the outlet of the driver's side is way too small, and can not be opened much at all.

SWS

 

[riotwarrior]

In my opinion...which ain't worth much...3 cents on a good day. I say clean up the ports do minimal to change the shape and KISS just polish the crap out of them for a diesel. Especially if your not familiar with porting and how easy it is to get "thin" walls and bowls.

For my own now...well that's entirely different, having ported quite a few heads, most with very good results, I'll stick with what I do because we are force feeding these engines and that makes a difference compared to NA. Also Seawalker has a point about pinch points, that is another story though because all we are doing is moving the proverbial weak link to a different location, the exhaust manifolds.

Blending in the plenum on the intake....good idea...

Oh ya Gary is right...keep the head porting on exhaust side...weee smaller than manifold and keep manifold same as gasket, on the intake...keep the head tad larger than gasket...make the manifold same size as gasket...now both are weeee lil bit here not lots...just small bit to help with reversion both sides!

Heck I remember the old AR headers years gone by ....any one else?

 

[idiabuse]

cleaning up the castings, yes, porting the heads NO.
I bought new casting heads and I had to port them
just so the intake port would match the intake.
I thought it would take alot of matching but the intake
ports opened right up to OEM size.
The new castings had much smaller intake opening that
needed work.

My old 7.3 heads I looked and looked but making the head
better in terms of flow, I found no place to improve flow.

So the next best place to improve flow is at the valve seat.
and I did just that with a SERDI radiused valve job.

If you know what you are looking at you can see the multiple angles.

You must be registered for see images

You must be registered for see images

You must be registered for see images

 

[Black dawg]

I really dont think they need to be opened up, the ports are pretty big for the cfm requirement already. sometimes airflow can defy logic, without a flowbench you dont know if you are helping or hurting.
look at that little tiny prechamber hole. I wonder how much of what comes through the intake valve is forced into that space.

 

[riotwarrior]

cleaning up the castings, yes, porting the heads NO.
I bought new casting heads and I had to port them
just so the intake port would match the intake.
I thought it would take alot of matching but the intake
ports opened right up to OEM size.
The new castings had much smaller intake opening that
needed work.

My old 7.3 heads I looked and looked but making the head
better in terms of flow, I found no place to improve flow.

So the next best place to improve flow is at the valve seat.
and I did just that with a SERDI radiused valve job.

If you know what you are looking at you can see the multiple angles.

You must be registered for see images

OMG...nice very very nice... Is that your own machine? Do you do VJ for others? Whats the cost?

 

[icanfixall]

The last picture clearly shows the ruff casting part of the intake port. I clean all that off and make a nice blend to the intake seat area. Nothing is left as cast in any of my intake or exhaust ports. A very important area that requires some attension is the roof of the exhaust port and the fllor. The roof it about 5/16 thick cast iron without any cooling around it. The floor has all the cooling passages under it. Feel inside and you will feel a sharp radius turn. That needs to changed to a larger radius for better flow. A large reverse cut burr works best here. You place it in the port ans use the back side of the burr dragging it over this tight raduis. We can port these heads much farther than a gasser head. All we are doing is pumping in air... No fuel... Fuel is injected after compression so its not going to form droplets of fuel on the highly polished ports like a gasser. A high polish port in a gasser will ruin the flow... Droplets of gas will break out and drop into the cylinders. That will reduce the power in the cylinders... We just push in air and then push it out... Some call it.... Sucks... Pops... Blows and goes.... A gasser engine turns some big rpms and we don't turn past 3800 rpm.... Usually... We can get away with more flash in our ports because of the low rpms we run... Still... cleaning up the ports can't decrease the flow in or out... True... the drivers side exhaust log it bend terribly but I do clean up the insides of both logs. Smoothing out the ruff stuff helps. A custom stainless steel header would really be a great idea. It just take s time and money and a little know how with a plasma cutter. Tig weld all the parts and its done....

 

[seawalkersee]

Javier, I do not have the ability to open the valve area in the chamber like that. I only have hand tools for porting. What you have done is nice, but I think it may be a bit overkill. I would need to look at my heads to see if there was any benefit to opening the head up on that side as I think my valves are lower (higher in your pic) than what you are showing. Before I went that route (to pay to have that done) I would go with a larger valve. This again would be in the name of power, and again, that is NOT what I am after. I am about the efficiency. If anything, the only piece I would cut there would be near the cyl. wall just to give it the ability to flow into the cyl.

Riotwarrior, what I have done is exactly what I was trying to do. What I have shown in my vid is EXACTLY what Gary is staing above. With the reduced restriction of flow, you can push more air. Remember, there is supposed to be no vacuum in the intake side. If there is a restriction, the engine loses efficiency. Now, you can reach a point of no return by going too much in the head and not touching the intake. I did match the intake to the gasket (you would be surprised how much you can take off of some of the runners) to get it a better flow with no trips, edges or anything of the sort.

Again, I did not go all the way to the gasket on the exhaust side because I did not want to create the vacuum in the port and a pinch point in the manifold. If I had more time and was going to make a custom header, I would have taken it that far.

SWS

 

[seawalkersee]

Remeber this, I am building my engine to make good power off idle and up. I want this engine to run at low RPMs most of the time and not HAVE to take it into the upper RPMs to get it to go down the road.

For those who have missed my other posts about my blower, I have a cam from Russ, and a spare blower off of my SC. I am putting it all together so I can run at the lowest RPMs possible.

With the fuel milage threads, you may have noticed I have posted this. Reason being is you can calculate your milage by RPM with these engines. It takes only so much fuel (Mel knows what it is) to run at any given RPM with no load. With enough air pushed in (maybe some H2 and H2O down the line) I believe I can get better than 20mpg with 33s, 3.50 gears and the 1/2 ton chassis of my Bronco.

Make the flow easy in and out of the engine and improve the volumectirc efficiency of the entire engine. Doing that will make it more efficient, AND increase power. Do it at lower RPMs and milage goes up.

SWS