Porting and polishing cylinder heads

[Tooheysmax]

You need to go out and get 2 40lb sacks of sand. One that's sharp, and one that has been tempered over time to be more spherical in grain.

Once you have acquired the sand, make sure you do this in a remote parking lot somewhere (a lot of sand is going to come out the tail pipe) and bring a buddy to help.

Start by removing the air cleaner assy off the intake. Have a buddy start the car and rev it to just under 500RPM below redline. SLOWLY start pouring in the "sharp" sand. This is what we call a Stage 1 port and polish, and honestly, it does most of the work enlarging the holes in the heads.

Secondly, after you have got through most of the first bag, pop open the second bag and repeat. This will polish up everything and remove the sharp edges created by the other sand.

If you want showroom quality, you can also finalize with a bottle of talcum powder in the same fashion. You can expect a smooth mirror finish.

EDIT: I forgot to add, you may want to purchase your sand sooner than later. Even if you don't use it now. Apparently there is a worldwide sand shortage.

Can I see your YouTube channel video on this tutorial.

 

[[486]]

Correct, but it has a very good chance of not making it worse....like screwing up the runner design can

might fuck up the timing chain retardation though

 

[SLOWPOKE693]

might fuck up the timing chain retardation though

It's a Range Rover, It's already retarded in more ways than one....

 

[YZRider]

One of the important parts is that once sonic flow is reached, you can't move any more air. Hotter less dense exhaust gas reaches that point at a much higher velocity, that's why the ports/valves are always smaller. The main reason you shouldn't go changing the port volume without a specific goal and knowing what you're doing. In a lot of cases you see guys filling ports to reduce the volume for gains at a different RPM range. Getting numbers on a flow bench can count for a lot, but port velocity is more important.

 

[Provience]

Well, fill in some areas and remove in others

There is a bunch a piece of string can tell you. Getting it smooth flowing is important.

 

[YZRider]

Well, fill in some areas and remove in others

There is a bunch a piece of string can tell you. Getting it smooth flowing is important.

Yep, moose knuckles at the seat and guide bosses, probably to reduce the casting reject rate, that flow more efficiently once cleaned up. Seen a few instances where guys hog out material and wonder why their shit runs bad.

 

[Kyle]

might fuck up the timing chain retardation though

Yes too low of heads can do that

 

[det107]

Kyle

I have this tool. I used it one time on Isuzu heads back in the late 90's? Let me know if you want it-

 

[Takotruckin]

Aluminum. Jag Land Rover 5.0SC. No aftermarket. A pulley and tune and exhaust can get me to 675hp. Hoping to flirt with 700

I might be wrong here… but isn’t cylinder head flow WAY less critical in a FI application? I seem to remember it not being worth it when you can just add 1 psi of boost and make a bigger difference.

 

[ANGRYBLACK]

Yes it is a DIY thing. But like a linked suspension it takes more research than work. I'm too old and lazy to go find direct links but , many years ago on Camaraoz28.com there were great tech posted in the advanced tech section. Read anything like the bible in there from LT1 1980 Malibu and Mr Horsepower along with the same cronies that follow a pattern in threads. There is one of the S.A.M.. guys posting in there as well as a few of the OG Comp Cams tech line guys. I just can't remember who is who anymore. Mr Horsepower is actually C. Riddick of Reher Morrison racing engines and has worked with Honda Racing on their head program.



My opinion is that you leave them alone. What you gain in the ports you will lose at the exhaust manifolds and i'm sure that the rover folks left little on the table. That's just the way they design. If you must waste your time and ruin what OEM did , then just polish up the ports everywhere except the short turn radius. Smooth the intake ports with a 120 grit finish on flap wheels.You can smooth the exhaust to a much finer finish like 320.

What you will gain for the cost of the proper cheap tools to do it aren't worth it. You need a proper high rpm 1/4 collet die grinder. I like the dewalts. Then about 3-500 in consumables. i have been using Ruff Stuff https://www.ruffstuff.com/ since my 1st tuned port head i ever hogged.

You really need to buy a few pairs of used heads and try a few things here and there then test. On a real flowbench and not some supasucka vacuuum that you whip up on your bench.Most high end head shops will flow 2 ports for under $150.

I'm sure i am very slow but a pair of Big Block Chevy 781 cast iron heads takes me about 2 weeks. That gets me 20+ CFM under the peak. It takes me the same amount of time to run through a pair of alloy heads. That's a lotta time for minimal gains if any.

I don't want to deter anyone from getting into a set of heads. I actually love port work so much i once bought a flowbench. But the days of crappy smog heads are long gone as is the large gains from porting later model anything heads.

 

[Outahand]

Back in the day I did a few gasket matches of intake and exhaust ports and manifolds on different motors in my first cars.

When I rebuilt my first GN motor in the mid 90's I spent a lot of time on the heads thinking I was doing a great job. When I was finished I had a valve job done. The machinist said it looked like I spent a lot of time, he hoped I didn't hurt the flow too much.

Looking back I was just lucky I didn't punch through anywhere The heads are still running today. Been used in a pretty stock application.

One thing Lawrence Conley wrote once was your boost is a measure of the restriction of your engine. That kind of made things click.

 

[billdacat]

One of the important parts is that once sonic flow is reached, you can't move any more air. Hotter less dense exhaust gas reaches that point at a much higher velocity, that's why the ports/valves are always smaller. The main reason you shouldn't go changing the port volume without a specific goal and knowing what you're doing. In a lot of cases you see guys filling ports to reduce the volume for gains at a different RPM range. Getting numbers on a flow bench can count for a lot, but port velocity is more important.

That is what I remember.... It is sort of rocket science. You need to know where to remove material; then you have to match the cylinder head volume. (CC'ing the head and cylinders). Removing material from the head is going to lower compression ratio; new custom pistons would then be in your future. And then you go round and round. Cleaning up a head and port are no-brainers... Just don't get carried away.
IMHO: I wouldn't fuck with it beyond a good cleaning.

 

[Kyle]

Kyle

I have this tool. I used it one time on Isuzu heads back in the late 90's? Let me know if you want it-

What? that’s the exact tool i borrowed last time. You giving it away or?

 

[det107]

You giving it away or...

... Yes, you certainly can have it. PM sent-

 

[Kyle]

Can’t post pics but the damage is impressive

 

[Kyle]

Well that escalated quickly. Valve Tool worked perfect on the 3 valves not mangled on this head 😂