Port, Polish, Headwork: Order of operations

[Rasmus]

Looking at doing port work on my heads.



^^^ Not my work or heads. Fuji K's work from Nabisco.

For those more experienced with head work what's the ideal order of operations to perform the work so I'm not stepping on my own work? I'm looking for a light port job. That is, removing the casting flash, blending the throats with the bowls, removing sharp steps in the metal where the air flows.

1. Check Head Deck for level and deck as needed
2. Replace Valve guides
3. Remove casting flash and sandroll intake ports
4. Remove casting flash and sandroll exhaust ports
5. Port work on dogleg exhaust
6. Blend throat into valve inserts, removing those steps and bumps and machine marks
7. Blend in the steps near the valve heads in the combustion chambers, especially around the exhaust valve seats "Deshroud Valves"
8. Blend in other sharp corners on the combustion chamber without removing too much material just so there's not a sharp edge that can get really hot and cause detonation.
9. Polish or recut valve seats to match valves
10. Clean
11. Clean some more
12. Install valves, springs, oil seals, retainers
13. Measure for shimless-buckets
14. Order buckets
15. Install buckets and camshafts


Is there a better order to do this in?

[Rasmus]

[Mechie3]

Don't know all that you're including in some steps, but gasket matching the intake sides somewhere in steps 4 and 6 means you aren't redoing work later after you've opened it up.

[Sgt.Gator]

The usual thought is port work on a turbo Subaru is not cost effective unless you are going for very high HP. It's one of those things that brings small ROI, but if you screw it up will cost you big. Are you going for 400+ HP?

[Rasmus]

My goal is 400-450 crank HP. By way of calculation, the Borg Warner EFR7163 and my 2.33L I've selected predicts it could top out at 580hp and 430lb/ft. I don't want to tune it that high.

[THE FURNACE]

and Fast Tumbleweed!

[Hindsight]

Rasmus, do you think the 7163 is the right size for your power goal? Seems like you could go smaller and get boost sooner?

[Rasmus]

Rasmus, do you think the 7163 is the right size for your power goal? Seems like you could go smaller and get boost sooner?

Great question. But this one I actually considered before. The problem with running the EFR7064 on my 2.33L is my gearing for AutoX.

EFR 7163 at a nice 1.5 bar (22psi). Spools up fast, achieving full boost at 2700 RPM (232 hp/454 ft-lb). Peak power is 575 hp at 7300 RPM if left at 22 psi. Peak torques at 2700 RPM: 454 ft-lb. Tapers off to 340 hp at 8800RPM, 7psi where it exceeds the choke line. Probably could run it up to 9100 RPM or so to stretch a gear but I'd be well past the choke line and at zero boost.

EFR 7064 at a nice 1.5 bar (22psi). Spools up quicker, achieving full boost at 2500 RPM (215hp/450 ft-lb. Peak power is 510 hp at 6450 RPM if left at 22 psi. Peak torques at 2500 RPM: 450 ft-lb. Tapers off to 313 hp at 8100 RPM, 7psi where it exceeds the choke line. Probably could run it up to 8400 RPM or so to stretch a gear but I'd be well past the choke line and at zero boost.

So the real thing with my build is I'm running a 4.444 final drive. So this thing can spin. While the 7064 gets me an extra 200 rpm at the start the 7163 gets me 700 rpm at the top. And every shift you don't do gets you .5 - .9 secs in autox. Upshifting then having to downshift will make your time 1 - 2 seconds slower.

The EFR 6758 and 6258 don't offer twin scroll turbine housings.

[Hindsight]

Hah, I should have know you calculated it down to the RPM! Crazy that the 7163 makes 22 psi by 2700 RPM. Really hard to imagine.