Disabling intake and exhaust valves (going to 8 valves in a 16-v head)

[niky]

Amazing! Man... makes me want to start looking for 1.8 cams for my 2.0 again...

[Gasoline Fumes]

Originally Posted by Ang84Indy

I had no idea that you could run a 4-valve head with a 2-valve cam! I'm very interested!

I'm actually still running the 16v cam, just half of the rocker arms. The cam swap was not possible due to the cam lobes hitting the oil retaining wall on the cylinder head. I don't know how different that wall is on the HF head. I probably could notch my head a little to clear the cam.

[Gasoline Fumes]

A video!

http://www.youtube.com/watch?v=JJ-JhKniuVM

[hawk2100n]

Originally Posted by Gasoline Fumes

I'm actually still running the 16v cam, just half of the rocker arms. The cam swap was not possible due to the cam lobes hitting the oil retaining wall on the cylinder head. I don't know how different that wall is on the HF head. I probably could notch my head a little to clear the cam.

The 8V cam probably has significantly higher lift than the 16v cam. Curious to see how this comes out, the FE system will still assume 16 V and the associated airflow and fuel accordingly. Maybe the decrease in power will improve driving habits more than anything, although I would accuse my 106 hp 16v Civic of being too powerful.

[Christ]

Unfortunatley, I have no use for a 350 LOL.

Anything diesel laying around? Or bikes, scooters, etc...

[orangustang]

I wonder if you would be able to achieve better efficiency by leaving the second exhaust valve functional, like the first stage on the 3-stage VTEC engines. If I had a SOHC rocker-arm setup like yours, I would think it worthwhile to play around with disabling one intake valve, then one exhaust valve, then one of each, and see which works best. They all seem like they would have their advantages, but I'm not sure which one seems the most advantageous.

2 intake, 1 exhaust = increased EGR effect from decreased exhaust flow, but higher VE from better intake flow
1 intake, 2 exhaust = lets less air into the engine for reduced consumption, but removes some exhaust restriction for better performance
1 intake, 1 exhaust = less total flow, still balanced like the 4-valve. Definitely way less power with the 4-valve lift, as you've seen.

I'm not sure which of these would result in the best fuel economy. As I said, there's some reasoning to support each concept, and it probably depends on your driving style.

[mechman600]

SUBSCRIBED. Great thread. Finally, real world testing of an idea the rest of us are too scared to try!

Unfortunately, the 1ZZ-FE in my wife's Toyota has a shim under bucket valvetrain, so no rockers to omit.

[Christ]

I might have a junk 16V head laying around if you want to practice clearancing it for the HF cam... You can have it if you want.

[Gasoline Fumes]

Originally Posted by Christ

Unfortunatley, I have no use for a 350 LOL.

Anything diesel laying around? Or bikes, scooters, etc...

I have a few old mopeds....

Originally Posted by Christ

I might have a junk 16V head laying around if you want to practice clearancing it for the HF cam... You can have it if you want.

Thanks, but I actually have a spare head I can play with.

Originally Posted by orangustang

I wonder if you would be able to achieve better efficiency by leaving the second exhaust valve functional, like the first stage on the 3-stage VTEC engines. If I had a SOHC rocker-arm setup like yours, I would think it worthwhile to play around with disabling one intake valve, then one exhaust valve, then one of each, and see which works best. They all seem like they would have their advantages, but I'm not sure which one seems the most advantageous.

2 intake, 1 exhaust = increased EGR effect from decreased exhaust flow, but higher VE from better intake flow
1 intake, 2 exhaust = lets less air into the engine for reduced consumption, but removes some exhaust restriction for better performance
1 intake, 1 exhaust = less total flow, still balanced like the 4-valve. Definitely way less power with the 4-valve lift, as you've seen.

I'm not sure which of these would result in the best fuel economy. As I said, there's some reasoning to support each concept, and it probably depends on your driving style.

I've been wondering the same thing.

Originally Posted by hawk2100n

The 8V cam probably has significantly higher lift than the 16v cam. Curious to see how this comes out, the FE system will still assume 16 V and the associated airflow and fuel accordingly. Maybe the decrease in power will improve driving habits more than anything, although I would accuse my 106 hp 16v Civic of being too powerful.

It's running in closed loop, but I don't know if that can fully compensate for the reduced airflow.

[MetroMPG]

Any more news? I noticed you posted a fuel log entry since doing the valve work (and your new side skirts):

2nd best tank for you so far - 60 mpg.

First full tank with the side skirts. The 16-valve to 8-valve conversion was done during this tank. I'm very happy with the MPG considering that this tank included some heavy-footed testing of the new 8-valve powerband, using the car as a battery charger and some non-hypermiled driving.