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

[Gasoline Fumes]

My current tank isn't looking great at around the halfway mark, maybe 50 MPG. But that's with a lot of almost-normal driving on a trip. I'm planning to fill up so I can start over. It's hard to test mods with no MPG readout, especially when most of my percent above EPA comes from driving style. But even 50 MPG is impressive for a car that used to get 38. I should drive a tank without hypermiling to see how the mods alone help, but I don't think I remember how to drive normally.

I do wonder if it's running rich with less airflow. But then I wonder if there really is less airflow. Obviously there is at 5000 RPM and full throttle, but at 2000 RPM with the throttle barely open, I'm wondering if the throttle plate is more of a restriction than the disabled valves.

I was back at the junkyard and looked at the HF head. It doesn't have much of an oil retaining wall like my 16V engine. I guess with roller rockers, the cam doesn't need to sit in a pool of oil. So I could cut away the part that interferes with the cam lobes, I just need to figure out how to do it without getting metal pieces all over the head and in the oil.

[2003protege]

subbin'. Very cool.

[t vago]

Hm... I might try this on my wife's car. She's been wanting it to get better in-town gas mileage (it currently gets 19 MPG). If I can get about a 25% improvement, that'd truly be awesome.

[Gasoline Fumes]

Originally Posted by t vago

Hm... I might try this on my wife's car. She's been wanting it to get better in-town gas mileage (it currently gets 19 MPG). If I can get about a 25% improvement, that'd truly be awesome.

What car and what type of valvetrain? I think you want to keep the oiling system as it was with all the valves. The spacers I used cover the now-unused oil holes in the rocker shafts for the deleted rocker arms. Leaving those holes open could potentially affect oil pressure in the head.

[t vago]

Originally Posted by Gasoline Fumes

What car and what type of valvetrain? I think you want to keep the oiling system as it was with all the valves. The spacers I used cover the now-unused oil holes in the rocker shafts for the deleted rocker arms. Leaving those holes open could potentially affect oil pressure in the head.

The car is a 2002 Sebring Convertible GTC with a transplanted Chrysler 3.5L V6 engine. It is a SOHC design with 24 valves. For each cylinder, there are two separate intake valve rocker arms, and one combined exhaust valve rocker arm assembly.

If I were to do this, I'd probably go to a junkyard to find a head from a junked 3.5L engine, and get measurements of the pivot shaft, so I can find or fabricate spacers to block off the oil holes as you mentioned.

[CrazyLee]

If you wanted to reduce the valve number, just remove the rockers to 1 of the intake valves (3 valves/cyl) and you are done. You won't even need to pull the heads. Just block the oil holes as noted above.

It wouldn't breathe very well then, but that cuts down the air (and fuel) flow.

[ERTW]

Taking out a rocker arm isn't ideal. Epoxy would do wonders

[JasonG]

Except JB weld breaks down under constant exposure to petroleum products.
Not to side track, has anyone tried re grinding a V-Tec cam for econo ?
Basicaally a custom cam grind to mimick the 1st and 3rdd stages of the unobtainable 3 stage engine ?

My vote is for the 1 intake and 2 exhaust setup.

Don't forget to re-index your plugs towards the single intake valve.

[ultimx]

Wow that's a pretty nifty idea. What did you record without the mod on highway? Shouldn't it be tuned to maximize your changes? Curious to see what afr's your running with that mod. Most def subscribed.

[Gasoline Fumes]

Originally Posted by t vago

The car is a 2002 Sebring Convertible GTC with a transplanted Chrysler 3.5L V6 engine. It is a SOHC design with 24 valves. For each cylinder, there are two separate intake valve rocker arms, and one combined exhaust valve rocker arm assembly.

If I were to do this, I'd probably go to a junkyard to find a head from a junked 3.5L engine, and get measurements of the pivot shaft, so I can find or fabricate spacers to block off the oil holes as you mentioned.

That should work just fine.