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

[ultimx]

Agreed, the reason why I stated jumper harness is cause where I live, u need to revert back to it each time u smog. Idk about the op's location.

[slownugly]

I wasn't really suggesting jumpering in an obd1 ecu. That would just be adding a band aid on the problem. He should switch it back to stock

[Potenza]

Well, the experiment is over, and I am back to 4 valves / cylinder. I was uncomfortable with the pinging, which occurred under almost any load. The return to stock got rid of the pinging.

As I said, I had been hoping for an increase in low-end torque, and that was not a result. There was a decrease in power. I believe this decrease in power was also responsible for negligible fuel economy increase. I had to use more throttle than before to accelerate.

One of the clear changes was less valvetrain weight and resistance. The engine revved easier. This was bad in terms of hitting my 3k RPM max shift point (with lesser power) and for the auto transmission, which seemed a little "confused" at times. But the benefit was to idle and cruising, requiring less power for both events. As a highway-only car, this might be a good mod. Combined with the acceleration deficit, the overall results seemed negligible, as I said.

That said, the economy results are hardly scientific. I ran the 3v setup for half a tank, and it's a good tank. That said, there are too many variables. 1) It was much more highway than usual. 2) I'm running Shell 93 in an attempt to combat the pinging. 3) I got a flat tire and swapped on a set of alloys over the stock steel wheels. 4) I removed the spare tire and tools after the flat, decreasing weight.

So my "results" are based solely on keeping a constant eye on the ScanGauge. Idling required 1hp less - a good indication of the decreased resistance - though MPG is still 0 in that situation, obviously. Highway readings seemed 1hp lower and 1mpg higher at 55mph than my usual.

[Potenza]

Gasoline Fumes mentioned getting a spacer from an older Civic to put in place of where the rocker arm had been, to cover the oil hole so as not to affect oil pressure. I was trying to find the spacer, officially called a "shaft collar," when I realized that my car came stock with them. A trip to the junkyard got me 4 more for $1.

While there, I compared the collar to the rocker arm to find that the collar was not as long. At first I thought it wouldn't work and would have to make a custom length part. Then it occurred to me that I could use the spring as a variable and swap the pieces around. My focus was on removing rocker arm B. In doing so, I replaced the rocker arm with the spring. Upon returning to stock, I realized that the spring was therefore not blocking the oil hole as Gasoline Fumes had suggested. I couldn't think of any other way I could have done it apart from a custom piece, so I didn't feel bad.

But it hit me in bed last night that if I would have removed rocker arm A instead, I could have simply put the collar in place of that, with the spring still being the variable, taking up the extra slack. Ugh. I've never been good at puzzles.

So I don't know if that caused any issues or not. Indeed the whole rocker arm assembly seemed a lot more oily when I took it out the second time. But whether that affected the pressure or caused the pinging or any issues, I can't say. Maybe it had no effect at all.

Stock setup:


3v:


Thanks to Gasoline Fumes for being the pioneer and giving me the courage to try something like this, as well as to everyone else for your advice and help.

[Potenza]

Okay one more note, because I had mentioned the valvetrain noise. Turns out, after returning to stock and adjusting the clearance again, there is still plenty of noise. I may have never noticed before because I listen to music nearly 100% of the time and only went silent after the 3v mod to listen for issues. I still think the 3v was a bit noisier, but not overly so.

[NeilBlanchard]

It would seem to be difficult to rework the way a combustion chamber is designed to work. They engineered it for a particular swirl and a certain flame spread, etc, and to change this after the fact would seem problematic. If you disable one intake valve or the other, and one exhaust valve or the other, you have a profound effect on the mixing and flow. In other words, the valve sizes and their placement and the shape of the chamber and the placement of the spark plug, that would have been better if it was designed for a 2 valve or a 3 valve to begin with, are very hard to get from a 4 valve design.

Also, the fuel metering and the intake and exhaust tracts are all designed for the flow through the 4 valves. It's hard to change any design, unless you can change all the things that are involved.

I see you've come to basically this same conclusion - it makes sense to me.

[justme1969]

Wow Ill bet you lost nearly all potential vaccume for HVAC PCV Brake booster etc.
This is also factored into the displacement of the head and valves.
Kia sephia has a cold air intake horn I removed a Year back My car suffers from too much Vac.
It actually over powers the brake booster return spring. Ive searched everything else and few things could cause this phenomenon.
Ive burned through alot of brakes fuel and brake system parts to sort it out.
I have settled for drilling a number 50 sized hole just after the booster check valve to prevent it mostly.
yep heck of a thing the more throttle the less vaccume but as higher rpms are achieved vac. goes up sharply applying brakes.
Mabe this could be a good system for student drivers LOL.

[renault_megane_dci]

Usually, cam lobes are made to lift the valve a quarter of its diameter.
I assume the 8V variant from Honda has bigger valves so the lobes are taller.

On a side note, there is an alternative that can be done on DOHC engines :
http://ecomodder.com/forum/showthrea...nes-23535.html

[Potenza]

Basically what I was trying to mimic was the low-cam operation of the VTEC engine in the current Civic and the 1st gen Fit:

Depending on engine load and rpm, an electronic controller determines which cam profile will be used and exactly how the intake valves will operate (usually around 3,400 rpm). At low revs, where low lift and shorter duration provide optimal operation, the timing of the two intake valves is staggered and the lift asymmetrically skewed in favor of the primary valve. This helps to create a swirl effect within the combustion chamber that increases the efficiency of the burn process. At higher rpm, a hydraulically actuated spool valve causes a locking pin to engage the secondary rocker arm with the primary one, transitioning the secondary valve into a long-duration mode that increases the volume of air/fuel mixture moving into the combustion chamber. The additional air/fuel mixture helps increase power at high rpms.

Since I never drive my car above 3400RPM, the swirl effect of the single intake valve seems ideal for torque and economy. Honda switched the current Fit to a full-time 4 valve operation, and while it gained 8 peak horsepower, it only gained 1lb-ft of peak torque, and fuel economy dropped by 1mpg.

So the theory is there, but obviously it's not as simple as deactivating one of the intake valves on any given engine without more of the supplemental factors, like specific cam lobe profiles, intake port design, etc. (At least on my OBDII, automatic sedan test car.) A VTEC cylinder head with cam and valvetrain (and ECU) would do the trick - complete with automated self-deactivation! There was one at the junkyard when I was there... but I'm not sure if I need another project just yet.

[Gasoline Fumes]

Originally Posted by Potenza

So I don't know if that caused any issues or not. Indeed the whole rocker arm assembly seemed a lot more oily when I took it out the second time. But whether that affected the pressure or caused the pinging or any issues, I can't say. Maybe it had no effect at all.

I doubt it made a difference. My only concern was long-term wear.

Thanks to Gasoline Fumes for being the pioneer and giving me the courage to try something like this, as well as to everyone else for your advice and help.

No problem! I'm sorry it didn't work on your car. Sometimes I miss my other valves. The best 0-60 MPH time I can get now is 20 seconds!