the zander

In light of the current trend in gasoline prices, more specifically their steady rise, i have refined the goals of my camaro build a little. I am slowly building a forged 350 TPI motor with the intent to mate it to a TKO600 and drop it in my 86 when complete. During my selection of components aimed at yielding an acceptable compromise between all-out performance, and affordable fuel ecomony somthing new (to me) occured. if i am able to run the 350 on only four cylinders during my daily commute ect, and revert to the full displacment only when performance is required i could benefit from both the fuel economy of a 175cu motor and the performance of a stump-pulling 350. The system could be as simple as a set of relays wired in-series with the injectors for cylinders 8, 3, 5, 2 (every second cylinder in firing order). No computer modifications would be required because the fuel-per-cylinder is constant. the only downside i could imagine would be rouger operation (how much rougher i can't predict) My question to those on the forum would be this, has anyone tried? failed? succeded? or does anyone see a gaping flaw in my logic?

-Alexander

MattODoom

iTrader: (1)

Simply cutting off the injectors will do you a whole lot of nothing. If the motor even ran, it would probably get worse fuel economy. The ECM would go nuts the second half the cylinders started dumping gobs of raw air into the exhaust and the O2 pegged lean.

If youre just stopping the fuel you are still wasting all the energy used to compress the air for no reason. A modern cylinder deactivation system makes the lifters collapse, so no air is drawn into or exhausted from the cylinder.

That's my understanding anyways.

the zander

[MattODoom]
good point regarding the exhaust, i suppose it would become very oxygen rich, although given a standalone engine managment system (ie: MSII) it could be corrected. Because now with 4 cylinders firing, and 4 pumping air a new a/f ratio could be calulated. Somthing like 26:1, which would be equivalent to 13:1 in the 4 operational cylinders. And in regards to the pumping losses you sighted (power required to compress the intake air charge) you neglected to take into account what happens on the next cycle, the energy imparted to the air is transfered back to the piston. simply put, while it takes energy to compress the air in the cylinder that energy is regained during the next cycle as the compressed air pushes the piston down. there is another system in a modern combustion engine that uses much the same principal. Namely the camshaft/rocker/ valve spring arrangment.

So perhapes with an alternate fuel table this would be possible.

Anyone else care to take a stab at anything i might have missed? just imagine, 400HP, 40MPG! (sound good to anyone else?)

-Alexander

Xophertony

LS7 crate engine time. displacement on demand built in.

QuickStyle

i read an article once about a product that was for pushrod engines. it basically was a variable of different ratio rockers, and you could set it to a lower ratio for less lift under low load/rpm conditions, and set a higher ratio for high load/rpm conditions. and was supposed to save gas, and give more power, seemed pretty legit to me. i cannot recall the name of it, but if anyone remembers this, post a link please, i would like to read about it again. i believe it was in the $500-$800 range and came with 16 rockers and a computer and some other stuff to make it work.

gurkgurkgurk

the only problem i would see is that those 4 cylinders would have to lug around the 4 other dead cylinders, which would actually cause even worse fuel economy, it would be like having a misfire, but no fuel going into it, youd just have air, then the o2 sensor would just adjust the mixture and pump out more gas.

the only way i could see fuel improvement in a v8 would be perhaps if we adopted some sort of vtech or vvt system so that not only could we program it for all out performance but also for ultimate fuel economy, its something like the old civics which first came out with v tech, instead of like the later years that optimized valve timing for performance and speed, the original v tech actually was made so you could use less gas at certain rpms

jwscab

find yourself a 5.3l out of a truck/suv with the cylinder deactivation built in. transplant the whole shebang, engine/pcm/trans. preferably a 2wd chassis so you don't have to muck with the trans tailshaft.

Dale

iTrader: (12)

http://www.hotrocker.com/

MattODoom

iTrader: (1)

Indeed, I guess you would recover a lot of the energy, but youd lose some due to blowby and valve timing.

MattODoom

iTrader: (1)

Would the fact that the gen IIIs have a different firing order effect doing this on a gen 1?