rpm when towing

Wow
So complicated
Very unscientific as compared:
Home is at the base of the Grapevine
Learn by watching water temp if only factory guages
Steep hill temps will climb fast with rpms in the lower 2k's...
so downshift and spin it mid to upper 2k's... Life is good
YRMV

Thanks everyone. Have got my answer
I think we can close this thread because the last 2 pages have nothing to do with my rpm question. Maybe we can start a new thread
Happy passover Easter

4x4ord wrote:
Wikipedia explains how the air fuel ratio in direct injection gasoline engines can vary from ultra lean (as lean as 65:1) to stoichiometric to slightly richer than stoichiometric during full power.

Click


Edit: I copied and pasted the part that of the write up that explains ultra lean operation:

Ultra lean burn or stratified charge mode is used for light-load running conditions, at constant or reducing road speeds, where no acceleration is required. The fuel is not injected at the intake stroke but rather at the latter stages of the compression stroke. The combustion takes place in a cavity on the piston's surface which has a toroidal or an ovoidal shape, and is placed either in the center (for central injector), or displaced to one side of the piston that is closer to the injector. The cavity creates the swirl effect so that the small amount of air-fuel mixture is optimally placed near the spark plug. This stratified charge is surrounded mostly by air and residual gases, which keeps the fuel and the flame away from the cylinder walls. Decreased combustion temperature allows for lowest emissions and heat losses and increases air quantity by reducing dilation, which delivers additional power. This technique enables the use of ultra-lean mixtures that would be impossible with carburetors or conventional fuel injection.

I am aware of these engines and even knew someone who had a Civic with a lean burn system. However, these engines were dumped in the early to mid 2000's because they could pass upcoming emissions since you cannot put a three way catalyst on lean burning engines. You can only put a two way catalyst on lean burning engines and have to have another way to deal with NOx which would more than likely negate any of the benefits of a lean burning gasoline engines over a diesel.

As I said before, I don't know of any DI engine in production today that are designed to run on an air/fuel ratio too far outside of stoich at 14.7:1. I know that it can be done, but I am more concerned about real world not would-a, could-a, should-a land that doesn't currently exist.

Wikipedia explains how the air fuel ratio in direct injection gasoline engines can vary from ultra lean (as lean as 65:1) to stoichiometric to slightly richer than stoichiometric during full power.

Click


Edit: I copied and pasted the part that of the write up that explains ultra lean operation:

Ultra lean burn or stratified charge mode is used for light-load running conditions, at constant or reducing road speeds, where no acceleration is required. The fuel is not injected at the intake stroke but rather at the latter stages of the compression stroke. The combustion takes place in a cavity on the piston's surface which has a toroidal or an ovoidal shape, and is placed either in the center (for central injector), or displaced to one side of the piston that is closer to the injector. The cavity creates the swirl effect so that the small amount of air-fuel mixture is optimally placed near the spark plug. This stratified charge is surrounded mostly by air and residual gases, which keeps the fuel and the flame away from the cylinder walls. Decreased combustion temperature allows for lowest emissions and heat losses and increases air quantity by reducing dilation, which delivers additional power. This technique enables the use of ultra-lean mixtures that would be impossible with carburetors or conventional fuel injection.

ShinerBock wrote:


I haven't heard about DI engines no longer being regulated to 14.7:1? What engines are these?

Every DI I have hooked my OBD Torque App up to from my Ecoboost truck to my wife's old Audi(both turbocharged) have been regulated to an A/F of around 14.7:1 with a very narrow range. The only time either engines ran lean was the brief instant after going WOT it would add too much air before the injectors could compensate. It would go no more than 15.0:1 though. After that it would run rich at 13.2:1 if you left your foot into it and then start to go back to stoich as you picked up speed. In normal driving or idle they always stayed around 14.7:1 +/- .5. My diesel on the other hand will go anywhere from 20:1 to 80:1 depending on engine load. At Idle, it will go even higher than that to upwards of 100:1.

I know some DI engines have high compression ratios like the 6.2L Ecotec with 11.5:1(probably why 93 octane is recommended), but I have not heard about any mass produced DI engine getting to the 15:1 and up compression ratios of diesels or the 17.3:1 of my Cummins.

I might be wrong regarding DI engines no longer needing to be regulated to around a 14.7:1 A/F ratio. I'll look into that before I say anything more.

Newer vgt turbos are a big part of the torque curves these days too. And tuning ability.

It seams that Mazda is doing the reverse to diesel engines by lowering the compression ratio of their diesel to 14:1(which lowers combustion temps) so they don't have to have any emission devices.

SKYACTIV-D

wilber1 wrote:
Mazda Skyactive gas engines are using a 14:1 compression ratio. The are planning on going to 18:1 with gas engines.

Skyactive 2

Interesting! Thanks for the link.

Mazda Skyactive gas engines are using a 14:1 compression ratio. The are planning on going to 18:1 with gas engines.

Skyactive 2

4x4ord wrote:


The DI gasoline engines are no longer regulated to a 14.7 air/fuel ratio nor is the compression ratio limited. Preignition can't happen without fuel being injected.

I haven't heard about DI engines no longer being regulated to 14.7:1? What engines are these?

Every DI I have hooked my OBD Torque App up to from my Ecoboost truck to my wife's old Audi(both turbocharged) have been regulated to an A/F of around 14.7:1 with a very narrow range. The only time either engines ran lean was the brief instant after going WOT it would add too much air before the injectors could compensate. It would go no more than 15.0:1 though. After that it would run rich at 13.2:1 if you left your foot into it and then start to go back to stoich as you picked up speed. In normal driving or idle they always stayed around 14.7:1 +/- .5. My diesel on the other hand will go anywhere from 20:1 to 80:1 depending on engine load. At Idle, it will go even higher than that to upwards of 100:1.

I know some DI engines have high compression ratios like the 6.2L Ecotec with 11.5:1(probably why 93 octane is recommended), but I have not heard about any mass produced DI engine getting to the 15:1 and up compression ratios of diesels or the 17.3:1 of my Cummins.