Improving lean burn

[oil pan 4]

Originally Posted by Ryland

the CA sold VX does not and thus gets slightly worse gas mileage.

Saving the world by burning more gas.
Yay go government.

[cbaber]

I have a couple things to add. First, lean-burn is most efficient at low loads and low rpms. Trying to use it all the time probably wont help all that much. It's similar to Vtec, you can't just flip it on anywhere to gain economy or performance. Honda designed these engines very well from the factory and messing with it probably won't do you much good.

Second, VX and HX engines without LB would still get pretty good mileage. It's not like they would only get 30 mpg if they didn't have LB. My old engine with a crippled cylinder at 25 psi compression would not go into LB, yet I still got 34 mpg even with it limping along.

[steffen707]

Originally Posted by cbaber

I have a couple things to add. First, lean-burn is most efficient at low loads and low rpms. Trying to use it all the time probably wont help all that much. It's similar to Vtec, you can't just flip it on anywhere to gain economy or performance. Honda designed these engines very well from the factory and messing with it probably won't do you much good.

Second, VX and HX engines without LB would still get pretty good mileage. It's not like they would only get 30 mpg if they didn't have LB. My old engine with a crippled cylinder at 25 psi compression would not go into LB, yet I still got 34 mpg even with it limping along.

While you may be right, you can actually flip VTEC on whenever you want. you might not gain performance though. The vtec crossover point is usually calculated on a dyno so that you get the best performance out of the low cam lobes and then the best out of the high cam. BUT you can turn it on at any rpm.

And though 30-ish mile per gallon is good, its a lot away from 50mpg.

[cbaber]

Originally Posted by steffen707

While you may be right, you can actually flip VTEC on whenever you want. you might not gain performance though. The vtec crossover point is usually calculated on a dyno so that you get the best performance out of the low cam lobes and then the best out of the high cam. BUT you can turn it on at any rpm.

And though 30-ish mile per gallon is good, its a lot away from 50mpg.

I know you can control Vtec engagement but the point of my post is why would you want to turn it on sooner or later than stock? Your not gaining anything out of it. And its not as easy as flipping a switch. Along with sending the proper signals you would need to tell the ECU to adjust fuel and timing to go along with the change in cam profile.

Regular D16's without leanburn wont do 50 mpg with regular driving so I dont know why you would expect the VX or HX engine to do that without leanburn. There are some members on here that can get 60+ mpg out of a regular D16 but this is because of driving technique and aero mods, not anything special in the motor.

I guess the answer to your original question is that the VX and DX motors not in lean burn are essentially regular motors. They are not handicapped in any way when not using LB simply because of the unique head design and the other differences. You could easily achieve what a normal d16 would if you completely disabled LB on a VX/HX motor.

[steffen707]

Originally Posted by cbaber

I know you can control Vtec engagement but the point of my post is why would you want to turn it on sooner or later than stock? Your not gaining anything out of it. And its not as easy as flipping a switch. Along with sending the proper signals you would need to tell the ECU to adjust fuel and timing to go along with the change in cam profile.

I think you're missing my point, if you were able to trick the ecu into thinking it should go into lean burn, it will adjust fuel and timing for you.

On the cam thing, I was thinking that if the engine were operating with all 4 valves as "normal" you might get better gas mileage,

And yes I have friends who can get 40mpg on their stock d16's Its not easy, but can be done. And if they're averaging 40mpg, then they are getting above 40mpg while cruising.

[steffen707]

Originally Posted by cbaber

I guess the answer to your original question is that the VX and DX motors not in lean burn are essentially regular motors. They are not handicapped in any way when not using LB simply because of the unique head design and the other differences. You could easily achieve what a normal d16 would if you completely disabled LB on a VX/HX motor.

I'll try to find the link that explains why the vx is worse when not in lean burn.