bigben

iTrader: (4)

The rising fuel prices have me doing some brainstorming.

- Would there be any adverse affects of turning the boost all the way down? I'm sure the fuel and timing maps need to be adjusted to take full advantage of this.
- Will turning the mbc all the way down actually get rid of the turbo building any boost, or would I still get a psi or two?
- Is there a formula or optimal settings for AFR's and timing to achieve more mpg's?

I understand that it all starts with the driver and their particular driving habits, but I wanna take this a step further. Does anyone have any advice on this topic? I'm only looking for serious feedback, so if anyone says "search", I will personally come through your monitor like Samara and punch you right in the baby maker, lol. Seriously, this is a serious question. I'm sure I'm not the only one thinking about this because the fuel prices aren't going down.

vortico

iTrader: (38)

I think you would still be boosting to waste gate pressure. I know if you leave your stock bcs unplugged you still make some boost (shop forgot to reconnect it on my vehicle when they did a clutch job.) I could most defiantly be wrong though.

RoadSpike

iTrader: (5)

1) No adverse effects from turning boost down to minimum

2) No boost is still regulated through the wastegate so your wastegate would be the minimum pressure unless your MBC has a higher minimum boost pressure than your wastegate than mbc's minimum pressure would apply if coonnected.

3) AFR wise you have to go lean between 15-16 AFR and increase timing. I do not recommend boosting like this as the EGR temps are going to skyrocket on you and you risk melting something.

In general you will be adding timing to increase power to the fuel your removing and this will require full time open loop via the open loop load tables to work as desired. Idle will still need to sit around 14.7 otherwise its going to start to sound like you have cams.

For those with MIVEC adjusting your settings may increase engine torque for a given AFR and increase mpg. All of these changes you should be able to monitor via evoscan with its instant mpg function.

bigben

iTrader: (4)

So, the idle can be adjusted on stock cams so it will lope? That could be useful to me, hehe. I do need my tune refreshed, so I might just have my tuner come up with an eco map for me. I don't self tune (yet), but I've been doing my homework.

JohnBradley

iTrader: (30)

You dont have to turn the boost down to make the car more efficient. There are numerous lean cruise threads about setting the car up to cruise in open loop at 15.5-16.0 AFRs. Leaner than that makes no difference on gas. Tire size (taller), pressure (40ish), and then driving habits as well as some aero are going to be the other parts of the puzzle.

ecktt

I could not have said it better.

bigben

iTrader: (4)

Any aero parts in particular? The only one I've really had plans to purchase was the Beatrush underpanel.

fryedchikin

If you do a lot of driving at highway speeds, removal of the front air dam and wing would be some good aero mods to start with.

kronik5383

iTrader: (1)

interesting......as i already have cams i can make it lope some more

VGergo

iTrader: (3)

On E85 where is the best cruesing economy afr around 16.5 ?

Kracka

iTrader: (49)

Just modulate your right foot...seriously.

Benja

I sit 15.6-16.1 on E85 at cruise with 40* timing, drives great!

bigben

iTrader: (4)

I know, I know, lol. I think this plus leaning the cruise cells and adjusting the timing is all that can really be done.

lanasa

I would say Merlin puts it best in his tuning guide:

AFR refers to how many parts of air are mixed with how many parts of fuel. So an
11:1 AFR means that 11 parts of air are being mixed with 1 part of fuel to create
the air/fuel mixture. When your EVO is at idle or when your EVO is at cruising
speeds your AFR is around 14.5-14.7:1. This is known as stoichometric or stoich for
short.
It has been found that the 14.7:1 mixture produces the least amount of emissions.
And since city cars spend 90% of their time at idle, or in cruise, then that is the
number that the manufacturers use to reduce the emissions on their car.
It is worth noting that the 14.7:1 AFR does not produce the best gas mileage. The
best gas mileage is produced at approximately 15.2:1 AFR.
What AFR produces the best power for gasoline? Gasoline gives the best power
when it burns at an AFR of 12.5:1. This is regardless of whether the car is normally
aspirated, turbocharged, or supercharged.

The following summary shows the story – for gasoline:
AFR COMMENT
06:1 Rich run limit.
09:1 Low power with black haze.
11.5:1 Rich best torque at WOT.
12.5:1 Safe best power at WOT.
13.2:1 Lean best torque at WOT.
14.7:1 Stociometric ideal burn AFR for gasoline.
15.5:1 Lean light load, cruise/part throttle.
16.2:1 Best economy, cruise/part throttle.
18:1 Lean run limit.

lanasa

I have been thinking about tuning my evo x to 15:2:1 at cruse and keep the max boost 10 PSI. I know when I use the COB AP and would flash their economy flash it would keep my boost under 10 psi. Just remember not to drive your car hard while it is like that, stop and flash it back before showing off.