SpikeLS1

I'm a V8 mulletmobile guys, so my new EVO's turbo has me clueless at the moment. So please forgive me if this is utterly stupid and will not work!!

Can you use a boost controller to dial down (or turn off) the boost below 3500 rpms? If you did this would the car get better fuel economy at highway cruising speeds, like say 80-90mph?

I make regular highway trips from St. Louis to LA and back, and I've been taking my Camaro since the EVO gets pretty poor highway miles per gallon. I'd prefer to take the EVO, but having to stop for gas every 3 hours or less SUCKS...

If this would work I will buy one and give it a try. It would be killer if I could have 2 alternate boost settings - 1) economy no boost below 3.5k for highway droning 2) 19psi all the way from <3k to 7k for highest performance when commuting.

Z1 Performance

iTrader: (185)

The turbo is driven by exhaust velocity, and as a result is only really making positive manifold pressure unless you are on the throttle. While cruising at say 3000 rpm, you are running total vacuum.

evo_dan

I don't think you can turn boost down below stock settings with a boost controller. Turning boost off or all the way down on the controller only turns boost back down to stock level.

zlancer

iTrader: (1)

you would also need an air fuel controller of some sort to lean out the mixture if you take away the boost or else it would run really rich...or actually....i don't kno how it would run.

EvoInSoCal

iTrader: (1)

Yes a boost controller might help you out in this department, but it all depends on the way you drive your evo. If you floor it all the time to pass traffic, or getting on the freeway etc... then setting the boost lower will help you with some gas consumption. But if you cruise long stretches of freeway without really getting on it bast say 3000-4000 rpms in 5th, then a boost controller won't help much at all. Also, remember that you wouldn't be able to ever turn the boost off completely, and you can only turn the boost down to whatever PSI/boost setting the spring in the wastegate is set to. I think on our cars, you can get it down to about 14 psi, but that's about it. One reason you are having bad milage is the fact that our evo's run pretty rich out of the box. If you are concerned about gas milage, look into putting a fuel controller like a APEX'i SAFC or similar piggy back unit to lean out the fuel a little. Of course dyno it to set it properly, but this will help you out with performance and to gain more gas milage for your cruising needs.

good luck!

lomax6

yea I'm having the same prob... I'm getting a boost controller and Safc 2 next tuesday though

silverEVO8

iTrader: (12)

Gentlemen, I would urge extreme caution before leaning out the car with SAFCs or similar devices. You could end up with serious high EGTs and detonation. Saving $$ on gas and blowing the engine is not good economics Correct me if I'm wrong, but the car runs leanest and with the highest EGTs at the 3000-3500 rpm in high gear....

Maybe dialing down the boost might help if you tend to be heavy on the gas, but that's an expensive way to do it (it would need to be a good EBC). Why not just get a second set of tires? Perhaps something with a narrower profile and less sticky rubber. I'd guess that between the best tire choice with optimal air pressure and judicious driving techniques, one would get the best and safest results for better highway fuel economy.....

ChillinEvoVIII

dude... i guess uhavent noticed... our car.... comes BUTT rich to prevent detonation...( mitsu doesnt want to pay for ****t up cars bcuz it was running lean at all... mitsu cant go over the power rating they gave our 271hp.273lbs(supposbly) and running it leaner would equal more power.... lean it out!! and dont b sucha *****.... just my .02

Graysilvia

hhhmm.....I was under the impression that at cruise the ECU is in closed loop mode, meaning, it looks at the O2 voltages and decides how much fuel to inject, therefore maximizing fuel milage. The only time it just looks the A/F up in a table is at WOT, AKA open loop mode. This is when the A/F should be pig rich, which it is....

timzcat

iTrader: (10)

Get the car tuned on a dyno with some type of fuel management.
Wideband is the way to go, judging by EGT is not as accurate.

Coolguy949

iTrader: (10)

Actually, I belelive we have a 12 PSI wastegate actuator (i think that's what it's called) basically if you were to pull the vacuum line or completely turn off all boost control, it would only boost 12 PSI. I know that's the case with TD05H 20G internal wastegate turbos for eclipses.

silverEVO8

iTrader: (12)

I did not say don't do it, I said "use extreme caution". I'll stand by my words, particularly if all that people are doing is leaning out the car by trial and error to get more fuel economy....

I don't know where you got your info, but I have it from credible sources that the EGT gauge is a much more accurate and instant tool to determine rich/lean conditions than any wide band sensor. Sure, the best wide band sensors out there which are used at the dyno, are very good and accurate, but they are no where near as fast acting as the EGT gauge.....

Eric Lyublinsky

iTrader: (5)

The really best way to gain MPG is driving habits. For example. try drive in the highest vacume posiable. 2nd is keeping the TPS under 60%, because after 60% the ecu goes in closed loop.

Now your FPR is 1:1 so more boost would equel more fuel.

USP45

iTrader: (13)

I do not think that the car will ever get great gas mileage until a six speed tranny is brought to the U.S. That is one of the major reasons the Z28 gets such great highway miles, that 6th gear really knocks the RPM's down on the highway. Interesting side note, my g/f's uncle has about 40 cars including a couple of Vipers. About two weeks ago we all went for a drive in the hill country in Texas all day Sunday, we took an M roadster, a Mini Cooper S, and I ended up with the R/T 10 Viper. Number one, the Evo is fast, but the Viper is scary fast. It broke the rears loose at 70 in third when I went to pass a couple of cars and this from a rolling no clutch drop start. Nothing like going down the highway passing through 80 in the wrong lane while sideways. Anyway, when not driving hard the car only turns about 1400 RPM's at 70 in 6th and gets over 20 MPG. Actually I was very impressed for this being a 488 cu. in. V-10. Just makes the point that the US Evo could really use a six speed tranny like everyone else gets, it would get some great highway numbers.

timzcat

iTrader: (10)

So when you go to the dyno you want to use a EGT to tune instead of a Wideband?
Nothing tells you a/f like a wideband. actual a/f is more important than the exhaust temp. Temperature is relative, if you have a weak cylinder it will cool the exhaust temperatures even though you could be lean. Not to mention your monitoring #1 exhaust for the most part.