would turning the boost down increase mpg?

[Powerslave]

just a thought has anyone tried this? Personally i'm addidcted to 18 psi, but i got to thinking just for s&g truning the boost down to like 5 or less to see if a dramatic increase in mpg would occurr. Anyone tried this with the standback or a boost controller?

 

[nate0123]

you're only boosting 18 PSI at WOT

get your foot off the floor, stay out of boost, and your MPG will increase

 

[grease_monkey]

Well I haven't done this. *no turbo* But i do know a little about history. In the 1950's and 1960's engine's made their power using high compression. Gasoline was cheap, high octane, and there was tons of it. Also the gas was leaded instead of the traditional unleaded that we use today. As economist and gas became short aka the last '70's. But before that believe it or not General Motors *ahem* (lol sorry) was the first company to introduce the turbocharger into production cars. Anyway since economist wanted less pollution and NOx (yes nitrous oxide is in your exhaust) and Carbon monoxide. They decided to lower the compression ratios. Because of this companys started using turbochargers to compensate for gas mileage and power loss. I know that doesn't really help you with anything but history is always good ot know.

 

[Powerslave]

i really seem to average about 20mpg no matter haow i drive exept i get about 26 on the highway, 18psi 15 psi...a mix of hwy and city always about 20mpg. Heavy foot or not

 

[x'ed]

I was running 10psi and started getting about 30 miles per gallon when I had been getting about 16-17. I, like you, have no self control and can't stop myself from punching it whenever I get a chance just to feel the boost.

 

[Powerslave]

man your getting 30mpg at 10 psi, thats cool!! i'm gonna try 5 just for fun, see what happens. But i don't know how long I can go with out my 18psi....its like dr jekell and mr hyde..lol

 

[grease_monkey]

I'm curious, I will admit i'm mostly a muscle car guy. Our rule of them is that whenever boosting an engine, supercharged, turbo, whatever is that you don't run more than about 8 lbs of boost on a 9:1 compression engine. Decreasing the compression ratio will allow more boost. Also that you should only use 4 bolt main engines and no 2 bolt mains. I was just wondering how(if you know)these little engines with 9:1 compression can run 18lbs of boost and sometimes more than that. Obviously everything must be forged but I was just wondering if you could help me out. Thanks

 

[Powerslave]

the disi injectors spray fuel into the cylenders at lik 1300psi or something like that vs 100psi fore standard port injection, this cuases the fuel to be in an evaporative state wich reduces the tempeture thus allowing for more boost and compression similar to meth injection.

 

[grease_monkey]

Hmmm that can be understandable but I still don't understand how these engines can handle that much cylinder pressure. Are he walls extreamly thick, or something? How many bolts are on the cranks main journals?

 

[shane02pro5]

(drive2)I average about 12mpg if that makes you feel any better. 1-1/2 miles to work and all local driving! Well that's before I lost 3rd gear and toasted my 2nd gear synchro!

 

[Powerslave]

hey man its a "Ford MZR" its tough enough...(usa)

 

[grease_monkey]

Haha damn that sucks. But hey i get about 7 mpg on my Nova so don't feel too bad and it takes premium

 

[Powerslave]

(drive2)I average about 12mpg if that makes you feel any better. 1-1/2 miles to work and all local driving! Well that's before I lost 3rd gear and toasted my 2nd gear synchro!

lol, yeah even if i'm driving rreeeeeealll hard I still seem to get around 20mpg

 

[grease_monkey]

Haha, well i still wonder how they do it...but thank you

 

[Mid_Life_Crisis]

I was just wondering how(if you know)these little engines with 9:1 compression can run 18lbs of boost and sometimes more than that. Obviously everything must be forged but I was just wondering if you could help me out. Thanks

They can't all run those boost pressures. The Speed engines are direct cylinder injection which means that the fuel is literally sprayed directly into the cylinder under extreme pressures. This approach causes dramatically improved atomization of the fuel as it expands into the combustion chamber. This process has a remarkable cooling effect inside the cylinder, which allows the higher boost levels even with high mechanical compression ratios.
Highly modded engines with beefed internals and additional detonation inhibitors can also run higher boost levels on high compression but for the most part you won't find factory stock engines running both like those in the 3, 6, and CX7.

 

[grease_monkey]

Thanks, that makes a lot of sense. Considering the only big difference between my engine and a new engine is the fuel system...well and computer to control it all. Thanks man.

 

[Jays07MS3]

2nd gen DSM's have 8.5:1 comp ratio and run 15 psi stock. People push 18-20psi with big turbos all the time on those engines. I have a feeling a lot of turbo 4-bangers handle 10-15 psi on 8.5 to 9:1 ratios. More of a norm than an anomaly.

 

[nig3]

Only under wot it would save gas, but would make no difference normal driving.

 

[grease_monkey]

Under normal driving it may make a slight difference but not enough to be noticable or aka enough to care about.