You are confusing yourself by focusing on one part of the equation, fuel. Remember, to burn more fuel, more air is also needed. More air/ same fuel = leaner a/f.

A/F - The mass of air supplied to the engine divided by the mass of fuel supplied in the same period of time. The stoichiometric, or chemically correct, air-fuel ratio is the exact ratio necessary to burn all the carbon and hydrogen in the fuel to carbon dioxide and water with no oxygen remaining.

 

I know what a/f and stoich is 14.7.1 (at sea level ) but turbo cars never run anywhere near stoich under boost. But if you ran a turbo car at stoich your egts are going to be extremely dangerously high. But im done arguing this maybe shiv can enlighten us when he blows the engine hehe

 

Is this a evo board or a BMW board

 

DI engines run leaner because they inject less fuel than a regular engine. If you tried to run as lean with a regular motor, it probably wouldn't combust.
Here are some links I found:

http://www.answers.com/topic/gasoline-direct-injection

http://www.daimlerchrysler.com/dccom...0-0-0-0-0.html

 

DI Runs leaner, because as mentioned before, the fuel injector directs the fuel at the spark plug. The Mixture at the plug is stoich, and in the rest of the combustion chamber is lean. The reason why you don't get detonation, is because the rest of the cumbustion chamber doesn't have fuel in it to detonate, it's just compressed air. The O2's read lean because there is insufficient fuel to burn all of the oxygen in the cylinder, but it's not a particularly bad thing.

Think of it this way. In a stoich running gasoline engine (not DI) you have X parts fuel and 14.7X parts air. That ratio of air and fuel (theoretically) is perfectly mixed within the cylinder. (Realistically you have pockets that are richer and leaner, but the point is that there is some amount of fuel everywhere in the mix).

Now think of the compressed cylinder in a DI engine as a jelly breakfast pastery, those breakfast things that are all dough, and have jelly in the middle on the top. Imagine the part with the jelly is where the fuel is at a stoich mixture, and the rest of the pastrey has no fuel at all, just pure air, or such a small residue of fuel that it is so lean it can't combust. That small pocket on the top (the jelly) combusts with the spark, the rest of the air is paritally used for fueling the jelly fire, the rest leaves on the exhaust stroke unburnt (lean O2 reading when the jelly was actually stoich). Make sense?

 

Great, just great...now I'm hungry!

In answer to Atlmethevo...it's a car board, sorta. Might as well get the hang of what works and what doesn't concerning DI...the Evo X is rumored to be DI.

 

wow the 335i is quick....can't wait to see what the engine can really do when the tiny turbo's are swapped for bigger twins and a huge single..

 

looking forward to dynos with basic bolt ons!

 

+100000

 

BMW doesn't typically leave much on the table for HP with exhausts. They flow fairly well.... of course they are boat anchors.

 

i saw one at SF yesterday, that thing looks incredible but, i still dont see why they finally got with turbo.. and not kept NA like they always had, was it because japanese technology caught up with the germys? is350 with 306 horse?

lanevo.

 

btw, i do not believe it should be added with bigger twins or even a bigger turbo period, the car is running high compression. the exhaust would freeup random ratings, but i see that it would have incredible power adding. overall, i wish i got one of those instead of the MR. i hate the service of mitsubishi, sorry from a owner of lexus to a mitsubishi, very far different.

lanevo

 

Fat powerband, good power, good fuel economy.

 

they went turbo cuz they wanted v8 performance without a v8 block's weight...and it seems they succeeded. low end torque is like a v8 with 300 torque at 1400rpm....crazy. also to get better MPG than a v8....almost 300whp/300wtq stock and 29 highway MPG is just amazing.


if u're gettin horrible service go to another dealership. u're in california...there are plenty of dealerships here that offer great service and are mod friendly. PM me if u want to know which one's to go.

 

Both good points, and don't forget the visual appeal of the car.

-Carl