[ChrisCNC]

That's the type of information I'm after Cody, thank you! I'm very interested in this stuff and know very little about it all.

I'm starting these threads with little knowledge (obviously) so I appreciate it when you, Bill or others that really know how things work provide an answer. I'm interested in this and know little, I'd like to learn more. I know you guys are busy and don't have time to be a tutor (nor would you want to, probably I'm sure I'm probably 1 of about a bazzillin people wanting to glean information from you) So I REALLY appreciate any time taken to help me better understand what's going on. I'm reading other forums and articles as I have time, but it's not a very effecient method of learning since I have to weed through other self-prescribed experts that are really full of 'stuff' other than knowledge.

My premise (until your last post) was that:

- Given that engines run on fuel and air, there must be an optimal fuel/air ratio range. I assume that diesels have a broader range than gas but that if there is too much air and not enough fuel then the engine is running too lean and too rich if it is vice-versa.

- The MAP Sensor measures absolute mainifold pressure so it would be a likely place for a programmer to get their information to maintain the ratio with varying burdens on the engine. If a programmer wanted to attempt to stay in the ratio range through extended accels, extended towing or other engine loads then they would want a sensor (or sensors) that would provide them with the information they need throughout a targeted RPM range.

-If a provided sensor is unable to do this then I would think that it could be improved or "upgraded".

However, the stock injectors are typically maxed out at 13 psi, that would help explain why accurate higher boost numbers aren't all that critical and that the fueling strategy becomes pretty trivial at boosts exceeding this number. I'm sure you're still in a pretty optimal fuel ratio range well beyond that number too which really would take care of probably 90% of all typical driving. Is there a boost number that comes to mind that is beginning to be too much air and not enough fuel?

What psi's are bigger injectors good for (just rough estimates) like stage I, stage II injectors? I know that in gas engines, that rich/lean fuel mixes will act to lower/raise EGT's. Is the same true for diesel engines? i.e. when the engine is running under-fueled that the egt's go up? I've ridden in small planes where the pilots have individual control of the fuel mix to each individual engine cylinder and have a pyrometer on every exhaust port and while in steady flight will adjust the ratios to each cylinder until they have EGTs the same on all exhaust ports. Of course this is more critical because of altitude.

At what point in your opinion would it make sense to replace a stock turbo (other than because it was needing replaced because it was damaged)? Seems to me that the stock turbo would cover the needs of a lightly modified truck pretty well.

Thank you again,