03RCSB

iTrader: (2)

Almost 600 miles on the 80e and not a single issue, the past 200 miles I've been giving it a beating, 2nd gear Wot highway pulls, 4psi launches and its taking everything the turbo kit can give it. Just bumped up the boost on the ride home today from 6psi to 9.5psi. Pulls hard and showing a fat 11.0 on the wideband up until it shifts.

Have some concerns with fueling though. Everyone says 11.7 or slightly richer is the safe spot for boost but is that for the entire boosted rpm range? What im seeing is this;

-0 to 6 psi, 11.0 wideband reading regardless of rpm tps
-6 to 9.5 psi, 11.0 Wideband reading WOT highway pull 4krpm to shift point
This is the one that I dont like
-6 to 9.5 psi in the lower rpm range say 2500 to 4k is showing 12.5-13.1 on the wideband.

If I ease into it part throttle once i hit boost the wideband goes 11.0, as it climbs over 6psi it begins to head into the mid to upper 12s, I get out of it.

Should this thing get right into the 11s and stay there throughout the entire pull? I'd rather not have to shop for a new longblock.

Atomic

iTrader: (42)

It needs to richen up to your max torque AFR at peak torque rpm, before and after that it can be slightly leaner.

03RCSB

iTrader: (2)

I was told by Justin not to worry, Not that I am doubting him, he has done a great job with the truck so far but man that 13 scares me. Not sure what to do here, at WOT it looks like I can keep upping the boost and still have enough pump to stay fat but not sure what its going to do to that already lean mid-range.

Atomic

iTrader: (42)

The reason you run it richer for max performance (and especially rich for boost) is a matter of heat. Heat creates pressure, and excessive pressure creates excessive heat. With excessive heat you start to run into a detonation problem (which is relatively independent of pressure). So in order to avoid detonation you run fuel-rich to keep the combustion temperature down (fuel-lean would work the same way, but for a different reason). Detonation is the biggest concern at peak cylinder pressure, which is the same point in the powerband as peak torque. This is a product of the engine VE characteristics (especially camshaft choice).

My point is, fueling is very forgiving far away from peak torque, but needs to be very close once you get close to peak cylinder pressure.

03RCSB

iTrader: (2)

So if peak tq is when cylinder pressure is at its highest. Id just want to check the tq curve for my cam, find the peak and that is where fueling needs to be more precise and can be less accurate the farther away in the curve it is?

Atomic

iTrader: (42)

More or less, yes.

Also keep in mind spark advance plays a role in cylinder pressures when you change fueling and boost...

03RCSB

iTrader: (2)

With the amount of variables effecting cylinder pressure and not being able to see the tune, I'm limited to what the tuner recommends. Would watching knock through the aeroforce be of any use? or would it be too late by the time it picked anything up?

03RCSB

iTrader: (2)

Had the truck out this weekend and shot a little burnout video. Def dont have enough stall for the cam/turbo but can justify buying $1000 stall. Also keeping me in traction so.


I threw the cam in there before I thought i'd ever do a turbo so I may swap it out this winter for somethin with a little more low end grunt. Figure that's cheaper than a stall.

black00chev

iTrader: (2)

stock 80e stall? funny how it seemed to take almost zero effort to do that burnout.

03RCSB

iTrader: (2)

It came from behind a 4.8l so I guess its the stock high stall but its night and day from the zero traction 60e, 3:73 combo I had before. Don't get me wrong, with the SYTY shuffle I can build 4psi on the line easy but if I just mash it from a dead stop it doesn't really move out until 3k or so. This was also without using the line lock, still havent gotten around to looking at that.

Highway pulls are just insane with the gearing though.