Fast355

Really don't give a **** what you think to be honest. Its a damn engine and not exactly re-inventing the wheel. His primaries are causing weak scavenging and weak low-midrange torque. Doesn't take rocket science to figure it out. My old 350 moves PLENTY OF AIR through it, more than most LS engines. In the neighborhood of 360-380 gms/sec from 5,200 rpm clear though 6,000 rpm. More than many cammed 6.0Ls I have datalogged. In fact I am running stock 2002 25.1 lb/hr 6.0L injectors at 52 psi at 122% duty cycle at the moment and need to up the pressure on the marine regulator or toss in larger 8.1 injectors. 1 5/8" Tri-Ys work GREAT on the street for it. Keep thinking 1 7/8" are better for a stock 4.8 or 5.3 and putting that mindset onto others without the knowledge to call you out on it. He is after low-midrange torque and part-throttle efficiency from the sound of it with a stock 4.8L engine. No need for anything larger than 1 5/8" on his setup.

I have a 4.8 datalog with catless long tubes that didn't break 240 gms/sec air flow with the older heads and stock cam. Truck was an absolute TURD and it had Pacesetter long tubes on it.

Fast355

Not on 20s at 5,300 lbs without boost with a transmission and driveline that sucks the equivalent amount of power as a 4L80E and 9.5" 14-bolt they are not!!! Also keep in mind in the days I was messing with the Dodge, NOBODY had any form of transmission tuning. I was running those times with all the stock torque management nannies in place.

TXsilverado

iTrader: (19)

stock 5.3 means boost to you? LOL, so when I stepped up to a bone stock 5.7 it went 13.26. with a cam it went 12.49. budget heads put it at 12.19 on motor with an extended cab Silverado. on motor, less gear, blah blah blah. with "oversized" exhaust. you'll have more excuses I'm sure. I'm nowhere near the fastest N/A ecsb either. it's not our fault that you picked a dodge to play with. the fact is, if tri y headers worked, EVERYONE on this forum would have them. don't try to compare your vortec 350 to a LS engine. stock for stock, I give the vortec 350 the edge on down low grunt...but there is a reason that they are no longer made, and people swap them for an LS.

GMCtrk

iTrader: (27)

You are full of ****. There's no way in hell your old 350 is pulling 1g/cyl of airmass. Absolutely no way.

smokeshow

iTrader: (16)

The smaller primaries scavenging concept is a real thing for lower mass flow rates...no use arguing that. And Fast...you have to realize that engine calibration is only a comparison of airflow models, one of which you trust more than another. If what you are comparing your plant (process to be calibrated/tuned) to isn't trustworthy, who is to say the calibration values you generate are any good either? I don't believe for a second that your cylinder airmass went from 0.64g/cyl at peak torque to 1.02g/cyl at peak torque with a cam and some bolt-ons, no matter who makes the engine. 0.64g/cyl at peak torque falling to 0.58g/cyl at the shift is not a drastic enough drop to attribute the gains from your cam and exhaust to it being previously over-restricted. I see drops like that in cylinder airmass at redline in cam-only cars all the time. So there is something wrong with your reference model. Just because you have to jack up VE values (which is how the PCM calculates that cylinder airmass) doesn't necessarily mean that your engine is breathing better. It often means that the model you are calibrating is absorbing errors from your reference model. This is why it's crucial to use accurate injector calibration data, make sure your wideband is calibrated and the slope/offset used to interpret the analog signal is accurate, etc, etc...

GMCtrk

iTrader: (27)

Correct, the airmass calculation is fudged (badly) because of incorrect VE values due to inadequate fueling.

Stock silverado injectors can support about 300 hp.

Fast355

Funny that the LQ9 injectors I am running supported 345 NET HP just fine. VE tables are pretty accurate and have values approaching 120% in places. PE air/fuel ratio is right on target in the tune.

1.02 gm/cyl air mass and 360-380 GMS/SEC is being achieved on the STOCK Express MAF table with a stock 2002 Express MAF sensor.

smokeshow

iTrader: (16)

I dunno... I just ran some numbers real quick, and even accepting your 120% VE number in the equation, assuming 80°F air, you'd still need about 12kpa over sea level pressure to achieve those cylinder airmass numbers. Drop your self-generated VE values and that MAP requirement increases even more. As far as I know, the best technology in the world is only in the 130% range for naturally aspirated VE. Even you should find it hard to believe that your old 350 is touching 120%. Take it as a hit to your pride or constructive criticism, take it however you want...but those values aren't realistic. The math says otherwise.

Fast355

Average Air/Mass


Maximum Air/Mass


Maximum Airflow


WOT


WOT 2


You can definaetly tell its my **** poorly geared Express as well with the 4L80E/3.73 combination allowing for a stupid amount of speed in 1st gear for the RPM the engine is turning.

B1S1 02 sensor is also dead to the world because I had my wideband in its position and closed loop/fuel trims disabled in the tune. There are some spikes in airmass on a couple of heavy throttle hits from closed throttles as air rushes into the plenum, but I saw a 1.02 gm/cyl average in this particular datalog.

smokeshow

iTrader: (16)

Did you read my post before last? I can go into a tune and within 30 seconds make it say that my cylinders have 10 grams of air in them each. YOU are responsible for the accuracy of those numbers. Your reference model is flawed.