_zebra

iTrader: (5)

so i went to DBR High Performance's "No Cars Allowed" truck show today & they had Maximum Dyno out there with their portable rig, so i figured it'd be nice to get a baseline run before i get the LTs & cam.

for those of y'all who don't know my specs:

• 99 NBS Sierra 1500 RCSB 4x4
• NV3500 takin' abuse from a stock (for now) 01 LM7
• AIRAID filter & tube
• MellowTone chambered muffler - single 3" in/dual 2.25" out the back
• BlackBear 93 tune
• 3.73s turnin' some 265/75-16s

with the fuss i hear about stock drive shafts not liking to go past ~130mph & the dyno guys said it's best to use the 1:1 gear (4th), i only pulled to 5000rpm



ps - i love how it says i drive a "Serria"

my heart sank when i saw the numbers, but after talkin to a bunch of guys who also dynoed today & have already pulled on other machines before, this one was pretty far off. i noticed that it only showed around 120mph as it was logging when 5000rpm in 4th mathematically equals 126.2mph. another example was a Kenne Bell Lightning with forged internals on 17psi read 520hp today when he'd previously pulled 575hp at the shop when he did his engine work & with the factory blower. that same truck also had a timeslip for 11.76, so i didn't put a lot of stock in the dyno today, but it'll sure show a nice increase after the LTs & cam on a real dyno

care to share y'all's opinions?



ps - here's the thread criteria:
NAME: zebra86
YEAR: 1999
MAKE: GMC
MODEL: Sierra 1500
BODY: RCSB
ENGINE: 5.3L LM7
TRANNY: nv3500
DRIVE: 4wd
MODS: airaid, chambered muffler, BB 93 tune
LOCKED OR NOT: stick, baby!
CORRECTION FACTOR: ain't sure (not that i'm gonna make the list, so it don't matter)
DYNO: Dynocom
DATE: 3.13.10
HP: 225
TQ: 283
New chart

fastjweb

iTrader: (2)

my 05 crew cab with 5.3 made 287hp and 318tq with bolt ons and superchips. no cam or longtubes, just things in my sig. i was told mine did pretty good, he usuallys sees the 5.3s with my mods alot lower, so dont know if yours is good or bad.

SLOXCAB

iTrader: (7)

i laid down 285hp and 310tq before cam and converter but hopefully for you that dyno was reading to low

norris_83

iTrader: (4)

for a '99 5.3 with a NV3500 thats not bad at all! Your motor is rich, thats gotta cost at least 10-15hp/tq..

dc_justin

iTrader: (13)

It's actually not affecting power output by any significant amount (MAYBE 1-2hp). A noticeable power loss doesn't start to occur until the 10s. I believe I even have a dyno graph here somewhere from Julien's (spoolin) truck showing no difference at all on runs ranging from 11:1 - 13:1.

Cat converter protection kicked in there at 2500rpm due to such a slow ramping run causing it to fattening up there a bit.

_zebra

iTrader: (5)

it's an 01 engine, so it has the bigger injectors & the tighter LSA cam

seein's how i don't know a thing about tuning, what's an ideal A:F ratio? on my best pull, it got down to 11.4 around 5000rpm

dc_justin

iTrader: (13)

The ideal AF range is one that is rich enough to keep combustion chamber temperatures manageable while not being too rich that it affects flame propagation. All of my tests, even on very low compression engines, show comparable power output in the 11-13 AF ratio range.

krambo

iTrader: (4)

Sorry if it is a hijack but it is still on topic: Justin, do you suggest adding more fuel around peak TQ and lean it out toward peak HP, then fatten to red line? I have talked to countless dyno operators and tuners who state this yields the best results with all else being equal.

To the OP, Yea, the drive shaft thing always got me nervous but I still pushed it. The dyno is fun and scary at the same time...that equals an addicting game

dc_justin

iTrader: (13)

The only time I can see a benefit there is if you are running it very lean (relatively speaking) to begin with. I've never come up with a situation where this was needed to optimize torque curve.

_zebra

iTrader: (5)

call me stupid or unobservant or something, but i just realized you're "that" Justin...

seein's how you're the one who tuned my truck, do you see anything based on this chart that needs to be changed? i realized right about the time i was paying somebody to do my crank relearn that i shoulda went ahead & got a live scan tune, but i reckon i'll do that once i get my headers.

thanks

ps - i'm thinking the first run (graphed in black) might not've been in closed loop yet or something which might explain why it's richer overall. i warmed the engine until the gauge was close to 180ish, but we all know how accurate those are