dc_justin

iTrader: (13)

Once it's tuned for the headers, cat converter protection can be disabled and you won't have it fattening up as much.

I don't know that I would trust those dyno results all that much though, it shouldn't be nosing over at 4600rpm. Peak HP should be occurring somewhere around 5400rpm Did they use an actual tach reference or just calculate it based on roller speed?

_zebra

iTrader: (5)

and i doubt peak torque is at 2300, as shown on 2 of the runs

i just called the dyno guy & he said he was watching my tach & we decided to not pull past 5000 just based on the mathematical speed it would be at. like i mentioned earlier, he said a 4th gear pull was best & i didn't wanna throw the driveshaft, so supposedly 5000rpm would be ~126mph - sorta in the safe zone.

what would you recommend for future pulls? i plan on doing one after the headers (at an actual facility where it's permanently installed). and until then, does this tune need tweaking, do ya reckon?

dc_justin

iTrader: (13)

Run it in a lower gear! There is no such thing as a true 1:1 ratio. In addition to transmission multiplication, you have differential multiplication and multiplication due to the tire to roller diameter ratio.

Some have claimed that with an automatic, there is more power loss due to moving parts in 2nd vs 3rd gear, but in a manual, you don't have that issue.

_zebra

iTrader: (5)

gotcha. i was sorta thinking that, but i figured they knew better than i did.
i'll pull in 3rd next time - that'll give me plenty of room to rev... and speaking of that, what kind of limiters do you have set up there? i ask because when i was doing a before/after of my exhaust work last week, i did some pulls in 2nd & on one, i went up to 5500 & when it came back down, the throttle was almost unresponsive & barely would do anything so i put it in neutral, turned it off, restarted the engine, & everything was fine. (i wish some prius owners would think of that when they can't control their throttle ) any clue what happened? sorry for the vague description - i didn't try to duplicate the problem; i already thought i'd broke something



ps - what % drivetrain loss would you guestimate for my truck - manual trans, t-case, 29lb wheels with 39lb tires (272lb total)

_zebra

iTrader: (5)

:bump: for answer to the above post & also, what kind of numbers have y'all put down with similar 5.3 setups? all i have now is CAI, exhaust & BB 93 tune

Spoolin

iTrader: (8)

Hey OP, my stock 05' LM7 with flowmaster behind a 4l60e put down 253/284tq so those numbers aren't so bad.
Especially since your rich and that dyno is off kilter!

454navyss

iTrader: (46)

my 02 put down 250 with a Volant, Gibson shortys and catback and e fans on a stock tune and i was told that dyno was reading 10% low that day so your numbers seem about right to me

_zebra

iTrader: (5)

alright, thanks.

any clue about the whole throttle craziness thing?
it actually happened again today when i was practicing launching for this weekend. i shifted to 2nd kinda early (about 4500ish) but pulled that gear all the way to 5500 - then it happened again when i went to shift to 3rd - RPMs instantly fell off, so i put it in neutral & gave it some throttle to try & rev-match, but it just went to 3000 & back down to about 1500 and kept that cycle with any throttle position - up & down about once a second or so. the only way to get out of it was to kill & restart the engine.

TIM Z

iTrader: (12)

Dont worry bout the numbers man! , dynos are just another tuning tool.

_zebra

iTrader: (5)

so i just got back from a test run to try & nail down some specifics of this problem.

actually, i'm just gonna start a thread on it...



*edit*
https://www.performancetrucks.net/fo....php?p=4440433