Red Line or Rev limiter. How high should I go?

[DOA]

I have an 2007 Avalanche with a 5.3L. I have dialed in my LTFT and PE. I'm looking for the next tweak. What should I know with rasing my Rev limiter. Currently it is shifting at about 5500.

Thanks for your help,

Lance

[crazy27]

lance go 5900 rpm in 1-2 2-3 3-4 rpm that will give you a better jump in speed between gears

[06MonteSS]

get me a log...

see this post on the specific parameters to log:
http://diablosport.com/index.php?name=P ... opic&t=917

basically, log those parameters at normal cruise, with 20-25% throttle position for as much of it as you can... and also get a WOT run in there...

then you can send me the log and I'll take a look-see...

you can email it to me at: diablo.help AT gmail.com

[jcbst12]

Its up to you. Dyno sheets for the 5.3 say power tapers off at around 5450-5500 rpm and starts to decrease around 5600 and drop after 5700 ( if i remember correctly). Personally I would say 5700. Increasing firmness in the shifts will also decrease your time between shifts. Without increased shift firmness it will require a little more rpm as the timing will back off and the transmission will shift softer and slower, thus increasing shift time.

[DOA]

I realize that rasing the rev limit above 5500 could put me in lesser HP near the top, but I was hoping that would bring me up higher in the band after the shift.

I would assume that some of the mods I've done and some I plan to do have rasied my HP curve to higher RPMs, but maybe I'm wrong.

I've done the following mods:
Magnaflow cat back
Volant Intake
Nology Plugs
Taylor Wires
Diablo Performance tune (adjusted PE and LTFT)

Future Mods
Transgo Shift Kit
Headers (hopefully Long tubes)

[jcbst12]

You very well could be right, however I do not believe the peak will go much over 5700 rpm as the engine is limited by stock components such as cam, heads, injectors, manifolds, etc... There is only so much programming that can be done to overcome the physical restrictions. The only way to know for sure is to find HP and TQ data from a truck such as yours via dyno sheet or something of that nature and see at what rpm the HP topped off at. Ex: I managed to increase rpms with my 91' GMC but required higher flowing heads to do so. I found this out before hand by looking at website where people performed similar modifications and then either ran the 1/4 mile with it or ran it on a dyno.

[DOA]

How high have others gone with a internally stock 5.3?

Thanks for the help.

-LA

[jcbst12]

From what I've seen 5300 all the way up to 6000. It's a pretty rev. happy engine for a truck. Mikel says 5900, I've seen that before. I kept mine at 5700 as I'm not running the quarter mile just trying to squeeze the most from my engine when I need it. Its total your call. Try out 5700 and then 5900. See which one works best for you. Pay attention to the shifts and max speed in each gear too. If 5900 is too much you will notice the speed start to level off before a shift into the next gear.

[jcbst12]

I'm sorry I mean Crazy27 said 5900.

[DOA]

So no worries about harming the engine at those numbers? Just make sure I'm not robbing MPH at shifts?

Thanks

[sickREDsierra]

i would think surely your engine would be fine at those rpm's, you just arent making power beyond a certain point.. i would def. go to a dyno tuning facility and strap your truck to it.... if your arent making power beyond 56-5700 rpm, then its almost pointless...

i have seen MANY small block gen iii motors turn 6500 rpm with no prob, but with a larger cam and headers of course <and better valvetrain hardware>

[jcbst12]

That I'm not sure of. Thats the other reason I keep mine at 5700. The higher the engine revs, the more wear and tear on internals. But GM also keeps this low to prevent "premature" wear on the engine. I'm sure the physical limitation I talked about on this forum will prevent too much over-revving. I'd just consider 6000 as being the "fine line" and keep it below that ( considering thats where the dial stops ).

[DOA]

Thanks guys. I'll have to play with that.

Lew, Mike or anyone. Is there a procedure for advancing your spark further than the perfomance tune does?

I'm just looking for the next tweak. What else can I do with the Diablo?

Thanks

Lance

[crazy27]

hey guys ive got my rpms at 5800 1-2 5900 through out the rest of my gears and im very happy with the performance especailly after mike sent me a mod tune cause in 99.5 to 02 the trans shift ungodley hard between 1-2 gears after a wot from start....
but turn the truck off and it goes back to normal but mike solved that problem for me and since then......... O M G >>>>>>>>>IT SO MUCH FUN NOW WWWWWHHHHHHOOOOOOOOO HHHHHHHHHHOOOOOOOOOOOOOOO LOL

[06MonteSS]

DOA (Lance)... I'm going through your logs now... your ltft's are not dialed in by any means...

be back to ya in a few...

EDIT:

ok, went through those logs...

your average LTFT's at normal cruise/driving are at 4.95 and 1.11....

so adjust your injector slope to -3%.... for example: if you haven't changed anything yet, then make the slope setting -3%... but if you've already adjusted the slope, then go down another -3%... i.e. if you have the slope set to -4% already, then go down another -3 and make the setting be -7%...

leave both of the PE rpm settings at 0%...

make those changes, drive for about 30 miles, and then do another log and let's check the numbers...

-Lew