turbocdubs

Okay so i swapped in a ly6 in my 95 chevy.. finally got it around to getting it dyno tuned and the dyno graph seems to hit a wall at 4700.

mods are a .598/.615 lift cam
vvt delete of course
full boltons
basically brand new rebuild
24x crank
411 pcm
if anyone has any questions on what else i did i can include it im just not real sure what is all relevant to be honest.

dyno chart seems to be making great power up until 4700

i did a few logs to see if it was knock retarding or anything and nothing on the scan tool ill post the log if i can figure out.

tuner said afr never dropped, im assuming its got good fuel?



anyone got any ideas.. i feel like im being robbed of like 70hp

turbocdubs

went and watched the log a few times.. seems timing is around 40-42* then drops into the 20s???

thunderstruck507

iTrader: (18)

the lift of the cam tells us nothing really, what are the specs for duration and lobe separation (along with if it has advance ground in)?

was the cam degree'd or installed dot to dot? who ground the cam?

what intake manifold are you using? what filter setup? did the tuner check for restrictions in airflow by comparing MAP readings engine off key on versus WOT?

what valvesprings?

thunderstruck507

iTrader: (18)

most EFI ls engines are going to run 23-28* timing at WOT so that's normal

turbocdubs

226/238 -112 i believe
installed dot to dot
ly6 truck intake
tube to open filter, just a normal bolt on intake nothing crazy
not sure im going back tuesday for some more tuning.
and they are PAC dual valve springs dont have the part number handy

thunderstruck507

iTrader: (18)

I'm not really all that familiar with the rectangle headed 6.0l engines but the more I look at the graph the more odd it seems...notably how hard and fast torque starts to fall off after peak

my ls2 torque curve has barely dropped any even past 6000rpm

turbocdubs

i have no clue what it is. this is my first ls engine, pulls insanely hard midrange then you can kinda feel it just making noise. but its odd for sure

mkvamso

iTrader: (2)

What sort of vvt delete, what cam gear are you using, did you measure for pushrod length, any way to verify cam timing?
Dot to dot isn't always accurate, especially on the newer vvt engines

The graph looks like the cam is advanced a bunch

turbocdubs

just the typical
ls7 lifters
timing cover
ls2 cam gear
7.4 pushrods
not 100 sure on cam timing

mkvamso

iTrader: (2)

I would try and verify cam timing if possible
It sounds like the cam may be advanced pretty far

turbocdubs

gonna do a compression check.. but if it was off it would be the cam itself right? 1 tooth is ~16* right? and that would most likely be a failure with valve piston contact from what ive gathered

turbocdubs

so did a compression test

1: 212 2: 220
3: 215 4: 235
5: 212 6: 220
7: 210 8: 215

turbocdubs

pulled the cover how obvious is a tooth off? The teeth are close but i dont think 100% The crank dot is dead on with the center point of the chain dampener (where the red line is pointing). Notice how the cam dot is slightly left of the center point.

00fxd

I have a grade 1 suggestion because I don't know anything about ecm tuning, but when I first installed the LQ4 in my Corvette 6 years ago, I sent the ecm away for a tune to make it run. When I first got goin' I found that it felt like I threw an anchor out at 5800rpm. Turns out the factory tune retards the ign timing at that rpm to soften the shift for the automatic. Also it kicks the ign timing way back when it detects ping. It was an early deal - back then the tuner wasn't aware of these features. I had to send the ecm back to have both those features removed. Don't know if this is relevant to your thing.