LS699TA

okay i just did my first HC swap. I used a set of heads and cam from a friends 03 z06 with about 40,000 miles.

so now i notice it has alot of knock retard. usually .15 to 4.00 degrees but it seems to go away if I WOT. it comes and goes. and i have fixed all the banging metal and still have not noticed any change, same thing with teh timing. if i pull the max 5 degrees out with my predator, it still will knock like it did with 2 degrees added.

I read somewhere that the ls6 timing table and ls1 timing table are way different, with the ls6 having "fast burn" heads that dont need this much timing.

so i have pulled 4 degrees of timing from 1000- 4000rpm and 3 degrees from 4000rpm up. The Power Enrichment is +10% above 4k and +8% from 2-4k. the slope is at -6% (crappy 99 injectors) and it seems to idle fine and zero out the LTFT like it should.

I also should mention that we "decked" the heads or whatever you call it where we shaved the bottem to up the compression.

has anyone done this before? does anyone know the exact difference between the ls1 and ls6 spark tables? I use 104 gas and it still knocks, to be honest i cant tell if the race gas makes it knock less or not. but the knock is definatly still there with race gas.

could i have shaved the heads to much? what else could be causing this knock? bad installation? bad rocker arms? do you think the fuel pump or injectors could be causing a cylinder to lean out setting the KR off?

the car is a full bolt on 1999 that we swapped the heads and cam. it also has the ls6 intake and headers etc etc.

thanks for any help you

fast01

iTrader: (16)

If it's knocking on 104 it sounds like false knock. This could be related to any number of things, too many to list here. If you do a search on false knock I'm sure you'll come up with more than a few threads. As far as the timing goes, I run an LS6 in my '01 Z-28 and my timing is at about 18* at WOT and I'm still trapping around 113mph.

LS699TA

yeah WOT im at around 18-19 degrees... however, putting around town is where i get the knock retard. i think it might have to do with the "engine load" with the stock 1800 stall converter.

if you did the ls6 swap, what else did you do? i heard that the ls1 fuel setup wont feed the ls6 at high rpm. was yours a crate assembly or longblock? what size injectors did you use?

has anyone decked their heads? i wonder if i need to pull more timing since i decked the heads therby upping the compression.

fast01

iTrader: (16)

I bought a brand new long block from the dealer. As far as supporting mods when I swapped, I did nothing more than a tune (aside from what was aleady done). The first time out with the car through stock manifolds, a cat back, lid, and 3000 stall with 2.73's the car went 12.55 @111 on Eagle RSA's. You don't have to change the injectors or the pump. I'm spinning the car to 6800 RPM wothout a problem. In fact I had it dyno'd at Eastside Performance and it put down 373rwhp with 3.73's. Increased compression will make you more prone to detonation, but the 104 should clear that right up. Something's setting off your knock sensors.

LS699TA

well im on a stock converter and trapped 115 @ 13.1

i took your advice and pulled timing all the way to 18 degrees up all the way thru 7000rpm. it seems to knock considerablly less with the extra degree i pulled out.

my next question would be: does anyone have a graph or table or soemthing showing the spark (or timing) table for the ls1 and the ls6? I'd like to get it as close to perfect as possible while i wait to save for a real tune.

LS699TA

does anyone have any information on the ls6 timing table or spark map?

00pooterSS

iTrader: (40)

are you hearing the knock?

how much did you mill the heads, the 243's bring it to 10.5 CR stock mill.

LS699TA

no audible knock, im not sure about the milling, i had a knowledgable machinist do it for me though, whatever the ls6 standard is.

im pretty sure the problem lies in the tuning, i dont know what the ls6 timing tables look like compared to the ls1,

heres an old related thread with a nice graph

https://ls1tech.com/forums/showthrea...s6+compression

LS699TA

does anyone have any information on the ls6 timing table or spark map? i guess not....

well for the future thread searchers, it is my belief that the stock ls1 tune must have 5 degrees of timing pulled between 2-4kRPM and 2-3 degrees pulled from 4kRPM up for a WOT of around 20.

also the PE above 4k needs to be enriched ALOT and of course the shift points and rev limiter need to be raised.

caliswangin916

iTrader: (3)

just a reminder that different year ls1's had different timing tables. i know for sure between f body years.
i think 2000 had the most aggresive. someone correct me if i'm wrong on that.

99firehawk

iTrader: (1)

Are you sayin' that because the 99's have smaller injectors?

1Bad00SS

iTrader: (2)

Get an expiereienced tuner with the aid of a dyno and your problems will go away.

DrkPhx

iTrader: (15)

How much did you mill the heads and what head gaskets did you use? The C5 ZO6 uses 22 degrees of total timing from 4000 rpms up. The 99 LS1 uses 23-25 of timing from 4000-4800 rpms (basically a dip) then goes to 28 from 5600 rpm up. Assuming this is false knock, you can desensitize the knock sensors so they respond slower and are not as aggressive. Also, what is the injector duty cycle at WOT?

krill

He got banned, do a search on his last posts and you will find out why