disassembled

iTrader: (3)

Hi i just talked to a person that builds turbo kits for a living. He told me to prevent my manifolds from cracking on my turbo setup that i should run a lot of timing(he runs 28 on his turbo wrangler without issues) because i told him i was planning on running about 15 degrees max until i get it on a dyno and had a pro tune it for me. Here's my setup: HPE forged Iron 398, CAS twin turbo (log style manifolds running t3/t4 turbos) and a megasquirt controlling the fuel. I have 95lb injectors, nasty perf rails, and nasty perf dual intank kit. I looked up some tunes on horist's hptuners bin site and found a 99 turbo LS1 tune and figured i would just put that in so i can start the car and drive it around.

Is it true that the more timing i add the lower the EGT's? What would be the safest amount of timing i could run on 91? I have an intercooled setup and if funds permit i will put an alky kit on.


Greg

SSpdDmon

iTrader: (10)

I think that guy's on crack personally. Anyone else? Last I heard, people run a richer AFR to keep temps down - not more spark.

jimmyblue

iTrader: (11)

Timing too late, and the gas is still burning when it leaves.
That's lost power, and higher temperature. You wanted to
expand the gas inside, take the heat as mechanical instead.

But 28 degrees is what NA people get away with. If he's got
some smog-heads Jeep motor running 28, that doesn't mean
a 10:1 (or better) motor can take it.

You might run more than 15, but I'd creep up on it and not
take this dude's tuning advice literally. Like, even if he's a
hella plumber, fixing TVs may not be something to try with
a pipe wrench.

BOOSTNSS

iTrader: (1)

Well i new to the ls1 turbos but on turbo buicks i am not scared 93 pump gas and 30* timing with some alky and it loves it, race gas and run 36-40* timing. but for some reason ls1 dont like it. so tune on the safe side, my car will be tuned soon with 93 and alky and i am hopping for 20* total timing anything lower seems no good but who knows how long it will stay together for???

oange ss

iTrader: (50)

....you're killin me !!!!!!!!!!

NicD

iTrader: (7)

LS1's do not take and do not like a lot of timing on pump gas with forced induction like some other motors do. You run 28 deg of timing at WOT under boost and kiss it goodbye. Hell 28 is quite a bit on 91 oct with an N/A motor and more often than not you have to turn that down to prevent pinging out here. But yes in general, more timing = lower EGTs.

oxidizr

iTrader: (4)

I have tuned several LS1 GTOs running Magnachargers and both at 7 PSI.

This GTO is a dual power adder running 25* max timing @ WOT on 100 octane and 22* on 91 octane CA pump gas.
http://www.ls2gto.com/forums/showthread.php?t=42252

This GTO is a Maggy only car and is running 28* max timing @ WOT on 100 octane and 24* on 91 octane CA pump gas.
http://www.ls2gto.com/forums/showthread.php?t=34926

Both of these cars are dialy driven and driven hard a the track. These cars haver been logged on street and track conditions and show 0 KR.

I have also tuned some LT, CAI, Cat-back GTO's and only seen 24-25* max timing before KR.
http://www.ls2gto.com/forums/showthread.php?t=35787
http://www.ls2gto.com/forums/showthread.php?t=35792

My expereince would tend to reinforce the fact that at least root blowers do like timing ... I cant confirm the lower egt BUT i can throw a few thermocouplers in the next dyno sessions.

P Mack

iTrader: (6)

The sooner the spark ignites, the sooner the gas starts pushing against the piston on the power stroke, the more energy the gas imparts to the piston, the less energy is left over as temperature at the bottom of the stroke. So theoretically, yes more timing means lower egt. It's conservation of energy.

On a related note, apparently rally cars retard the timing to keep the turbo spooled when off the throttle.

disassembled

iTrader: (3)

Thanks for the info guys! I am going to use slowhawks tune for a TTI t76 turbo kit for my timing and just use my Megasquirt to set my target AFR for the different boost levels.


Greg