I finally got the l92 into the tahoe with the x-link and lpe trigger converter. I just have a couple things to button up and it will be start time. That being said, what kind of in boost timing have you l92 top end guys been running? I looked at the zl1 and zr1 tables and I'm amazed at the timing they run. It's pretty high. I was runing 17-19 before, depending on the rpm. I should be at 10psi on this one. Just looking for some insight. I noticed idle ranges are WAY higher than the older cathedral stuff. Is this due to slow air at low rpm or just because it's a huge bore?

 

Keep in mind they are in a much lighter car, you can load your engine much more so timing will be lower. Start conservative and work up. As for low rpm, I would expect more timing with the lower air velocity but can profile is gonna play a role also.

 

What turbo wheel sizes you running?

 

I agree with the weight, which is why I used an escalade timing table for my 0-.64 area. Then I took my 10:1 compression 6L boosted areas and added -3* to lower it down a bit. From there I will work my way up depending on egt's. I'm pretty stoked about all this, better flowing heads, bigger intake/tb and bigger engine. Not to mention the fact that I have to lower my truck back down some. Going to the aluminum engine it raised up quite a bit.

 

its a TC78 with the 68mm turbine wheel in a .96 open A/R housing.

i wanted to upgrade the turbo this year but i have to have an engine to be able to run a turbo...

 

Where are you getting this information from? Nothing about a vehicle's weight changes cylinder air mass. I've had a theory that this particular piece of information was birthed of people misdiagnosing a poor tune as a correlation between timing and vehicle weight. It is possible to rev quickly through a range where the timing is above the knock limit, but since you don't spend but a few milliseconds there, it never gets a chance to detonate. Lighter vehicles at the same torque output as a heavier vehicle will obviously rev faster through a given RPM range, so I can see where that conclusion comes from. You run way too much timing (or the mixture is too lean or transient fueling is off, take your pick) in an area of your tune that you don't often operate in. Put the setup in a heavier vehicle and the engine must lug through that same RPM range where the tune is incorrect and it experiences detonation. But it isn't due to the vehicle's weight. It is improper tuning that shows its ugly face when the weight:torque ratio increases.

 

I guess everyone has their ideas. Put a high comp motor in a 4k car with low gears and tune it max effort, then do the same in a 6k truck with 3.08s and see which takes more timing. All else the same.

 

If tuned properly, they will be identical. I know lots of old timers and hobbyists alike have adopted that mindset due to their observations with engines detonating when they get loaded down more, but its only a result of adding weight...the weight doesn't cause it. A poor tune does. When I put 6000lbs behind my truck, it doesn't suddenly start detonating...

 

I used my egt gauge to help dial in my part throttle timing. I started out low and slowly increased it until the temps stopped droppping. When i first started my timing was low 30s and the egt temps were in the 1200s. I ended up in the 42-38 timing range and egts are around 1050*.

But i regularly smoke crack but only when I stay in a Holiday Inn Express sooooo. Yeah....

 

this is what I do. when I first went turbo I had my timing low. got an egt gauge later on and found out they were way high. like 1800+ in boost.

on a side note, any body know what causes you to randomly get abs, stability control and traction control lights?