timing only tune

[oldred95]

My dad bought a 06 LBZ back in January and just last weekend we put a Diamond Eye 4 inch turbo back exhaust on it and I've loaded a couple different tunes in it with efi live. The current tune is supposed to be around 100 hp over stock and it feels like it. The power comes on very hard and fast from 3/4 throttle on but it just feels too extreme for an otherwise stock truck. I've been reading and timing seems to come up a lot. From what I'm gathering by reading and looking at the timing on various tunes diesels seem to run the low timing at low load and increase the timing at higher load and engine speed. This seems to be the exact opposite of a gas engine which I'm used to dealing with. I know on a gas engine for the most part in stock form you can gain pretty significant power and economy just by getting the timing right and the fuel otherwise needs next to no changing. Would the same concept apply to a diesel? Optimize the timing and leave the turbo and fuel settings alone? We really aren't needing more power just more economy. Can timing be altered without having to mess with boost and fuel?

[Dmaxink]

Yes timing can play a large key in economy and can be tuned to stock boost and fueling to have positive gains.

[oldred95]

Cool. I figured that was the case but there is just so much incomplete information when you search its hard to ever really know.

I read that on a stock LBZ the spot on cruise light load timing seems to be around 7 degrees. Anymore and you start firing too soon and the piston is fighting the explosion on its way up on the compression stroke. I've seen this with gas engines.

Can someone explain the correlation to me between engine speed and load and desired timing of a diesel engine? By the appearance of the stock table it seems to be pretty much the opposite of what a gas engine would want at similar speed and load.

[killerbee]

http://killerbeeperformance.com/download/tuning/Timing%20the%20Diesel.pdf

[oldred95]

Whats the reasoning behind the timing dropping off so much right in the mid range where you would want it most? Its basically at 0 from 50 to 90 mm3 at 1700 rpms and from 1700-2900 it stays at 0 as the load increases from 50 mm3 on. Based on what I read from the link killerbee posted it seems like a conservative table could be built to provide some really nice gains. Lets say I start with a peak timing of 18 degrees at 3000 rpms from 90 mm3 on and around 7 degrees in the areas of cruise and then make a smooth transition between the two, would that not make for a decent starting point?

[oldred95]

Been playing around with it and came up with something that looks functional. I don't think its too much but I will let you decide. Why can't they do a little smoothing of these tables from the factory? It may not make much difference in feel but it sure looks a lot nicer.

http://img.photobucket.com/albums/v604/oldred95/LBZtimingcurve.jpg
http://img.photobucket.com/albums/v604/oldred95/LBZtiminggraph.jpg

[rcr1978]

watch your higher timing in low rpm higher load areas, when going up hills, slow acceleration your going to get some hazing. You need some engery to help spool the turbo a little and not keep to much in the cylinder. It's even worse on vehicles with bigger turbos, make sure to log your timing chances are you are not going to get exactly what you put in that table above.