looking for big help with tuning an extremely large cam in my ls1

[oztracktuning]

Desired air flow is right B4307
B4603 is idle speed

You may also need to bump up your VE table cells to higher values. at 400 and 800 Kpa and 1200 Kpa

Timing at around 0.20g/cylinder - above and below at the same rev ranges will need to be increased up toward 30 deg

[01blkss]

Desired air flow is right B4307
B4603 is idle speed

You may also need to bump up your VE table cells to higher values. at 400 and 800 Kpa and 1200 Kpa

Timing at around 0.20g/cylinder - above and below at the same rev ranges will need to be increased up toward 30 deg

ok cool...should i just allow the Auto VE tuning to take care of the VE tables...i have been doing that with great results thus far...

i have an LC-1 linked to my EFIlive.

Thanks for the help guys~
Louie

[oztracktuning]

Dont follow auto Ve with the idle cells. It can lead you astray with a big cam. Use it to get you roughly close and then look at pulse width and try to identify variations in pulse width that cause variations in afr. You want to trim the VE cells to get afrs to be more constant by cause and effect ie. pulse width causing afr variation.
Minimum variation in afr will make for a good idle

[white2001s10]

I also would not use auto-VE tuning for idle or anything around idle either.
It's not going to work correctly first of all.
Second, you're likely not going to get best idle at 14.6:1 AFR anyway.
The AFR you end up at will depend a lot on where your spark advance is set for idle.

[01blkss]

I also would not use auto-VE tuning for idle or anything around idle either.
It's not going to work correctly first of all.
Second, you're likely not going to get best idle at 14.6:1 AFR anyway.
The AFR you end up at will depend a lot on where your spark advance is set for idle.

interesting...

What is suggested for idle VE tuning? how should i go about setting it up? and what is a good idle AFR to use?

thanks
Louie

[white2001s10]

You use a wideband and datalogging.
It depends on what the engine responds best to.

You have to keep some things in mind and in perspective.
Your AFR on the NB or WBO2 isn't neccessarily the AFR of what is burning in the chamber. It also isn't always reflective of the amount of fuel the injectors (PW pulse width) are putting in.

For example you may see your AFR go up from 15.0 to 15.5 simply by increasing the spark advance from 20* to 25*. You're not putting in any more or less fuel than before, but the AFR in the exhaust has changed.
You may see the exact opposite as well.

The engine may end up liking to idle at 15.5 or 16.0 or 13.0:1 AFR on the wideband.
This is why a lot of folks run OLSD tunes with the monster camshafts. That way you can ignore the factory O2's.

[01blkss]

For example you may see your AFR go up from 15.0 to 15.5 simply by increasing the spark advance from 20* to 25*. You're not putting in any more or less fuel than before, but the AFR in the exhaust has changed.
You may see the exact opposite as well.

i have seen that and i was honestly very concerned with it...i was sure that i never changed any but spark...and i noticed that my WB02 was reading much differently...

I asked at ls1tech.com but apparently i should have asked here...

Thanks for the help i really do appreciate it. i cant wait for wednesday when the install is done and i can get to the tuning!

Louie

[white2001s10]

There's a post on LS1tech
http://ls1tech.com/forums/showthread.php?t=503274

where KVU talks a little about changing AFR.

The fuel, spark, AFR, and engine loading are all very inter-related functions.

In general, starting the spark earlier will burn up more fuel in the chamber.
There is simply more burn-time to combine the fuel & oxygen.

Loading the engine down will slow the piston speed. This also allows more burn-time and can show up on the wideband as a richer or leaner AFR. Sometimes you may notice during a street or track run that you are richer in first gear and leaner in high gear, or the other way around.

The reason why it's not always the same is probably due to misfires brought about by the lean or rich condition in the chambers.

As a common example, you can have misfires in the chamber and still see an average AFR of 14.6:1 at the wideband. If you unplug an injector or have a bad sparkplug the closed loop routine will compensate to bring the average AFR back.
Here you can see clearly that the AFR in the chamber where it counts doesn't neccessarily match the AFR in the exhaust.

Excessive camshaft duration and overlap will also throw the AFR off in the exhaust during lower RPM operation. The pressure differences during the overlap period can move either extra oxygen, and/or extra fuel into the exhaust instead of being trapped in the chamber to burn there.
The amounts of each can change as engine speed changes. Exhaust pressure pulses arriving back at the exhaust valve during overlap will change their timing with engine speed.

The result can be that to keep the AFR happy in the chamber where it counts, the AFR on your wideband may produce a very odd AFR vs RPM curve down low.

[superls1]

You use a wideband and datalogging.
It depends on what the engine responds best to.

You have to keep some things in mind and in perspective.
Your AFR on the NB or WBO2 isn't neccessarily the AFR of what is burning in the chamber. It also isn't always reflective of the amount of fuel the injectors (PW pulse width) are putting in.

For example you may see your AFR go up from 15.0 to 15.5 simply by increasing the spark advance from 20* to 25*. You're not putting in any more or less fuel than before, but the AFR in the exhaust has changed.
You may see the exact opposite as well.

The engine may end up liking to idle at 15.5 or 16.0 or 13.0:1 AFR on the wideband.
This is why a lot of folks run OLSD tunes with the monster camshafts. That way you can ignore the factory O2's.

Are you only talking about idle with a big cam? What are your thoughts on this:

First, realize that for combustion to occur, there needs to be fuel (such as hydrocarbon) and a source of oxygenates (i.e. oxygen and/or molecules or partial molecules which contain oxygen). In addition, there are diluents which are present in the mixture but do not contribute to the actual combustion (for example, nitrogen [N2]). This holds true for any combustion event, whether inside of an internal combustion engine or a small campfire.

Second, every atom is conserved in the combustion process, so it is possible to use exhaust gas constituents to reconstruct the amount of fuel and oxygenates before combustion. If this was not the case, then wideband oxygen sensors would not be capable of determining pre-combustion air/fuel ratio.

It is possible to express the combustion event as a balance of input reactants: fuel, oxygenates, and diluents (for example gasoline mixed with air) to the resultant combustion products (i.e. the composition of exhaust gas). Note that this is a chemical balance, meaning that every element needs to be accounted for in its molecular balance, before and after the combustion event. In other words, if we know the proportions of fuel, oxygenates, and diluents entering the engine, one can determine the species composition in the exhaust gas. And we can work backwards. If we know the species in the exhaust we can determine the ratios of air and fuel (both in molar quantity and molecular mass).

See this for more detail.

Idle issues can be tough with big cams, I just wouldn't want people to think that WB's don't work.

[white2001s10]

Second, every atom is conserved in the combustion process, so it is possible to use exhaust gas constituents to reconstruct the amount of fuel and oxygenates before combustion. If this was not the case, then wideband oxygen sensors would not be capable of determining pre-combustion air/fuel ratio.

It is possible to express the combustion event as a balance of input reactants: fuel, oxygenates, and diluents (for example gasoline mixed with air) to the resultant combustion products (i.e. the composition of exhaust gas). Note that this is a chemical balance, meaning that every element needs to be accounted for in its molecular balance, before and after the combustion event. In other words, if we know the proportions of fuel, oxygenates, and diluents entering the engine, one can determine the species composition in the exhaust gas. And we can work backwards. If we know the species in the exhaust we can determine the ratios of air and fuel (both in molar quantity and molecular mass).

I don't agree at all. I think someone has innocently confused a wideband O2 sensor with a much more complex (and expensive) 5-gas analyzer.
A wideband doesn't do all of that... not at all.
A wideband O2 sensor is still measuring oxygen. It's still measuring the difference in oxygen inside the pipe as compared to outside the pipe.
The difference in a narrow-band and a wide-band is that narrowbands only have decent resolution very near stoich by design. The wideband has much greater resolution.