A/F ratio???

hotrodder_101 · Mar 21, 2014

How are y'all tuning these things without monitoring air/fuel ratio? I'm coming from race cars so that is why I'm asking.

Gearhead · Mar 21, 2014

Egts and smoke output. This is a fuel throttled engine.... don't have to worry about running it lean.

hotrodder_101 · Mar 22, 2014

Well, when do you get into danger with the egts? I don't like all that smoke. If it smokes a little that's ok, but not like a freight train....

Gearhead · Mar 22, 2014

hotrodder_101 said:
Well, when do you get into danger with the egts? I don't like all that smoke. If it smokes a little that's ok, but not like a freight train....

I have the lowest smoke in the industry. Smoke comes from a race-only setup, mismatched components, or tuning that doesn't reference the smoke control maps properly.

ckrueg · Mar 22, 2014

Usually more smoke also means more egts.

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hotrodder_101 · Mar 22, 2014

Well, there has to be a point where you will lean the engine out to where it will cause damage.

duddy · Mar 22, 2014

leaning out a diesel will not hurt it. it is like running an air compressor at that point. over fueling is the only issue, as to washing down cylinders. Forget your gas ratio training when coming to the diesel world, saves alot of headaches.

hotrodder_101 · Mar 22, 2014

Ok. I'm thinking about gasoline engines too much. On these diesels, the fuel is injected at the point of ignition. There can be no detonation. So just adjust fuel until I am happy with the amount of smoke produced?

duddy · Mar 22, 2014

Yup, and if you can't back the fuel off, or adjust the injection timing, to get the smoke to go away to your liking, find a way to push the air in faster. With all the dodge dbags that play with efi, I think anyone with any engine background can figure out how to get a diesel to work to their liking.

And yes I will be running Gearhead's tunes in the near future! He took what should be simple to a high, near perfectionist level with his tuning.

Luke@MillerPerformance · Mar 22, 2014

duddy said:
Yup, and if you can't back the fuel off, or adjust the injection timing, to get the smoke to go away to your liking, find a way to push the air in faster. With all the dodge dbags that play with efi, I think anyone with any engine background can figure out how to get a diesel to work to their liking.

And yes I will be running Gearhead's tunes in the near future! He took what should be simple to a high, near perfectionist level with his tuning.

After a certain point with the Dodges even EFI Live gets tricky to back the smoke down with big injectors. If you're trying to use Smarty UDC, well they smoke until the turbo(s) light. Duramax is easy to get clean, they're a lot more responsive to timing and fuel changes, same with the common rail PSD.

As far as tuning diesel vs. gas, it's all about timing in a diesel. Smarty as a pretty good article on the basics. http://madselectronics.com/downloadfiles/SmartyUDCsw_TuningTips.pdf

duddy · Mar 22, 2014

mpdtune said:
After a certain point with the Dodges even EFI Live gets tricky to back the smoke down with big injectors. If you're trying to use Smarty UDC, well they smoke until the turbo(s) light. Duramax is easy to get clean, they're a lot more responsive to timing and fuel changes, same with the common rail PSD.

As far as tuning diesel vs. gas, it's all about timing in a diesel. Smarty as a pretty good article on the basics. http://madselectronics.com/downloadfiles/SmartyUDCsw_TuningTips.pdf

Nice, good explanations.

hotrodder_101 · Mar 22, 2014

This is great info. Seems like something that runs on the MCC software. When you make timing changes, do you retard or advance? The truck will be stock for a while.

powerstroked08 · Mar 22, 2014

More timing(advanced) will drop backpressure that drives the turbos while raising the cylinder pressure while providing a better burn(because of having more time to burn the fuel) But you need to be very careful not to go too far with it because it can raise the cylinder pressure so much you start to cause major damage.

hotrodder_101 · Mar 22, 2014

It sounds like you need a good mix between advancing the timing and egts. Is there a indication when it's advanced too much other than engine damage?

Gearhead · Mar 23, 2014

hotrodder_101 said:
It sounds like you need a good mix between advancing the timing and egts. Is there a indication when it's advanced too much other than engine damage?

Yes, the engine will start fighting itself and you BSFC starts getting bad because the cylinder pressure is causing more resistance than the power you are adding by advancing the timing.