Marine Intake

[Supercharged111]

I put the air intake and MAF back on this, using the Lingefelter 100MM MAF transfer curve for the LS3/LS7 MAF. Runs very smooth now. Still need to do some more work on the VE tables but have them roughed in enough that it runs well.

FWIW its actually running well with the stock transient fuel settings although I can tell they are a bit lean and need to be opened up a bit, but it does not bog, spit, pop or hesitate.

Let the weather cool off some then it'll rear its head.

 

[L31MaxExpress]

Let the weather cool off some then it'll rear its head.

Maybe it is not cold enough. I just started it in 45F in misty rain. After it ran a few minutes, I got it to bog just a little on the initial throttle opening but I have not touched the P59 transient fueling for the L31. FWIW the E85 still in this tank is from October as well, so I am trying to run it mostly empty before putting some fresh gas in it.

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[L31MaxExpress]

Let the weather cool off some then it'll rear its head.

38F now. I tried adding fuel in the transients. Seems to have made the throttle response from idle worse. I drove it around town a few minutes ago. Wideband showed dead lean on very light throttle tip-in. It was ok stone cold, but as it got to operating temp it began to lightly stumble. I could not get on it very hard though, it is cold and rainy. Transient fueling is one place TBIs are much easier to get right. I am not sure if it is a tune issue or months old E85 now. Fuel gauge just hit E while I was driving around but it is innacurate and I have never put more than 22-23 gallons in it on E with a 31 gallon tank. Best guess is it still has 8-9 gallons of E85 in it that I still want to burn out of the tank. On the highway it will go 100 miles on E before I even consider stopping for fuel. What I ran before with the P01 is totally different from how the P59 uses transient fuel as well. Probably going to take hours of messing with it to get it right.

I am going to pull a 2005 8.1L factory tune and look at it. The tiny injectors in it spray nearly on the port floor and it loves fuel. The 8.1L factory values may be a better starting point than the 350 or LS ones with injectors pointed at the back of the intake valves.

 

[L31MaxExpress]

So I ended up messing around with the transient fueling several times. It is still in the 30s and very windy here, meaning the engine cools off very quickly which is rare. What better weather than to mess with the transient fueling. I have let it cool almost completely down to ambient 3 times. I think I have the transients at least to the point where it drives nicely now and has good response at all engine temperatures. In HP Tuners I ended up adding 25% to the whole Evaporation Boil Time table. I ended up bumping the whole Fuel Impact Table 50% at a time. So I went to 150% (still very lean but it stopped popping into the intake), then 200% (still somewhat lean to the point you could feel it hesitate but getting better), then finally 250% (might still be a shade lean but instant throttle response). I also increased the gain factor up to 1.00 up to 128 gms/sec airflow. I drove it with the coolant temps starting out at about 45*F. It was responsive to moderate throttle even cold and remained resposive as the engine temperature increased and it went into closed loop. I will probably leave it as it sits now and drive it a bit more to see if it stays happy. I may add a little more to the boil time table just to see how it reacts. If that does not provide the result I am looking for it might get another 25-50% added to the impact table. It is crazy to think that those values are now 2.5x what GM calibrated them for on the 350 then again, this 383 moves 2x the airflow and makes 2x the power and has alot more intake port surface area to keep coated with fuel. Its 100x better than what it was before though and probably better than it has been since this engine has been in it. I still have not been able to hit it WOT from a stop with a load on it as the 30-40% hit I made hazed the tires on the still damp road.

 

[L31MaxExpress]

If you look at the narrowband 02 voltages, you can tell how lean the engine was becoming as the throttle was opened. After the transient settings were changed the narrowband 02 voltages now rise with throttle, indicating the presence of less oxygen in the exhaust stream from the mixture staying richer.

Lean Tip In

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What I will call a "Good" tip-in

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[L31MaxExpress]

In Park I stabbed it WOT a few times from idle and it rips up the rpm range quickly and smoothly.

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[PlayingWithTBI]

Is it that cold or is your IAT not working?

 

[L31MaxExpress]

Is it that cold or is your IAT not working?

My IATs are that cold. 38F outside.

 

[PlayingWithTBI]

My IATs are that cold. 38F outside.

BRRRR!

 

[L31MaxExpress]

BRRRR!

Yep, warmer than the other day. It got down to 19F here with a windchill that felt like 4F. In roughly 1 weeks time, it has been from that extreme to 75F, sunny and humid with a real feel of 82F back to 38F and feels like it is in the upper 20s with windchill right now. Probably explains why my allergies are trying to murder me and I have a sinus headache.