Marine Intake

[L31MaxExpress]

Welp spoke too soon on the transient tuning. Started it up and the injectors suddenly jumped to 400% duty cycle after 30 seconds of running or so. Got it to refire using clear flood mode, then it was instantly back to 400% duty cycle. I reflashed the previous calibration and it fired right up and did not repeat.

I honestly do not understand what would have caused that to happen especially at idle with no throttle movement. Maybe the flash became partially corrupted from low battery voltage from the short runs and multiple reflashes. Will try messing around with it tomorrow. Threw the battery charger on it earlier and will probably throw the same file back in it and try it again.

 

[HotWheelsBurban]

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.

Texas weather, gotta love it! We've not had the freezing temperatures down on my end of I-45, but it's been doing the cold, windy, almost sleet raining thing for a few days, then gradual warmup to the 70s, then cold again, wash rinse repeat....

 

[Supercharged111]

When I did too big of global bumps on the impact factor table my truck also went pig rich, but it didn't run just fine before that.

 

[L31MaxExpress]

Remembering I have alot more overlap now, I pulled up a Gen III EOIT spread sheet I downloaded a while back this morning. Adjusted my EOIT to about 10* before BDC on the intake stroke then plugged in various pulsewidths. It moved all the warmup and normal part throttle fueling up to ~4,000 rpm after the exhaust valve closes. WOT fuel under 3,000 is also all in after EVC. Above 3,000 the pulsewidth and rpm are just too high to allow for the necessary fuel to find its way in between EVC and IVC making the SOIT earlier than EVC. Boundary is set at 7.4 and Normal at 7.2 (up to temp) makes EOIT point at 530* of crank rotation relative to TDC on the compression/power stroke. BDC on the intake stroke is 540* by the same scale. IVC is 605.5*. Fired it up with the coolant temp reading 37F. It is much happier and very little unburnt fuel smell from the exhaust even before the cats lit off. Now to address a couple small exhaust leaks and really get it dialed in. I can tell it has too much transient fuel now.

 

[L31MaxExpress]

When I did too big of global bumps on the impact factor table my truck also went pig rich, but it didn't run just fine before that.

Just a thought, have you used the GenIII EOIT spread sheet to make sure you are not injecting fuel past an open exhaust valve? I just taught myself how to use a better spreadsheet that I found on HPTuners forum a while back. Seems to have really made a difference in my setup. For s's and grins I plugged in a L31 with both the stock cam and the 395 cam and all the EOIT is in the purple rather than the green with the stock L31 settings, meaning fuel is getting injected past an open exhaust valve all the time. Its not as critical on the stock cam as it has less overlap, but on a marine cam a lot of the fuel is getting sucked or blown right out of the tailpipe, especially with your blower. I plugged the settings I was using before with the old L31 and 395 cam and I was still getting some of the fuel injected while the exhaust valve was open despite having made changes that seemed to work ok. Using the spreadsheet helps walk a fine line between injecting after the exhaust valve is closed or mostly closed and heating the fuel as much as possible on the way in.

 

[Supercharged111]

I have not, and I gave it a Google and I'm not sure if I have that? I have injection timing available, but I've never monkeyed with it. Ever since the cam startup has not been the same, though getting VE and MAF dialed in better made a difference there. If you have a link to that spreadsheet I'd love to give it a shot. I suspect I'll deal with that on my Z06 as it's getting a bit more cam than my truck has once I round up a few more parts for it.

 

[L31MaxExpress]

I have not, and I gave it a Google and I'm not sure if I have that? I have injection timing available, but I've never monkeyed with it. Ever since the cam startup has not been the same, though getting VE and MAF dialed in better made a difference there. If you have a link to that spreadsheet I'd love to give it a shot. I suspect I'll deal with that on my Z06 as it's getting a bit more cam than my truck has once I round up a few more parts for it.

PM me your email and I will send it to you. I forget what post I found it on in the HP Tuners forum.

 

[yevgenievich]

PM me your email and I will send it to you. I forget what post I found it on in the HP Tuners forum.

Sorry, but sent you a pm as well. Using p59 ecu on my tahoe and was trying to see about cleaning up idle a bit

 

[L31MaxExpress]

I was able to make a good WOT pull to 5,300 rpm this evening. Rather unimpressive actually. I have the same MAF transfer that I was running with the ported truck intake, meaning the MAF is reading the same way. I compared a data log I took back on October 15th with the one this evening. It was 98 KPA barometric pressure and the IATs started out at 95*F then. When I ran it earlier it was 97 KPA barometric pressure and the IAT started at 52*F. Granted this is not exactly scientific, but it is what the PCM is using to calculate fuel delivery and delivered torque and it is realistically fairly consistent run to run. I have not taken it above 5,300 yet with the marine intake to get the numbers at a higher rpm. I wanted the marine intake on this engine because I had it. That and I was tired of stubbing my toes on it at the shop. At first glance it appears that a ported truck intake is not that far off the number of a ported marine intake despite having the spider in the center of the plenum. That being said 1 gm/sec is about 1.2 hp or 1 rwhp, which means I should be up a solid 10 hp if the gain in airflow equates to power. Also keep in mind that I pulled Rhoads V-Max lifters out of this and put standard GM LS7 lifters at 1.5 turns preload into this too. The lifter change may have had some effect in the 3,000-4,000 rpm range.

RPM-----Airflow Change (GMS/SEC)
3,000---(+8)
3,250---(+12)
3,500---(-8)
3,750---(+10)
4,000---(-0.5)
4,250---(+9)
4,500---(-1)
4,750---(+2)
5,000---(-7)
5,250---(+12)

 

[Supercharged111]

Man, if my truck is making 320whp up here it's making more juice than I thought. Probably a little lower than that as I have 33s, but still. I would have figured 400 at the crank at sea level tops. I always find it odd the way airflow can sometimes fluctuate throughout the range. Why the hesitation to take it past 5300? Seems if there is a definitive gain yet to be found, that's where it'll be. Kinda like the LS6 heads and intake. At stock and lower (my race class) power levels there really isn't much of any difference, but get a motor that happily pulls past 6000 and suddenly a cam does so much more with the LS6 stuff than the LS1 stuff.