Turbo 5.3 help!

[Gono]

About the build. SBE 5.3, TSP turbo cam, DBW truck intake, 80lb deka injectors, air to air intercooler, On3 7875 turbo, AEM wideband and boost controller, precision turbo wastegate, dual valve springs, built 4L80e (Jake's perf).

So its been an interesting journey into the turbo world. attached is the latest tune and log. the problem I'm having is truck bogging down after about 3-4 psi boost. If I roll into it, it'll go to about 6 psi and then it flattens out. forget about just flooring the peddle for some sweet burnouts because instant bog down. I've tried to keep timing as simple as possible since I blew the previous engine up to knock. I also adjusted the boost enrichment to ramp in from 14.68 to 11.75 at 200 kPa. I new to this and have thick skin so you can't hurt my feelings. I would appreciate honest and brutal feedback. Cheers, thx.

[5FDP]

Can't check the tune at this moment but fueling should not still be at stoich when you are in boost. Starting at 100kpa you need to be commanding at least into the 12's and then richer to the final commanded AFR of 11.75 like you typed out. Ideally you should be at that value past 5-7psi and even that might be too lean depending on how much boost you run.

So your Power enrichment settings should have you down into the 12's then the boost enrichment needs to carry over to the 100kpa cell and then get richer as boost rises.

Have PE enable to 90 kpa and boost enrichment kpa be 105kpa.

Also remove the 1 bar MAP channel from your logs, it's causing the charts to read the wrong map kpa because you are logging 2 different MAP channels.

[Gono]

As far as I can tell, I'm getting into boost at around 40% throttle. Since I was getting into boost at a what thought was early, I was based my ratio by BE only. Looking at my tune, PE was coming in at 55kPa and commanding 13.0. Can I assume that PE was coming in too early and I was too rich before getting into boost? So I changed PE to command 12.5 at all rpms and boost starts at 12.5 and continues up to 11.8 @ 200kPa. I removed the extra MAP channel.

[Gono]

Did you get a chance to look at the tune?

[5FDP]

If you changed the PE/BE stuff it will be better but you didn't post an updated tune file.

Your timing curves are really bad, please go back to stock on those. You need to be watching your cylinder airmass in the logs to see where you need to adjust timing and not just throw 30 degrees of timing at it everywhere. This is not a small block engine with a carb. Timing should level off once you reach boost and that could happen even well before go over .80 cylinder airmass.

Pick a number, a safe number and stick with that as you dial in the fueling. Something around 12-15 degrees of timing on low to medium boost. You can tweak it how you want later on.

[Gono]

So I went back to the stock timing table for the high/low. I get into boost around .76 g/cyl. At this point I interpolated the timing going down to 12 degrees at 1.2 g/cyl. Will this work? or at the point of getting into boost should I g0 straight to 12-15 degrees? I haven't driven it yet, I can and I'll watch for any KR.

[5FDP]

That should be fine on the timing. Leave it there until you are done calibrating all the fueling, then you can add timing if you want.

You just don't want the 25-30 degrees of timing everywhere like the previous tune had.

[cobaltssoverbooster]

Gono,
general rule of thumb is to pull about .75* of ignition per lb of boost.
typically a natural aspirated LS is all in at about 19-22* on pump gas. some get more but this is a decent average.

using this rule:
@ 5 psi = 18.2*
@10 psi = 14.5*
@15 psi = 11.0* typically we try to keep from running bellow 11* ignition advance. If you have on point fueling and your boost wont let you run 11* advance then you should consider backing down a tad to allow the engine to operate in more favorable load conditions.

record boost pressure against your ignition map and that will tell you where to populate these values. from here you can interpolate data and then smooth the range to come up with a great starting point.
focus on keeping ignition and fuel maps smooth to get good results.


5F has you on the right track. Keep pushing forward.

[Gono]

So, going back through my logs, I noticed that at about 5 lbs boost, my airmass is at 1.2+. I'm running a P01 computer and airmass maxes out at 1.2. Is there a way to increase the resolution in the map? Or past 1.2 the graph is maxed out and that's the value I'm stuck with?

[5FDP]

That's all you get.

Consider this though, if the fueling is not completely dialed in the cylinder airmass will read high if it's overly rich.

You would have to scale the the tune to gain back any resolution. Or just live with it like most guys do.

If it still shreds tires at your last value and makes stupid power do you really need to control the timing number over 1.2 so long as the tune is safe? That's how I look at it.

[Gono]

Here's the first drive with stock timing tables up to boost and interpolated to 12* at 1.2 g/cyl. It just doesn't want to push higher that 3200ish rpm. The more gas i give it, the more it feels like it boggs. I've pushed through what I thought were boggy points before and I knocked holes in my block so I'm trying to go as slowly as possible. Looking at the log, nothing seems to jump out at me, luckily no KR! Maybe some video would help describe my issues. Any thoughts?

[5FDP]

I'd richen the fuel up on your BE, make it go down into the 11's quicker, because you are still asking for 12's AFR at over 7-9 psi of boost. Like at 135kpa start asking for 1.25. Fueling is off on the commanded too, sometimes rising into the 13's in boost.

Max out your maximum torque vs rpm table, that could be holding you back.

What spark plugs are you running and what's the gap?

Log your injector data in the logs too. Only look at this real quick, also it's kinda hard to feel what it's like without driving it.

[Gono]

I maxed out the torque vs rpm table and made the fueling adjustments. I running TR6 gapped @ .028". Is that too closed?

[cobaltssoverbooster]

No Gap is fine.

[Gono]

Just went back through the original post and noticed that I didn't mention that it's a 5.3 with 6.0 heads. I think that would lower the compression to about 8.5 to 1. I'm assuming that would allow me to run more timing? And possibly explain lower power?

[5FDP]

Timing isn't the issue you are having. It should pull like a freight train all the way through the RPM range at 7-10psi of boost and 12-14 degrees of timing.

[Gono]

That's what I've hoped for since i started the "Boost" campaign. So as far as the hot side is concerned, I teed the blow off exhaust into the exit of the turbo. Is there a downside to this? Maybe an increase in back pressure? The only reason I did it was to eliminate an extra run of piping. Looking back, I thought it wouldn't make a difference since it was running into the exhaust of the turbo. Now having problems, I can see that it might restrict the flow of exhaust out of the turbo?

[Gono]

Here's the latest failed attempt. Seems to accelerate a little better than before, but still won't go much over 3300+ rpm. I read a post of someone having a problem reaching higher RPM and it ended up being a crank sensor. I'll check that this afternoon. What would shimming the crank sensor do? It seems like it either would work or it wouldn't. What does higher RPM do to the crank sensor that a lower RPM doesn't? Simple questions, but I'm still new to this. thx.

[cobaltssoverbooster]

if you can maintain a desired boost level without creep then it is fine.
in the ls world a single waste gate is typically 50-60mm.

if you have no boost creep then your fuel and/or traction control settings are causing undesired effects.

[5FDP]

I'm not really seeing anything else on the engine side that is stopping it. Can you hold it in 1st or 2nd gear and make power over 3,000rpm??