Quick question on boost #s and pulley combos C7Z

[kenand1988]

Right now I have a 2.3 upper and 9% lower on the stock blower, stock exhaust manifold minus cats, halltech stinger intake. MAT is good around 120 and drops during a pull. I also run e30. I have THE absolute tightest possible belt and the upper is a griptech. On the hit I may see around 14-14.5 psi and that quickly drops to 12.5-13.5 through the duration of the pull. I have monitored it both with the boost pid and by subtracting baro from manifold pressure. They are about the same usually. I changed the belt because of that dip right after the hit thinking I had belt slip. My question is what would be normal boost for this pulley combo and is that normal to see a spike in pressure initially. I'm guessing it is. Nothing should be restricting it in the tune.

[TriPinTaZ]

I went through something similar on a ZL1. Turned out to be the Bypass Valve was hooked up incorrectly. Make sure your throttle isn't closing either.

[kenand1988]

I went through something similar on a ZL1. Turned out to be the Bypass Valve was hooked up incorrectly. Make sure your throttle isn't closing either.

Can you elaborate a little more? the bypass valve has vacuum lines and a grey connector to the solenoid I believe. Are those what you are saying to check? The lever stop for the bypass has been adjusted so the bypass can be fully closed. I gather from your response though that my boost #s arent typical and should be higher?

[TriPinTaZ]

I was assuming you are stock heads and cam. Boost should increase as RPMs rise. I was only stating that I saw the same behavior on a ZL1 with the vacuum lines hooked up to the solenoid wrong. Just something to check. It could be belt slip too.

If you're heads cam with an unported bower, boost may fall over time to redline as the blower itself is now a restriction. But I can't see a scenario where you hit 14-15psi on the hit and then it immediately drops to 12psi. There is something wrong there.

[kenand1988]

Here is a copy of the tune, I dont think boost could be limited by it but it wouldn't hurt to have a second set of eyes look. I will look at the bypass again. Stock the blower made 9-10 psi max. So is a gain of 3-4 psi for a 9% lower and 2.3 upper about right?Z06 IW9 Halltech FF 2.3 Final.hpt

[TriPinTaZ]

I don't see anything in the tune that would limit boost. There are a couple of odd looking tables like spark, flex fuel and VTT. But that wouldn't limit boost.

[GHuggins]

The only things different from what I normally do are knock airmass, cylinder airmass, inlet temp airmass - all limits under supercharger tab. Then under SC/Turbo tab - boost max, knock airmass and pressure ratio gain.

Not to say any of those are your problem as there's not a log to reference - just some things I do differently.

May even be wot variable cam settings if it's a stock cam - if stock this is the one scenario where closer to 0 is better up top.

[kenand1988]

The only things different from what I normally do are knock airmass, cylinder airmass, inlet temp airmass - all limits under supercharger tab. Then under SC/Turbo tab - boost max, knock airmass and pressure ratio gain.

Not to say any of those are your problem as there's not a log to reference - just some things I do differently.

May even be wot variable cam settings if it's a stock cam - if stock this is the one scenario where closer to 0 is better up top.

Yes, its stock. I wasnt sure what cam timing would yield the best results. Here is a log. I am working on a fuel solution. I did not change anything under supercharger boost limits except max pressure. The cam is stock. new upper7.hpl9

[GHuggins]

Jason can comment on this as he tunes lt4's constantly, but just looking at the log I do see a couple of issues. First your exceeding your DD torque table, but it's not closing throttle - this is if I'm thinking of the correct labeling of the numbers too of course - found that interesting - you might need to go back to stock torque model. You are right at the max airmass settings, but honestly it looks like one of two things because of how glitchy it is - either your belt is slipping or cam timing changing is causing boost to flow right out (cylinder airmass and map bounce up and down) You might also want to allow for more boost - unless your right at sea level - in your timing map - looks like you just cut a chunk right where it's running instead of tapering it?

Didn't look it over in detail - just what I saw and Jason can definitely chime in more on it.

[kenand1988]

Jason can comment on this as he tunes lt4's constantly, but just looking at the log I do see a couple of issues. First your exceeding your DD torque table, but it's not closing throttle - this is if I'm thinking of the correct labeling of the numbers too of course - found that interesting - you might need to go back to stock torque model. You are right at the max airmass settings, but honestly it looks like one of two things because of how glitchy it is - either your belt is slipping or cam timing changing is causing boost to flow right out (cylinder airmass and map bounce up and down) You might also want to allow for more boost - unless your right at sea level - in your timing map - looks like you just cut a chunk right where it's running instead of tapering it?

Didn't look it over in detail - just what I saw and Jason can definitely chime in more on it.

Thanks for taking a look. For a stock cam what timing is ideal for wot? And would you change anything you mentioned before about the "knock airmass, cylinder airmass, inlet temp airmass - all limits under supercharger tab. Then under SC/Turbo tab - boost max, knock airmass and pressure ratio gain. "

[GHuggins]

You're right at them, so once you get the boost back right you'll possibly be exceeding them.

[kenand1988]

You're right at them, so once you get the boost back right you'll possibly be exceeding them.

The only thing I could see needing to changed under tq mgmt sc is the variable cam max airmass because that is at 1.6 and I'm somewhat close to that now even with lower boost. The air temp delta stuff looks like safety setting for high MATs and the knock airmass is already at 1.95g.

Under sc/tc boost control I can go ahead and up the max boost pressure but the rest I dont know what would need to be touched, for example I'm not sure what pressure ratio gain is.

Unless my tensioner is just not applying enough force I dont see how I could have belt slip. I would like to try some different cam timing but not sure which way to go. I've seen you mention closer to 0 being more optimal for stock cam but at the same time I've read advancing it is better too so unless I were to do a dozen 60-130 pulls and really abuse the motor I won't know for sure but I'm sure you guys know. If I could be pointed in the right direction I can do some testing but would really like to limit how much I beat on it.

[TriPinTaZ]

I looked at your log and I don't see belt slip or the spike to 14psi and a drop to 12psi. The boost levels look about right on an unported blower with stock throttle body and a standard aftermarket intake.



I also made some changes to your tune in the effort to show you, what I think is a better logic for tuning these cars.

Z06 IW9 Halltech FF 2.3 Final-SBTedit.hpt

[kenand1988]

I looked at your log and I don't see belt slip or the spike to 14psi and a drop to 12psi. The boost levels look about right on an unported blower with stock throttle body and a standard aftermarket intake.



I also made some changes to your tune in the effort to show you, what I think is a better logic for tuning these cars.

Z06 IW9 Halltech FF 2.3 Final-SBTedit.hpt

Wow you did a lot man, thanks. I will try and get a log of the boost spike thing I am talking about. I must have not saved the log I had it on. I follow nearly all your changes and understand their logic except for driver demand. I thought its best to set DD to close to what the engine tq pid is saying and then bump it up a little. Why set it it to under what the tq value is going to be?

[GHuggins]

The only thing I could see needing to changed under tq mgmt sc is the variable cam max airmass because that is at 1.6 and I'm somewhat close to that now even with lower boost. The air temp delta stuff looks like safety setting for high MATs and the knock airmass is already at 1.95g.

Under sc/tc boost control I can go ahead and up the max boost pressure but the rest I dont know what would need to be touched, for example I'm not sure what pressure ratio gain is.

Unless my tensioner is just not applying enough force I dont see how I could have belt slip. I would like to try some different cam timing but not sure which way to go. I've seen you mention closer to 0 being more optimal for stock cam but at the same time I've read advancing it is better too so unless I were to do a dozen 60-130 pulls and really abuse the motor I won't know for sure but I'm sure you guys know. If I could be pointed in the right direction I can do some testing but would really like to limit how much I beat on it.

Same things - higher numbers like the OE is more retarded - closer to 0 is more advanced. Better with boost on stock cams. AM cams entirely different story - usually better with retard.

I saw map and corresponding airmass bouncing in the log with boost spiking and dropping off pretty bad - also make sure your filter isn't collapsing or something like that.

[kenand1988]

Same things - higher numbers like the OE is more retarded - closer to 0 is more advanced. Better with boost on stock cams. AM cams entirely different story - usually better with retard.

I saw map and corresponding airmass bouncing in the log with boost spiking and dropping off pretty bad - also make sure your filter isn't collapsing or something like that.

OK that does help I thought moving higher in the positive direction was advancing it like ignition timing but it's the opposite. So there's more overlap with retarded timing. The filter is a halltech filter I don't think it could be collapsing. I don't see how the air intake could be a restriction. I was more leaning toward belt slip or bypass not functioning properly.

[GHuggins]

Overlap doesn't change - single cam design. What does change are the opening and closing points of the valves - open sooner or later. With it being more advanced - you would be opening it sooner and allowing more fill time. Not exactly sure why AM cams like it retarded with boost, but they do - anywhere from 4 to 7 degrees "usually" depending on the cam design. Guess since they're already such wide lobes they don't need the fill time, but instead need the exhaust time to compensate for the head designs...

[TriPinTaZ]

Wow you did a lot man, thanks. I will try and get a log of the boost spike thing I am talking about. I must have not saved the log I had it on. I follow nearly all your changes and understand their logic except for driver demand. I thought its best to set DD to close to what the engine tq pid is saying and then bump it up a little. Why set it it to under what the tq value is going to be?

The Driver Demand table isn't just related to Engine Torque, it's actually commanding how much Axle Torque you want. You have different gears that multiply the torque differently. So Driver Demand value's do not have to be higher than Virtual Torque. They certainly are not in the stock tune either. The Virtual Torque Tables are also only accurate with the OEM parts. Once you go pulley, intake, etc.....the Virtual Torque Tables are no longer accurate. But it doesn't matter, the real goal with the Virtual Torque tables is to get the throttle angle you command, the timing you command, and calculate the torque being sent to the TCM(auto cars) so that the car shifts properly.


Give the tune a try. Log it and make sure you are getting the spark and throttle angle commanded. The changes I made were directly from my personal Z06 so I'm pretty sure you will have no issues.

Also, do you have the PID's associated with boost set to fastest interval? I've found this causes some jagged edges in the data graph since it is sampling so fast. I suppose there are a couple of dips that could be belt slip. If you want to rule out belt slip, DSX makes a new idler kit that increases the belt wrap on the upper pulley. We've had good results with that kit.

[kenand1988]

I must admit your burble tune is much better than mine. I couldnt get it to pop every shift like yours does. I kept my hi and lo tables and flex stuff but i will try yours too. I can tell it picked up some down low and a little up top going off the log and airflow. I'm very happy with it. I will see how much the JMS bap improves the fuel situation but eventually plan on going to a dsx system. Here is a log if you were curiousnew upper9 slicks.hpl

[TriPinTaZ]

That's why I'm the resident burble tuner. lol There is a little more to it than just the minimum spark tables.

Log looks fine, you're definitely in need of the JMS. You can probably push to E40 with the JMS. If you're going to stick with the stock cam(fuel lobe) and stock LT4 hpfp and stock LT4 injectors, you will gain nothing by going to the DSX over the JMS. The JMS can flow more than the stock high side can handle. Also, I' recommend setting the JMS to no higher than 17.5 volts. I usually recommend about 17.35-17.45 range. Some FPCM's start to misbehave if you go higher than 17.5 volts.