The changes noted will not be noticable if you are monitoring coolant temp but the water will definitely be a lot better for it due to its natural capabilities over 50/50. It never hurts to run water wetter in the actual engine as well. Especially since those early gen Z06's had known cooling system issues. I would personally do it.Originally Posted by kenand1988
I take it you like your power up high? Those centrifugal blowers like to be wound out to start making their power.
Last edited by ZLRob; 10-20-2022 at 08:35 PM.
low side drop2.hpllow side drop3.hpl
Here are a couple logs. First one is long theres one pull in there not to redline. Low side did better but its very spiky which is why i think replacing the check valve could be a good idea. Second log was much like before in the first log I shared. It feels very strong but the low side dips again and doesnt lose more psi it just goes to the normal psi which is a little weird. Also saw a spike in knock upon letting off.
I had a centrifugal a&a Lt1 c7 which was a lot fun itll be great to compare the power and curves. We will do a baseline dyno before putting on a different supercharger.
I see the lean spike you were referring to. It seems like Cyl. 8 is most unhappy when it occurred. Fuel pressure looked super stable for the majority of the "low side drop 3 log"... lower than what you would like to see, but stable. Let me look at your tune file again and make sure everything looks good, because for some reason the majority seem to bias that particular low pressure while you are running it, which is 57 psi. The good news here is that you are not running out of fuel up top on the high side at any point so you're good there.. but still, the low side is a little concerning.
What kind of fuel are you putting into this thing by the way?
the tune i put in it is the one you uploaded, no changes. I had just put in half a tank of 91 from a loves gas station I thought about putting in that 100 but wanted to see if there were any issues with 91 first. I'm in arizona Idk if i mentioned that so no 93 for me.
No I know, I was saying let me check the one I sent you and see if there is anything else I can do on the software side. There's part of your problem though. You are running octane too low for this vehicle. LT4's run aggressive timing and nearly ride the knock sensors in factory configuration. If you don't have access to 93 or higher (Don't feel bad. I'm in CA and don't have access to it either) you are going to have to start filling with 91/100 octane mix (5g 100, the rest 91 on a full tank) or switch over to flex fuel because knock on 91 is just a thing with these engines unfortunately.
Oh ok I see, yes it appears to be even more aggressive on the z06 than the zl1 when i looked at your spark in some areas. I'm not sure which i'll do both 100 octane and e50 are relatively the same distance from me about 30 minutes. I can fill 2 5 gallon gas cans with either and mix as desired. on the stock fuel system i think the 100 octane would just be better due to the weird pressure things we're seeing. how absolutely flat that fuel pressure went during log 3 is weird to me you know? no fluctuation at all? makes me think the sensor itself or fuel pump driver module could be to blame. One being super easy to access and the other being quite difficult to get to. I'm less inclined to think its the pump itself though.
Give this a shot and take a log. Let me know how it turns out. Feel free to do a change comparison log to see what I changed.
Attachment 125292
There was some fluctuation at first, but there was a moment in time where it was holding pressure rock solid no matter what. It may have to do with the changes I made to the LPFP itself. This newest revision ups the desired fuel pressures, max desired rail pressures and diag boost voltage required time so hopefully this helps your weird LP fuel issue.
Just a warning. DO NOT run flex fuel or full E85 on the Z unless you are fully tuned for it and have a flex fuel sensor setup to see how much E content you are at. For the moment I would only advise running 91/100 mix until/ unless you get fully tuned for flex fuel or full E85.
Just to give you an example of a pretty darn rock solid run, here is my most latest log running flex fuel E55 using a JMS boost a pump and upped LPFP pressures in HPT. You'll see the fuel pressure is super stable.
Attachment 125293
Lol yes I do appreciate your words of caution, not being sarcastic. You never know on these forums what level of knowledge the other person on the keyboard might have. The build will be in phases
Phase 1 stock fuel system ESS blower 10-12psi
Phase 2 cam, flex fuel, dsx aux e30 12+ psi
Phase 3 Port injection intake e30-e50 ~15psi
All of that is very subject to change depending on the needs of the increasing boost. Goal is to make 800-900 wheel. The blower can do it, im certain of that.
No worries! I wouldn't ever try to give someone advice on their car especially ones as sophisticated as these if I didn't own one or at least was familiar with the platform myself. I'm far from what I would consider an expert, but when it comes to these sort of changes, I am very familiar with them because I just had to do it to my own to get things stabilized for proper tuning, and drivability in high RPM ranges.
In the meantime give the revision I sent over to you a reflash on your PCM. See how the log fares out (and please share it with me) and if the changes are for the better, we'll call it good for the time being. If they do not look good, flash it back to the previous revision. At least we know you are doing well with the few parameters I modified in your first revision. This one, I changed to see if we can influence the LP pump to swing up higher in the PSI range. I'd really like to see at minimum around 65, preferably around 70-74 psi at full gun. No fuel pump can ever maintain one constant pressure so there will always be a small pressure swing as it provides fuel output, but the idea in this revision is to bring the pressure into a higher range and keep that swing relatively consistent, so you don't have to mess with the fuel system mechanically at all now and so it can handle many mods in the future.
As an FYI, as far as I am aware, the Corvettes have a much more stout fueling system than the ZL1 for whatever reason and from what I have read they can handle full E85 conversions without the need to mix 91 or whatever octane you have available in premium into them. That being said, I am by no means a subject matter expert on the LT4 Corvette's and I strongly recommend you make sure what I am saying is accurate before you try and just dump full E into the tank willy nilly. Lol. Just so you and anyone reading this is aware, the majority of E benefits (at least on these platforms) runs out after E50- E60 and the power gains on anything past are pretty meager after that.
Last edited by ZLRob; 10-21-2022 at 03:59 AM.
I will certainly do that, ill flash it and do a couple pulls tomorrow for validation. I did no tuning on my c7 lt1, i just sold a 2020 mustang gt that made 915wheel with the same ess blower, i worked with a couple people to develop that software and im now fairly comfortable with tuning gen 2 or gen 3 s550. There is a lot less complication with these GM vehicle tunes which is a breath of fresh air lol but I did not want to start making changes without seeing if I could get help from someone who had done it before.
On anything under a 2019 I do not think full e85 can be done safely. Most I see people do normally is e50. Idk if you knew but a 2019 z06 has a low side pump from a zr1 which is why they don't have any issues going full e. Safe is a relative term in tuning though. Just look at the stock gm tune and how much knock there is and they deemed that ok. You can clearly flow enough to the high side at below 60psi although I've seen people say at minimum it needs to be 72. I ran e50 in the mustang. I saw no real gain on e85 it just taxed the whole fuel system even more.
The only reason you can flow enough right now to the high side is because of your current octane rating and the amount of timing you are running. Once you start raising the octane value, timing can be added, and then as a subsequent result of adding more timing you need more fuel to match that extra power and that's where fuel pressure required needs to go up or else the high side starts running out, once that starts running out your injector pulse width goes up too high, a lot of lean activity then ultimately boom if you ride it like that for too long.
It's not that GM allows all that knock to occur or they deem it "ok." There is nothing a manufacturer can do about excessive knock other than trip a CEL and pull timing when it starts occurring, and even then the only time a CEL gets tripped is if there is a legitimate malfunction in the circuit or sensor. Some engines are naturally noisy, the LT4's are not unless they have bad fuel in them. To that end, I think GM could have probably done a better job emphasizing just how crucial it is that you run TOP OF THE LINE fuel in them, because if they did I don't think a lot of people wouldn't be having tuning questions or issues down the road like you or myself have had.
Last edited by ZLRob; 10-21-2022 at 10:06 AM.
Note sure what youre saying by this. The manufacturer is really the only one that has the ability to make it so there is no knock and destruction on pump gas either through the mechanics of the engine or the software calibration of both. My point is GM software allows excessive knock and it would have been easily apparent to any engineer. The west has always had 91 so manufacturers are compelled to develop software and engines that can perform well on 91 or 93. Gm could have neutered the tune and made it safer and they chose not to.
This is not an engine that they wanted to neuter is my point. These are specialty vehicles not tailored for your average Joe who is happy driving a Camry with a low compression ratio engine. They wanted maximum performance out of it while still meeting EPA regulations and they deemed that the minimum amount of octane needed to achieve max power without knocking was 93, but even with 93 the sensors are still on the ragged edge of knocking. They designed these cars for the track and with saying that track folks understand that there is a special way of going about things to get the most out of your car (eg tuning, race fuel, special tires etc.) GM knew this, so they intentionally chose not to detune it, as they figured if they did they would be committing a disservice to the end consumer. Z06 and ZL1.
Getting back to the business, did you get a chance to run your revision yet?
Last edited by ZLRob; 10-21-2022 at 08:08 PM.
Im having issue with the fuel pressure sensor which makes sense. It comes and goes. When it goes out it defaults to 57.9 for some reason. If you look back at my log3 pull youll see it did that. Idk if im polling too many pids or the sensor is not reporting correctly. I will do a pull once I can get it to function right. i'll try only reading the very minimum pids first.
Hmm... That would make sense and wouldn't be outside of the scope of abnormal, as I have seen some pressure sensors go on Chevys before. I don't think you are graphing too many items, as I poll many items like you do and have never had an issue with an excessive amount of PIDs. If you have relatively easy access to the pressure sensor, it wouldn't hurt to bust out some test equipment and give some good old fashion testing.
The low side sensor is on the fuel pump which is in the tank. A complete nightmare to get to. The torque tube has to be removed and possible the whole rear cradle. Not worth chasing imo. High side pressure works I may be able to fit my own sensor somewhere in the system before the high side.
Can you do a pull and log your fuel pressure sensor voltage so we can see if mine is about right.
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