Any advice for AFR and timing on a forged 392 running a 2.9 Whipple at 12-14 psi? I'm fairly new to the Dodge tuning world and had one dropped off yesterday to tune. Seems like knock sensors need dialed back quite a bit so I want to be careful and try to get a little advice from those more experienced with these cars.
Thanks
I am already at 1.75 times the stock knock sensor voltage values and still getting tip in knock and peak torque knock with almost no boost (3-4psi) on my twin turbo, forged 392 setup (9.5:1 compression). I am running about 100-102 octane and logging my knock sensor voltages. I get some spikes sometimes over 4 volts on the knock sensors which to me seems like legit knock. I truly hope not as I am barely pushing this setup so far.
At tip in timing is around 8-9* and I am targeting 11:1 AFR, all very conservative. Once I have everything dialed in I hope to be closer to 11.5 AFR and maybe a degree or two more timing. I get to about 13-14* of timing near redline now and knock has all but gone to zero by then.
on my 9:1 compression 426ci whipple setup, on 93 octane and 15-16psi of boost I was able to run around 16-17* of total timing (near 7k rpm redline) and had knock sensor values about 2x stock. Plugs showed no signs of any detonation.
Once I dialed it up with some meth and eventually some MS109 I got well over 20 degrees timing and AFRs around 11.7-11.8, which is where I found peak power.
I'm 11.0 or so and single digit timing right now at 10 psi. Haven't swapped pulleys yet. Still stock knock sensor settings. I noticed a hesitation during light acceleration when I first drove the car and looked and it pulled so much timing as soon as the blower started spinning. I'm not going to allow it to pull that much timing from now on. I'm going to stay with this conservative timing and AFR in the table and slowly start dialing back knock sensors I guess.
best bet is to tune the knock sensors with a fuel you are confident in wouldn't produce any knock given your AFR and timing. 10psi on a 392 with single digit timing should have zero knock with 100 octane. So I would log rpm voltage by RPM, get a good average of 3-4 WOT pulls and take the average voltage as your starting point.
I don't have easy access to high octane fuel other than E85 and this car doesn't have the fuel system for it so I guess all I can do is watch for voltage spikes to make sure it doesn't seem real and check plugs.
I use VP Octanium, order it off amazon or summit.
Seem to work pretty good? I've thought about getting something like that for testing but always been a little skeptical
Works great, it is legit stuff. Best part is it doesn't alter stoich, just straight octane increase.
Will traction control spark retard be sent over the knock retard PID on these cars? Was driving it on street earlier and it was wet and didn't think about that. Just did a 4th gear pull with no knock retard and stock knock sensor calibration on the same tune.
No, I do not believe so.
Think a stock pump with voltage booster and 60 lbs injectors is enough for this? Seems like I'm really compensating for something but I can't seem to see a way to log fuel pressure on this car. I guess Dodge doesn't have a fuel pressure sensor?
No onboard fuel pressure sensor, need to hook in your own. I think you will be borderline ok with that setup depending on the actual voltage being applied to the pump. What year and model is the car? The newest have pulswidth limiters which is dodge's way of monitoring fuel pressure, you maybe hitting the limit, result would be throttle body closing and no more PW being commanded.
2016. I never even looked at the injector things from the Whipple base tune I'm using because it cruises around very close. It is really close up until higher RPM WOT also. Wonder if this is why they commanded something stupid rich in PE up top. Maybe they didn't actually want AFR to be that but were compensating in that way.
Using stock SRT pump, that should be plenty of fuel.
If your numbers are looking screwy, you should try using the Open loop base/fuel mass mult/vacuum mult table.
Rescale it for boost (neg numbers are boost, pos numbers are vac) and it will do boost comps for you.
Example in attached file.
"Think a stock pump with voltage booster and 60 lbs injectors is enough for this? Seems like I'm really compensating for something but I can't seem to see a way to log fuel pressure on this car. I guess Dodge doesn't have a fuel pressure sensor?"
Last edited by Hemituna; 04-03-2018 at 04:31 PM.
Thanks. I'll check out the files when u get home. Got fuel close hacking PE and am running a good amount of timing with less than one degree of knock now with stock knock sensor calibration.
Ill switch to this method to get it to hit closer to commanded before swapping and to a smaller pulley
Depending on what ECU you are using, TM uses the knock sensors.
2016 ChargerOriginally Posted by Jay@HAP
Very good idea. I like it. Still debating on turning neural network off. I'm guessing this cam timing would be more appropriate for the car I'm tuning than what was in the Magnuson 392 car you posted a long time ago? Thanks again for all the help you give. You really go above and beyond sharing things like this in a Dodge tuning world where help is tough to come by.
Does a 2016 Scat Pack have widebands or is all that stuff just in the tune because of the Hellcat?
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