6Speeder

We tuned my 2015 Z06 and ran into a problem. Previously with a Halltech CAI, Mamo TB, Innovators West 9% lower pulley, and Norcal cat delete pipes on factory tune it ran well, but way rich it made 673 SAE RWHP and 720 SAE RWTQ. That's on a dynojet dyno. I then added a fuel sensor for flex fuel.
Before someone else says it. I know, I know, I broke all my own rules on this one.
1. I used a different dyno. (no choice here, it's the tuner's dyno). It's not even the same TYPE dyno, it's a dynocom dyno, and extremely "frugal" on it's HP values. It reads AT LEAST 3% lower than a dyno jet.
2. On ALL the runs (musta' been 20+ runs) I was spinning the tires on the dyno.
3. I didn't get a "before" run to compare to.
4. The conditions aren't the same as my other dyno runs so I really can't compare. It was 26 freeking degrees!!!

However, I believe the dyno results were acceptable for tuning, not comparison to earlier runs. 91 octane is the best E10 available here, tuned it, got some gains. How much? Don't know, we tuned, checked results, tuned some more, were satisfied that there were on more gains to be had. We then added 15 gallons of winter E 85 (really E 72 on my gauge) and tuned for it. Got more gains, BUT got a problem. At 6600 RPM it pulled 6 degrees of timing, causing a drop in power. Yes, we reset the redline to 6,800 RPM. We went through all the tables in HPtuners and can't see why. There is no KR there, it appears to be torque management, but why, and what do we do about it?

My final numbers were 684 SAE RWHP and 736 SAE RWTQ. I believe, on the dyno I always use, it'll be AT LEAST 705 SAE RWHP and 758 SAE RWTQ on a proven Dynojet. The issue that we need help with is the timing being pulled at 6,600 RPM.
Any ideas?

Higgs Boson

in short, the torque model needs to be adjusted properly.

second, if all your mods are listed, you don't have enough fuel capacity to run E85 and your injector pulse width is probably way too high, the ECM is backing up spark lead to allow a longer injection window without spraying through spark. ask your tuner what your IPW is on the pull(s).

get port injection (or god forbid meth injection as a band aid) and find the real potential for your combo.

6Speeder

If I was at sea level, you'd probably be correct. I'm at 6,000 feet and have about 17 to 20% more range. My IPW isn't the problem.

I appreciate all inputs however.
Wayne

HNK

timmyZ06

I dont understand why lots of people have so many issues with spraying meth??!! Its cools down AIT's, it help keeps intakes valves clean, its cheap 40$ (VP M1)
Make a lil more power, and reliable when using a good kit like Alkycontrol. Even more only spraying in boost, so no need to figure out gas filling stop up front!
I do know that it wont be sprayed evenly on all cylinders though, this is why you dont want to tune aggresive on meth!

timmyZ06

OP, your issue lies in the torque management tables, mostly likely and also keep an eye on the IPW

Higgs Boson

what is your IPW?

also, there is an acceleration based rpm limiter that needs to be zero'd out.....is it?

Higgs Boson

my issue with meth is not with methanol in and of itself (which is not that much different from ethanol), it is with meth kits leaking, needing rebuilding, invisible fires, using windshield washer reservoir as a meth tank, the way they are installed, etc.

timmyZ06

I agree! But there is a good way to do it! Like a fuel system could be dangerous as well! Using NX lids for spraying, using standalone meth cell, for the pump rebuilt, well when using straight meth its inevitable!! 170$ on 2 years aint that bad though.

for the invisible fire, we just have to ask Ricky Bobby!!😂😂

Higgs Boson

lol

Mr. Gizmo

6Speeder

I'll get back to you on the IPW. I don't have HPtuners data right now. The tune accepted the redline change, so that limiter must have been turned off.

6Speeder

Factory red line was 6,600. It wasn't knocking or hot.

Higgs Boson

it's not a hard limiter. it will still rev to redline.

6Speeder

My max injector duty cycle at 6,000 feet, running E-74 fuel was 37%, no loss of fuel pressure ever. I don't think I'd have any problems even at sea level.

Higgs Boson

I am sorry, I don't need to know what injector duty cycle is, I was asking for injector pulse width.

Just so you know, since we are talking about injector duty cycle, 80% is considered maximum for port injection. Direct injection has about 1/3 of the time to complete injection vs port so what % would that give us?

80 * .3 = 24%, granted you can squeak out a bit more with adjustments to injection timing but 37% I would say you are indeed out of fuel at any altitude.

What is injector pulse width at WOT? Stock is about 4.9ms, you can get away with about 5.5 - 6ms before you start running into issues so if you are at 8, 9, 10+ ms then you are out of fuel. Again, IPW, not IDC.

6Speeder

Really?

Granted I'm just learning about direct injection but I've seen two other C7 Z's with wilder mods than mine, making more power than mine with no problems. The only one running out of fuel had an upper pulley, and an 18% lower. He could only run about E-50 before fuel pressure started to drop.

Consider, I'm at 6,000 feet and the summer DA is usually much higher. There's just not enough air here for me to be running out of fuel. With all my mods I'm only making about 20 rwhp more than a stock car at sea level. A Halltech CAI equipped but otherwise stock Z is making twice that much over stock, if I'm out of fuel they certainly would be. Tuners at lower altitudes than I are pushing much more power than I have without fueling changes. How is that so?

What is your source that direct injection must be done so much quicker? I am an engineer (EE) and can speak math. I know a fair amount about port injection and E-85 Vs. E-10.

Give me a reputable source so I can educate myself.

FYREANT

6Speeder

From what I've read, if you use the accepted norm of 310 degrees of fuel input, that's over 40% of time for pulse width, not one third, compared to port injection. At 6,500 that gives right at 8 milliseconds of acceptable IPW, and 6.3 is what I measured. I don't see the problem.

Higgs Boson

I'm just asking a question that took a really long time to get answered, don't get your panties in a bunch. Now that you have answered it, 6.3 ms, we can proceed....not a big deal at all. (btw, did you measure it based on logging IDC or did you log the pid for IPW?)

Yes, you should be fine there, but you are on the cusp of being limited. Keep in mind also that direct injection isn't only about total injection time. Exhaust valve comes into play, not just intake valve. Where the mixture is in the cylinder in relation to spark and piston location also matters now. It's less time than you think.

However. being only 20 hp up on a sea level car and at 6.3ms instead of 5 or less does raise other questions about the tune that I guess I won't ask since youre a little hard to talk to.....I mean, you asked the question....presumably asking in need of help? The ECM will retard spark and advance injection timing to keep you from spraying through it and start of injection timing and pulse width can tell us a lot about what is happening.