Timing for 150 wet

[minytrker]

I was told to pull 2 degs per 100 shot. Now my z06 I have tuned right now with 26-28 degs timing at wot and a a/f of 12.8. Now thats a few more degs of timing from stock. Do I start pulling timing back from there or do I need to go back to stock timing tables and pull timing. Can I just start pulling timing from about 75%-WOT? And last for a 150 wet what should I set my a/f at?

What else do you need to do for nitrous? I have several f-bodys to tune all with 200-300 wet/dry shots.

[redhardsupra]

nitrous just makes the air in cylinder denser and colder, so what you want to do is figure out your NA area and your 'spray' area on the timing chart, as they're based against cylinder airmass. so let's say NA your car gets best power at 28* and goes mostly hovers around .80g/cyl, so you have 28* in the respective cells. anything past .80g/cyl it's gonna be spray area, as your car is not capable of getting there by itself. so then you have to figure out how much spray puts you how far down the cylinder airmass axis. 50 shot at 2600rpm is gonna make as much extra cylinder pressure as 100 shot at 5200rpm, so you gotta watch out not only how much but where in the rev range you're at. so once you find the ranges of different spray values, adjust them appoprietly depending on cylinder pressures and rpm.

[minytrker]

Thank you very much that helps alot. What a/f do I need to shoot for?

[redhardsupra]

the more effective compression you get (some call it torque, some call it DynCylAir.. ;) ) the less timing and the richer you wanna run it. the logic is the same as car with boost--more compression needs less timing and richer mix.

[Dirk Diggler]

11.5-11.75 is what i would shoot(to be safe) for and back in the SBC days guys would pull 2* for every 50 horse.

[redhardsupra]

Dirk, shouldn't the target AFR/timing be adjusted depening on amount of spray/rpm range applied, just like a boosted application?

[minytrker]

The cars I need to tune in the near future are running 3 stages of nitrous. I have to get my cars dialed in for one stage first though. I figured I would just start out small and keep working my way up to my 150 shot. I also have a progressive controller so that should help some since I can control how much its spraying.

[Beer99C5]

While I understand what redhardsupra is saying about dynair, but doesn't that only applies to dry shots? Dry is sprayed through the MAF and it is seen. What about a wet kit where the fuel/nitrous is dumped into the intake and is unmeasured (metered by the jets only?)?

[VYSSLS1]

the biggest shot ive used so far was a approx 380hp and was runnig 11.9 afr and 15 ign timing, no knock detected.

[Redline Motorsports]

While I understand what redhardsupra is saying about dynair, but doesn't that only applies to dry shots? Dry is sprayed through the MAF and it is seen. What about a wet kit where the fuel/nitrous is dumped into the intake and is unmeasured (metered by the jets only?)?

How about this theory; if the spray is introduced, post MAF, the motor is still going to draw more air into the motor as power output increases....no? If more air is drawn into the engine, shouldn't the MAF report this increase?

Secondly, the motors AFR is independent from the nitrous kit. I would dial in the AFR NA and then dial in the AFR on spray through jetting changes. Most nitrous/fuel jet combinations are very rich as it is so the nitrous side can be increased to lean up the AFR when activated. This should be done vs. reducing the fuel jet as its the fuel that is providing the additional power.

As far as timing is concerned, same thing as a NA motor. Tune timing to peak cylinder pressure. Which in a NOS application, happens very early in the rpm band. Best thing is to dial in lower then anticipated timing and add a couple degrees until you hit KR.

Howard

[Ira]

How about this theory; if the spray is introduced, post MAF, the motor is still going to draw more air into the motor as power output increases....no? If more air is drawn into the engine, shouldn't the MAF report this increase?

Howard

If the Nitrous is introduced post MAF you'll most likely find the MAF reading decreases by the amout of N2O introduced. The power comes from the N2O displacing the air and introduced post MAF it also requires you put in the matching amout of fuel.

I thought that the N2O tunes allowed an external input to tell the ECM that the nitrous was activated. Maybe we could convince Ross to use an analog input and allow the selection of 5 spark tables like he's doing for the diesels so that the spark tables can be properly calibrated for progressive shots.

Ira