aidandj

iTrader: (5)

It could also be weisco 9:1s. Is there a way to visually differentiate between weisco 9:1 and 8.6:1

18psi

iTrader: (76)

if you're capping boost to wg on track then I don't see any reason to run such low timing at full boost, but it's no big deal you can start there and work your way up.
Burning valves is a real thing.

aidandj

iTrader: (5)

Eventually we want 300hp on the track. Right now wastegate is fine. Wish I had an EGT sensor.

Don't worry. Those high boost cells will get dyno tuned.

aidandj

iTrader: (5)

Dyno date has been confirmed. Det cans have been built. Shooting for 350hp or 20psi whichever comes first I think.

You mention burning valves. Without an EGT sensor is there any way to tell if we are running too much retard. The sweet spot is going to be something that runs fine on california gas, but isn't too retarded.

Was planning on doing a pull. Adding 2 degrees and seeing how it reacted. If we gain power try again. Repeat until power does not rise. Retard 2-3 degrees from there for safety?

codrus

IMHO, if you're going to run track days in California, run the tank 50/50 with 100 octane. It's an extra $2.50/gallon to do that, even you burn a tank and a half that's only $45. Way cheaper than detonating or burning a valve.

IMHO, 12 degrees is way too little. I was seeing EGTs over 1600F (maxed out my gauge) when running 15-ish at the track.

As far as dyno tuning, you've got the basic idea, but you will also need to find the shape of the curve. So do a pull, add 2 degrees, do another pull. Continue to add timing in any cell where it's adding power, leave it alone in the cells where it is not. At some point drop it down to 1 degree at a time instead of 2. I go for backing it off 1-2 degrees, rather than 2-3. You probably want to start at the lowest row you can reliably control boost at and mirror all of your changes into all of the cells above it. That is, if you're doing the 130 row and you add +2 degrees to everything 2500 RPM and higher, add +2 to the 170, 205, etc rows as well. The shape of the MBT curve is pretty similar between rows, and this will save time vs trying to tune the shape for each one.

I doubt you'll get to MBT on CA 91 octane, even at 8 psi.

One thing to be careful of is that you either need to pay close attention to the MAP between runs or have rock solid closed loop EBC. As you add or remove timing you change the amount of energy delivered to the turbine changes both because the engine is making more power (thus getting to higher revs sooner) but also because it's extracting more energy from expanding the gas, thus leaving less to expand across the turbine. If you're just looking at raw torque then this change in MAP can mask the actual effects of the timing. Ideally you want to look at the effects of timing on torque/MAP, but I don't know of any dyno software that plots this.

You may want to consider rebinning it so that one of your rows matches the mechanical wastegate to make this simpler. Forget about easy conversion to psi -- you don't care about psi. Train yourself to think in kpa.

--Ian

codrus

Other suggestions on making dyno tuning work better: save a pre-dyno and a post-dyno tune (duh), but also save intermediate tunes along the way named in a way you can figure out which is which. That way if you get lost in what you're doing you can throw out the working map, go back to the one from 2-3 runs ago and resync without losing all your work.

Log every run into a separate file, named by the run number, and keep the run numbers in sync with the dyno operator's run numbers, so that you can match them up later. Keep notes on what you do for each run, identify it by number (and maybe timestamp), write down a sentence as to what your goal is for this run, do it, analyze the results, then write down the results of your analysis and any changes you made as a result of it. Then start a new section for the next run.

For example, my last dyno session notes start like this:

Synergy dyno 10/22/15

run 1 -- baseline at 190 kpa to. dynojet # is 35
run 36 -- backup run at 190, a bit lean
run 37 -- turn on closed loop still at 190
run 38 -- closed loop didn't work -- turn on autotune and run at 190
*1.05 fuel for 165/660 and up/right
run 39 -- re-run, added fuel is good
run 40 - verify MBT, -2 degrees 165 and up
run 41 - was past MBT (lost 3 hp), -2 more degrees 165 and up
run 42 -- only down 1 more hp, -2 more 165 and up
run 43 - was down 5 hp, so add those 2 back and 165 and up. Reset for 215 kpa

etc.

--Ian

18psi

iTrader: (76)

Ian is completely on point. I usually end up with 27-50 maps after all is said and done and at least twice as many datalogs

aidandj

iTrader: (5)

I like it. No closed loop so I will be watching how MAP changes. Jason has a paper on why dynos should plot map vs torque, but nobody has done it.

Good point on the notes. It will help keep track of everything.

aidandj

iTrader: (5)

So is there a point where you are limited by det and burning exhaust valves? Where you are retarded enough to burn valves but advancing any creates det? Hopefully that's a Cali only gas.

patsmx5

iTrader: (16)

That's reaching the limit of the fuel octane, and why fast cars typically run higher octane. As you are suggesting, you will reach a point with CA91 where you're backed in a corner with no way to make more power safely. At that point you are octane limited.

18psi

iTrader: (76)

I guess if you were pushing a ton of boost and a ton of fuel through there, then trying to compensate with timing for the other two being way off. Just a guess though, cause I haven't really pushed miata's on 91 to try that.
I know that when I do this with evo's and subaru's there's basically a det cap, and if you keep upping boost and throwing fuel at it, the car is basically blowing fire out the tailpipe but still not making any more power, and obviously knocking, and obviously running insane EGT's.

Maybe Ian has tested this on a BP on pump gas and can chime in tho

aidandj

iTrader: (5)

So the goal should be get close to MBT on Oregon pump. And run 100 half and half.

Id like to keep the low boost usable on ca91. This is hard to tune for a fuel you can't get.

Because the wastegate tune is a track tune we will be going with conservative timing anyways.

patsmx5

iTrader: (16)

Yeap. I used to run 28 PSI on 93 octane with 9:1 compression, and doing that required very safe timing values to keep the detonation away. I bet the EGTs were crazy.... Glad I'm not doing that anymore, E85 is amazing.

codrus

I tested this on a BP on 100 octane gas and on my motor it's around 22 psi and 370 rwhp. :-)

It's going to vary pretty widely with the motor build, turbo type, exhaust back pressure, etc. My old motor never pinged, even at 18 psi on a 2560, my new motor pings at 12 on the 2863, even though the nominal compression ratio is the same.

I've actually never run my car on CA 91 at more than 7 psi. Even when I was running 12-15 on a 2560 I was using 2 parts 91 to 1 part 100 to make 94 which was enough to get to the flow limits on the 2560.

I burned some exhaust valves on my stock motor way back when. In retrospect, I think that may be due to using the Link Piggyback and some very conservative timing. I didn't have an EGT gauge at that point, so I'm not sure how hot it was.

IMHO, your goal should be to tune to 1-2 degrees off the lower of the detonation limit or MBT on Oregon 91, then when you take it to the track throw in 4-5 gallons of 100 octane as insurance.

When you say "usable on CA 91", do you mean street usable or track usable? Street usable is a lot less stringent requirement, because you aren't going to drive it as hard (or as hot) and you won't be wearing a helmet or going as fast, so it's a lot easier to hear detonation and back off if necessary.

--Ian

aidandj

iTrader: (5)

Street use for CA91. I'll make sure Ed doesn't go full boost on the **** water. Now that he has a trailer he might actually be fine.

I think I'm gonna make him get an egt gauge. We I'll tune this weekend and then double check EGTs with the gauge.

codrus

If I were doing it over, I probably wouldn't bother with a gauge. Thermocouple, driver chip, read it with the megasquirt, log it, and set up an idiot light if it's too high (CEL or something).

--Ian

aidandj

iTrader: (5)

That's what I will have on my car.. I was going to just find a basic cheap thermocouple gauge not a specific one for cars. Then grab an eBay thermocouple and go for it. I might even have a fluke that does thermocouples.

x_25

You can get 200mV DRO meters cheap. I was going to use one of those and an ebay thermo couple and just use a rough look up table (>xmv is bad kinda thing).

codrus

FWIW, a lot of generic thermocouple gauges don't go high enough.

--Ian

aidandj

iTrader: (5)

Cool. Will keep in mind