Vell

Hello,

A friend of mine is working in a shop providing a shiny Dyno Dynamics ...
I'm allowed to use it to tune my FD by myself next week.

From the past two years I've read a lot of things, all the FAQ / Manuals / tricks and everything on this board and some others.
My question is "dumb", but I prefer ask before than saying "oh it was that" after :

What's the best manner to do it properly ? (assuming it's a drift car)

I mean, I know that I should start with AFRs, getting something smooth and conservative, looking carefully to the knock.
Then, go to the leading ignition map, with a trailing map setted up at 15° split under boost, near from 0° under vacuum, maybe negative split.
Leading should be from 30° in vacuum to 15° near the 1 bar / 15 psi, and I should not forget to change both maps before writing the data ^^

I'm not looking for the max power output, I just want the car to run SAFE, the last week end of the month will be a drift week end so hard on the engine.


Following arghx's advices (and others), I will run two "tricks"

1 - 0° leading (still 15° split) @ 8000 (all cells for this col)
2 - Sequential turbo control to get ~0.9 / 1 bar on the single

Here's my mods :

- Street ported engine, fresh, built by Carl Hayward in UK
- GReddy TD06sh25g on short runners, Greddy WG
- GReddy exhaust 3.75"
- 4x850cc with 50 psi base pressure (assuming 1000cc in the PFC)
- Stock fuel pump + Bosh 044 inline
- PFC & Datalogit, of course
- Waste gate solenoid in place
- No IDLE control, no emission control, blocked off everything
- No OMP (1:100 2 stroke oil in fuel)
- V-Mounted

Gauges :
- Fuel pressure
- EGT
- AEM Uego wideband (should be able to use the LM-1 from the shop)
- Boost
- Water temp
- Oil pressure (I have the oil temp too, but no t-piece so I may swap if the pressure on the stock dashbord corelate)


My fuel is the same as your 93.


And, yes, I've searched the forum a lot, I've found very interesting informations, but wanted to be sure "one last time" before doing something wrong

As I know I can count on your answers : thank you guys !

Jobro

iTrader: (2)

Be more conservative.

150:1 to 200:1 premix.
Fuel pressure between 36psi and 43psi.
No negative split.

24 degrees timing at 0psi
30degrees timing at full vacuum at lower revs, upto 36 degrees timing at full vacuum above 3000rpm.

5 to 8 degrees split at light load is a good idea.
12-15 degrees split on boost is OK.

Something down to 10 degrees timing at 1bar boost. You can always add more later.

I would have a good go of tuning it on the road or at the race track first and then get it on the dyno to refine the faults you find in using the car in its real conditions. You don't drive on the dyno on a daily basis what you care about is how it drives on the road...

Vell

The main problem ... this is a track car, not registered ... so I can't really do this on the road ...
anyway, very appreciable input you give me there !

I was thinking about making a conservative map on dyno (Power output + EGT + knock based), then going back for a few degres near the peak torque and at high RPM to be a bit more conservative for drifting (which means a lot of high RPM in second and third gears).

arghx

iTrader: (3)

draft some maps and post them up. Does the dyno have loading capability?

Vell

There is the basemap, following Jobro's advices : http://vell.fr/RX7/V2%202011%2007%2023.dat

odd values for the idle, but this is the last thing I'm worried about.
This is why I don't run negative lag on primaries neither.

Oh, and I don't know about the dyno ... I hope so, to pull a bit harder on the third gear.

thewird

iTrader: (8)

Why would you zero the timing at 8,000 RPM? You should feel a loss of power up there and a drastic limit is not necessary. Rotary engines don't get hurt like pistons do when they over-rev. Just raise your RPM limit to 8,500 RPM. Keep in mind the PowerFC adds timing around peak torque which is something you can't control so watch your timing in your logs when tuning.

thewird

Vell

THIS is the point
When drifting, I don't want to go WOT every time, just bouncing the rev limiter ... I want a "notice", then I can regulate the throttle by myself. And when I'm not able to do it, the engine doesn't get hurt by the lack of fuel. This thing is gonna happen all the time.

About the timing, very nice information, I'll be very carefull and look for it in the logs. Thanks !

arghx

iTrader: (3)

The overrev fuel cut on the PFC is a hard cut. You can't really "bounce" off of it in my experience. Setting timing to 0 like that should work. One of the users on here "Sandro" (he is a member of the tuning group) uses that method for autocross. He sets 8000rpm to 0 L and -15T (15 split). He has discussed it on these forums before so you've probably read about that.

I have my hard fuel cut set to 8650. Overrev fuel cut actually kicks in around 150rpm less than the setting. The PFC seems to add an extra degree or two to the value in the leading map once you get over ~4000rpm.

Vell

Oh, just had a look and I've made a mistake, it wasn't you that told me to set 0° at 8000 RPM, but "cewrx7r1". As you both are helping a lot there it's confusing in my head, I should read a bit less
Anyway, I'm gonna give a try and let you know. I'm running the same : 0° / 15° split for the whole 8000 RPM column.

This "extra advance" will be considered, again, thanks ! I'm sure you saved me a lot of time

Last question : EGTs wise ... not higher than 950°C for a hot track day ? If the temps goes higher I assume my feets will burn (rhd inside)

tony94s4

iTrader: (1)

So is that 0* @ 8k after the map retard corection or 0 before map corection,
dont know much about rotary timing or PFC,

lets say if you have another 15* retard at 15psi that would be -15* leading on wastespark
wouldnt that be a problem @ 8k+ rpm?

Vell

Hmm, that's an interesting question ... I hope it won't ?!

arghx

iTrader: (3)

Maybe this will clear things up. This is from Sandro, the aforementioned member of the tuning group:



Leading



Trailing



Split



During autocross, the RPM (blue) bouncing up and down as timing (green & purple) oscillates. Throttle (red) is about halfway down.



Cells in use are in yellow (ghost trace). The PFC is doing heavy interpolation here.

Vell

Thanks a lot, this is an important answer to me.

It may be interesting to follow his way for my car, with a 8000 / 8600 last columns, rev limiter at ~8500 (which shouldn't be hit), it will let the PFC "regulating" somewhere near 8200/8300 RPM.

As for my current setting it should do the same around 7300/7400...

tony94s4

iTrader: (1)

I am impressed with the pfc tables,
I was thinking my stoneage microtech ignition maps lol,
sorry for confusion

Vell

Another question : my knock readings are rising with the RPMs, the sensor is not loose at all, tightened more than required. I'm still getting it idling naturaly aspirated, maybe random noises ... ?

@3000 rpm I have something like 50. And I have lots of values like this, not only one or two cells.

It may be caused by something else ? I'm thinking about a bad shield actually but don't want to redo the wiring if it's not possible.

arghx

iTrader: (3)

It's often difficult to track down the source of such noisy readings. The first thing I would try to do is retard both leading and trailing by about 5-10 degrees, as a temporary experiment. See if that affects knock readings at all (it probably won't but just try it). Otherwise you don't have many options besides looking for loose items vibrating in the engine bay, checking/cleaning ground wires, or replacing the sensor.

On my FC3S the knock sensor reading is almost useless. It is located in the middle iron on the 87-88 engines (same housing as the engine mounts) and is thus prone to noise. It's relatively low near idle but will steadily increase and peak at about 70 during high rpm runs, even when there is no actual knock occurring.

thewird

iTrader: (8)

The knock sensor is very noisy on a lot of cars. Often under full WOT and boost it comes down to almost 0. The only time I even look at the knock reading is under WOT. You have to look at average knock for your particular vehicle as all rx7's seem to have varying amounts of noise. If knock increases during a pull, you can try adding fuel or retarding the timing to see if it drops down to that average again. Generally the knock sensor is not used for accurate tuning as its not very accurate/consistent.

thewird

Vell

Okay, if the retard doesn't change anything I'll try an other sensor on the rear housing and will run another shielded wire with clean grounds. I hope it will do the job because I don't want to loose another engine :/ (reason unknown for the failure, or should I say too many reasons ...)

At the first start I was having a lot of random noises, now not really, I can just hear the seals in the engine, or something that seems to be internal. Or maybe a sticky injector, I'll take a look at it too.

edit : oh, I'm stupid, I cleaned them up right before, they were opening / closing nicely.

Vell

Hello,

Definately something vibrating and causing noises. It may be the exhaust with a tight fit ... maybe something else... don't know.
Anyway, I'm now running the knock sensor on the rear housing with a new wire and the reading is still the same.

Without changing anything, just pushing the engine with bare hands, the knock readings are lower. When I look at the logs they are just funny ^^
So I will no wonder anymore about it and see if it's good when boosting.

As I have many informations to do a safe tune (thanks to you guys !) and the water injection, it should be fine. I will not push the engine so hard and be careful.

I will be back with the logs from the dyno and the track, should be more informative

Again, many thanks !

philiwily

your injector settings in settings 5 are not right, you need to change the rear primary if you haven't already.

Vell

Hello,

phil : yes it has been modified
Unfortunately, the car had some troubles with the coils and the waste gate. After a 1,5 bar (stock MAP) run I decided to stop it before something goes wrong.

By the way, the 0° in the last row was a very good idea in my case !

I will redo a dyno session in october or november and everything should be fine this time.
Luckily I have someone who allows me to run the dyno a whole day or two if necessary !