23Racer

After 2 years of screwing around with the car and many false starts, we have had success with our ITB setup. Yesterday we went to Shannonville with the latest tune in the car. It started fine (a first!!!!!) and in the first session ran okay, but I was suffering from a bunch of misfires, surges and stumbles. We took a look at the Maps and the Autotune results. Dave made the changes and I went out again.

It really cleared up and started to go very well. I was making some serious power and the car ran well to about 8500, but still had a bad stumble at around 5000 with some severe surging. I came in and we checked the logs. Dave tweaked the MAP a bit more, leaned it down some, increased the pump shot and leaned out the above 9,000 rpm bin. We added more fuel to the car and I went out again.

WowOwowOwow...........

The car hit a sweet spot in the tuning. It flat out flew. It pulled strong from about 4500 rpm, but as the rpms hit about 7500 rpm it just screamed. I was able to pull with a Z06 Vette on huge Hoosiers, on the straights and out corner him. Coming on to the front straight, I could drift the car like a V8 car. It just wanted to rev to the moon. I ran the car for over 30 minutes without a peep or cough and it was better on the last lap than the first. I have to say I was tickled to death with the performance. All of the work and struggles are near the end. The car flat out flies and above 7500 rpm it seems to get crisper with a different note and the rate of pull continued to grow until the driver chickened out at about 9200. We just have a few issues to deal with now.

First, the car is going so much quicker that the brakes on the car won't work. I need to put a set of 4 piston calipers and bigger rotors on the car (finally). At the track, I was pushing on the pedal as hard as I could. It wouldn't lock a tire, the pads weren't fading and the pedal wasn't soft. The front pads were wearing so fast that after a total of about 75 minutes on track, I used up a set of front pads (Hawk Blues). The fronts were wearing so fast that after the day, the front wheels were completely black and the dust went down both sides of the car. At least 3 times I went way off line, just because the car wouldn't stop fast enough based on the new speed I was getting. This is a good and bad problem.

Secondly, in a number of the tighter corners I could blow the back tires off the car if I used all the motor that was available. I need stickier or bigger back tires if I race at Shannonville. Myabe I need to go up to Al's size of tire, 245x1?.

Finally, I need better shock control. There is so much more in the car now. I need to control it better. Luckily I have a set of new 3 ways in the garage. I just have to make a proper mount for the rears.

Somedays life is very good. I can hardly wait for Mosport on the 20th.

Eric

Neo

iTrader: (4)

Damn!
Great news Eric!!

Can't wait to see the small improvements.

Nismo Convert86

iTrader: (7)

Awesome to hear Eric, but remember they run best before they blow :P J/K

23Racer

No kidding. The car pulls so strong that it reaches 9,000 so easily you are tempted to just keep pushing the keg higher. I have to have Dave put a rev limiter on the car now as I know that I will just keep adding a couple of hundred rpm to the shift point until it does blow :P

I just can't believe that all the problems we had over the last 2 years was because of the base Megasquirt software glitches that were corrected when we switched to a newer level. To give you some idea of the changes we have made, most of the fuel pots have been reduced by over 12% and the timing pulled back by 5 degrees across the board.

All we are working on now is overrun richness and trimming the cold start fuel map. You guys should come to Mosport on the 20th. First to take part in Al's lapping session at lunch. The second to watch me throw the RX7 off in 8 the first time I go through the corner about 30 kmh faster than I have ever gone through it before in the RX7.

Eric

rotarygreg

yet another reason i cant wait for the 20th now. glad its all going well. I remember at the beggining of the season the rx8club did a few hours of lapping at shannonville that Al set up and you were there tuning. you seemed to have figured something major out by the end of that day as you were passing me at the start of the back straight with some serious power compared to the early runs. i can't wait to see it in its new form. see you on the 20th.

thewird

iTrader: (8)

Always like hearing these stories. Just be careful with the leaning out part. It will keep feeling better and better until it finally says its time. Ask me how I know

thewird

23Racer

Yeah I am concerned about going too lean. I used to race 2 stroke karts so I am really aware of this issue. We are just trying to get all the bins in the 12.5:1 range. I forgot to add that I am also scared of destroying the gearbox. I will have to treat it like glass again.

Eric

Aaron Cake

iTrader: (1)

Was the only problem then the mismatch of the hub and pulley? I can't even count how many times that has screwed me up. So much so that all the spare hubs and pulleys get marked now in several places.

Glad to hear the car is running like a raped ape.

23Racer

Aaron, the problem is that we had an S4 Hub, an S5 eccentric shaft and a TII crank pulley. What we did was find TDC again, mark it on the pulley (just about 4 degrees retarded from marks on pulley) then use my Racing Beat crank pulley to add other markings to confirm actual timing.

It turns out that the timing was correct all along and had little to no contributioon to the starting and running issues. What was causing issues was the following (for those that care);

1) Primary issue was faulty version of main chip software. This caused all kinds of issues trying to get the car to run consistently. Updated the software version and everything started to click.

2) Fuel maps developed with faulty software were all over the place. We needed to richen low end about 10%, lean out top end by about 12% (from about 73 to 61). Increase the starting pulse very close to where Aaron recommended, increase the accel pump shot at least 10%. Part throttle settings needed to be richened a fair amount and the overrun needed to be richer as well to minimize bucking when shifting gears. The fuel map is surprising flat when viewed in 3D.

3) Increase starting timing to about 20 degrees BTDC.

4) Lock all other timing to about 18 degrees BTDC.

5) Install 255 LPH fuel pump.

6) Replace the fouled plugs.

7) Make sure we only try to start the car with at least 12.5 volts in the battery.

One funny thing is that one bin needs to be far richer than the bins on both sides. The 5,000 rpm bin is at least 10% richer than the bins on either side. It needed this to minimize a very severe lean surge. This must be a resonance point in the induction system, because after we did that the car would pull very hard from about 4500 rpm.

Again, the best thing is that it starts and runs just like a stocker, but with a pretty strong Braap BRAP at an 1,800 rpm idle.

Eric

thewird

iTrader: (8)

That might have something to do with injector staging. What ECU are you using?

thewird

23Racer

We use no injector staging. All the injectors fire at once as it is running Alpha N mapping. We run one injector per throttle throat. The car is working very well now with no lean surges, so we don't want to mess with it.

We are using a Megasquirt and other than the full of bugs first set of software, it has been great.

Eric