Nissan 370Z Forum - View Single Post

Denny McLain · 10-10-2009, 03:30 PM

In reviewing the logs and dyno sheets from yesterday:

1. The AccessPort logged fuel/air ratio is a bit erratic below 4000 rpm, however pretty consistent above 4000 rpm logging consistently between .7 and .9 below the dyno 02 readings. Certainly wouldn't go by the numbers given by the Accessport until you do a similar type validation. Cobb said they would vary by given car but once a baseline is established, should be repeatable. Think .2 (factoring in the below scale variance) from the dyno is probably within limits of what a wideband 02 would vary from one run to another. Just remember mine was only consistant above 4000 rpm.

2. Running the dyno numbers into my average hp within usable powerband yielded a 9 hp average increase in 1st gear, 15 hp average increase in 2nd gear, 13 hp increase in 3rd gear and a 14 hp increase in 4th gear. Very usable power increase and overall a good dyno session.

3. The car has learned on top and between 7500 and 8000 the power curve has improved. Raising the rev limit to 8200 estimating output above 8000 rpm will yield a 2 hp average increase in 1st gear, 1 in 2nd, 1 in 3rd and 3 in 4th.

4. Changing the timing..... dunno? In reviewing the timing logs from my last (and best run) which I put the stock timing tables back in both of +2 degrees logs and -2 degree logs act like they did do something. The -2 did did pull timing out in certain areas but increased slightly in the midrange. The +2 added timing below but lost it all plus some on top.

Need to schedule another dyno session as my thought process is by leaning the car out it's going into detonation in the midrange and pulling out timing may actually increase power/timing in that area.

5. Even though disappointed with the limited amount of points to change the fuel/air programming, the readout is quite linear indicating no need to go into the MAF for fine tuning

6. The fuel/air from last session was quite a bit leaner. The person helping me tune said I'd probably need more fuel than expected as more and more gas stations are going to 10% ethanol. Hard to say, but that could have been the case so ending up adding quite a bit of fuel. The car seems to like around 12.8 to 1 the best.

7. MAF A and B voltage on the logs indicate one side is getting more air than the other plus A and B calibration scales vary from side to side. Need to mull this over with my tuning buddy as he really knows quite a bit more but my thoughts are the factory has compensated for the factory intake. Now that table needs to be tweaked for the Gen 3 intake. Any thoughts?

8. Non-linear tachometer. For some reason I've felt a disconnect with the tack and the person driving my car on the dyno is an old salty mechanic and drag racer. He also noticed the tack seemed to speed up at times and lag at times. This was unsolicited and surprised me as I couldn't quite get my thumb of the tack. It's also reads 200 rpm higher.

Bottom line....... Think the AccessPort is working better. Don't take it to the bank as a little more experimentation needs to be done but finally think there might be a little light at the end of the tunnel.

Ain't this a bitch...something good happened for a change. What's up wud dis?

10-10-2009, 03:30 PM	#129 (permalink)
Denny McLain Enthusiast Member Join Date: Feb 2009 Location: Double Oak Tx Posts: 255 Drives: 370Z, 96CE hotrod Rep Power: 16	In reviewing the logs and dyno sheets from yesterday: 1. The AccessPort logged fuel/air ratio is a bit erratic below 4000 rpm, however pretty consistent above 4000 rpm logging consistently between .7 and .9 below the dyno 02 readings. Certainly wouldn't go by the numbers given by the Accessport until you do a similar type validation. Cobb said they would vary by given car but once a baseline is established, should be repeatable. Think .2 (factoring in the below scale variance) from the dyno is probably within limits of what a wideband 02 would vary from one run to another. Just remember mine was only consistant above 4000 rpm. 2. Running the dyno numbers into my average hp within usable powerband yielded a 9 hp average increase in 1st gear, 15 hp average increase in 2nd gear, 13 hp increase in 3rd gear and a 14 hp increase in 4th gear. Very usable power increase and overall a good dyno session. 3. The car has learned on top and between 7500 and 8000 the power curve has improved. Raising the rev limit to 8200 estimating output above 8000 rpm will yield a 2 hp average increase in 1st gear, 1 in 2nd, 1 in 3rd and 3 in 4th. 4. Changing the timing..... dunno? In reviewing the timing logs from my last (and best run) which I put the stock timing tables back in both of +2 degrees logs and -2 degree logs act like they did do something. The -2 did did pull timing out in certain areas but increased slightly in the midrange. The +2 added timing below but lost it all plus some on top. Need to schedule another dyno session as my thought process is by leaning the car out it's going into detonation in the midrange and pulling out timing may actually increase power/timing in that area. 5. Even though disappointed with the limited amount of points to change the fuel/air programming, the readout is quite linear indicating no need to go into the MAF for fine tuning 6. The fuel/air from last session was quite a bit leaner. The person helping me tune said I'd probably need more fuel than expected as more and more gas stations are going to 10% ethanol. Hard to say, but that could have been the case so ending up adding quite a bit of fuel. The car seems to like around 12.8 to 1 the best. 7. MAF A and B voltage on the logs indicate one side is getting more air than the other plus A and B calibration scales vary from side to side. Need to mull this over with my tuning buddy as he really knows quite a bit more but my thoughts are the factory has compensated for the factory intake. Now that table needs to be tweaked for the Gen 3 intake. Any thoughts? 8. Non-linear tachometer. For some reason I've felt a disconnect with the tack and the person driving my car on the dyno is an old salty mechanic and drag racer. He also noticed the tack seemed to speed up at times and lag at times. This was unsolicited and surprised me as I couldn't quite get my thumb of the tack. It's also reads 200 rpm higher. Bottom line....... Think the AccessPort is working better. Don't take it to the bank as a little more experimentation needs to be done but finally think there might be a little light at the end of the tunnel. Ain't this a bitch...something good happened for a change. What's up wud dis? Last edited by Denny McLain; 10-10-2009 at 03:32 PM.