Dyno Results 09/03
Tested with Tube Header and T3/T4 turbo, stock MC Cam, 20psi boost pressure, 3" exhaust with/o cat, 8.4:1 compression, and 034EFI Stage IIb fuel/ignition system running 45lb injectors, Audi Factory Turbo Ign. Coil. Initial distributor timing set at 12degrees BTDC. Ambient was about 85F, small 2' fan, 4-wheel DynoJet. Also, the equivalent of 95 octane fuel in the tank to prevent detonation.
Max Wheel Power: 291.3 @ 5900RPM
Max Wheel Torque 306.5@ 4550 RPM
Note: Blue line represends 07/03 dyno run, Red line represents current 09/03 dyno run
This equates to about 350-375 flywheel hp and 370-385 ft/lbs torque depending on your correction figures. The only real change from 07/03 was an increase in boost, mainly from 17psi to 20psi. 22+psi was attempted but I backed off, more below. Funny how a tweek here and a butt tweek there kills the power, last time I left with 256hp, this time my first run with the same pressure resulted in about 245hp, turns out I had it a little lean, adding the fuel back immediately pumped me up to about 270hp at 18psi. Then I turned up the boost, muhahahahaha. My goal was 300 wheel hp, just missed it...this time.
Preface
Again, I'm very happy with the results, I've yet to be let down by the dyno, there is just no way to tune a high hp car like this but on the dyno. On the street I do runs on the freeway in 3rd gear, but the acceleration is so powerful, speeds go from 50mph to close to 100 in just seconds. The track is not the place to tune a car, they frown on having loose laptops floating around the interior, plus you really need to focus on driving the car at the track, not diddling with keys, the track is much less forgiving than the street, one stray span of attention and its all over, you may miss a turn or somone may collect you up in their front end. Anyway, a stock 10v long block making close to 400 crank, well what can I say =)
Session Goal
Evertime you go to the dyno, or mod the car for that matter, you have to have a goal in mind, something quantifiable. Preferrably this goal fits into an overall strategy for the vehicle. By October I'll have installed the latest 034efi Stage IIc ECU with direct fire ignition, but I really want to push the Stage IIb system with distributor as far as it will go. My goal today was to benchmark the tuning for 20+ psi, close the the max 22psi I'll run in this car due to the 255kPA MAP sensor we use. The challenge in tuning a 10v at this level is not fueling, after the first 2 runs I had a good fuel mixture that I was happy with - out of the 8 or so runs I did today, 6 of them were focused on dialing in the ignition maps and coil dwell settings. Those of you worried about fueling a hp motor might want to take notice of that fact. BTW, at 6500RPM I'm running a full 14.5MS of 45lb injector to get a 12.5:1 A/F ratio, that's a nice chunk of fuel.
By the way, thanks to local S-Car owner Chris Leal for coming out to breathe fumes with me and bang heads about tuning solutions.
The Retard Rears its Ugly Head...
After a couple runs to set a good base fuel map (mainly a tweek here or there to the Injector Scaler # in 034EFI'speak), I turned to boost up to about 20psi. The car laid down some good 18psi runs, everything was running well, no pinging, a solid 270hp or so, so up the boost went. I've been fighting a certain tuning phenomenon on the car for a while, and so are other 034EFI customers, once the boost goes past 15psi or so, and thus the power levels with it, on street gas, too much retard is required to prevent pinging, so much so that combustion is lost all together. So far in my experience, the only solution is to advance ignition timing by running higher octane fuel, this is just a reality all engine tuners face, especially with poor performing street gas. ATP has confirmed this for the 8v application as well. The problem is not nearly as bad in the 20v motors (both the 4v and 5v heads), the 10v combustion chamber limits knock prevention and just doesn't perform near the levels of the computer designed comb. chambers of the later cars with much better "swirl" and flame propagation characteristics.
At 20+psi, I began fighting a tuning battle to balance the ignition system settings on a narrow, compromised plane - 2 things began happening:
1- I began to get a slow miss through the 4-5krpm range (basically the torque peak), causing power loss (a big no no, got it?)
2- A hard cutout right at about 6krpm
After isolating different changes to different runs to determine the result, here is what we came up with:
1- Slow midrange miss is caused by too retarded ignition timing. By advancing the timing into pinging we could eliminate the miss pretty much all together. One thing that is tough to differentiate is the effect of too much retard or too much advance. Nothing can be heard in these conditions, I use a Saab APC knock box to monitor pinging (the unit flashes an LED when its sensor senses knock), but a hard miss will cause the unit to respond. Eventually finding the right values for advance the midrange miss was eliminated all together. Solution: Higher octane fuel, lower compression, or anything that increases the detonation threshold.
2- The hard cutout was caused by coil saturation. Initially I was running a coil "Target Dwell Time" of 3.5MS, I've found that most coils can only take about 4MS before burning out. This is a sensitive parameter to tune, too much Dwell Time and the coil will overheat and saturate, not having enough time to recharge. Too little dwell and not only will the spark not have enough time to light off the mixture, the rotor may miss the distributor cap trigger for that cylinder alltogether. Excessive retard only aggrivates the situation because you're waiting longer to deliver a shorter spark, this value really comes into play when pushing the envelope to the edge. Backing off to 2.0MS eliminated the miss, but lowered power output in the midrange, finally a 2.8 was the best balance, keeping power up in the midrange and allowing the coil to fire all the way to 7rpm. In the dynoplot above, you can see the power only went to about 6krpm, this was one of the runs I was dealing with the issue which was moslty resolved. I do believe the coil is running at its limit, however, so I'll be putting in a better coil for one last test. Solution: Stronger, better coil if you're sticking to a IIb dist. system, or going to IIc with direct fire coils which only fire 1/5th as much time.
20psi is about all she would do today, the miss'ing was just too much to balance out, thus a better coil and higher octane fuel will be needed to go all the way to 22psi.
Upcoming Tests
-I'm really anxious to see what this motor will do with some more flow through it, especially in light of Mike Gough's ego busting 14.1sec run on 6psi (yes, a stock MC with an Elgin turbo cam). Next week I'll be putting in a special Elgin cam I had made up and going back for another test, I really believe that the cam will put this motor into the solid 300's wheel hp, especially with a better coil and a little more 100 octane.
-By the end of the fall I'll have the StageIIc 034system fully developed and ready to release. I'm anxious to baseline the motor running DIS versus Dist.
-In the Spring of '04 I hope to have the flowed 2.3 10v installed, the head in this motor flows 160cfm versus the 125 or so in a stock 10v, this motor should make some power, especially with a cam.
-Even on the dyno, the massive new Stage II Intercooler never showed more than about 4 degree C increase in a full run, that's with a car sitting still folks. Guess I'll leave the IC alone.
-More tuning coming soon, you think my wife would give me a 4-wheel dyno for Christmas?
Oh ya...
The car is fast, really fast, no doubt in my mind that that 13.2sec quarter mile run I did is waiting to be shattered.
On the way home a poor, brand new RX-8 pulled up next to me on the freeway, flexing 250 some rotary-tuned hp..can you say buyers remorse? Ahh, the satisfaction ;)
Other 5 cylinder Dyno Plots:
-Tony Lum's 10-valve UrQuattro with K24 and CIS at 15psi made 152 wheel hp, download the PDF
-Brenden Rudack's 034efi equipped, RS2 turboed Type 44 quattro, made 259hp but interestingly only 219ft/lbs torque dyno plot
-Mike Pederson's 2.2 highly modified 20v UrS4 at 3 different boost levels - See Jpeg
Stay tuned for more upgrades and dyno testing in the future.
Email Javad Shadzi for any thoughts or questions
