Excellent write up.Just pulled my car back into the garage after my track outing. I towed it there even though the track is only 30 minutes away just in case there were any "mishaps." The track's conditions today were horrible! 95+ temps and they used gravel and sand to prep the track I think. It was so bad that everyone left after an hour or so because of the conditions. This left me, a few other turbo Buik's and a handful of bikes. It was not the night to throw an et on the board, but a good night to get some testing done else where on the track. After I realized the car was not going to 60', I pretty much tried to launch off idle to get accurate trap speeds to see what worked in the tuning department. I will use trap speeds since my et's were not important imo.
I made 8 passes in 4 hours, so I learned a good deal.
First, the test tube test showed I was working with e80 today (this was from the sample I took from the fuel rail.)
For the first pass (not really a full pass, but checking to make sure car was working...I always do this and get some flack for it but it makes me gain confidence in the car for that day.), I cut the balls off the tune and turned the boost down as far as it would go, which was about 20 psi with my 6768 and stock wastegate setup. This netted my a trap speed of 116. I pulled the old plugs and put in some new r5671a-9's gapped at .025 so I could get some readings for the rest of the evening. The data log showed my fueling was on par so I turned the boost up a bit.
2nd pass. My timing was set for 20 degrees across the board on my dfi from 20 psi to 30+ psi and 4500 rpm and up. The car went 121, on about 21 psi. The a/f ratio was about 11.1, with the dfi subtracting about 3%. I ended up never touching the ve table all night because 3% is acceptable to me.
The 3rd and 4th run I turned the boost up a little more and the car responded with a 123 trap. Boost was at 22 creeping to 24 at the end of the run. My duty cycle was at 90% so I never turned the boost up the rest of the night.
Runs 5 and 6 were more of the same, just me out there having funI did read a different plug after each run. I'm new to reading the plugs for e85, so I was just basically looking for a peppered effect on the porcelain showing detonation. The plugs would never show any all night.
Run 7 I turned the timing to 23 degrees. Holy sh!t did it respond! I'm dealing with a converter right now that has some serious slippage. The car blew right through it in 1st gear and hit the rev limiter at 6900 rpms! Traps went to 124.3.
Last run was exactly 20 minutes after the 7th so the car was still hot but it was my last pass before the track closed. Same tune as 7 but I eased into the gas a little more off the line. The car went 125.2. I was very happy with that. That's enough for a mid 10 sec pass on a good 60'.
So, I learned that 96# injectors should get you mid 10's. E85 likes timing. No signs of detonation yet. Car spooled fast in 95 degree heat. A full tank of gas cost me what 3 gallons of what c16 cost:tongue: I'm wondering how long plugs are going to last. After 7 runs, the plugs still look brand new.
In the future, I want to take some fuel out, turn up the boost, and go to a track that hooks
The best part about today was......I had fun and the car ain't broke! And that's what it's all about.
If you're going to be playing with the timing, you need to learn to read the ground strap of the plug real quick. BTW, I like your choice of plug. Can you post a pic of one of the plugs, focusing on the ground strap?
Starting with 20 degrees of timing was very smart. 20 degrees is very low for alcohol. You're going to see some impressive gains as the timing is moved up. To give you an idea, I run 30 degrees at 30 psi boost with 100% methanol.
I like to keep the timing on the conservative side. As you step up on the timing, you'll notice a point where the performance increase begins to nose over. Don't push the timing to get that little extra performance. It's not worth it. Pick a conservative timing setting and leave it. All the while reading your plugs very carefully.
You want to look for heat discoloration of the ground strap. This is an indicator of a good timing setting. The discoloration should extend half way back the ground strap. The further the heat discoloration extends back towards the thread end, the more heat that's being developed. On an NGK, you only want to see that heat discoloration extend halfway back. No further.
The 11.1 a/f ratio reading is about perfect. Don't start leaning it until you've found a good timing setting first. I wouldn't lean it any further than 11.3:1 for a final tune with a conservative timing setting.
A conservative timing setting for me would be 2 degrees retarded from the point where further timing increases is netting little performance increase.
Again, very good write up. I enjoyed reading it. Thanks.
