mightyquickz28

iTrader: (8)

So I went to the track (Lebanon Valley, Upstate NY) with my new combo for the first time.

• Car = 96 Z28 coupe
• Engine = built for turbo 5.3, PRC stage 2.5 heads, Isky Triple 12 cam, LS1 intake, Edelbrock TB
• Tune = 3bar Speed Density
• Fuel = Twin 340 aeromotive in-tank pumps, -8AN/-6AN PTFE braided hose feed/return, E85, Aeromotive boost referenced FPR
• Turbo = single PT7675 w/Billet wheel, .96 A/R, 3" front mount intercooler, boost set to 14psi
• Trans = Built Transbraked TH350 w/9.5" Vigilante, stalled to about 3800 rpm
• Rear end = Hybrid Ford 8.8 with 3.08 gears
• Tires out back = New M/T 315x35x17 Drag radials, ran at 17psi

It was at the annual Musclepalooza event, which was absolutely packed with hundreds of cars running, so I only took two passes.

• Pass #1 - Foot braked it, but the back end started to push the car through the lights. Fortunately, the tree was at the last yellow and I floored it. Glanced over at the opponents car, then the tach. Shifted right at 6k from 1st to 2nd, then after the tach was above 6K, shifted again. Glanced at the boost gauge and it had a steady 10psi all thru 3rd. What the?... Went to the time slip booth. Sixty foot = 1.9, 1/4 ET 11.9 @ 118mph. Yuck... I pressed the history button on my boost controller and it said that, at least somewhere in the pass, it had gotten to 14.9 psi.
• Pass #2 - Disappointed in the first pass and absolutely puzzled why the boost gauge showed 10 psi during 3rd gear while having gone as high as 14.x psi, I turned the Turbosmart Boost Tee up a couple of clicks. As I staged in the first yellow, I decided "What the hell, lets try the transbrake" so I foot braked till she creeped into the 2nd yellow, then hit the transbrake button and stepped harder on the gas. On the last light she took off pretty well. After checking the tach for shift points, I glanced up at the boost gauge. Ugh... 10 psi is showing and staying there. At the end of the track, I turn onto the return road and head to the timeslip booth. On the way, I press the history button. This was able to attain 16.x PSI. This run is a little better. The time slip said, sixty foot = 1.7, 1/4 ET = 11.3 @ 120.9 mph.

After that, I put my fuel jugs and ramps in the hatch, headed home. After arriving there, I pulled up the HPTuners log for the last run. I exported it to a .csv file, then loaded it into an excel spreadsheet. I looked for lean spots, rich spots, timing retard and RPM variances. Here's what I found,

• Other that a little Knock retard around 4,000 during launch (which went to zero by 5,600 and never returned after that) the advance was 14 degrees. After 5,600 rpm, the advance was 13 degrees, till it got to 5,700 rpm at which time the advance fell to 12 degrees. By 5,900 rpm, advance was 11 degrees.
• Lamba vacillated between .75 and .69.The first knock detection correlated to about 2psi boost and 4,000 rpm where the lambda was .79 (during the foot brake)
• As I reviewed the RPM pattern, I noticed that during shifts, the RPM was only dropping 300rpm for 1st to 2nd and 200 rpm for 2nd to 3rd gear. Looks like I'm blowing thru the converter.
• Lastly, have any of you guys noticed this before? As you make the pass, sporadically, the RPM dips instead of always accelerating. I don't know what this could be. I switched plugs from TR6's to BR7ES gapped at .25, so I don't think it's blowing out the spark. There's no knock retard during most of this behavior and it's not running rich or lean.

sbcgenII

iTrader: (1)

Can you post your logs?

mightyquickz28

iTrader: (8)

Well, I tried but my web hosting site must have a file size limit. It sat there all night during the copy process but never completed. I'll trim the file and see if it allows at least the pass portion to copy.

mightyquickz28

iTrader: (8)

Try this (excel in .xls format)
http://www.taekwondoplus.org/z28/20170528_trimmed.xls

Game ova

I see you are using eboost. Is the gate pressure setting within 5 psi of your target? And where is sensitivity set? And I hope that converter is for a turbo application, if not... you might want to quit running it till you have a turbo specific converter.

87lsttop

iTrader: (2)

If you were blowing spark you would definitely hear it popping. At least my car did. Backfired and fell on its face. As far as the rpm drop sounds like you are definitely blowing thru converter. That .69 lambda is pretty dang rich. May try to lean it out a hair and see what happens.

mightyquickz28

iTrader: (8)

Actually running a manual boost controller, turbosmart Boost Tee.

The converter, I bought specifically from Precision for my turbo'd application. My mistake, it's beginning to appear, was switching from 3.55's to 3.08's, thinking I needed that gear to keep from running out of motor by the end of the quarter mile. And.. I thought the 3.08's would load the turbo better. Guess I've got a few options now, none of which will be cheap.

• Buy some more 3.55's and have them installed($600 - $800 for gears and install?)
• Send the TC back to Precision for a restalll ($24x I think he said)
• Go to a 4L80E now as I intended to do later and get the proper TC stall then.

The Torque converter guys I've spoken to all seem to concur that the 3.08's and at TH350 are a bad combo for my Turbo setup. Recommending to get a better gear ratio or the better 1st gears of a 4L60E or a 4L80E.

mightyquickz28

iTrader: (8)

Ah.. .is that right? It felt 'uneven' at WOT, which may have been the Torque converter getting blown thru. I assumed it was the spark being blown out. Thanks for the insight on the popping symptom.

stevieturbo

The only oddity I'm seeing on that graph really, is at 5000rpm rpm pretty much drops instantly ?

ie from 5k to pretty much zero in 0.024seconds. Which is almost physically impossible without major damage

So looks to me like a crank trigger issue, whether that's sensor, power to sensor, ground etc etc or ecu related problem.

ECU clearly still has power, as boost and temperature still record til the log stops.

But presumably your logging stops when the engine stops...or it thinks the crank has stopped turning ? As no data is recorded thereafter

RonSSNova

iTrader: (3)

Sure would like to see that log file.

stevieturbo

He posted a short log file above. Although it only shows rpm drop off a cliff then it stops logging.

Ratical

iTrader: (82)

As far as the trans/gear ideas here is my opinion.

The 4L80E will not help the launch. It has a 2.48 gear as opposed to a 2.52 in the TH350.

3.08 gear with a TH350 especially with 315's is not a bad combo. I run a 3.5 gear with a 1.8 glide and 31" tall tires.

Call PTC and ask them to restall your converter. They will restall competitors converters as well as their own. Be very accurate in your cars details and don't be focused on the "stall speed" They will set you up with what you need. They are very knowledgeable with turbo car setups.

mightyquickz28

iTrader: (8)

I decided to buy new Ford performance 3.55 gears and installation kit. The installer tells me the turnaround is about a week. At least he's somewhat nearby (20'ish miles away in Albany, NY). I also ordered a custom PTC torque converter, specific to my car with the 3.55's and the rest of my combo.
I'll either send the Vigilante off for a re-stall or sell it as is.