Latest Test-N-Tune Results

[Kevin87TurboT]

I just got back from Memphis Motorsports Park Test-N-Tune. I only made two passes tonight because I was helping a friend troubleshoot his '87 Turbo T. On my first pass, I heard some detonation and lifted just after the 1/8 mile. Upon reviewing the datalog, I saw a peak of 5 deg timing retard in 3rd gear with the converter locked. On the second pass, I bumped up the alky just a little, but left the timing at 25 degrees. (I was running around 23 lbs of boost.) The 1/8 mile was decent, a 7.96 @ 85 +, but around the 900 foot mark, the car popped through the intake and I lifted. Later, I stepped into it again and it felt great. On the datalog, I only saw 2 degrees retard at the top of 2nd gear. Anybody got an idea of what caused the pop? Was I being too aggressive with the tune?

It's still a stock turbo, stock valvespring, stock timing chain car with 160K miles on it. I guess it's on borrowed time at this level of tune :biggrin: I ran a 7.85 @ 86 + mph at the GS Nationals a couple of weeks ago, with a better sixty foot and better air. The engine still runs great.

 

[Kevin87TurboT]

Anybody got an idea as to what could be happening?

 

[VadersV6]

Usually, being extremely rich can cause a pop through the intake, and a lean condition will cause popping in the exhaust. Valve float can cause intake popping, as well as bad cam timing from an extremely loose chain. Exhaust leaks early in the system can cause popping through the exhaust. Intermittent misfires at WOT can cause intake popping as well. Theres alot of things that can lead to it. Just look closer into what this car would most likely be experiencing. Judging by the OG valve springs and timing chain, I'd say thats a likely candidate.
What are your O2's like?
Any early exhaust cracks or leaks?
Have you ohmed out the coil packs and all the plug wires?

 

[Kevin87TurboT]

Vader,
Thanks for the reply. The air/fuel varied between 10.9 and 11.4:1 The knock sensor only detected 2 degrees max. The plug wires and coil pack were replaced just before I got the car last year. They're a little over a year old. I haven't checked the resistance on them yet. I haven't found any exhaust leaks. I like your idea about the worn valve springs and timing chain. That makes sense to me. I guess that means that it's time to install the new roller cam/timing chain, heads, and turbo.
Thanks.
Kevin

 

[2QUIK6]

Usually valve float will just cause loss of power at the top end. I bet its a weak coil pack or ign module. The ohm test on a coil is not very accurrate, I've seen many of them ohm correctly but still be weak on a coil tester and pop at WOT.
23# on stock turbo and 25 degrees timing on alky is asking for trouble, not to mention a brittle plastic timing chain thats 19 years old.
If measuring AFR with a narrow band stock O2, it isn't very accurrate, the mv reading at wot can be a good indicator, with pump and alky, shoot for around 790-800mv.

 

[VadersV6]

Keep in mind that the A/F will not really be what you think it is, because you're spraying alky.
I would keep fuel where it is and reduce timing a couple degrees. If A/F looks ok and you get 2 degrees of KR, pull 2 degrees. 4 degrees of KR, pull 4 degrees. Still detonating, add a smidge of fuel. No detonation, pull fuel until you get KR. Personally, I dont like the idea of ANY degrees of KR.
But by the way that stock motor runs, doesnt sound like you need anyone's advise. Strong running car there!

 

[Kevin87TurboT]

2QUIK6,
Thanks for the help. I may install another coil/module, just to see how it performs. I was reading the A/F with a WB O2. The car is equipped with an XFI system.

Vader,
Thanks again. You're right about the A/F ratio. I'm not reading the actual A/F because of the alky. There's quite a bit of alky going through this engine. My Duty Cycle for the Stock Injectors is less than 60% at WOT...so my Alkycontrol kit is supplying the rest of the fuel.

Kevin

 

[Razor]

How bout a new set of Ac Delco plugs gapped to .032..

Then work on doing the chain and valvesprings..

Target 11.0-11.2 on the XFI with alky, timing at 23.. and watch your logs.\

Sounds like an ignition issue you had.

 

[Razor]

2QUIK6,
You're right about the A/F ratio. I'm not reading the actual A/F because of the alky.

Says who.. its a reference your looking at. You need to see if the car likes 10.5 or 11.5 or 12.5.. the amount of alcohol will vary the way the sensor reads, yes.. but your motor may like 11.2 vs mine at 11.4.. or someone else's at 10.8. See what makes the most MPH.. work from there.

The springs are hurting you for upper end pull.

 

[Kevin87TurboT]

Razor,
Thanks for the tips. I installed new Autolite 24s gapped at .032" last weekend. The ACs and the Autolites performed the same...both had the pop on the big end. I'll try the coil/module next. I'll also be bolting on some ported heads and hyd roller cam in the next couple weeks.

As far as the A/F ratio not being perfectly accurate, I was referring to the XFI's gasoline calibration for the WB. It reads the alcohol like it does gasoline. That's not to say that it's not repeatable...it's very consistant.

I've tried A/F ratios from 9:1 to 11.5:1. It picked up a lot of performance by leaning it out.
Thanks.
Kevin

 

[VadersV6]

The alky has far less energy content and burn rate....I dont know....it just seems like the O2's couldnt be trusted. Razor....you have the most experience here so Ill direct the question at you- Will gasoline that has been 75% burned off yield the same amount of left over oxygen as Alky, which has been 75% burned off? If not, how can you use an O2 sensor and the related hardware/software which has been programmed to know what the A/F is based on burning gasoline, not alky....to tune? Seems like EGT's would be the only way to go.

 

[Razor]

How do you know its not 70% or 80%..

Your O2 will give you a reading. If you tune properly the alcohol is used to suppress knock. Past that point you look at what gives the most performance as far as O2 is concerned. And that becomes your reference.

Some cars like 750's others like 800's.. that 30.00 dollar O2 is just a tuning aid.. as is your EGT. The wideband will yield a better picture. But I have seen plenty of cars tuned on stock O2's and get some serious numbers. Hell my buddy Roy ran 9.4 on a stock computer and a scanmasterII. He would tune to 680-690's on race gas.. See what works for one.. doesnt work for someone else.

Perfect example how not to use EGT.. timing affects EGT. higher timing decreases EGT's.. so somebody has an 18 degree chip and runs 1700's someone else has a 27 degree chip and runs 1500's. Both make power.. throw alky into the equation.. hehehe

Tuning is seeing what your car makes the most power on. Splitting atoms on amount of X/Y/Z may make the car faster on paper.. but not in real life.

Tune your cars safe and fat.. work from there.. once you hit a certain point leaning it out.. it will not make more MPH. If the car makes the same MPH at 11.3 and 11.5 for air fuel.. run it at 11.3.

Cal Hartlines FAST target is 11.0 for air fuel. See you need to see how to make power.. dont go by this or that.

Cheers

 

[VadersV6]

When I said 75%, it was just a random number to make a point. If Alky is burned off 90%, will there be the same amount of left over O2 in the exhaust as if it were straight gas that had been 90% burned off? Personally, I dont really care about O2's. I throw in as much timing as I can without knock. Then I pull fuel until I start getting KR. Then I add 2-4% fuel and leave it. Whatever number I end up at is my magic number. With Alky, I can get O2's in the 600's and have no KR. With straight gas, less timing and less boost (of course), Ill have MAD KR at that range. It wont go away until Im in the mid 800's. It just seems to me that different fuels yield different "happy" O2 numbers.

 

[2QUIK6]

It just seems to me that different fuels yield different "happy" O2 numbers.

Yep, and different cars too with the same fuel...just takes a lot of careful experimentation 800mv O2 is a starting point, or 10.8 AFR with about 18-20 degrees and then get leaner and add timing little by little if no knock..for all of the beginners reading this

 

[Razor]

When I said 75%, it was just a random number to make a point. If Alky is burned off 90%, will there be the same amount of left over O2 in the exhaust as if it were straight gas that had been 90% burned off? Personally, I dont really care about O2's. I throw in as much timing as I can without knock. Then I pull fuel until I start getting KR. Then I add 2-4% fuel and leave it. Whatever number I end up at is my magic number. With Alky, I can get O2's in the 600's and have no KR. With straight gas, less timing and less boost (of course), Ill have MAD KR at that range. It wont go away until Im in the mid 800's. It just seems to me that different fuels yield different "happy" O2 numbers.

The reason you can run 600's is due to the added knock suppression afforded by the alky. Your car will be slow running in the 600's with alcohol. In other words, if you had a wideband.. you may have seen 12.8:1-13.0:1 air fuel.. which with pump gas on the verge of knocking will knock. Vs having the additional octane present to stop the knock. Example you run 12 PSI with 100 unleaded.. 680's it wont knock.

The stoich is different on alcohol and gasoline. You need to burn twice as much alky to make the same power as gasoline. The content is the same.. air and fuel. So if you reduce your fuel by 10%, then you introduce 20% alcohol.. your back at square one air fuel wise. This increased volume has the cooling effect. Something that carb'd applications provide by having time for the gasoline to cool the charge before it enters the head.

Timing also plays a role with your O2. The leaner and hotter.. the lower the number. Note also how the O2 sensor starts at 840... then goes down to 780 a few seconds latter. So it works like a thermometer as well. Yet injector DC stayed the same. If not your motor when you stabbed it would jump to 780 and stay at 780 the entire run. The more heat the less it reads.

Start fat mid-high 10's for AF, timing low.. and watch for any signs of knock.

 

[bilt2run]

Razors kit

I finally installed Your kit (Razors) and at setting 2.5-3.0 I am currently making 40 Psi with my 45A, 60 lbs. motrons and an extender chip. I have not messed with any timing or fuel via the Gen II translator. The most Knock with pump gas and HOT conditions has been 1.8 This kit is far better than any others I have used.

 

[Kevin87TurboT]

I just got back from Memphis Motorsports Park Test-N-Tune. I only made two passes tonight because I was helping a friend troubleshoot his '87 Turbo T. On my first pass, I heard some detonation and lifted just after the 1/8 mile. Upon reviewing the datalog, I saw a peak of 5 deg timing retard in 3rd gear with the converter locked. On the second pass, I bumped up the alky just a little, but left the timing at 25 degrees. (I was running around 23 lbs of boost.) The 1/8 mile was decent, a 7.96 @ 85 +, but around the 900 foot mark, the car popped through the intake and I lifted. Later, I stepped into it again and it felt great. On the datalog, I only saw 2 degrees retard at the top of 2nd gear. Anybody got an idea of what caused the pop? Was I being too aggressive with the tune?

It's still a stock turbo, stock valvespring, stock timing chain car with 160K miles on it. I guess it's on borrowed time at this level of tune :biggrin: I ran a 7.85 @ 86 + mph at the GS Nationals a couple of weeks ago, with a better sixty foot and better air. The engine still runs great.

I finally found the problem with the popping through the intake. It was almost as if the key was being turned off. The 12 V battery cable was being grounded out by the PS header as the engine torqued over. That's why it only happened when I really leaned on it. After strapping the cable away from the header I took it to the local 600' track last night. I made 6 passes, my best four were 7.55, 7.57, 7.57 and 7.60. It ran perfect all night.

 

[Quick6'n'-K.C.]

I finally found the problem with the popping through the intake. It was almost as if the key was being turned off. The 12 V battery cable was being grounded out by the PS header as the engine torqued over. That's why it only happened when I really leaned on it. After strapping the cable away from the header I took it to the local 600' track last night. I made 6 passes, my best four were 7.55, 7.57, 7.57 and 7.60. It ran perfect all night.

I had this problem in the past but my scantools would go nuts.

What mph did you get in the 1/8th and what did you finally get your a/f ratio set to with the stock turbo?
Mine made the most power at 11.4:1 on 92 and meth with locked convertor.
25° of timing and 21-22psi of boost

BW

 

[Kevin87TurboT]

I had this problem in the past but my scantools would go nuts.

What mph did you get in the 1/8th and what did you finally get your a/f ratio set to with the stock turbo?
Mine made the most power at 11.4:1 on 92 and meth with locked convertor.
25° of timing and 21-22psi of boost

BW

Hi Bryan,
My best mph was 87. I had a couple of good aborted passes at Bowling Green at the Nats, before I fixed the problem. The best of which was my best 60' and 330' ever, a 1.65 and a 3.97 respectively. I'd like to have those passes back since I fixed the problem. My A/F is 11.2, the timing is 26 deg, the boost is 23 lbs. The transmission is taking over 2.3 seconds to accomplish the 1-2 shift now. I'm sure the band is on borrowed time. I'll put my new TCI Super Streetfighter 2004R in next week. It also has a transbrake.
Kevin

 

[Razor]

The best of which was my best 60' and 330' ever, a 1.65 and a 3.97 respectively.
Kevin

Ya mean 4.97