Diagnose my poor track times... part 2

[JDSfastGN]

So I made a similar post last year after racing at the Buick vs Ford shootout. Since this thread.

http://www.turbobuick.com/forums/threads/car-isnt-mphing-like-it-should-advice-bison-lol.402640/

I’ve pulled the trans and went through it while I sent the converter out to PTC be tightened up a bit. It now stalls around 2800 compared to 3100-3200 0 boost yet I’m still getting slippage in the realm of 14-15%. What if anything can cause a false slippage reading? The car makes boost and rpms easily. I also swapped to a recessed plug, new alky pump, and all new alky wiring/control box to replace my original from 04, went back to stock headers due to bad luck with aftermarkets and removed about 40 lbs of weight.

My best pass was this weekend was a pitiful 11.18 @121.72. That was with 27 psi. At 22-23 psi it ran 11.2@121.78 and went 97 in the 1/8th vs 99.8 in the 27 psi pass. The car just doesn’t want to backhalf at all. On my final pass I ran 11.40 @ 121.75 with the car gurgling a bit at the top of 1st and 2nd gear due to going too rich (went to a 10.6 a/f trying to suppress knock) It went 95.8 mph in the 1/8th and picked up to 121.75. The transmission is still shifting early under heavy load on the 1-2 (almost instantly in 2nd gear off the line except for my last run which is hurting my 60 ft but what I’m really concerned with is the back half and lack of mph when turning up the boost.

The engine has been in the car since 08-09 and maybe has 10-15000 miles but when it comes out, it comes out to play hard usually. I plan on a leakdown test soon but the car runs clean and doesn’t smoke. I do have a bit of oil I noticed on the #6 exhaust port when I took the header off a while back but the plugs all looked good before I changed them on race day. The car has been 127-128 just a few years ago on this same motor and setup and has been as fast as 104 in the 1/8th. When I had the trans apart all the clutches looked great and neither the forwards or directs showed signs of slipping so if the trans is not slipping and the converter is showing slippage could the motor be making the boost and rpms and just not the power to push the car to the mph I’m expecting?

The knock is a bit confusing and obviously could be hurting mph a bit. I’m almost 100% positive its false but I have been over the car a dozen times looking for anything loose or banging and there is nothing. It’s so weird that on the street the night before I took it out and with the same gas and alky settings it pulled clean and had no knock. I even dumped a bit of 104 UL in the tank to see if that helped. Turning the alky up equaled an aborted run due bogging and surging. If this is a wall of text let me know and I’ll gladly clarify anything.



1st pass (no power logger run or Time slip) timing: 23/21 boost: 23 psi with a/f set to 10.8 1/2nd and 10.7 3/4th 11.29@121.78

2nd pass timing: 23/21 boost: 26-28 psi with a/f set to 10.8 1/2nd and 10.7 3/4th

3rd pass timing 23/21 26-27 psi was aborted after setting a/f to 10.6/10.5 and turning the alky from 6.5 to 7.5



4th and final pass timing: 23/21 boost: 26ish a/f commanded was 10.6/10.5 and I dropped the alky back from 7.5 down to 6.

I got killed this run both at the tree and ET/MPH. The trans actually shifted correctly into 2nd gear but the surging killed any power in the 1st half of the track.

If I had gotten one more pass in I would have liked to have leaned it back out to 10.9-11.0 just to see what it did. I was also tempted to unplug the knock sensor and if it blew it blew, but I didn’t.

 

[JDSfastGN]

Is there a way to delete this thread? Id rather it be in the timeslip combo section?

 

[Chuck Leeper]

Is there a way to delete this thread? Id rather it be in the timeslip combo section?

Why??

 

[bison]

Being at 10.6:1 a/f will not be felt on a pass and is probably close to what you should be running. Are these numbers pulled from logs with calibrated sensors/transducers? What is the final rpm during a pass?


BPE2013@hotmail.com

 

[JDSfastGN]

Why??

Ill leave it here if nobody minds it being posted in two sections I just figured it fit more into the timeslip and combo

Being at 10.6:1 a/f will not be felt on a pass and is probably close to what you should be running. Are these numbers pulled from logs with calibrated sensors/transducers? What is the final rpm during a pass?


BPE2013@hotmail.com

Hey Bison. Im going to borrow a friends LC1 WB and compare it to my Zeitronix and see if there is a difference. The air/fuel is logged via my 6.0 chip with powerlogger. I attached my first and last power logger runs in the first post. You would have to switch over the powerlogger to a zeitronix WB setup to see the correct numbers. Final rpm was 5425-5500 with a 3.23 and a 28" tall tire. his equates to 14-15% slippage even though I just got it back from PTC. They modified it from a 17 blade to a 16 and added a sprag. I trust them and am now wondering if the car is just just making any power at all for the given mph. The knock recorded is not helping but its been an issue at the track for a long time even when it was running 127-128 consistently.

 

[BARRACUDA1968]

Looked at one of your logs and I hope that KR is false because it's hanging around quite a while. You have 14.1 KR at the 1-2 shift.

You have KR in the burnout box and while staging. I see the car leave and KR gets suppressed to .05 and while that happens the MPG takes a flat line and then increases with more KR. Looks like you're lifting on this pass and pedaling it a bit according to TPS. Your TPS voltage drops with every gear change? Not an expert by any means so correct me if this is normal.

You average 3.0 of KR all the way through 3rd gear and final rpm is 5553. PL mph is off the time slip and I'm not sure what your WB is so I show way lean looking at the AFR in the log.

 

[JDSfastGN]

Looked at one of your logs and I hope that KR is false because it's hanging around quite a while.

You have KR in the burnout box and while staging. I see the car leave and KR gets suppressed to .05 and while that happens the MPG takes a flat line and then increases with more KR. Looks like you're lifting on this pass and pedaling it a bit according to TPS. Your TPS voltage drops with every gear change? Not an expert by any means so correct me if this is normal.

You average 3.0 of KR all the way through 3rd gear and final rpm is 5553. PL mph is off the time slip and I'm not sure what your WB is so I show way lean looking at the AFR in the log.

Thanks for looking. I have a badddd habit of lifting on shifts and it was amplified on the final run because it was falling over at the upper rpms after I richened it up some. Its a Zeitronix and held the commanded a/f pretty well. The PL mph is off because most tuning happens on my 26" tires and I didn't change it for the track.

 

[BARRACUDA1968]

I would think the timing retard throughout the entire run can't be helping the car get down the track. You may have a converter issue just not coupling or you're down on power? Not sure how much power we're talking to slow you up 6-7 mph but it's gotta be a few ponies for sure.

Last year I had a converter not up to par and my new one picked up 10 mph and 7 10ths on the same basic tune. I did go from a 25" tire to a 28 so that figures in but it was mostly converter. That motor was hurt at the time and I didn't know it until this spring. One hole down and oil in the exhaust port when I took it apart. Plugs looked good too.

You gotta get that KR figured out.

 

[JDSfastGN]

I would think the timing retard throughout the entire run can't be helping the car get down the track. You may have a converter issue just not coupling or you're down on power? Not sure how much power we're talking to slow you up 6-7 mph but it's gotta be a few ponies for sure.

Last year I had a converter not up to par and my new one picked up 10 mph and 7 10ths on the same basic tune. I did go from a 25" tire to a 28 so that figures in but it was mostly converter. That motor was hurt at the time and I didn't know it until this spring. One hole down and oil in the exhaust port when I took it apart. Plugs looked good too.

You gotta get that KR figured out.

I plan on making a few passes this evening from a roll and seeing how the knock is. It hardly knocks from a roll on the street and I had it tuned to 0 knock at 26-27 psi the night before trailering it to Oklahoma. It looks real to me and I realize I could be losing a bit of power as well. I still plan on a leakdown test this weekend hopefully just to see. The converter is fresh so it leads me to lean towards something else that making it look inefficient. The plugs were brand new and only pulled onto the trailer and staging lanes before the first pass. I got KR on the run according to the scan master so I pulled a plug and it looked great with no signs of detonation. Same thing on the 3rd pass.

 

[bison]

I wouldn't expect coupling at that rpm with that gearing. Probably almost the same as my car with a 29" slick not including the extra growth. My slip was over 7.5% @136mph assuming 29.5" tire and possibly even taller tire and I had a 17 blade in it. I don't have ds rpm on that car so data is slightly in error. The car should pick up 25% mph the second half of not out of turbo. At 120mph Id bet my slip was in the teens. If you have KR all the way through 3rd you need to address it asap. 3 degrees of timing on proper running is probably 40hp or possibly more. That's most of your lost mph right there


BPE2013@hotmail.com

 

[JDSfastGN]

Bison, knock withstanding, would swapping back to a 3.42 be beneficial in your opinion? The 0ptions for a 27" slick are few and far between. I drove my car about 40 miles to dinner and back tonight and consistently got knock once the boost got to 15 psi, Even slowly building that boost on the trans-brake created 14* of knock. I plan on attacking this full on this weekend. If I can't figure it out I may make a trip to the track in the next few weeks and go with a full tank of 104 or 11o unleaded and unplug the knock sensor to see if my lost mph is hiding there.

 

[BARRACUDA1968]

One thing I would do is get a new knock sensor on hand. Loosen yours and re-torque it to 14 ft pounds. Make sure you don't have a wire issue to the knock sensor or a bad connection. If that doesn't help try the new sensor. I had major knock issues last year once in a while and checked my Knock sensor and it was finger tight from previous owner.

I can't imagine you having this much KR and you can't hear it in the motor or something rattling that's causing it.

If you want an idea about gear changes and tire height go here and play with the calculator.

http://www.ringpinion.com/Calculators/Calc_RPM.aspx

One thing I learned years ago about tires and advertised height and section width etc is most advertised measurements are off, some by a lot so just because they advertise 27" or 28" height don't mean they will measure that when the brown truck comes. Less gear at the big end should help couple as long as you're pushing through the converter now. On the flip side my converter couples harder with more power which seem to be down on based on mph.

I think if you get this KR issue under control you will have a different opinion on your gearing and converter. Sometimes the combo has to work together to let one part (like the converter) do it's job. You have timing retard at the first yellow bulb to the 1320.

 

[JDSfastGN]

Alright, I don't know why it took making a post for me to click and accept that its probably the elephant in the room (ie. knock retard) that is causing a large loss in power and mph. I looked back at last years runs and I didn't have but a few small hiccups of knock on my passes that year but I made quite a few changes since then so like both of you stated I need to figure out the knock. I have replaced the sensor a couple of times over the past few years and it has fixed a false knock issue once before. I may order a new connector as the current one seems loose as well. You are correct about the tire height. I'm going to measure the real height and take a guess at how much it grows down the track and see what it really was slipping at.

 

[BARRACUDA1968]

I would certainly think this has got to be false knock due to sensor/wiring or something in the tranny/converter setting it off. When my old motor started to go my KR was unexplainable and I couldn't detect any bearing noises etc until one day and it was all over. If you've been dealing with this for this long and you still have a motor in one piece something else must be setting it off if the A/F is in line which yours is.

I'd trace the knock sensor wire as far back as you can go for a crimp or a short. Maybe it's rubbed itself through somehow and is grounding out. Good luck with the search and keep us posted.

 

[Ttype6]

A compression test might reveal something. Do you know what valve springs you have and their installed height?
Do you know what your lifter preload is?

 

[Chuck Leeper]

Again... Ring seal going away and oil in the cyl causing knock??
A data log of crankcase psi when new and monitored as the miles stack up, could indicate the seal going away.
Just a tip I learned from WJ....

 

[we4Mateo]

It could very well be real knock, I don't think that can be determined yet. Even if it isn't real, it's pulling real timing. Put a few gallons of 110 and if it goes away, then you know. Don't unplug the knock sensor! It's there for a reason and works great when properly installed with good wiring.

 

[RED LS1]

I see 2 time slips with piss poor 60fts. If I were you I would be addressing that. It looks to leave with good power but it doesn't appear to be a stable launch. Almost like the suspension is unloading the tires after the initial hit. On the first one it bounced and in the second video it broke loose for a moment. Imagine how the rest of that slip would be affected if it had a 1.55 or faster 60ft.

 

[Ttype6]

I see 2 time slips with piss poor 60fts. If I were you I would be addressing that. It looks to leave with good power but it doesn't appear to be a stable launch. Almost like the suspension is unloading the tires after the initial hit. On the first one it bounced and in the second video it broke loose for a moment. Imagine how the rest of that slip would be affected if it had a 1.55 or faster 60ft.

He should still MPH much better. He's not troubled by his elapsed time. He's troubled by his MPH.

 

[RED LS1]

He should still MPH much better. He's not troubled by his elapsed time. He's troubled by his MPH.

I agree with that. Especially if the car is pulling timing. 121 is not too far off for an 11.1 pass. If it MPH more in the past it's probably being lost in the KR. However, let's call a horse a horse. The car should have quite a few tenths and MPH just from the 60ft. A 1/4 mile run is incremental and the first 60 feet contribute to the wheel speed and engine RPM it takes to obtain the most E.T and MPH the car is capable of.