Need tuning help, low MPH in 1/4

[jskarateka]

OK guys, I'm going to try and be as complete as I can because I may not be able to respond to any reply's for a day or two. Most of the 'cool guy' parts I have are listed in sig. I've been trying to get this thing to do a high 11 for a long time but I suck at tuning. It currently runs upper 12's with a best of on last time out:

60'..........1.773
330'........5.115
1/8..........7.947
1/8mph..87.02
1000'......10.404
1/4..........12.498
1/4mph..107.34

That was with the TT alky chip, which was burned for the combo in my sig, and left the way Eric set it.

- About half 93 octain, half 100 octain in tank (for a little safety)
- Sunny 83 degrees, track prep fair
- Tire pressure 18 lbs
- Leaving at 5 lbs (any higher would spin)
- Alky dial at 6.5 (running denatured)
- Boost at 22#,
- Timing was 22.9 in 1st, 20.8 in second (Eric's settings)
- No knock
- Narrow band O2's at .811 (wide band setup is next project)
- Shifting at 5K
- Crossing finish at about 5100
- Not locking converter, not shifting into OD
- Runs and pulls steady, no stumble, no 'nose over' at the end
- Did not try opening dump pipe (sort of forgot about it)


- Turned the boost up to 25#, MPH dropped about 1mph which surprised me.
- Left boost at 25# and added 3% overall fuel, no change (still slighty slower).
- Left boost at 25# and subtracted 3% overall fuel, no change (still slighty slower).
- Put boost back down to 23# and chip back to Eric's default setting, MPH went back up to 107.
- Left boost a 23# and took 3% out of 1st gear fuel only and added .7 degree overall timing. (still 107)

No knock on any runs but I do not have all the run logs saved.

I'm far from an expert with these cars but I'm not exactly a newbe either. I've been working on this car, racing it, and reading tons of posts on here for several years now but I can't seem to get it into 11's which many have achieved with far less 'cool guy' parts than me. I guess my main request is for any general advise, procedures, recomendations, on tuning for my particular issue. Any would be appreciated and thank you in advance.

Power logger file is attached, please note that MPH is reading higher than actual (speedo is off but axle ratio has not been changed).

 

[DIAZ 87]

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[jskarateka]

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28 inch

 

[UNGN]

unless you have flow masters or other bad mufflers, opening the dump probably won't help.

Locking the converter will help, as will more timing in 2nd & 3rd.

With 1/2 a tank of 100, you had enough octane to run 107 mph on straight gas with no alchy with a 100 octane race chip.

 

[Mr.Spool]

to my knowledge the ptc 10inch shouldnt be locked at wot,you should contact dusty and verify.your 20mph on the backhalf not terrible for all stock with 23psi,your 60ft and 330 need alot of work to me,leave more on boost use the ebrake to hold the car and come out hard.

 

[JimP]

I was going to say valve springs but looks like you've changed those already. I'm sure one of the guru's will respond soon enough. From your time slip I see your only picking up 20 mph in the last half. My car usually picks up 26-27 mph there my 02's narrow band were closer to .790 with alky, I also need a wide band.

 

[UNGN]

to my knowledge the ptc 10inch shouldnt be locked at wot,you should contact dusty and verify.your 20mph on the backhalf not terrible for all stock with 23psi,your 60ft and 330 need alot of work to me,leave more on boost use the ebrake to hold the car and come out hard.

For 23 psi with a TA49, 107mph sucks.

My car would run closer to 115-116 mph. With 3 mph for a not locking the converter, there is still a missing 5 mph.

107 mph is easy with a stock turbo, 20 psi and 100/93 octane mix (and no alchy) if you lock the D5.

 

[Mr.Spool]

the boost was at 22 and timing was at 20.8 from 2nd on and he is at 12.49 the mph is a little low but on a stock motor and very low timing i don't think thats way off track.20 psi on a stock turbo with higher timing and 22 on a 49 with low timing should be very close.

 

[Mr.Spool]

more boost with more timing in the lower gears only cutting timing back in 3rd,with a ebrake launch will get the car moving if everything is working right.a wideband would help as my car with a 49 never went fast on 810's 02.

 

[turb0buick57]

60'..........1.773
330'........5.115
1/8..........7.947
1/8mph..87.02
1000'......10.404
1/4..........12.498
1/4mph..107.34

.

What was your 60ft on the 25#s of boost runs? Im guessing slower than the 1.77 sixty?

Seems you andI are battling similiar issues with similar combos. I'm still looking for 11s but what helped move me to the low 12s consistantly on 1.7x sixty with 23lbs of boost is moving the alky gain down to 5 with stock progressive controller settings. With the gain on 6 I had way too much alky spraying and could not get passed 106-107mph.

 

[jskarateka]

What was your 60ft on the 25#s of boost runs? Im guessing slower than the 1.77 sixty?

Seems you andI are battling similiar issues with similar combos. I'm still looking for 11s but what helped move me to the low 12s consistantly on 1.7x sixty with 23lbs of boost is moving the alky gain down to 5 with stock progressive controller settings. With the gain on 6 I had way too much alky spraying and could not get passed 106-107mph.

60ft was about the same 1.78-1.82 range. I can hold more boost at the line but then it breaks loose when I launch, or sometimes it will stick then break after a few feet. The BFG 275/60 15 drag radials I'm using at the track are pretty old, I got them used, probably part of the problem.

Looks like next time out I'll try raising timing more and lowering alky gain (not both, slowly one at a time).

Thanks guys.

 

[hensleyt]

I have several time slips just like that.I was using a street chip with ALKY,only adjusting timing(+ 4*in 1/2 +3*in 3/4).and hit the wall at 106-107 .I installed a ALKY chip with a 85mph convertor lock WALLA first pass 11.93 @ 110 .No changes to the chip.I think locking the convertor was the ticket.I have made 15 passes last 5 @11.90 112.5mph.I say lock the convertor.