BUILD THREAD 86 GP 2+2~Blown 6.0

[81cutlass]

90 miles to the track and back and made it home safe!

I wanted to determine if my trans is good or bad, it's ok. I didn't miss any shifts because of bad syncros but it pops out of 2nd on the return road after the pass, but it's fine on the street usually. The track didn't have enough prep to hold a WOT 1st to 2nd shift so I couldn't try out what I think is the worst gear.

The track was 'street tire prep' tonight which meant a wave of the traction compound 10ft out and that's about it. Smaller turnout so they don't want to go all out with prep, half the cars are on street tires that will kill the prep anyway and there's a shortage so they want to save it for a big turnout, I can't blame them.

Didn't have the conditions to run a 10 but I was able to get my fueling happy. It's a solid 11.1-11.6 across the range. I also didn't have the conditions to tune my shocks or my launch RPM and clutch clamp time but that was a stretch.

1st pass I wasn't used to how fast the rpm comes up with the 4.30's or the poor traction so it smacked the limiter hard

2nd pass it spun stupid hard

3rd pass I lowered the launch RPM from 4800 to 3400, it still spun but I rolled into it and took my foot off the throttle during the 1-2 and 2-3 shift

4th pass it spun 15ft out, I pedaled, off the throttle during 1-2 and 2-3

5th pass was a near copy of 4 but I kept my foot in on the 2-3 and it stuck with 17psi in the tires.

The car ran a best of 12.02 at 122 with 18-19 degrees shifting at like 6500-6700 at 10 psi.

It ran 122mph last fall shifting at 6200 with 11.5 psi and same 18-19 degrees so 400-500 rpm added to the shift rpm is equal to 1.5psi of boost. The 4.30 gear seemed to help.

Overall 12.02 with a pedal that took .6 seconds and off the power for .5 second on the 1-2 shift and a 1.97 60ft isn't terrible for a 5% prep night. If it was prepped I would have been in that 1.66-1.72 60 and wouldn't have had to pedal or lift shift on 1-2, I see an easy .5-.7 second right there.

I still don't know if I'm going to do the trans before drag weekend or not. It's not bad or good enough to make a definite decision.

The new owner of the wagon was out. Blowing the tires off at the 1/8 mile

Track

Street

Nice cruise back home

 

[81cutlass]

Spin city (this is pass #5 after I decided to take it soft

IAT peaks at 170 at the end of the run. High but not mega concerning. And happy flat fuel curve. That's dialed in nice now.

And this is what 4800 rpm launch on near zero prep looks like lolz. Let out, let hook, roll in, spin, let out, let hook, roll in, spin. Smack rev limiter when it finally does hook. Zoinks.

 

[Supercharged111]

90 miles to the track and back and made it home safe!

I wanted to determine if my trans is good or bad, it's ok. I didn't miss any shifts because of bad syncros but it pops out of 2nd on the return road after the pass, but it's fine on the street usually. The track didn't have enough prep to hold a WOT 1st to 2nd shift so I couldn't try out what I think is the worst gear.

The track was 'street tire prep' tonight which meant a wave of the traction compound 10ft out and that's about it. Smaller turnout so they don't want to go all out with prep, half the cars are on street tires that will kill the prep anyway and there's a shortage so they want to save it for a big turnout, I can't blame them.

Didn't have the conditions to run a 10 but I was able to get my fueling happy. It's a solid 11.1-11.6 across the range. I also didn't have the conditions to tune my shocks or my launch RPM and clutch clamp time but that was a stretch.

1st pass I wasn't used to how fast the rpm comes up with the 4.30's or the poor traction so it smacked the limiter hard

2nd pass it spun stupid hard

3rd pass I lowered the launch RPM from 4800 to 3400, it still spun but I rolled into it and took my foot off the throttle during the 1-2 and 2-3 shift

4th pass it spun 15ft out, I pedaled, off the throttle during 1-2 and 2-3

5th pass was a near copy of 4 but I kept my foot in on the 2-3 and it stuck with 17psi in the tires.

The car ran a best of 12.02 at 122 with 18-19 degrees shifting at like 6500-6700 at 10 psi.

It ran 122mph last fall shifting at 6200 with 11.5 psi and same 18-19 degrees so 400-500 rpm added to the shift rpm is equal to 1.5psi of boost. The 4.30 gear seemed to help.

Overall 12.02 with a pedal that took .6 seconds and off the power for .5 second on the 1-2 shift and a 1.97 60ft isn't terrible for a 5% prep night. If it was prepped I would have been in that 1.66-1.72 60 and wouldn't have had to pedal or lift shift on 1-2, I see an easy .5-.7 second right there.

I still don't know if I'm going to do the trans before drag weekend or not. It's not bad or good enough to make a definite decision.


View attachment 203378

The new owner of the wagon was out. Blowing the tires off at the 1/8 mile
View attachment 203379

Track

View attachment 203380
Street
View attachment 203381
Nice cruise back home
View attachment 203382

Pff, T56s are easy. No balls if you don't fix it before the big event.

 

[Supercharged111]

Spin city (this is pass #5 after I decided to take it soft
View attachment 203383

IAT peaks at 170 at the end of the run. High but not mega concerning. And happy flat fuel curve. That's dialed in nice now.
View attachment 203384

170 IAT? I'm running 190+ in the intercooled tow pigs. Still faster than N/A. I forget what I used to run in the intercooled Corolla that made WAY more boost, but it definitely didn't exceed 170. Neither did water. 1.6L is so much easier to keep under control than 5.7+ of freedom iron.

 

[64nailhead]

Sounds like a win to me. Bad prep is just that - bad. And it makes it difficult to make decision about what to do.

Any wheel shake? Thinking back this used to be an issue.

Were you checking tire pressures as you went along? Asking because mine always increase and I have to keep dropping about a 1-2lbs between runs.

Also great to hear that you have the tune in a happy spot - one less thig to have to manage next time.

 

[64nailhead]

Pff, T56s are easy. No balls if you don't fix it before the big event.

I agree - you know you're on borrowed time with it.

 

[motorheadmike]

Looks like good progress. Did you consider leaving in 2nd?

 

[81cutlass]

Pff, T56s are easy. No balls if you don't fix it before the big event.

170 IAT? I'm running 190+ in the intercooled tow pigs. Still faster than N/A. I forget what I used to run in the intercooled Corolla that made WAY more boost, but it definitely didn't exceed 170. Neither did water. 1.6L is so much easier to keep under control than 5.7+ of freedom iron.

Ugh, fine, I'll order the parts, lol. I was trying to save the week & $800 until this fall but it's a $500 t56 that I have beat mercilessly for 6 years with boarderline too much power so I will relent.
My aftercooler water temp never goes over 100f so the intercooler brick is only able to reject so much heat from the inlet air. It's more than I'd like but not unacceptable in my book.

Sounds like a win to me. Bad prep is just that - bad. And it makes it difficult to make decision about what to do.

Any wheel shake? Thinking back this used to be an issue.

Were you checking tire pressures as you went along? Asking because mine always increase and I have to keep dropping about a 1-2lbs between runs.

Also great to hear that you have the tune in a happy spot - one less thig to have to manage next time.

Yeah the general consensus of the near zero prep was disappointment but I'm still glad I made it out. I had some people say the car was surprisingly fast considering the conditions and the fact that it's a heavy radial car. There was a few floppy tire light bracket cars there that didn't seem to have as much of an issue but I'm not complaining. I didn't spend a ton of time watching other cars run but I think a 12.02 was one of the faster driven to the track passes that was made.

No tire shake this time, It did used to be an issue. I think correcting the instant center, getting the double adjustable rear shocks & removing the slop between my UCA bushing ID and the OD of the housing bushing to UCA bolt eliminated that issue.

I did check tire pressure, I left it at 19 to start the night from where I was last fall (I cut the 1.66 60 on that) and worked down to a 17 on my last pass. I too see abut 0.5-1psi rise every pass. I think my improved time on the last pass is just down to me pedaling it semi ok-ish and not anything related to the tire pressure or suspension tuning. 100% on bad prep being bad. It's hard to tune launch RPM, shock settings or tire pressure in when it won't hook in any situation.

Looks like good progress. Did you consider leaving in 2nd?

I did not. I should try that next time. I know with my 3.73's it wouldn't have been pretty but the 4.30's might change that.


Also another chapter in RPM is good-

Left is my best pass from 2021, 11.5 psi, 6200rpm shifts.
The right is one pass from last night. 10 PSI, 6600-6700rpm shifts. Same timing on both.

Between the 1/8 and 1/4 It picked up 27.4 mph last year and 30.1 mph last night. It picked up 2.5 additional mph in the last half with 1.5psi less boost and just adding RPM between the shifts.

 

[motorheadmike]

Ugh, fine, I'll order the parts, lol. I was trying to save the week & $800 until this fall but it's a $500 t56 that I have beat mercilessly for 6 years with boarderline too much power so I will relent.
My aftercooler water temp never goes over 100f so the intercooler brick is only able to reject so much heat from the inlet air. It's more than I'd like but not unacceptable in my book.



Yeah the general consensus of the near zero prep was disappointment but I'm still glad I made it out. I had some people say the car was surprisingly fast considering the conditions and the fact that it's a heavy radial car. There was a few floppy tire light bracket cars there that didn't seem to have as much of an issue but I'm not complaining. I didn't spend a ton of time watching other cars run but I think a 12.02 was one of the faster driven to the track passes that was made.

No tire shake this time, It did used to be an issue. I think correcting the instant center, getting the double adjustable rear shocks & removing the slop between my UCA bushing ID and the OD of the housing bushing to UCA bolt eliminated that issue.

I did check tire pressure, I left it at 19 to start the night from where I was last fall (I cut the 1.66 60 on that) and worked down to a 17 on my last pass. I too see abut 0.5-1psi rise every pass. I think my improved time on the last pass is just down to me pedaling it semi ok-ish and not anything related to the tire pressure or suspension tuning. 100% on bad prep being bad. It's hard to tune launch RPM, shock settings or tire pressure in when it won't hook in any situation.



I did not. I should try that next time. I know with my 3.73's it wouldn't have been pretty but the 4.30's might change that.


Also another chapter in RPM is good-

Left is my best pass from 2021, 11.5 psi, 6200rpm shifts.
The right is one pass from last night. 10 PSI, 6600-6700rpm shifts. Same timing on both.

Between the 1/8 and 1/4 It picked up 27.4 mph last year and 30.1 mph last night. It picked up 2.5 additional mph in the last half with 1.5psi less boost and just adding RPM between the shifts.
View attachment 203401 View attachment 203402

Amazing the difference that a 60' time makes, eh?

But, yes - you are still leaving a lot of time on the table by short-shifting it below 7000rpms. Understood that making clean runs makes that near impossible get consistency/feel. And yes, numerically your gear change has opened up a world of possibilities, 1-4 vs. 2-5 down the strip. The torque multiplication factor of the 4.30s and first gear are only an advantage when traction is present. Otherwise you'll find leaving in second to be a benefit/compromise.

I am also, personally, pleased to see how much our cars had in common with respect to power production. Seems like I was on the right track to my goals before... well... you know.

 

[Tony1968]

Amazing the difference that a 60' time makes, eh?

But, yes - you are still leaving a lot of time on the table by short-shifting it below 7000rpms. Understood that making clean runs makes that near impossible get consistency/feel. And yes, numerically your gear change has opened up a world of possibilities, 1-4 vs. 2-5 down the strip. The torque multiplication factor of the 4.30s and first gear are only an advantage when traction is present. Otherwise you'll find leaving in second to be a benefit/compromise.

I am also, personally, pleased to see how much our cars had in common with respect to power production. Seems like I was on the right track to my goals before... well... you know.

My TransAm had T56 with 4.56 rear
I started off in 2nd gear mostly turning my 6 speed into a 5.
Most races are won and lost in first 60'
Old timer i knew used to tell me back in the day it was mostly racing from a stop through the intersection. Around 60 feet. Go figure.