LS2/T56/240Z 1/8 mile 8/23/13 Lawrenceburg, TN

[RebekahsZ]

I'm sitting in the Dairy Queen parking lot breaking my diet watching all the high school kids celebrate a football victory after making about 15-20 passes at TnT. First night on the 26x9x15 Hoosier drag slicks. Hot, humid night with bad DAs. Ran anywhere from 7.08 to 7.35, mostly in the mid 7.20s with 1.6 60's. spent most of the night trying to fond some traction. This car used to hook great but I've evidently lost my mojo. Finished the night getting least spinning with tire pressures down to 11psi. Played with the two step a bunch and finally settled on 3200rpm. A learning night but nothing broke and I finished the night hot-lapping working on my light. I suck. Only did one .600 but my best was a couple of .525s. Have settled on a setup that seems to be limited by my 250# autocross springs. Consensus is that they are too stiff. Hoping to go to Jakes Dragstrip in Moulton,AL next Saturday where I have set my 1.4 60' times. Eager to burn these tires up and get back to MTs. Oh, I got bottled by a truck that ran 7.30s all night then cut a 6.55 when he lined up against me. That was funny-I beat him off the line by a mile then he just blew past me. I did my fair share of dealing out pain, so it was a good night. So happy with the fuel injection-seems everybody was fighting jets with the bad air, and I just hot-lapped away. First car in the staging lanes and last to leave the track. Representing!

[Zfan1]

Sounds like fun, win or lose.  I run a 250 lb 10" spring out back and it works well. Maybe a 200-225 lb spring will work better for you.  Have you ever tried a Mickey Thompson drag radial, I run a 255/60-15 out back and love them.

[RebekahsZ]

Zfan-you solid axle?

[RebekahsZ]

My buddy gets great weight transfer with stock spring that are,what, like 100#? I think jnjdragracing and 1QuickZ are on stock springs too. I think I've found the best I'm gonna have with the current setup. Next year I will try to get double adjustable konis. I can get an initial hook by lowering my 2-step but as soon as the two step clicks off, the tires spin just off engine torque as soon as the rpm is unrestrained. It is like I need some sort of progressive controller ( I know that is supposed to be the driver).. The porpoising I see on video seems to be from a double-hook. Hook (weight transfers back and load springs)-spin (weight transfers forward)-hook (weight transfers back, and get down the track).

[RebekahsZ]

I spent the afternoon watching videos. It looks like the weight transfer off the rear wheels is the RESULT of spinning, not the cause of it. If I try to time the spinning, it times out to the instant the 2-step clicks off. So, Saturday night the plan is to depress the gas pedal not to the floor, but only to the point the 2-step rpm is exceeded. Then delay going to the floor till after the clutch is out, on a one count. It seems that it takes one second to the second hook in the double hook I now have. So, maybe I can have the benefits of a 2-step yet not have it switch off so abruptly causing spin.

[Zfan1]

Nope, 300ZXT  3.70 rear end, with CV's and Modern Motorsport stub axles.  I tried 200 lb springs and got to much squat.

[RebekahsZ]

I think a lot of my trouble is having the T56 instead of an auto. Been dreaming about building a second car that is purpose built for 1/8-mile drag. A buddy is sending me the info on a clean 260z that he has found. Would have to be TOTALLY rust free, so not likely to follow thru with this. I would strip it TOTALLY, lighten it, fiberglass fenders, doors, hood and hatch. Cheap paint job. Two seats (my family enjoys a joy-ride). 8.50 cage, wheelie bars. Glass windshield, but lexan elsewhere. narrowed 9", four bar, tubbed. Cell, dual pump for wet nitrous system. Fender dump headers. Not sure on transmission, but likely a Powerglide mated to a variety of stock junkyard motors, either 4.8, 5.3, 6.0 or 6.2 based on what I could get cheap and just spray the hello out of whatever motor I got. Swap intake and pan and throw it in and treat it badly. Would just swap intake to LS1 version unless I stumbled across a cheap FAST. Would dzus fastener everything on it that I could and focus the build on ease of servicing major assemblies. Keep ride height high to clear crappy return tracks and hard wheelie landings. Stock front end with adjustable droop straps. Tach, oil pressure, fuel pressure and temps only. Goal would be to run in a motor only 7.0 bracket class starting as a foot brake then moving up to a Pro class. Save spray for grudge nights with plan of running in low 5s. The compromises I've made to drag race a car that has more in common with a road race car are getting pretty tedious. And one autocross a month is just too little to justify the compromises. Although I hope Matt Isbell will have me to AMP again in the spring, and I'll open the season with a trip to Arkansas for their solo II weekend at Blytheville again. Driving car to work this week since I didn't break it this weekend at the track for a change. Put about an hour on it tonight running errands. My buddy with the SBC/T350 280z broke an axle u-joint last night and destroyed the yoke on his axle, so he is down for a couple weeks until he gets another axle and puts some better u-joints in it. I may be loaning him a diff, since he says his sounds terrible since the axle broke.

[RebekahsZ]

With regard to tire movement under load: video also showed that the tire is still moving forward in the wheel well before the car moves forward. This is in spite of the aluminum LCA bushings that I thought would help. While the tire isn't hitting the fender since I trimmed the fender, there is no way that I could ever go up to 27" or 28" tires, which is my hope if I nitrous next year. But, there was significant improvement in vehicle stability at the fast end of the track. It could be from the Hoosiers, but I don't think so, because I ran those down to 11psi and it still ran straighter. So it wasn't for nothing, although I now remember why I removed the aluminum bushings: they make your fillings fall out when you hit the smallest joint in the pavement.

[SUNNY Z]

I noticed some big end stability in my Hoosier QTPs over the ET drags.

[RebekahsZ]

Sent an email to MT and Hoosier. Haven't heard back from Hoosier, but MT tech said with my weight and hp, my tires should be aired to 6-12 psi. 6psi! That's like driving on a dish rag. They said that the tread "peeling" was normal but undesireable. Said that when that happens, I should just swap the tires side-to-side to spin it off by reversing the direction of tire rotation. I'm learning.

[RebekahsZ]

Just looked at timeslips. An even 20 passes. Best light: .512; best 60': 1.566; best ET: 7.13; best mph: 100. A lot of crappy driving and poor traction otherwise. That is 48 full throttle passes in two weeks without a motor or powertrain breakage running thru three gears a pass. Knock on wood-going back to Lawrenceburg Friday-I need another DQ Blizzard! Focus this trip is part throttle launches off the two-step and timing the lights (as always). Gotta go thru my 3.70 diff tomorrow night to loan to Dwight and Terry so I have somebody to race. Hopefully I can press in some axle u-joints for them Wed so they can reassemble on Thurs and join me at the track on Friday. Watch 'em beat me!

Edited August 27, 2013 by RebekahsZ

[RebekahsZ]

Just disassembled and inspected my spare open 3.70 diff, retorqued ring gear and carrier yoke bolts with red locktite, installed new cover gasket.  All to help "loan" it to my buddy to get my competition's 280z back on the track.  Hope to press in some new u-joints for him tomorrow night.  Don't you guys wanna come race (?)-I'll even fix your cars!  Love a close race.

[zgeezer]

Just disassembled and inspected my spare open 3.70 diff, retorqued ring gear and carrier yoke bolts with red locktite, installed new cover gasket.  All to help "loan" it to my buddy to get my competition's 280z back on the track.  Hope to press in some new u-joints for him tomorrow night.  Don't you guys wanna come race (?)-I'll even fix your cars!  Love a close race.

I look forward to reading about your progress.  Have you considered changing out the 3.70 for a 3.54 or 3.36?  Here's a a post and several replies off of ls1tech.com regarding 2:7?:1 r&p in comparison to 3:73 and such.  Scroll down to about post #22-24 for time and e.t. comparisons. Look here.http://ls1tech.com/forums/gears-axles/3260-considering-going-3-73-gears-2-73s-crazy.html

 

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[RebekahsZ]

How fun.  I was just working with a gearing calculator earlier tonight because I am going Saturday to pick up a parts car that I hope has a 3.36 R200 in it-that's a rare diff.  The problem I have is in having a car that I want to do EVERYTHING with.  I'm frequently running out of 2d gear autocrossing and I'm running out of 3rd gear in the 1/8th-mile.  I want to be close to red-line (factory rev-limiter), which I believe is at 6200rpm.  My computer tuner (who builds open road top speed LS corvettes) discouraged me from increasing the rev-limiter limit in order to keep the motor together.  So, I'm playing with all the gear/tire/speed calculators.  With my current power, the best I have done is 100mph in the 1/8th and 126 in the 1/4.  With a 150 shot of NO2, I should be at about 108 in the 1/8th and 135 in the 1/4.

 

The 3.90/26 tire combo is great for 1/4-mile (4th gear), but sucks for 1/8th (3rd gear).  Way too short for 1/8 gear-on rev limiter before 600'.

The 3.54/26 tire combo is just a hair too short for 3rd gear 1/8-mile.  On rev limiter at about 640' but when it comes on it is like car is hitting brakes.

The 3.54/26 should be pretty good in the 1/4 with or without nitrous.

The 3.36/26 combo should be perfect for 1/8-mile crossing line at 6200 rpm at 100mph but the rpms are too low for 1/4.

 

The 3.54/28 tire combo should be perfect for 1/8-mile:  6000rpm at 100mph, but is lugging thru the traps in the 1/4th.

The 3.36/28 tire combo is good for nitrous (est 108mph), but the rpms are too low in the 1/8th at 100mph (n/a).

 

One of my projects this winter is to clearance the rear wheelwells and flare them to accommodate 26X10s for the 1/4 and 28X10.5s for the 1/8th.  That way I'm just swapping tires and not diffs.  I feel like I'm doing a pretty good job of wringing 100% out of this car.  And, every blue moon I drive it well enough to deserve it.  I hate to cut it, but it has been cut before to remove rust, so the car is only worth the fun that it gives us.

 

I really think for autocrossing, I'd do better with the 3.36 since most of those tires are only 24-26" tall (low profile).  I'm going from 9" wide rear tires to 10" rear tires - I'm traction limited, not power limited.  And this motor is totally stock!!  I will be gaining about 100# this winter between the rollbar and the bellhousing.  Tossing around a cam kit...but I'm not sure that will really help me-maybe just move my rpm band around some without adding real power.

 

BTW-most of the discussion on LS1tech that you sent me was for auto trans cars.  If your axle has too high of a gear, you can make the tranny slip to cover it up.

Edited October 7, 2013 by RebekahsZ