Danny Richie

Hey guys, Just looking for some feedback. I have lots of racing experience but not much in a new Vette with street legal tires. Lots of new things to learn about these cars...

I am running a 2006 Vette with some bolt on's. I have an automatic with a 3800 rpm FTI converter. I am still running the stock 2.56 rear end gear. And I am running some Hoosier drag radials that are 335/30/18's.

Three runs on 3/29: I was running 25 pounds of air pressure and leaving at about 1500 rpms.

60 ft 1.6557
330 ft 4.881
660 ft 7.5052
mph 91.93

60 ft 1.6904
330 ft 4.8738
660 ft 7.4719
mph 92.50

60 ft 1.6493
330 ft 4.8592
660 ft 7.4527
mph 92.88

Two runs on 4/18: I dropped the tire pressure to 24 pounds and again left at about 1500 rpms.

60 ft 1.6893
330 ft 4.8658
660 ft 7.4509
mph 93.38

60 ft 1.6695
330 ft 4.8267
660 ft 7.4044
mph 93.50

All runs were with traction controlled turned back on. Yes, I know I am being cautious.

Wondering what it might take to drop a couple more tenths though.

How low can I drop the air pressure on these drag radials before I twist them off the rim? I'd hate to do that.

And I am pretty sure I can leave harder with this converter but wanted to just make a few clean passes with no problems first. And bringing the rpms up on this converter at the line is is going to take some practice.

Will dropping the rear end gear to a 3.15 or 3.42 make much difference? I hate to give up my 27 to 28 miles per gallon on the highway for only a marginal change.

I just feel like my 60 ft times are not what they could be.

Thoughts?

Joe_G

I'm a manual guy but I'll mention a few things.

You can go down to 15 before you spin the tires on the rim. But you don't want to, less air is more rolling resistance. If you are not spinning you can go up in air but it won't make a huge difference.

Take off traction control and see if you are spinning. Traction control really slows you down if it kicks in, it's dramatic.

Skinnies up front and taking out your passenger seat (along with any other extra loose items for weight control) will give you 1.5 to .2.

Overall your times are very good, that's a low to mid 11 run on very few mods. That converter is treating you very well. I add .4 from ⅛ to ¼ as a rule of thumb.

Others like Theofel or Hoxxoh might chime in with recommendations on the launch, flashing from idle vs. holding at RPM. PM them if they don't see this.

Videos and HP Tuner scans of the runs help a lot if you really get into this. Even an iPhone video from the driver window on a cheap mount can show you a lot of things, in your case, launch RPM and shift points that will allow further refinement.

Notice everything you can see in this video, launch RPM, shift points, etc.

Danny Richie

I'll try a pass with no traction control. On launch the tires turn over a turn or two so I am sure traction control is kicking in some to try to control that.

Okay.

I can data log the runs with EFI Live. I have a wideband in the exhaust as well.

Pretty cool watching that. It's a lot like sitting in my own car from the perspective of everything looks the same. You launch hard though, shift high, and are geared low.

Thanks for the help. It is exactly what I was looking for.

Joe_G

My pleasure.

Since you have EFI live you can scan your car each time and verify shift points, TCC slip, all sorts of things and tweak from there. If you post up scans or screen shots from scans experienced racer/tuners like Hoxxoh will share their experience with you.

I bought that cheap suction cup mount from Best buy and used my iPhone. I wish I'd been doing that all the time. I also wish I could see my shifting hand but couldn't. My car is a convertible so I don't have much room to mount behind me...I could mess around with it.

Danny Richie

Here is one of my runs that my daughter recorded with her notebook.

https://www.youtube.com/watch?v=KoRK...ature=youtu.be

Yep, mine is a convertible too. They let me slide on it at these test and tunes.

Joe_G

⅛ mile is usually more lenient as the top speeds aren't nearly as high.

FYI never tried filming with a notebook, if that's a tablet like a current iPad or iPhone, if you film sideways (with the volume buttons down) it'll be full screen 1080p like my film above.

Danny Richie

And here I am on a by-run: https://www.youtube.com/watch?v=MuVp...ature=youtu.be

Geared a bit high huh?

Danny Richie

I know, but my daughter didn't know that. Better luck next time...

Joe_G

lol me neither until someone gave me the hot tip, just passing it along!

Danny Richie

I asked her afterword, why didn't you turn it over sideways...

The response, "I don't know".

Joe_G

I really love helping people out if I see a little tip to pass along, I often take the opportunity.

My wife tells me to mind my own business, nobody is asking for my help. So I try to balance it out, share info, vs try to not sound like a know it all.

In this case you asked me so I figured I'm good sharing my thoughts!

Joe_G

And by the way, if someone could share a tip with me on a lens that would allow us to zoom in on the boards to see what the times were with our iPhones, that would be a tip well received!

iOS 7 zooms video but it's too grainy.

I like videos like my sig that zoom in on the 60 foot then the time.

Danny Richie

So do you think it is worth the money to drop a gear?

First four gears in the A6 are 4.03, 2.36, 1.53, and 1.15

I think the first four gears in the 6 speed manual are 2.66, 1.78, 1.33, and 1.00

So the A6 Auto has a much wider spaced gear set and the first one is pretty low. So take off isn't bad even with the 2.56 rear end ratio, but it still feels like it takes a while to wind out first gear.

And I wonder how much I'd be hitting that 27 to 28 miles per gallon on the highway if I drop a gear.

Joe_G

Thesubfloor did a comparison 3:42 to 2:56. I think from memory it was about a tenth at his high 9 second level.

I would not do it if I was you.

Pm him to chime in, he is well versed in ways to make a stalled a6 quick.

Danny Richie

Thanks Joe.

I was kind of thinking about a 3.15 gear, but just don't know if it is worth it or not. I'll shoot Thesubfloor a PM.

Danny Richie

thesubfloor has exceeded their stored private messages quota and cannot accept further messages until they clear some space.

Oooops....

Joe_G

I don't think it is cost effective, but I emailed Christopher (subfloor) to chime in.

Skinnies and seat out are a much cheaper .1 to .15. Gears would be way down the mod list on your car in my opinion, there is lower hanging fruit.

You could get the benefit of gears with shorter drag radials like 315/30/17 like I run. That is much cheaper and the lighter weight will help also. You will need to adjust your shift points for shorter tires.

That said you have more in your car by playing with launch technique before you spend any more money. Make sure you are shifting at redline also on your scans, that tall radial might be causing you to short shift.

subfloor@centurytrans

I'll try to address several of your questions all in one shot.

As for gears, they'll make the car feel a LOT more responsive on the street but will only knock less than a tenth off your ET because of having to make an extra shift. With the 2.56 diff you're crossing the traps in 3rd but it'll be in 4th if you went to either 3.15s or 3.42s. The other added benefit however is that it'll take up a lot of the "mushiness" I'm pretty sure you're having with the 3800 stall. I'm running a Yank SS4000 with a C6 Z06 3.42 diff and the car is still very streetable. I did however go back to 2.56s once (when I cracked the differential case of my 3.42s) and definitely didn't like how loose the converter felt on the street.

As Joe mentioned, going to a 315/35/17 will help a lot because they're both lighter and shorter tires. I've switched over to an even wider 335/35/17 Hoosier but was still able to cut a best 60ft time of 1.36 with the 315s. I cut a 1.35 60ft in my avatar picture.

Running it with TC on is definitely hurting both your ET and 60ft and as long as you've done a decent burnout you shouldn't have to worry about losing traction. The other problem with traction control is that it only comes on as necessary so if you're looking to bracket race and hence run the car as consistently as possible, you definitely don't want it on.

As for air pressure, I've found that I hook the best when I'm running 18.75psi. The general rule of thumb is to run as much air pressure as possible to reduce rolling resistance at the top end so you might get away with running more than that. You might at least want to experiment a little to see what your car likes.

It's hard to tell from your timeslips how well the car is hooking but with TC on I'm guessing you're not getting much (if any) slippage off the line. If you do decide to finally turn it off, the upside is that your car will be considerably faster but the downside is that it'll be less forgiving if the track prep isn't great, if you're not running the proper air pressure in your tires or didn't do a proper burnout.

It's hard to say what the best launch RPM would be with that converter but I think you should definitely try something higher like 2000RPM which is what I usually launch my car at. Even though I could easily launch mine a lot higher, I've found that with my 2-step set to that RPM I cut the best lights.

If you decide to get into this hard core, I'd definitely recommend buying the MSD 8733 2-step as it makes staging the car and bringing it up to the desired launch RPM pretty much a no-brainer. All I do is pre-stage the car, bump it forward only just enough to light the bottom bulb, step on the gas just enough until the engine hits the launch RPM and then go. Without the 2-step it was more of a challenge to get the car staged properly and get it up to the desired launch RPM all at the same time.

A workaround to being able to always leave at the same RPM (but without a 2-step) is to pre-stage the car, step on the gas enough to hit your target RPM and then while still keeping it there, bump forward until you light the second bulb. This is a lot easier than staging the car completely and then bringing up the RPM.

As for staging, shallow staging vs regular staging can knock off up to a full tenth off your ET because you're kinda getting a bit of a running start when the car launches.

A lot of people with A6s suggest using the paddles to shift the car manually while doing their burnouts but I tried that several times and found it didn't work nearly as well as just letting it shift itself. My burnouts are typically around 6 seconds long (based on my scans) and what I do is hit the tires hard initially to get them spinning (which is easy if you've got a linelock but still doable without one) wait until I start to see smoke and then actually accelerate coming out of the box. Believe it or not I actually hit speeds upwards of 130 during my burnout.

Scanning your passes will also definitely help as it's highly likely that one or more of your shift points isn't anywhere close to optimal.

That covers everything I can think of for now but feel free to ask more questions if you have them.

Christopher

Danny Richie

Wow, what a wealth of information. I will follow these suggestions and let you guys know how things work out.

Thanks!

Mike Beck

I never saw that before. Shallow Staging vs. Regular Staging......

Shallow Staging (Pre Stage & Stage bulbs both on) will give you more rollout, better ET, slower R/T.

Deep Staging (Normal Staging to me!) will give you less rollout, slower ET (I lose .08), and a better R/T.

Now, in Bracket Racing the only thing that matters is R/T. The ET is kinda meaningless, just needs to be predictable.