Thanks for the heads-up Bobby. I'm assuming that "more gear" means a taller FD.

If that magic number is close to accurate, then with ideal gearing a trap of 103.63 would result in an ET of 12.882. That means I would have to cut something in the neighborhood of a 1.5 sixty foot to get a 12.8 at that speed.

On the flip side, according to that same constant, the ideal trap speed for my ET would be a 98 flat.

I definitely don't think it's very accurate; this isn't a high stall A4 fbody after all. But, I think it does reinforce my point that these cars might be over-geared.

Actually, this piques my interest. I'm gonna throw together a spreadsheet that demonstrates this magic number.

 

Ok, I threw together a quick spreadsheet that calculates a number of figures for some 6MT and 5AT guys. There were a couple of forced induction cars thrown into the mix.

For the 5AT guys, I included Nismo G(NA coupe), ma_sha1(s/c g35X), Crappyday(NA coupe), FL-G35(s/c coupe), and bosssho(NA coupe).

For the 6MT guys, I included myself(NA sedan), ttrank(TT sedan), ShAdY908 (TT coupe?), jouvert00 (NA coupe?), BobbyD (NA sedan), and ZXIMan (NA sedan).

Everybody that I included was in the 13's, except for Crappyday(with a low 14.1), and every one of them cut a 2.1 sixty foot or better. This spreadsheet shows each person's transmission, NA/FI, ET and Trap, and Sixty foot. Additionally, each person's GF is calculated, along with the GF margin, Ideal ET, Ideal MPH, and the actual ET Margin and MPH Margin.

Let me explain the terms. GF is what I'm calling the Gear Factor. The ideal gear factor, according to the information BobbyD posted, is 1335. I ended up finding a reference to this information here: http://www.flowtechinduction.com/technical.htm#drag

The Gear Factor column shows the person's actual gear factor, which is ET multiplied by MPH. Next is "GF Margin", which is the difference between this alleged ideal gear factor versus the actual gear factor. Next follows the Ideal ET, which what the person should run if using the ideal gear factor. After that is the Ideal Margin, which is what the person should be trapping at his actual ET when using the ideal gear factor. Next is the ET Margin, which shows the margin between the actual ET and the Ideal ET. And last is the MPH Margin, which shows how must faster(or slower) the person's actual trap is versus the ideal trap.

In every case, the actual gear factors exceeded the ideal gear factors. If this whole gear factor business is legit, then that means our cars are overgeared. On average, the gear factor for the 5AT's was 1388, with a margin of 53. On average, the gear factor for the 6MT's was 1426, with a margin of 91.

The average 5AT was running 5 tenths short of ideal, and 3.87mph faster than ideal. The average 6MT was running 8 tenths short of ideal, and 6.97mph faster than ideal.

For those that are interested, I have attached the spreadsheet(zipped because of file extension), and an screenshot of the spreadsheet for those that don't want to download the excel file.

This might all be useless analysis. After all, this magical gear factor is heavily dependent on traction. If a guy cuts a 1.8, his actual gear factor will be much closer to ideal than if e cuts a 2.0. That's the reason I tried to limit my sampling to those with 2.1 sixty foots or better.

Some one might notice the disparity across the launches. One might argue that the 5ATs are closer to the ideal gear factor because of lower sixty foots. Well, for this sampling, the average 60 foot for the 5AT's was a 2.061, versus an average of 2.097 for the 6MT guys.

Like I said in the previous post, I don't think this magical factor of 1335 is entirely accurate. But by performing this analysis, I have proven that the underscored my belief that the 6MT's are overgeared versus the 5AT's.

 

I have to agree that the gearing is almost ideal, for 6MT anyways. A taller tire and slightly more gear combined should help. The general consesus is to go through the traps at peak hp or 200-400 rpms over that. Your car is capable of 1.8-1.9 60' foots with the right technique. After watching some of your videos, drag radials and 6000 rpms launches should result in much better times. My suggestion is to work on your launch and you'll be rewarded.
I would try more tire pressure or less heat in the tires depending on the track. Bogging down really kills the elapsed time.

 

Thanks for the tips Bobby. I'm still learning the the DR's. The first 40 some-odd passes don't count IMO because I couldn't do a burnout. I could only spin them over a few times, so I wasn't getting nearly the benefit from the tires that I could have.

I only have 11 passes on these tires now that I can heat them up. The last time out wasn't very effective, because I didn't really know my launch rpms(damned protree). I started the night out with the tires at 19psi cold, then dropped them to 16psi semi-warm after 3 passes. I've only tried slipping the clutch once, and I really bogged on that run, but I don't know my launch rpms for that run.

As for revs and power, I make 261.9hp at 6 grand, and 264.08 at 6340rpms. I cross the line in 4th at about 6200, so I'm right in the middle of my peak hp.

 

Next time out, pay no attention to the tree and focus on the launch and you're technique. I've watched many single turbo Supras sit at the line to boost and get a they have a 5 second reaction time. Who cares?

I suggest revving up to about 5000rpms, slip the clutch to feel the car rolling (don't add additional gas), and then release the clutch very quickly while feeding in the gas hard. Dumping the clutch won't work with the DRs. You'll either spin too much, bog, or both. You need to the lurching to a minimum.

The DRs need to be warm, but not too warm and definitely not cold. You should start out at 18psi and see how that does. DRs are safe to about 14psi. Use no more the 22psi. When you've gotten into the lower 1.9s, then you know you have the temp and psi down.

 

Well, it looks like I'm going back to the track again this Sunday. The forecast calls for a high of 91, so that means this place will be in the mid to upper nineties in the afternoon sun. I'm not looking to improve my PB, and if I do, it may only be by one or two hundredths.

I'm going more for the launching practice than anything else, and I'm also curious to see how much I can pick up in the big end with my stock airbox.

Back in the Fall/Winter of 05, when I was mostly stock, I was picking up about 21.9mph up top. I didn't hit the 1/4 track again until the following August(06), with successive trips in October and November. By that time I had upgraded the clutch and flywheel, and put in the stillen airbox. From that point forward, I was struggling to pick up 21mph flat in the second half, unless I missed a shift. For some reason if I missed a shift I might pick up 24 or even 25mph.

After I got the DR's and the ecu+tune, I was back to picking up between 21 and 21.5 mph. Then the last trip out(when it was cool), I picked up 22.5mph on my only run with my stock airbox.

I have no idea how it will behave in the heat.

 

I too will be curious to see how the stock airbox behaves. Why did you swap the intakes? Driveabily wise, which do you prefer?

 

No real reason, just a hunch. I knew some mod introduced into the car was hurting it's top-end. The airbox was simply the easiest to return to stock, so it seemed like a logical starting point.

Honestly I can't feel a difference in day-to-day driving. And I didn't see a difference on the dyno. I think the difference may only be felt when speeds exceed maybe 60mph(just a figure off the top of my head). I do miss the sound though.

I do have to say that my car pulls remarkably well up top now, after the ecu and tune, even in the heat. In 100 degree weather it feels like it pulls beyond 85/90 like my car did stock at 70/75 in the heat.

 

Did you make it out?

 

Trey when was the last time u have done alignment to the car?
If u have DRs u should brake in to very low 2s or even 1.9s 60ft. Recently i did my alignemnt, and i had -2.0 camber in the rear and that explained why i could't do lower than 2.2 on street tires. Too bad i am lowered and don't want to buy a camber kit to fix that problem, handling makes up for it.

As far as CL doing 13.5 with 2.0x and trapping 100mph sounds the guy was BSing.

 

Nope - it turns out there was going to be some big event at the track with which the regular t&t would be inter-mixed. We checked with some people that attended last year, and each said he could get very few runs in. That, coupled with a doubling of the gate-fees convinced us to stay home.

However, we will be going back to an 1/8th mile track this Saturday.

 

It's been about 15 months since my last alignment, and the only changes since then include my stillen sways. At my last trip to the track(1/8th mile), I finally hit a few low 2.0's and a couple of high 1.9's.

But don't underestimate how difficult this is to do.

 

Negative rear camber does negatively influence grip on the launch, but the IRS is inherently a bad design for launching, even if you put camber at 0. There are lots of 350Zs with far more camber running DRs and slicks with no issues grabbing 1.7-low 1.9 60 foots. I think Trey's launching problems are a combination of inexperience with DRs, the initial issues with the burnout, his light flywheel, and traction at the track he runs at.

 

Slow shifting on your part and honda/acuras are actually geared pretty good. Way better then are cars. Our cars are geared like dirt

 

I'm not exactly a slow shifter...