Drag newby, please help estimate 1/4 mile from 1/8 mile times
 

I just went to a drag stip for the 1st time yesterday with my '06 IS350, and got much better times than I was even hoping for. Acording to Dragtimes.com, my 1/8 mile times were quicker than all but Roro's, but his IS350 has a stripped interior and a supercharger. Anyway, since all the 1/4 mile tracks around are closed for at least a month due to winter, I would like to hear your input about what my 1/4 mile times might be based on my 1/8 mile times.

Below are my best 4 runs:

1/8 mile ET -- 1/8 mile MPH ---- 60 Foot
8.534 -------------- 83.19 ----------------- 2.043
8.575 -------------- 83.23 ----------------- 2.075
8.572 -------------- 82.82 ----------------- 2.070
8.596 -------------- 83.05 ----------------- 2.067

Below are the top 10 registered times for IS350's on Dragtimes.com:

.1/4 Mile ET -- 1/4 Mile MPH -- 1/8 Mile ET -- 1/8 Mile MPH -- 0-60 Foot ET -- CarYearDriver
1)13.140 --------- 105.840 -------- 8.474 -------- 84.500 ---------- 1.996 ------ Lexus IS350 Sport2006 RoRo
2)13.362 --------- 104.640 -------- 8.685 -------- 83.370 ---------- 2.083 ------ Lexus IS350 Sport Package2006 David H.
3)13.382 --------- 105.060 -------- 8.639 -------- 83.210 ---------- 2.039 ------ Lexus IS350 Sport Package2006 Cole
4)13.405 --------- 104.340 -------- 8.725 -------- 83.180 ---------- 2.099 ------ Lexus IS350 Sport Package2006 David H.
5)13.407 --------- 103.900 -------- 8.712 -------- 83.020 ---------- 2.102 ------ Lexus IS350 Sport Package2006 David H.
6)13.440 --------- 105.140 -------- 8.680 -------- 83.420 ---------- 2.090 ------ Lexus IS350 Sport Package2006 Cole
7)13.474 --------- 103.500 -------- 8.709 -------- 82.460 ---------- 2.024 ------ Lexus IS350 Sport Package2006 Cole
8)13.491 --------- 103.800 -------- 8.746 -------- 83.000 ---------- 2.136 ------ Lexus IS350 Luxury Package2006 TT
9)13.531 --------- 103.160 -------- 8.761 -------- 82.170 ---------- 2.087 ------ Lexus IS350 Sport Package2006 Cole
10)13.542 -------- 104.900 -------- 8.710 -------- 81.840 ---------- 2.117 ------ Lexus IS350 Sport Package2006 Cole

When I look at the difference between 1/4 mile and 1/8 mile times and trap speeds from the 10 listed above (throwing out the best and worst cases for each senario), I get the following results:

Using diff between !/4 and 1/8: 13.211 - 13.304 sec
Using diff between 1/4 and 60': 13.322 - 13.467 sec
Using diff between trap speeds: 104.07 - 105.04 mph

My intuition says that the 60' times wouldn't be as significant as the 1/8 mile times since they are more significantly impacted by traction issues (which I had). I also think they are less significant since weight is more significant at the beginning of the run than it is at the end of the run.

BTW, I am a 201 lbs guy, and only removed the stuff in my trunk (spare tire, tools, etc.), and had a little over 1/4 tank of gas. My gut feeling is that imy times would have been in the 13.2 range (hopefully low in the range). Please let me know what you think ...

I think it's impossible to guesstimate 1/4 mile times based on 1/8 mile times. Just be patient and wait for the track to open for the full 1/4 mile run. Reason I say this is because my best 1/8 run was not my best 1/4 run. Too many variables to consider here. Just my .02 You obviously have a very good running car and with your 200+lbs and hitting consistent 8.5's I would have to guesstimate a 13.2ish with a 2.0x 60' time. Get some drag radials on that baby and let Troy drive it for a sub 2.0 60' time and I foresee some possible high 12's! Just make sure you get to the track when they first open up for some cooler weather conditions.

Actually, I did have Troy drive my car for a couple runs since he weighs ~50 lbs less than me. However, he was hesitant about doing the massive burnouts that I was doing, so he was only able to get into the 8.6's with my car.

Something else I've been thinking about is that my car has lower performance tires than stock (Dunlop Direzzas), which I think probably hurt my launches. I was only able to launch at about 1K RPMs without spinning them. On the other hand, my rear tires are lower profile than stock which gives it about 3.5% lower gearing (yet smaller contact patch). Because of these 2 factors, I think that my short track times would suffer from the traction, but my long track times would benefit from the lower gearing.

I agree that there are a lot of variables at play, but I have this strong feeling that my 1/4 mile times would be even better than my 1/8 mile times due to the "variables" (higher weight, lower gearing, and lower traction).

Only one way to find out. Wait and see! BTW..are your new wheels and tires lighter than stock? Also with the lower gearing I would think your 1/8 would better than your 1/4. Reason I say that is your 1/8 mph's are not as fast as the 8.5's would imply. There are 1/8 mile times of 8.6's and 8.7's with 83+ mph runs, which kinda show that the lower gearing is starting to have a negative affect.

I disagree about the gearing having a negative efffect anywhere. I think the gearing just compensated for my reduced traction and high weight once I got going. The gearing advantage would continue throughout the whole 1/4 mile since they would not require any extra gear changes.

I don't have any idea how my wheels / tires compare in weight to stocks. My front tires are new OEMs.

I did notice you had quite a bit of wheel spin off the line in your video. Sounds like the obvious route for you to go next is some sticky tires, but I can't find any drag radials that would fit in the 18" size. May wanna consider some 17" wheels this season with some sticky tires.

I agree that a different wheel / tire combo would be much better for my drag times, but I'm really not all that interested in drag racing for entertainment. I would compare the experience more closely to dyno testing than racing on a road course (actually fun). I will certainly go to the 1/4 mile track when it opens, but I doubt I will ever go again.

I did talk to a buiddy of mine that has a bunch of lite weight 16" wheels that he could loan me. If I could find some used 16" drag radials, I might consider that. I think they would be much more productive than 17's considering the gearing advantage.

**** it Gernby. Time for drag radials :)

haha we got Gernby hooked now. hehe he didn't seem that into dragging his car at first. Now i bet I see him at every drag night.

actually gernby there's an 1/8th mile in denton that might be closer to you.

Thursdays nights at kennedale are street cars only so it's kind of a fun night to go out there.

oh yea, let me know if you find out anything about feb 9th at ennis. I'll meet you out there.

Would the 16" 3rd gen rx-7 wheels fit the rear?

Unless I do more extensive mods, I really doubt I'll ever go to another 1/8 mile drag stip, and I think I'll only go to a 1/4 mile strip once. I'm much more "hooked" on the curvy stuff. Here's a few videos that I recorded in my previous car (S2000) on the curvy's. Texas World Speedway in College Station, TX; Motor Sport Ranch south of Fort Worth; BMW autocross in Mineral Wells, TX. This is truly entertaining, and worthy of expensive tire / wheel combos! I bought many sets of R compound tires for my S2000, and plan to do the same for my IS350's stock wheels.

I don't know anything about the RX7 wheels. I would epxect them to clear the rear brake calipers, but I have no idea if they would rub anywhere else, or be wide enough to support suitable tires for the IS350.

The reason why I'm confident 16" wheels would fit on the rear is because the "standard" IS350 wheels are 17", and the rear brakes are 1" smaller than the fronts.

Very nice time, I'd guess your car is a 13.2 car as well. I think your 1/4 time will be better than your 1/8 time but your MPH won't be as high due to the fact that your have lower gearing. Our car doesn't make much torque but the HP is there so it'll kick in once the torque got the car going. I think lower gearing only going to have negative impact once you take the car onto the highway, for the 1/4 track you'll be okay. If you can fit 16" in there with slick I don't see any reason why that car won't do 12s unless the tranny couldn't handle the power.

I spent some time putting together an accelleration chart from 5 MPH to 115 MPH to show how the lower gearing changed things for me. I used the exported torque data from my last dyno session, and combined it with lobuxracer's gearing spreadsheet. The benefits are obvious, but I can see how the trap speeds would be effected at certain distances since there will be some speeds that the stock gearing will start to catch up to the lower geared car. However, the stock car will never quite catch up before the lower geared car starts to pull away again.

Here's another version that shows where the advantages and disadvantages fall more clearly.