After an unsuccessful attempt at mounting 305/35/20 on OEM wheels (the car freaked out), I managed to get a set of 305/35/19 on 19" oem wheels.

Tire: Mickey Thompson 305/35/19
Wheel: oem 19x9.5 Tamana

As you might imagine the hook great. Actually, they have more bite than the car has torque. Well, at least at 1800rpm. After a burnout, the tire is so sticky, the car will not break the tires lose and the trans will stall around 1800rpm and just sit there. Trust me, an 1800rpm launch is not breath taking. However, the car will run 1.87-1.88 60' all day long...takes the variation out of the mix

Next step is to figure out a way around this issue or spray the car off the line

Here are a few pictures:

 

That's sweet! Do you know if the XKR has the same rear calipers and disks as the XFR? I have a 2010 XFR, that I'm looking to put drag radials on, but I'd like to avoid the stock 20" size, if at all possible. My 60' times are awful, but I'm hoping that some drag radials and a lot more practice will help that. Out of curiosity, how are you launching the car? Do you leave traction control enabled?

 

Thanks I'm not sure if the XFR has the same setup as the XKR...I'm sure someone here will chime in soon. Either way, you could just get a set of oem 19" wheels made for an XFR - I got mine from a great place on eBay.

Trust me, you do not want the 20" DRs.

The DRs will fix your 60' times - seriously, unless I/we can get around the brake boost / 1800rpm stall issue, you won't even need practice.

I leave with TRAC completely off.

1) burnout
2) foot on brake
3) right foot right to the ground, WOT
4) leave

 

Isn't 305 a little too wide for 9.5" wide wheel?

 

Thanks for the info...you're blazing a completely new trail here on this JF forum I think! Did you happen to get a video?

I'm a drag racing noob, but I think ideally that a drag car's torque converter is designed to utilize the engine's peak torque to avoid stalling, or at least move it to a higher rpm where it won't be as much of a problem. For the 5L S/C that would be at least above 2500 rpm on a stock engine, and maybe 4500 or so on an ECU flashed one. How expensive would it be to swap torque converters, and would that cause any problems for daily driving?

Btw, you wouldn't have that issue if you switch to road racing!

Bruce

 

if youre loading the convertor against the foor brake youll not get as high a stall as avail from a torque convertor. If you stomp the gas pedal when the last amber lights(adjust for best light) the convertor will "flash" higher than holding the brake and bringing the car to 1800rpm. that is unless youre already doing this

 

Mike - yup, 305's are a bit wide for a 9.5" wheel...but I was positive they would fit and they at least look close to the fronts.

Bruce, ha...luckily there aren't *too* many mods for this car. I'm trying to be good, unlike with the Supra...but you know how that goes

I have no idea if it's even possible to swap the converter in this car. Def not something I would do, I would guess it would be completely custom, if even possible. If I really get the itch, I'll spray a tiny shot at the line 'till 3500rpm or so Haha...true about road racing and I really do want to get into it soon. But Atco is so close to me and at this point, I'm basically trying to get the right tune and verify that the tune/mods are actually making power at the track. Road course is next and will def be leaning on you for advice.

Brutal, yeah I follow...I did that the first pass on Friday night, no difference. 60's were identical down to thousands of a second.

Once the car traps near 120 and runs into the 11s...I'll call it a day

Jay

 

no mods will ever work until the tune is spot on. So even if you spray it ,it will induce the TQ limiter in the TCU. The first things these cars need is someone to expose the ECU and the TQ limiters. Then we can tune around them for whatever we want. I just started to do more logging and it seems the more load I put on the engine the more the TCU pokes in the TQ limiter. Example, If I get a good hard launch without spin (Track Bite on my street) The car feels lugged down and I see my TPS and other gauges being reduced. Now with some wheel spin all gauges stay pegged.

Jay: I want to see if your wheels fit to prove this thereoy if I can?

 

Hey man...sorry, I owe you a call back. I'm free most of the day (exception mid afternoon) and this evening to talk.

Absolutely, try out the wheels any time you want.

 

Well i see from your sig now you have played with some serious hp. You know a convertor builder for racing/street can open the convertor and raise the stall by changing the vane angles and rewelding back together. You need to call some comapnies and ask. You might what to source 1 stocker first and have it done before hand so it can be a plug and play. Level10 trans, ipt both come to mind. You may also be able to source another convertor for another model like benz, bmw that uses same trans but alittle more stall. Keeping in mind that stall is subjective to weight, and torque output. More output= higher stall with same convertor

 

Loving this thread! Post any times you get with those slicks... Dying to see your 0-60 and 1/4!

Skeeter

 

Tomorrow I will be hitting the dno again, this time it will be a dynojet to see ifthe numbers vary much more as Icarus has. I was also thinking about adding some 100 unleaded cam2 and removing the air filters to see if there was any gain there just for research purposes. The weather will be against me as it will be 85 and muggy. If you guys have not seen the previous dyno videoes please go look on my youtube page, username is usasupra23

 

Brutal - Ha, yup...i've dealt a little bit in this area. Your post is right on. But I'm not (keep telling myself), I'm not going to mess with the car to that degree, re: swapping converters, etc.

Skeeter...yeah, the car runs consistant 12.25-12.31 time after time now. I have a regression calc that figures out 0-60 based on the splits of your 1/4 mile. Car is running 0-60 in 4.04sec

 

I just revisted the dyno again and will be uploading lots of data and video on YouTube from all angles and such. Lets just say ,even after my mods and tuning the Jags still have much more in them to be unleashed.
The only documented process I need to finish is to meet Philly Single at the track and lay down some sub 11.50 ET's.