I posted this over at TT. This is simply a cut and paste of that post.
Today I mounted a set of P275/60-17s to a set of stock off-road Titan wheels. The tires were just Goodyear Wranglers (like what I have on the stock 18" wheels that came with the truck). These tires are 29" tall when mounted and the 18" stockers were 32.5" tall. So the diameter decrease and the reduced rollout helped a litte with overall gearing. Traction started getting a little iffy, an occassional squeal, but they never "lit up" from a 1500-2000 rpm launch, stomp the throttle all the way to the floor. No problems with traction on nitrous. The truck now shifts into 4th gear with or without the nitrous. The bad thing is that it shifts rather lethargically and seemingly with some lash. I don't think the transmission is handling that well. Of interest there is that it is shifting into 4th at 5500 rpm instead of ~6100 like the other two shifts.
An interesting note for the VDC: at about 30mph with the VDC on, the slip light would flash just driving. With the VDC turned off I had no issues. It didn't feel like the brakes were being applied to the rear or anything but I wasn't going to try and make a run with the slip light going off, either. So there you have it, you have to run 4 same-height tires for the VDC to work OK. Or you can dive with it off.
The weather was humid (it rained on us almost all the way to a surprisingly dry track) and temps were in the low 70s. Last time I ran the 14.02 previous best on nitrous, the temps were in the high 50s. With the constant threat of rain, I didn't make any baseline passes with the stock 18" wheels and tires. I ran two identical 14.85s with just the shorter tires, an improvement of about 0.1 sec from the last visit but I also ran some 15.0s that day as well. I think the shorter tires were worth more like 0.15 secs, but that's just a guess.
They changed the readout for the scales at the track and I forgot to ask them if it was calibrated or not. My truck usually hovers around 4950-5000 pounds with me in it. Tonight it was at 5110. I know the wheels/tires on the back are definitely lighter so they either calibrated the scales at the track with this new readout or there is some new error in the gauge.
I also ran a 13.99 so the 13.98 wasn't the only 13 second run. But I also ran a slew of 14.0s too.
I think I'm going to get an OBD II scanner next so I can start knowing what things are doing with/without the nitrous on. As far as performance mods, I may finally break down and get a Volant. Or I may try junkyard searching for an electric fan setup to see what that does.
I hope everyone had a good Thanksgiving - I get to work Sat and Sun - oh yea...
Today I mounted a set of P275/60-17s to a set of stock off-road Titan wheels. The tires were just Goodyear Wranglers (like what I have on the stock 18" wheels that came with the truck). These tires are 29" tall when mounted and the 18" stockers were 32.5" tall. So the diameter decrease and the reduced rollout helped a litte with overall gearing. Traction started getting a little iffy, an occassional squeal, but they never "lit up" from a 1500-2000 rpm launch, stomp the throttle all the way to the floor. No problems with traction on nitrous. The truck now shifts into 4th gear with or without the nitrous. The bad thing is that it shifts rather lethargically and seemingly with some lash. I don't think the transmission is handling that well. Of interest there is that it is shifting into 4th at 5500 rpm instead of ~6100 like the other two shifts.
An interesting note for the VDC: at about 30mph with the VDC on, the slip light would flash just driving. With the VDC turned off I had no issues. It didn't feel like the brakes were being applied to the rear or anything but I wasn't going to try and make a run with the slip light going off, either. So there you have it, you have to run 4 same-height tires for the VDC to work OK. Or you can dive with it off.
The weather was humid (it rained on us almost all the way to a surprisingly dry track) and temps were in the low 70s. Last time I ran the 14.02 previous best on nitrous, the temps were in the high 50s. With the constant threat of rain, I didn't make any baseline passes with the stock 18" wheels and tires. I ran two identical 14.85s with just the shorter tires, an improvement of about 0.1 sec from the last visit but I also ran some 15.0s that day as well. I think the shorter tires were worth more like 0.15 secs, but that's just a guess.
They changed the readout for the scales at the track and I forgot to ask them if it was calibrated or not. My truck usually hovers around 4950-5000 pounds with me in it. Tonight it was at 5110. I know the wheels/tires on the back are definitely lighter so they either calibrated the scales at the track with this new readout or there is some new error in the gauge.
I also ran a 13.99 so the 13.98 wasn't the only 13 second run. But I also ran a slew of 14.0s too.
I think I'm going to get an OBD II scanner next so I can start knowing what things are doing with/without the nitrous on. As far as performance mods, I may finally break down and get a Volant. Or I may try junkyard searching for an electric fan setup to see what that does.
I hope everyone had a good Thanksgiving - I get to work Sat and Sun - oh yea...
