weather?

[redbird00]

i went to the track back in december and ran a 14.92 @ 92mph with a 2.2xx 60'(3.42, intake, cutout)weather was 0% humidity and cold(low 50's), then i got my torque converter(2800), tranny cooler and bmr sfc's, and went back and could only muster a 14.91 at 90 with a 1.99 60', weather was a little humid and a little warmer mid 70's, went back this last time, hpp3 and tires were the only new mods, and only ran a best of 15.2 at 89 with a 2.1 60', it was very humid(fixin to rain) and pretty warm high 70's low 80's, its not the hpp3 i programmed it back to stock and ran a 15.4, so its good for .2 at least...

now the question, how much does the weather affect times(ET's, mph, and 60's), does it really make that big of a difference? because i spent about a grand and saw no improvement, and i'm just wondering if its just the weather... and btw it was all at the same track and cutout was always open...

merlin

[ May 05, 2003: Message edited by: redbird00 ]

[ May 05, 2003: Message edited by: redbird00 ]</p>

[Bliggida]

Yeah Merlin, it can play a big differance.

With a cold track you aren't going to hook up very well (usually).

Humidity kills the oxygen level in the air, so your air intake charge is less dense. The cold dry winter air helped your engine make a few more horses, but didn't allow for to make any traction (probably).

A summer day with less than 50% humidity, and 70 degrees ambient air temperature should be good for your engine. And if the sun beats down on the track and brings it to near 100, that'll really help you to hook up.

Also a bigger converter will help your ET's, but launching at an RPM under your stall will absolutely kill your performance. With the stock converter at 1800-2200 RPM and you launching at 1500 you are flashing it pretty good. However 1500-1800 RPM on a 2800 converter and you just won't pull hard out of the hole.

As to why you are not hooking up, I am uncertain. For your launch RPM and power output, I would try running 275's or larger.

I just remembered, Your smaller rear tires will affect your final gearing too. If memory serves me, you are running 245/45/16's instead of 245/55/16's. A jump from 26.61 down to 24.68 overall tire diameter.
As a result at 4000 RPM in 3rd gear - with stock size tires and 3.42's you'll go 89 MPH, but with your current tires at 4,000 you will only go 82 MPH. ET will undoubtedly be affected as well. So while you upgraded in grip, you geared your car down (numerically higher) So now you have the equivalent of a 3.69:1 final drive ratio.

As part of this if your HPP3 isn't set up for your gearing and your new tire size. Your shift points that were off before, are now really off. And you may be going backwards which it sounds like we are doing.

At first I was thinking backwards and figured you had geared up the car (numerically lower) so that's why you are running slower - like you accidentally geared it back down to near a 3.23 gear. But no its up.

You may simply be putting more power to the wheels now than ever before, and those 245's just can't keep traction?

Next time you go out to the track I'll work with you on the car and see if we can dial in a better ET. I'd like to see you be able to hook up with a 2,500 RPM launch.

[ May 05, 2003: Message edited by: Bliggida ]</p>