Using gear ratio to determine 1/4 run, how accurate is it?

[Musclebishi]

As the title said, how accurate is it to use gear ratio to determine 1/4 mile run. I previously ran [email protected] at the track, but bogged the launch and missed the 1-2 shift giving way to the high ET time. I took another run but this time it was even worse for the 1-2 shift so I called it quit and came home. Weeks later, I tried another 1/4 run at an open road and here is the result. I use the gear ratio to determine my quarter mile run and based on my 121 trap speed i came up with 11.1/11.2 sec. I know this is too good to be true but I'm guessing I would be running somewhere in the 11s at the track with a decent launch and shifts. What do you guys think? Please analyze this log and give me your opinions. My mods are 7-hx35, jmf manifold, 255hp wired, 1600cc, 225-55-16 tire, and this is a 1G car.

 

[Musclebishi]

Well, I went to the track and got my result and it was awesome. I got my magic number 11 ([email protected]). It took me four passes to achieve it. The first three net me very low 12's because I was struggling with traction and shifting. The last pass I still struggle with tractions both 1st and 2nd but had my full concentration into shifting and nailed it. It was a great day for me.

As far as gear ratio goes, I forgot that they use the average of the last 60 or so foot at the end of the track to come up with the mph trap so using gear ratio will be off.

 

[4pistons]

Your gear ratio doesn't determine your ET, your horsepower does. Go here - ET Calculator -

Plug in your cars weight. I guessed at 3200 (probably high). Plug in your trap speed of 126mph. It calculates that on a perfect launch and run you could do 10.80's!!

In any case your making 500 whp which is great!!

Rick - '91 GSX

 

[Musclebishi]

Your gear ratio doesn't determine your ET, your horsepower does. Go here - ET Calculator -

Plug in your cars weight. I guessed at 3200 (probably high). Plug in your trap speed of 126mph. It calculates that on a perfect launch and run you could do 10.80's!!

In any case your making 500 whp which is great!!

Rick - '91 GSX

I don't really know my car's weight and I haven't really did any major weight diet other then the usual AC, radio, and chopped up of the bumper for my intercooler so I am guessing the weight is pretty much around 3375 with me in it.

I have used other calculators but each one has different outcome so I am not sure witch is right but one thing for sure is that trap speed doesn't lie. So with my trap of 126 I should be somewhere around 450-500 to the wheels.

I know the car has more in it if I could launch better and shift faster but given that this is pretty much a stock motor and trans I am very satisfy with the result.

 

[My1GLaser]

I weighed mine a couple weeks ago and it was 3280 with me in it and 1/4 tank of gas. No real weight reduction except no AC and I have a CF hood.

I ran 11.4 @ 122 with my 7 blade HX 35 at 27 psi on the stock IM. That's still my best ET. I have trapped 124, but I ran a high 11 or low 12 since I have been having tranny issues. (can't remember the ET)

Our 70-90 times are the same. I am getting about 53-54 lb/min of calibrated airflow. Your GM3bar is pegged, so I am not sure what boost you are running. We are in the neighborhood of 500 whp, you may be a little closer.

I am 60% E-85 and running 22* timing. I assume you are 100% E-85 based on your global but you are only running 19* timing. Have you tried increasing your timing advance?

I wish I could train myself to NLTS!!! I am jealous, but my right foot is made of lead