RX7Club.com - Mazda RX7 Forum

RX7Club.com - Mazda RX7 Forum (https://www.rx7club.com/)
-   Time Slips and Dyno (https://www.rx7club.com/time-slips-dyno-121/)
-   -   went to the 1320....some questions (https://www.rx7club.com/time-slips-dyno-121/went-1320-some-questions-436686/)

fd3virgin 06-23-05 06:45 AM

went to the 1320....some questions
 
went to the 1/4 mile track to see what my baby will do. here are the numbers
11.6 @ 117.2 with a 1.72 60'. my question is when i launch her do i run it out in first gear to red line or should i shift sooner. if so when should i shift from 1st to 2nd.

other runs 12.2 @ 116
11.8 @ 116.4
it was 80 degs that day
thanks oh, single turbo t78 with stock ports. should my mph be higher? kevin

rotorsownyou7 06-23-05 08:03 AM


Originally Posted by fd3virgin
went to the 1/4 mile track to see what my baby will do. here are the numbers
11.6 @ 117.2 with a 1.72 60'. my question is when i launch her do i run it out in first gear to red line or should i shift sooner. if so when should i shift from 1st to 2nd.

other runs 12.2 @ 116
11.8 @ 116.4
it was 80 degs that day
thanks oh, single turbo t78 with stock ports. should my mph be higher? kevin


What PSI were you running?

fd3virgin 06-23-05 08:04 AM

1 bar, i have a pfc with the single turbo. can i take the stock o2 sensor out to put in a wideband??? anyone

AMRAAM4 06-23-05 08:05 AM

I don't know the T78 graph Kevin, but from what I have seen I believe that after 6800rpm the boost/engine has reached a point where it begins a decrease in 1st gear. My guess according to this would be to shift into second around 6800-7k rpm.

RX7Wishing 06-23-05 08:06 AM

what kind of rubber you running on those times?


My best answer to your question is..... whatever you run your best times with. Everyones car is going to perform somewhat differently depending on modification's done. You were at the track. You should of experimented :)

fd3virgin 06-23-05 11:07 AM

et streets with 15 psi

turbodrx7 06-23-05 04:04 PM

i went up there, wanted to see you run, but got up there to late. Some random guy came up to me and started talking to me about my car, i had no idea who it was, he had a prelude and asked me if i still had my pettit(how the fuck did he know i had a pettit ecu) then he said there was another black fd so he obviously knew what an FD was. the mystery remains....

fd3virgin 06-23-05 10:26 PM

i was up there till about 900pm. i had no idea who it was. kevin

XSTransAm 06-25-05 02:49 PM

you could tell the best by looking at a dyno graph, You want to shift at a point which will keep you in the powerband when you hit second and have the least amount of lag possible. I think around 7800 is the ideal shift in my car, but then again my turbo is not the same as yours.

sk8world 06-26-05 11:41 PM

what was your 1/8th mile et and mph?

iron4jones 06-27-05 12:46 AM

I would have to agree with transam, look at your dynograph and shift at peak power. If you shift at redline and you havent been making power for 1000rpm it will just be wasted time. When you do shift at peak power it should get you right bak into your powerband. Im definetly no expert (look at my post about my first time at the track) but this makes the most sense to me.

saxyman990 06-28-05 03:12 PM


Originally Posted by iron4jones
I would have to agree with transam, look at your dynograph and shift at peak power. If you shift at redline and you havent been making power for 1000rpm it will just be wasted time. When you do shift at peak power it should get you right bak into your powerband. Im definetly no expert (look at my post about my first time at the track) but this makes the most sense to me.

NO! This has been posted so many times it's rediculous. For max acceleration you do NOT shift at peak power. You shift when the torque available at the rear wheels is more in the next gear than it is in the current gear. Jim had a great explanation in one of his threads (actually, he's probably posted this same explanation 20 times already, so I'll save him the trouble)


Originally Posted by jimlab
You don't shift at peak torque or at peak horsepower. You shift at the point at which torque at the axles (flywheel torque x transmission ratio x differential ratio x 0.85) in the current gear falls below what torque in the next higher gear would be. The result is something that looks like this.

https://www.rx7club.com/attachment.p...chmentid=73327

If the torque curve for the current gear crosses the line for the next higher gear you shift at that point (the last two data points are 7,500 and 8,000 rpm in this chart). If they don't cross (1st and 2nd gear, for example), you hold the gear to redline (8,000 rpm in this case). It's that simple.


XSTransAm 06-28-05 04:17 PM

fwiw, i wasent suggesting that you shift at peak power.

fd3virgin 06-28-05 05:49 PM


Originally Posted by saxyman990
NO! This has been posted so many times it's rediculous. For max acceleration you do NOT shift at peak power. You shift when the torque available at the rear wheels is more in the next gear than it is in the current gear. Jim had a great explanation in one of his threads (actually, he's probably posted this same explanation 20 times already, so I'll save him the trouble)


i still don't know when that is :( that doesn't show up on the dyno graph. looking at the graph i kinda get an idea of when to shift but that's for a stock fd? thanks still helps a bit. kevin

books 06-28-05 07:38 PM

I assume you could calculate what your torque values would be for any rpm in any gear as long as you had at least one dyno run. You would calculate this by using the gear ratio for each gear....if this for some reason is not valid you could just go to the dyno and perform runs in 1st, 2nd, 3rd, and 4th gears

ErnieT 06-29-05 08:51 PM

Kevin,
The best thing you can do in this situation is hand the keys to..........................................ME.... ...............................!!:)

fd3virgin 06-30-05 07:24 AM

haha,,, it does need a good wash, i want it back waxed too :). hey ernie, when are you going up there with your fd? talked to a pro drag racer at work and he gave me some tips. it might not apply b/c i don't have a 1400lb drag car with driver with 900+plus horses. he qualified at 7.43 in kentucky. kvn

LT1RX7 06-30-05 03:43 PM

What track were you at?

Cecil?

fd3virgin 06-30-05 11:03 PM

cecil, i might be going up there wednesday. kvn


All times are GMT -5. The time now is 07:08 AM.


© 2024 MH Sub I, LLC dba Internet Brands