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-   -   Quarter Mile Shift RPM (http://zr1.net/forum/showthread.php?t=3170)

Hammer 04-16-2007 07:08 AM

Quarter Mile Shift RPM
 
What RPM's do you shift at for best 1/4 mile times? I have shifted at about 6500 in the past and am curious if 6000 might give a better time. I am going this weekend and thought I would throw this out fot the H of it.

Aurora40 04-16-2007 07:14 PM

Re: Quarter Mile Shift RPM
 
Right before it hits the limiter. The car doesn't drop power much even stock, so it's making more power at the limit than it will wherever the revs drop to after the shift.

Hammer 04-16-2007 08:45 PM

Re: Quarter Mile Shift RPM
 
That's about what I been doing. Like I said, thought I would throw this out and see.

Thanks for the reply.

Demps 04-16-2007 10:32 PM

Re: Quarter Mile Shift RPM
 
Quote:

Originally Posted by Hammer
What RPM's do you shift at for best 1/4 mile times? I have shifted at about 6500 in the past and am curious if 6000 might give a better time. I am going this weekend and thought I would throw this out fot the H of it.

Let the skinny guy down the road show you:mrgreen: Ted

Jeffvette 04-17-2007 01:32 AM

Re: Quarter Mile Shift RPM
 
Quote:

Originally Posted by Aurora40
Right before it hits the limiter. The car doesn't drop power much even stock, so it's making more power at the limit than it will wherever the revs drop to after the shift.

The car loses significant power in the top end unless you have headers and porting. Only then will you acheive that flat power band at the top.

rkreigh 04-17-2007 05:34 AM

Re: Quarter Mile Shift RPM
 
run a dyno, see on the power curve where the power starts to "tail off"

if you shift way past the peak, as jeff mentioned, the car will slow down. on the stock cars often the power peak is around 6300, so shifting at 7k is going to make the car run slower. rear gears have alot to do with shift points too. with the stock gears you are pulling 3rd through the traps.

Hammer 04-17-2007 06:42 AM

Re: Quarter Mile Shift RPM
 
I do pull third at about 6500 through the traps. I will post more after this weekend. Thanks for the inputs fellas.

blackjack 04-17-2007 09:39 AM

Re: Quarter Mile Shift RPM
 
when the car is geared properly,you should be able to shift at peak horsepower,and the engine should come down close to its maximum torque in the next gear.
bj
91/1735

Aurora40 04-17-2007 11:54 AM

Re: Quarter Mile Shift RPM
 
Quote:

Originally Posted by Jeffvette
The car loses significant power in the top end unless you have headers and porting. Only then will you acheive that flat power band at the top.

Huh. I never dyno'd mine stock. The most-stock was with just a ported top end and stock manifolds/exhaust. It dropped off after about 6,200 rpm, but not very badly. I just figured stock would drop off more, but probably not tons more. Then again, I did find myself hitting the rev limiter a lot when I first put the ported top end on because it kept pulling vs dropping off. :dancing

Still, on the 1-2 shift (at 7,000 in 1st) I think the revs will drop to ~4,700 rpm. So as long as it doesn't drop that bad I'd still think you are better off running it to the limiter. :thumbsup:

Jeffvette 04-17-2007 12:59 PM

Re: Quarter Mile Shift RPM
 
Most stock cars at a 7K shift are back down to around 300 hp. and when you shift you are dropping the car back on the wrong spot of the power curve. You want to be hitting the curve where you are making the most power.


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