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Where do I want to shift?

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Mod69

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Discussion starter · #1 ·
First...thanks Mike for the dyno sheet. Now I need some input on where I should be shifting based on these numbers. And if it would be any different for the 1/8 mile and 1/4 mile.

Rpm Hp TQ
4500 584
5000 573
5500 586 560
6000 598 523
6500 591 477
7000 533

From what I have "searched" it seems that I would want to set my shift light for 5500 to 5800 so to "actually" have shift by the 6000 pk Hp. My car is an automatic if that matters. I have read some about short shifting so I am not completely sure whether I (my car) would be in this situation or not.
 
#3 ·
racecar100 said:
You have to play with diffrent RPM to fine the lowest ET. I'd start at 5500 and then try at 500 rpm at a time to find your best ET.
Click to expand...
I would start at 5500 as suggested but I would adjust up by 200 rpm's at a time as in try 5500 then try 5700 then 5900 if 5900 is to high drop back down by 100 to 5800 and so on till you find the sweet spot.
 
#4 ·
The fastest superstock cars use different different shift points for each gear. Usually first gear is shifted a bit higher in a 3 speed auto.....something like 6000-6300 and around 5800 for 2nd to 3rd......need more info though since you did not post TQ figures for the lower rpms.
 
#7 ·
from what I know my old 468, th350 with B&M shift kit, 3000 stall, 4:56 gears, 30X14-15 tire car. I set the shift light at 5600 1st-2nd and 5600 2nd-3rd and it went 12.80 - 12.83 everytime. I tried other veriables on same track lower first shift, higher first shift, higher second shift, lower second shift. I found my car just liked the same rpm shift from 1-2 as 2-3. and just so you know at a differnt track. I set the shift light at 5800 1st-2nd and 58002nd -3rd and car went 12.73 but tossed the fan belt on the 2nd-3rd shift so I lowered the shift point back to 5600. car went right back to 12.80-12.83.
 
Discussion starter · #8 ·
So regardless 5500 is probably a good starting point until I get the hang of driving the car anyways. I doubt I will be consistent enough for a while but who knows.
 
#11 ·
Looks like is carries well to 6500, so shift around 6500.
Try short shifting 1st gear, to see what it likes at the track.
 
#12 ·
67RS502 said:
Looks like is carries well to 6500, so shift around 6500.
Try short shifting 1st gear, to see what it likes at the track.
Click to expand...
I agree you should find peak hp and shift it above that and run it over both sides of the peak.
 
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#13 ·
I would set your shift lite at 6k because by the time you see the lite then react you will be several hundred rpms over the lite. The motor will be back down in the sweet spot and that will be a great start. Me and my friend found that 6200 rpm with a bbc drag race 454 was the best but that is when he had plenty of seat time.
 
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#15 ·
Too me that thing wants to actually make the shift in the 6500 or a hair over range. It's still hanging in well at 6500 rpm and after the shift it will be higher in the RPM range and making more TQ.


Spin 'er up some.....

JIM
 
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#16 ·
do you guys all have manual valve bodies or can you shift a regular old auto cos I was told that an auto will shift where it wants to shift regardless of where the stick is.

can someone shed light on this?
 
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#17 ·
Mod69 said:
First...thanks Mike for the dyno sheet. Now I need some input on where I should be shifting based on these numbers. And if it would be any different for the 1/8 mile and 1/4 mile.

Rpm Hp TQ
4500 584
5000 573
5500 586 560
6000 598 523
6500 591 477
7000 533

From what I have "searched" it seems that I would want to set my shift light for 5500 to 5800 so to "actually" have shift by the 6000 pk Hp. My car is an automatic if that matters. I have read some about short shifting so I am not completely sure whether I (my car) would be in this situation or not.
Click to expand...
In case I missed it, are these "real" numbers or "computer generated" numbers?

I agree on the 5500 to start then bump by small increments. The time slip will tell you what it likes. Don't exceed the intended max engine RPM.

Quick story, first upgrade I did was to a stock 350 in a 79 ralley sport, cam, intake, carb, header upgrade. It felt good with 6000 shifts (4 speed) and I ran it that way for a season or two (cant recall) then the final race of the season I'm on the bubble for street class (13.9 lowest dial in) and the car runs a 13.8x. First thing to try, 5500 shifts. The car goes out and runs a 13.7, I tweaked and tuned it every way from Sunday, and it picks up over a tenth just by revving it less.:sad: Trust the time slip.:yes:
 
#18 ·
If I understand your dyno results correctly (and filling in a few blanks), you have:

Rpm..TQ..HP
4500 584 500
5000 573 546
5500 560 586
6000 523 597
6500 477 590
7000 400 533

Based on this and assuming you have typical th350 gear ratios, to maximize the power under the curve, the 1-2 shift should be at about 7200 and the 2-3 shift at 7000. Disregarding the convertor stall, your recovery point in 2nd will be about 4300 and in 3rd will be about 4700. If you extrapolate the HP numbers at those points, you can see that power at the “exit” point of each shift approximately equals the power at the “entry” point of the next gear. If you shift before these points, you will be entering the next gear at a lower power… thus leaving performance on the table.
 
Discussion starter · #19 ·
I have forged pistons and H beam rods all from Scat and internally balanced. However, I thought that a cast crank, even Scat should only be rev'd to a max of 7000. I put a 7000 chip in my MSD box. Can anyone shed light on this.

Oh yeah, these are computer generated numbers.
 
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