Wondering what RPM to shift at when drag racing

MustangMatt1966 · Mar 25, 2004

I have a 66 coupe, with the stock 289 block bored .30 over with edelbrock heads and a bunch of "goodies". But i am an inexperienced drag racer and ran a 14.4 shifting at about 4,200 RPM. I am not sure what RPM I should be shifting at? Can anyone let me know? thanks

Matt

6Stang7 · Mar 25, 2004

Whatever redline is. Did you change the cam?

ddonaca351 · Mar 26, 2004

Well "goodies" is a bit vague.... but if it's mostly stock internals, just with headers and manifold / carb / etc... than I would say try 5000 and see where you are at. If the cam has been changed than try about 500 below the max advertised rpm of the cam (i.e. if it says 1500-6500 than try shifting at 6000)
I have had good luck (on a stock 5.0) shifting at 5000 1-2, and 5200 2-3/3-4.
In my fastback I'd turn it 5500 1-2, and 5800 2-3/3-4.
With the new motor in the 5.0 I buzz the motor 6000 1-2 and 6200 2-3/3-4
(imho) you want to shift so that (after the shift) the motor is in the area of peak torque (or just above), and can pull up through peak power. In the lower gears 1-2 you have slightly more advantage due to gearing, so I shift a hair earlier.
Im sure there is some scientific way of calculating the "perfect" shift-point, but I don't have a clue what it is.... lol, I just go by seat of the pants and the timeslip.
Hope this helps...
Dave-

12sec67 · Mar 26, 2004

if you have stock bolts holding together your main caps and connecting rods don't rev over 5500rpms otherwise it won't last very long.

MustangMatt1966 · Mar 26, 2004

thanks guys, no the internals of the engine are not stock. But see, i dont know what the redline is, i have an aftermarket tach. But i guess i will shift at about 5,500 to 5,800 somewherein there.

Matt

dodgestang · Mar 26, 2004

MustangMatt1966 said:
I have a 66 coupe, with the stock 289 block bored .30 over with edelbrock heads and a bunch of "goodies". But i am an inexperienced drag racer and ran a 14.4 shifting at about 4,200 RPM. I am not sure what RPM I should be shifting at? Can anyone let me know? thanks

Matt

There are only 2 ways I know of to figure out where your shift point is.

1. Take it to the dyno and get a power chart that way you can mathetically calculate the optimum shift points for each gear based on your spcific power band....remember shift points changes for each gear for maximum power application..you don't just take it to 5800 in first and then in 2nd and then in 3rd....

2. Run it down the track 30 times and figure it out where it likes to be shifted for the best times. You components will tell you when you are giving too much RPM to the car...cause it won't go as fast...sometimes people bolt on a lot of power adders that glow enough to make power at an RPM above what the bottom end is really capable of doing....the aftermarket heads will do this for you, but you didn't mention the intake? Either way 6k is about the max you want to spin a 289 basic bottom end with any kind of regularity.

Because of the mods made to the motor, I personally would spend the $150 for 3 pulls on a chassis dyno and have the tech optimize the car....you will pick up a few horses, the car will be running great, and you will be able to set your shifts without as much trail and error.

Fordfanboi · Mar 26, 2004

MustangMatt1966 said:
But see, i dont know what the redline is, i have an aftermarket tach.

Keep in mind, depending on the aftermarket tach, it may be lagging up to 500rpm, depending on how fast your motor winds up. Parked or in 1st, you can likely expect around 500rpm lag with inexpensive aftermarket tachs.

If you don't have a rev limiter, I'd definately recommend getting one asap. Missing a POWERshift can be nasty.

MustangMatt1966 · Mar 26, 2004

yeah, ran the car tonight, the launch was freaking horrible and the car bogged down really bad at the top of first. I dont know what happend, it either got to much gas, or it was because i dumped the clutch and was spinning and at the top of first it just wanted to die. When i let off thegas and slammed it again it flew, and then 2nd 3rd 4th were like a breeze and i cought right up to the other car. I have no idea what is going on in the launch. I was told to feather the clutch out to get it rolling then stomp it. Any sugestions?
thanks,
Matt

Lswhat · Mar 27, 2004

so me turning 8000rpms with a stock bottom end save for arp rod bolts and forged piston is a really bad idea even if it is still pulling way up there. it also doesnt take it very long in first gear to get there either, i havent pushed second that hard yet i only took it to 7000rpms. i find that a stock c4 doesnt not like those rpms at all the planetary tends to explode. and by the way my cam which is roller says the max rpm is 6500 which is why i can figure out why it keeps pulling to 8000rpms.

ddonaca351 · Mar 29, 2004

Lswhat said:
so me turning 8000rpms with a stock bottom end save for arp rod bolts and forged piston is a really bad idea even if it is still pulling way up there. it also doesnt take it very long in first gear to get there either, i havent pushed second that hard yet i only took it to 7000rpms. i find that a stock c4 doesnt not like those rpms at all the planetary tends to explode. and by the way my cam which is roller says the max rpm is 6500 which is why i can figure out why it keeps pulling to 8000rpms.

Ummmm, set your tach for a v8 instead of a v6....
DD

MustangMatt1966 · Mar 29, 2004

Edbert · Mar 29, 2004

ddonaca351 said:
Ummmm, set your tach for a v8 instead of a v6....

slick761 · Mar 30, 2004

haha speakin of over revvin I ran my 289 up to 7000 or so on a missed 1 2 shift....yea I was ****tin my pants. I heard valve clearance issues etc. I pulled over and gave myself a nut check cause I figured at least on was up in my stomach

Wondering what RPM to shift at when drag racing

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