First Gear Issue.....again

[Argess]

A while back, I was asking about the 1-2 shift, and got various replies. Looking back, I guess I didn't communicate myself very well, so would like to clarify things.

Most of you are probably familiar with this type of chart for the 427 Cobra:



You can see the shift at around 66 mph. I used this particular chart as it lists mph @ 6500 for each gear. So with a little interpolation, I assume the 1-2 shift is around 5570 rpm.

Here's another graph, similiar, but shows the shift a little closer to 70 mph, and is typical of others I've seen.



I don't shift like that. I usually get it somewhere in the 3000 rpm range in first, then shift to second so I am starting 2nd at the lower-end of the power band. I then run it up high in 2nd before the 2-3 shift. I do it by feel, not the tach (which has slow response, somtimes intermittent, plus my eyes are glued to the road during a hard accleration run, not the dash).

I can make the 1-2 shift higher, but it becomes less smooth and I don't think it's terribly healthy for the clutch, although I admit, the two are related to an extent.

So, my driving abilities aside, my tires aside, and knowing I only street drive, I have a question:

Who shifts close to 6000 rpm from 1st to 2nd, and who doesn't, and if you do, can you elaborate a bit on it?

Thank-you.

[rustyBob]

I have always shifted my car by the feel and sound of the engine i very rarely look at the tach unless i'm showing off for some body in the car with me then i will run it up to 5500 then shift and i have noticed that the tach will drop to about 3500 after the shift. what you are doing is called short shifting and that is easier on the power train so you are doing nothing wrong you are just playing it safe with the power train and thats not a bad thing,winding it to the moon and dropping the clutch is not good for things either,so pick a spot in the power band to leave the line in an rpm range that feels comfortable for you and shift when you feel it necessary(by sound and feel)and enjoy you self.

[Anthony]

Originally Posted by Argess

I don't shift like that. I usually get it somewhere in the 3000 rpm range in first, then shift to second so I am starting 2nd at the lower-end of the power band. I then run it up high in 2nd before the 2-3 shift. I do it by feel, not the tach (which has slow response, somtimes intermittent, plus my eyes are glued to the road during a hard accleration run, not the dash).

I can make the 1-2 shift higher, but it becomes less smooth and I don't think it's terribly healthy for the clutch, although I admit, the two are related to an extent.

So, my driving abilities aside, my tires aside, and knowing I only street drive, I have a question:

Who shifts close to 6000 rpm from 1st to 2nd, and who doesn't, and if you do, can you elaborate a bit on it?

Thank-you.

If you're only driving on the street, then it doesn;t matter.

If you're on the strip, and want to get a relatively good time, then you want to run the engine close to the redline at each shift. All things considered equal, you'll get the fastest time that way. If your car isn't set up optimally, you may find it better to short shift out of first (if 1st gear is too low), but in general you want to run your engine to close to redline. If you want to get technical, get your engine dyno'd, and find out the HP curve, and plan your shifts so they straddle the hp peak if possible.

[patrickt]

Performance Trends make a software program that takes your specific torque curve for your engine, your gear ratios, rear ratio, tires, etc. and then calculates the "perfect shift points" for you. Here's what it recommended for me and my car's set up. Basically, I just try and shift around 6000 and I have my rev limiter set to 6400. Every now and then I bounce off the limiter.

[Argess]

Thanks Guys. I think Rusty Bob described my "short shifting" in a way I like: "and that is easier on the power train so you are doing nothing wrong you are just playing it safe with the power train and thats not a bad thing"

It wasn't long after I joined this forum that I started to wonder just how much performance I could get from my car. From the stories I read, I envisioned all CC members winding out to 6000+ at every stoplight....LOL.

And some of the stories....spinning tires at 75 mph and such.....well, I definately don't have that kind of Hp under the hood......er..maybe if I was in 2nd at the time..... Crane did a computer analysis of my engine and got 480 Hp. I doubt it's that high as their software probably assumes perfect ignition timing and perfect fuel delivery. None the less, I am amazed at the number of people here who claim over 600 hp on the dyno.

Unfortunately, where I live, there is no dyno available. Nor is there much expertise around from which I can learn. So I'm on my own, learning as I go, but it's slow. Finsihed the car in 1996 and still only ahve a little over 5000 miles on it. (We have winter here).

My biggest hurdle is test runs on public roads.....too much darned traffic, and now that Sunday Shopping has been legalized, even mall parking lots are out (not to mention the police might show up).

I guess I'll stick with shifting by feel. It seems to work fine for me, and certainly from a rolling 20 mph in 2nd, I have no trouble with hard acceleration, although I watch it a bit on account of my BFG T/As. Honestly, 12" of rubber on each back tire and a limited slip diff, it just wants to go faster the more I push it. Wheelspin.......I've never done a burn-out yet....just taking it easy I suppose.

Anthony and Patrick have good points, and I suspect I could work out shift points based on a theoretical power curve based on cam specs, but as I mentioned before, I don't look at the tach much when I am test driving.

All in all, I didnt' really mean to ask another question with this thread. I was trying to explain why I asked this before in another thread. Basically, I don't do things like the test charts, so I was wondering if I was really doing something wrong. Or more to the point, if I tried it, would I screw it up really bad based on the enormous torque/power at the rear wheels with full revs in first gear.

Thanks again.

ps: I've watched as many Cobra runs as I could find on Youtube,etc, and to tell the truth, not very many looked (or sounded) much different than what I do. A few did, but some of those "few" also caused an "out-of-control" situation.

................and I really like that one with the Cobra beating the Viper....

[mdross1]

I worried about shift points when I drag raced,then I had a tach that lit when the shift point hit so I could concentrate down the 1/4.Street driving/racing,depends on what is sitting beside me,and the mood I am in.

[Rick Parker]

Maybe I'm overlooking the obvious but the "old" Road & Track road tests and related graphs were presented in a maximum effort situation. The accleration graph specifically was representative of a drag race application at or near "Red line" in each gear, not as a reccomendation of when to shift in everyday driving. The other graph represented the respective road incline that could be approached in a specific gear. Not sure what purpose those calculations serve in real life driving conditions, most of us would just shift into a lower gear.
I found them much more interesting than the current day presentations they use.

[Argess]

They do seem a bit "overdone" to me. That's really been the basis on my confusion. There were a lot of sources with very similiar graphs.

Wether I short-shift, or try to hit higher in 1st, at some point I am going to have to be in the lower part of the power band anyway. I prefer to take the smooth shift down low and climb up to the PB in 2nd, and continue shifting from there, just below and a bit above the peak of the power band, as the gear ratios dictate "the feel".