Best shift points from dyno graph?
 

My buddy Mike and I are heading to the track this Friday night and I really, really, really want a 12 second time slip. Anywho, I just looked over my dyno graph and it appears that I am shifting at too high of an rpm. First let me give you some quick background on where I am with my Stang:

From the dyno I made 290rwhp @ 5250 rpm and 312rwtq @ 4600 rpm.

Now, from the looks of the graph, my torque drops rapidly (312@4600 down to 240@6000) while my horsepower drops less (290@5250 to 265@6000). The last few times at the track I have been shifting at damn near 6100 rpm with many 13.1's, 13.2's @ 105-106mph.

Now for the question: Should I lower my shift points in order to take advantage of my torque, and if so, to what rpm should I shift? Or, will I lose more ET and mph by shifting lower?

I plan on doing some experimenting with shift points this Friday (1st run 5500, 2nd run 5700, etc.) but I thought I would see what kind of experiences you guys had with your Stang's.

Thanks in advance for any input.
E

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1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'

Shift 200rpms higher then where you made peak HP so thats 5450rpms, that will keep you in your power curve when you shift if your quick. Go get that 12! http://www.mustangworks.com/msgboard/biggrin.gif

If you are running D.O.T's or Slicks launch at 5000rpm and let the clutch fly.

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Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon! FIRST TIME OUT 12.16@111 WHEELS-UP

I'd be very interested in what your experimentation turns up. You may even want to shift as low as 5300 rpms. This will keep you completely in the meat of your power band. What gears are you running?

Definitely get back to us as to what you find out.

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351W 89 Mustang GT Convertible

Rick and Jim:

Thanks for the quick response.

I will be running BFG Drag Radials with ~21 psi and a quick clean off of the tires (no water box).

I am running a 3.55 gear with stock suspension (except bolt-in subs and Steeda uppers and lowers), and stock T5.

To complicate matters, I am really getting confused on my setup....let me elaborate: I have TFS TW heads ported out flowing 272cfm intake and 206cfm exhaust at .500" and 28 in of H20. Valves are 2.02 and 1.60, respectively. Now, with this setup, I have had countless people tell me that these heads are too much for my little 302 (which I agree with, however a ProCharger is in the works) and that if I want to really get power out of the motor, I need to shift it as high as possible. The last part seemed to make sense to me for a while, but after the dyno graph, I am very skeptical.

I too, am very interested in Friday's test and tune. I think I will try the 5300 rpm shift points and work up from there.

E

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1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'

Why its simple, 272 cfm on the int. is not too bad for a 302 at all. What U need to shift high and utilise those heads will be a suitable cam. Mine flows @ around 260-265cfm on the int.

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TFS heads, Holley intake, AFM B-2 cam, 77mm MAF, 65mmTB, Bassani X-pipe with cats and Autologic custom chip. NOS dry kit, 80hp shot just installed.
Black SN95
13.8 @105mph NA
13.2 @112mph 80hp NOS
Wet track, running on NOS setting on NA runs (pig rich and 8 deg timing)

Forgot to update sig

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TFS heads, Holley intake, AFM B-2 cam, 77mm MAF, 65mmTB, Bassani X-pipe with cats and Autologic custom chip. NOS dry kit, 80hp shot just installed.
Black SN95
13.8 @105mph NA
13.2 @112mph 80hp NOS
Wet track, running on NOS setting on NA runs (pig rich and 8 deg timing)

[b]12.9 @110mph best mph

blkrain: Is the 12.9 @ 110 on or off the bottle?

Just curious for comparison purposes.

Damn sig did not work well. Off bottle http://www.mustangworks.com/msgboard/biggrin.gif

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TFS heads, Holley intake, AFM B-2 cam,
Black SN95
13.8 @105mph NA
13.2 @112mph 80hp NOS
Wet track, running on NOS setting on NA runs (pig rich and 8 deg timing)

<B>12.9 @110mph best et


Ok its still not working. 13.06/7 (gotta find the damn slip) @111mph- best mph
12.9 @110mph best et


[This message has been edited by blkrain (edited 06-26-2001).]

blkrain CONGRATULATIONS!!! That is awesome! http://www.mustangworks.com/msgboard/smile.gif I remember conversing with you months ago about your setup and getting everything sorted out. Well, it looks as though you have! I would love to run a 12.9 @ 110!!!

With a 110 mph you really have a solid mid to mid/low 12 sec Stang!

Congrats again. http://www.mustangworks.com/msgboard/wink.gif
E

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1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'

The best way to figure out shift points is at the track. Take the advice from here, and try it. I'd say start by shifting at 5400, make a couple runs, then at 5500, and so on. You coul mathematically figure out shift points......get the tranny gear ratios, rear end ratio, and tire height. Make a chart of speed at each rpm, in each gear. then put that next to your dyno chart, and figure out where to shif to each gear, by finding which combo would give you the most average hp throughout the run. Its really complicated to do, and might take a while, but if you like math, it'd be fun.

Thank u very much. I was estatic as well, but I wouldn't have gone to the track cos I was just having bad luck with the track altogether. But I ran a buddy who ran 12.6@108 and 12.9@109 on drag radials and beat him by OVER 2-3 cars on the frewway (twice). Made me want to find out what it could do. My best 60 for the night was also a 2.01 as well http://www.mustangworks.com/msgboard/biggrin.gif
All in all, it was a good nite (even though I couldn't duplicate the 12 sec run). The trap speed remained the same all nite.


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TFS heads, Holley intake, AFM B-2 cam,
Black SN95
13.8 @105mph NA
13.2 @112mph 80hp NOS
Wet track, running on NOS setting on NA runs (pig rich and 8 deg timing)

[b]12.9 @110mph best et

I've got exactly what dinomite describes on my website. Though its really helpful in getting in the ballpark, and understanding what's happening, there's a bunch of other factors that aren't taken into account (such as time between shifts and clutch slippage). It makes for good reading though so you might check it out. Just follow the URL in my sig.


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Jeff Chambers
Trophy Stock #3
11.462 Seconds / 117.43 MPH
Chambers Racing Team

blkrain- Man you come a long ways sice the last time we talked, AWESOME job getting that 12. I went 12.16 @ 111 on a 1.645 60ft, only trapping 5100rpm, this Anderson cam needs more gear so with the 4:30's I should go mid 11's @ 117mph around 6300rpm. This Anderson cam was one of the best things I have done, Thanks.

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Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon! FIRST TIME OUT 12.16@111 WHEELS-UP

Jeff: Thanks for the link. Very informative and I'm very impressed with your ET's based upon the torphy stock setup. Looks like someone has done their homework.

Nice job http://www.mustangworks.com/msgboard/wink.gif
E

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1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'

Looks like it's time to scrap my Steeda cam and go with an Anderson cam. No wonder Anderson is so secretive about the cam specs...I would be too!

E

cool! i did it once, made up my own formula, and devised a way of doing it. I went through all the gears, getting wierd shift rpms, and then found that i had stupidly done it with something like a 20 in tire height, and that is obviously wrong. It took me so long to do the first time i didn't try it again, but i think it would be great fun to do, and i would suggest it, as it should give you a very good idea of where to shift, and then you just have to fine tune it at the track from there.

Thanks man. Sorry I haven't emailed U in a while. I was in the process of moving (school) and didn't have the time to post this. Also ever since the change in web design on this site, I have always had a hard time getting on here. I just got the DSL high speed conn. so I AM BACK BABY!!! except with bad news. I had to sell the stang to help fund grad school http://www.mustangworks.com/msgboard/frown.gif http://www.mustangworks.com/msgboard/frown.gif I will post a new topic and explain later. Gotta go (the books call again).

Oh yea, the Anderson cams, TFS heads, and holley systemax intake combo is the way to go on a stock bottom end 302. I loved the end result of all my toils.

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TFS heads, Holley intake, AFM B-2 cam,
Black SN95
13.8 @105mph NA
13.2 @112mph 80hp NOS
Wet track, running on NOS setting on NA runs (pig rich and 8 deg timing)

[b]12.9 @110mph best et

Eric, sure sounds like the shift points were a little on the high side. I got the car all cleaned and ready for Trails on Friday! Give me a call today and we can finalize the plans to meet at the track.

Just wanted to mention that my JMS chip is not in yet (probably this coming Tues. or Weds.) I know that I posted a topic earlier about getting my chip installed prior to the races tonight - but JMS just finished the chip yesterday.

So, tonight will be experimenting with shift points only - then in a couple weeks, I will take it back out with the custom burnt chip.

E

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1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'