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The Ubiquitous Jimmy V.
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Discussion Starter · #1 ·
I know everybody runs different amounts of boost and different combinations..I think this does effect shift points.
I tried shifting my car at 6000 as suggested here on the forums.I remember back when the first Cobra's in 96 were advised to shift @ 6000 also and they finnally realized later that 6800 to 7000 worked better.
I find myself shifting higher and getting better results.It could be that with just 12 1/2 to 13 1/2 lbs boost and headers it allows me more, or it just does not make that much difference and is just boost related.
I also find that holding 3rd gear longer,,in my case 6400..I get more MPH..I am currently shifting @ 6200 on the 1 to 2 and 2 to 3 shift..and 6400 on the 3 to 4 shift.
Thought i'd share my findings so far...
Any input from other racers welcome..

My setup is 3" pulley,,Headers,Exhaust..TB, and Cai with 9in Cone and heat shiels\d with Diablo chip..
 

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I think that you have far more exhaust capability than you do intake capability, Jim.

Maybe the blower is wanting more inlet air and that's why it wakes up more at higher RPMs. Higher RPMs means more vacuum on the inlet side of the blower.

Try a different (bigger) filter. Maybe that will lower 'optimal' shift points for you and save on wear and tear of your engine.

Just a thought...
 

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The Ubiquitous Jimmy V.
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Discussion Starter · #3 ·
HAMMER said:
I think that you have far more exhaust capability than you do intake capability, Jim.

Maybe the blower is wanting more inlet air and that's why it wakes up more at higher RPMs. Higher RPMs means more vacuum on the inlet side of the blower.

Try a different (bigger) filter. Maybe that will lower 'optimal' shift points for you and save on wear and tear of your engine.

Just a thought...
Are you saying i need a bigger blower???:lol

thank's your observation is something i didn't think of..Then again WTF do i know....:hammer
 

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Like you said, every car is different, and shift points may need to be different depending upon power, and where you make it, RPM-wise. My car dyno'd at 430 HP (peak at 5800 RPM) and 455 ft/lbs torque (peak at 3900 rpm). I now shift it from 1st to 2nd at about 6000, then 2nd to 3rd at 5800-5900, and the 3rd to 4th 5800-5900 rpm's. I keep the pedal down to maintain rpm (& HP). It took a while to get the take-off down, but can now get 1.75 to 1.85 fairly consistently, launching about 2700 rpm with Nitto 315's and not riding the clutch out. A line-loc to preload and GRC sub frames seemed to help with my launch. Two weekends in a row at Houston Raceway Park I have been able to get into the 11's, this with 92-94 F temps and 90+% humidity - I am quite pleased. I ran 11.93/118.4 and 11.94/117.9 one weekend, and 11.89/117.8 last weekend.
I found that shifting lower, after HP had peaked, was better than pushing the RPMs to 6300-6400, which was getting me 12.001 to 12.08 ET's. My $.02 !!
Mods: 6lb lower, Amazon CAI, Accufab TB, Amazon IC fans, Borla catback, Magnaflow catted X, Hurst line loc and the Nitto 315s. This is with Rick's Daiblosport chip tune.

Ratt Fink
 

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Im gonna try some diff shift points at the track in the morning. I just got my offroad X and catback on vs my stock piping and cats. The car has lost some tq, but has picked it up on the big end. The car seems to breath better from 5500-6500, before it died off early.

I see about 14psi in 3rd and 4th with my 2.80. I will try winding 3rd out to 6400 or so t-morow, I usually shift at 6000 on the 3-4.

I'll report back with some results.
 

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Jim,
I read where you recently installed a plasma booster on your car are you sure that could not of helped some towards your better times as of lately?
 

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IMO, looking at max power and max torque points from a dyno sheet can be misleading in determining what's best for ET at the track.

If I simply note that my car makes peak HP at, say, 5800 RPMs and shift there, I am not taking into consideration recovery time in the next gear. I have found that it is very important to pay attention to the RPM that I end up at when the clutch is fully engagued after a gear shift.

It's a matter of finding the balance between over taching one gear to optimize the powerband in the next - without going too far and without short-shifting.
 

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The Ubiquitous Jimmy V.
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Discussion Starter · #8 ·
HIGH ROLLER said:
Jim,
I read where you recently installed a plasma booster on your car are you sure that could not of helped some towards your better times as of lately?
I am sure thr PB didn't hurt anything..I will check it out next time on dyno..I am not a big dyno fan..I feel it runs better with allowing me to use a wider gap..
 

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HAMMER said:
IMO, looking at max power and max torque points from a dyno sheet can be misleading in determining what's best for ET at the track.

If I simply note that my car makes peak HP at, say, 5800 RPMs and shift there, I am not taking into consideration recovery time in the next gear. I have found that it is very important to pay attention to the RPM that I end up at when the clutch is fully engagued after a gear shift.

It's a matter of finding the balance between over taching one gear to optimize the powerband in the next - without going too far and without short-shifting.
You are certainly right. For me, I have the opportunity to run against some buddies that have Cobras with 450-465 HP and torque in a similar range, and who shift at 6300-6500. This is what helped me to figure out where to shift - I do better by shifting at a lower RPM when going to 3rd and to 4th, always keeping a WOT, and have either taken land back or increased my lead on them by doing so in many cases. For me, it matches what the dyno suggests. I cannot shift with them running side-by-side and do as well.

Ratt
 

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Nice times for the conditions RatFink, you are getting everything out of your car it seems!!
 

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The Ubiquitous Jimmy V.
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Discussion Starter · #11 ·
My car runs better shifting higher then 6200,,Before the headers it didn't.I am going to try 6400 next time and if it still improves ..We will know that the headers as that is only change made..Before Headers 6000 netted me best et and MPH..
 

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trey193 said:
Nice times for the conditions RatFink, you are getting everything out of your car it seems!!
Thanks, Trey193 !! I am gonna run one or two more times and see if I can get any better. If not, I plan to either go with an 8-lb lower ring or get a 3.2" or 3.4" upper pulley. With only the 6 lb lower, I am making 11-1/2 to 12 psi boost max, and I would like to get it up to 15-16 psi to see what I can do before cool weather gets here.
I have been told that the cool weather (we don't HAVE cold!), and an occassional lower humidity, will be a lot of fun - I can't wait to see !!

Ratt "pistons everywhere" Fink
 
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