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Author
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Topic: Shift Point?
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65_289
Gearhead Posts: 396
From:
Registered: Jul 2001
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posted 01-14-2002 09:45 PM
   
What is the best rpm to shift at? Is it right at peak hp? 500 rpm after peak hp? Or do the gear ratios of the tranny come in to play?------------------
1965 Coupe, Tremec 3550, Steeda Tri-Ax, Cable Clutch conversion, 3.25 gears, Biondo Line Lock, Ford XB3 longblock, x303 heads, B-Cam, 9:1 comp., Tri-y headers, cut-outs, Ford Racing high-torque mini-starter, Pertronix Ignitor & Flamethrower coil, 650 double pumper, Edelbrock RPM intake, K&N air, Holley electric fuel pump & AFPR, dual 2-chamber Flowmasters, Summit 3-way fronts, Rancho 5-way rears, 5-leaf springs, Chrome Export Brace, Griffen Radiator, Comp. Eng. subs.
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65_289
Gearhead Posts: 396
From:
Registered: Jul 2001
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posted 01-14-2002 10:38 PM
Nevermind. I found a website that calculates them for you.http://www.prestage.com/carmath/dynochart.asp
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V8 Thumper
Gearhead Posts: 603
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 01-15-2002 12:40 AM
Bitchin'!  There's a buncha cool links/calculators there, I wonder how accurate some of them are. Not a bad starting point, I imagine 
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Moneymaker
Administrator Posts: 11493
From: Lyons, IL, USA
Registered: May 99
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posted 01-15-2002 12:59 PM
We have found that "GENERALLY" 4 to 500 RPM over the point that peak HP is achieved is a good place to make gear changes in a 6500 RPM or less engine. The higher the RPM the larger the spread. ------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link
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65_289
Gearhead Posts: 396
From:
Registered: Jul 2001
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posted 01-15-2002 02:00 PM
quote:
Originally posted by Moneymaker:
We have found that "GENERALLY" 4 to 500 RPM over the point that peak HP is achieved is a good place to make gear changes in a 6500 RPM or less engine. The higher the RPM the larger the spread.
I just wonder how good Ford Racing puts these motors together. I'd hate to take it to 6500, only to have some cheap rod bolt decide to take a dump. 
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Kyle
Journeyman Posts: 64
From: Sumner, WA USA
Registered: Dec 2001
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posted 01-16-2002 12:32 PM
Did anybody else use this calculator? I put in the torque amounts estimated by dyno 2000 for my motor, added the C4 gearing, and it came bace saying that I need to shift at 8500 rpm! Peak HP is at 6500, and torque peaks at 5000rpm. So either Dyno 2000 is screwed up, or something isn't being accounted for.
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rd400d
Journeyman Posts: 7
From:
Registered: Jan 2002
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posted 01-20-2002 11:52 AM
I've never drove a really fast car (like 11's or quicker) but i've rode bikes since i was a kid and i always knew when to shift kinda like a harmony you have with the motor. Plus i'd imagine youd shift when the motor stops pulling or reaches that sound in the power band.
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Mario428
Journeyman Posts: 15
From: Charlottetown, PEI, Canada
Registered: Nov 2001
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posted 01-20-2002 12:48 PM
The Prestage.com calculator was a waste of 2 minutes of my life.
7500 rpm for a 6500 rpm max motor. Their calculations are based on a bogus formula using torque loss.
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