Rev Limiter Question

[2011BaseGT]

I just bought a SCT programmer and CAI from American Muscle. On the race tune 93, I noticed the rev limiter is set to 7,600 rpm.

This seems high to me. Probably because I'm just not used to the high revs. I shifted at 7,300 and the car was still pulling hard. Totally woke the car up. Unbelievable.

What RPM will these motors go to safely? I'm thinking of kicking it down to 7,200.

 

[VTXFrank]

I'd call 7300 safe. But still, I don't rev mine past 7,000 cause it isn't making any more power beyond 6800RPM according to my Dyno sheet. I hit 403HP at 6800 and by 7100, it's down to 393. Torque hits it's high of 370 at 5300RPM and drops to 290 at 7100. So no reason at all for me to spin the motor past 7,000RPM.

 

[killr3v]

I'd shift at 7300 and leave the redline where it is. This way you'll be right in the powerband in the next gear. It will also keep the computer from closing the throttle as you get close to 7300rpms

 

[Wnt2gofst]

I still shift at 7k. After that power starts falling on my dyno sheet as well.

 

[2011BaseGT]

Yeah, I set it to 7,200 and seems reasonable. I noticed after loading the program the soft limiter is now replaced with the stuttering-style rev limiter.

 

[mpf]

Yeah, I set it to 7,200 and seems reasonable. I noticed after loading the program the soft limiter is now replaced with the stuttering-style rev limiter.

Definitely a balls-out driver, gotta test the tuner's rev limiter, lol!

 

[Konablue10Gt]

I have the soft limiter set to 8000 and the hard limiter at 8200. I shift mine around 7300-7400 and have come through the traps as high as 7800 when I had 26in tall tires on the car.

If you guys havent used it yet, the two step feature works great too in the SCT tunes.

 

[GeorgeInNePa]

It's not about where the motor stops making power, it's about where the RPM drops to after the shift.

 

[fdjizm]

It's not about where the motor stops making power, it's about where the RPM drops to after the shift.

+50,000

 

[acrbill]

It's not about where the motor stops making power, it's about where the RPM drops to after the shift.

Exactly right. The 93 mustang GT peaked at 4200 RPM and if you shifted there you wouldn't be doing yourself any favors.

 

[Matt D]

It's not about where the motor stops making power, it's about where the RPM drops to after the shift.

Thank you.

That's Sig material right there.

 

[Wish I Had a Nice Car]

ok, so where do you want the RPM's to fall since we are on the subject. If you make peak power at say 6900-7000 rpms, im guessing you want it to drop into the 6700-6800 range? Cuz to me, it wouldnt make sense to have the RPMS drop passed the peak power.

 

[fdjizm]

You want them to drop to max torque mostly or a bit above, and dropping back into 6800 after a shift is mechanically impossible given the transmission ratios.

example. If I shift at 6000 rpm from 2nd to 3rd I would drop back to 3900 rpm
Well my max torque is between 4100 and 4800 rpm so if I shift at 6500 rpm I end up back at 4300 so i'm better off.
You would have to see where you stop making torque on the drop I haven't studied these 5.0's yet to say for sure.

 

[05yellowgt]

ok, so where do you want the RPM's to fall since we are on the subject. If you make peak power at say 6900-7000 rpms, im guessing you want it to drop into the 6700-6800 range? Cuz to me, it wouldnt make sense to have the RPMS drop passed the peak power.

Ideally when shifting to the next gear you want to be at or very near the torque peak so you can climb the power curve from there on up.

 

[gmantheman]

Isn't the ideal shift point (at the track) about 500 RPMs above peak hp?

 

[JJ@WMS]

UO

I just bought a SCT programmer and CAI from American Muscle. On the race tune 93, I noticed the rev limiter is set to 7,600 rpm.

This seems high to me. Probably because I'm just not used to the high revs. I shifted at 7,300 and the car was still pulling hard. Totally woke the car up. Unbelievable.

What RPM will these motors go to safely? I'm thinking of kicking it down to 7,200.

Warren Johnson once said that you should shift 10% beyond where your car makes its most power, so if your making your max power at 6800rpms then you should be shifting at 7480 using his match. I'm sure there is a fudge factor in there but its always worked for me.

Also now that you have a tune and are shifting higher let me know if I can help you when your clutch starts acting up. Our prices are unbeatable on Mcleod's lineup of clutches.

JJ

 

[DennyMcLain]

Unquestionably Warren knows his stuff but I've also heard other hardcore racers say to shift 400 rpm past peak power.

The bottom line is every car is different and the way I find the optimal shift point is plug the hp dyno sheet numbers, rear end gearing and gearing in each gear into an excel spreadsheet that computes average hp of a 1/4th mile simulated run. It really is all about the highest average hp for intended use. Then you take it to a track playing slightly with shift points to see if the math matches real world.

Again, depends upon the powerband and how the car is geared. Some dyno sheets (engines) are peaky while others are more rounded. Obviously on a peaky powerband you would shift a bit earlier and visa versa on a rounded (extended) power curve.

If you don't want to go to the bother, I'd say a rough guess would be the old hardcore racers rule.

UO

Warren Johnson once said that you should shift 10% beyond where your car makes its most power, so if your making your max power at 6800rpms then you should be shifting at 7480 using his match. I'm sure there is a fudge factor in there but its always worked for me.

Also now that you have a tune and are shifting higher let me know if I can help you when your clutch starts acting up. Our prices are unbeatable on Mcleod's lineup of clutches.

JJ

 

[DennyMcLain]

Finally got off my butt and plugged in the numbers into the Excell worksheet. Used Steeda's posted dyno sheet where the new 5.0's seem to pick up considerable performance after being driven for a while. Anyway, below is what created the highest average hp using the optional 255 tires/brake package and 3.73 gearing. btw....... 6500 rpm was peak power.

First Gear......shift as high as possible as there is a big drop between 1st n 2nd gears (7500 rpm - 45mph)
Second Gear...(7000 rpm - 63mph)
Third Gear... (6900 rpm - 88 mph) If you're running the 1/8th, third is good for 96 mph @ 7500 rpm
Fourth Gear... (7200 rpm - 122 mph)

Go get um!

 

[Wish I Had a Nice Car]

Finally got off my butt and plugged in the numbers into the Excell worksheet. Used Steeda's posted dyno sheet where the new 5.0's seem to pick up considerable performance after being driven for a while. Anyway, below is what created the highest average hp using the optional 255 tires/break package and 3.73 gearing. btw....... 6500 rpm was peak power.

First Gear......shift as high as possible as there is a big drop between 1st n 2nd gears (7500 rpm - 45mph)
Second Gear...(7000 rpm - 63mph)
Third Gear... (6900 rpm - 88 mph) If you're running the 1/8th, third is good for 96 mph @ 7500 rpm
Fourth Gear... (7200 rpm - 122 mph)

Go get um!

i may be dumb....but my how are you getting to 122mph at 7200rpms in 4th gear? I trap at 115@7300ish with the 3.73s, which was the gear ratio used.

 

[stang910]

i may be dumb....but my how are you getting to 122mph at 7200rpms in 4th gear? I trap at 115@7300ish with the 3.73s, which was the gear ratio used.

He's using the 19" tires in his example.