Redlining your engine.

[Reedy]

After a full day racing me & the guys I go with always comment that their engines feel more willing and powerful on the drive home. We never have a better explanation for it other than "blowing the cobwebs out". Either that or its just some kind of mind trick because we have lost the ability to modulate our throttle inputs after driving flat out all day.

[luke 3mps]

My friends have always commented on how my cars have a willingness to go even stock, i think its how u drive and break them in.

[Jeev]

Just a curiosity question... You name wouldn't happen to be Alan Case, would it?

[AlanC]

No Jeev my surname isn't Case.

[Doug_MPS6]

A look at the torque and BHP should tell you what is appropriate. In stock guise there is not much future in pushing too far beyond the peaks, at around 5500. The engines are so torquey it is more useful performance-wise to be in a new gear and pulling harder from down lower, say 2800 upwards. The occasional "cobweb clean" might seem to help, but is almost as likely to be an apocryphal benefit, and hardly warrants approaching valve bounce. An engine run through the normal rev range is likely to remain healthier in the long run. It is worth remembering that the big killer of all engines is piston speed. With forced induction engines such as these producing such massive power from low rpm, there is not a lot of mileage to be gained (figuratively as well as literally) in running stratospheric rpm and hence piston speeds.

[raymondato]

my experience is pretty much the same as Cton.

i only started revving out the car after my car got tuned, because i now have power going past 4-5k.

[Doug_MPS6]

I guess I should have added that if you plan on going much past design maximum on a regular basis, whether stock or modded (but unbalanced) it makes sense to ensure that your engine is balanced and blueprinted for the new rpm regime.

[Logan]

Never red line, normally change up around 5800-6000. No point as the power drops off.

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[Reedy]

That is not universally true as a lot of people suggest. The actual answer to shifting before the torque falls away is: It depends on what Vmax you are heading for, how much road you have and whether you can make full use of the gear you are shortshifting into.

I did a bunch of analysis on my own cars Dyno figures and came up with this graph, what it factors in gearing ratios and shows the relative torque at the wheels in all gears at any given RPM. (Ignore the units of measure on the Y axis, they are effectively nM reflected through the gear ratios, what matters is the relative values of each)



The takeaway here is that no matter what you do, the torque at the wheels in 2nd gear will never equal first, 3rd will never equal second, 4th starts to come close and you can make a good argument for short shifting into 5th or 6th gear but ONLY IF YOU ARE GOING TO REDLINE IT.

Calculations can get quite complicated when you are trying to do theory runs at certain tracks and trying to maximize gear ratios and torque at the wheels, my spreadsheet also factors in relative speeds at what rpm in what gear and also how shifting gears at any speed translates into engine RPM, that way you can calculate at what point on your torque curve upshifting at any given time will take the engine to.

Basically the conclusion I have come to with the gearing in the Gen II is: Redline it in all gears for maximum performance unless your vmax on the straight exceeds 200km/hr. In that case, short shift out of 4th gear only.

[AlanC]

Thanks for your input guys. Very interesting reading.