Hi this is my first post on the forums and I wanted to know more about when to shift. I’m having a hard time figuring out the best RPMs and hp to shift in engines like the I4 1.6 rally swap even using telemetry. I’ve heard that you should shift a bit after max power so that you are sitting in max power in the next gear. Could someone inform me on the specific RPMs or power after peak I should be shifting and how that varies from car to car?
Hello, to begin you need to understand torque in relation to power. Every engine has TQ (Torque) and HP (Horsepower), TQ is what does the work peak TQ will be different from peak HP in the powerband when you rev engines RPM higher after reaching peak TQ you are just wasting the engines efficiency. So you want your shifts to be between max and min TQ range to make efficient use of your engine. You accomplish this through proper gear ratios. Hope this helps.
Have a good-n
Min torque is delivered at idle RPM. Are you saying that for maximum acceleration, you are supposed to shift between idle RPM and max torque RPM? Wow, that couldn’t be more wrong…
And you need to understand torque at the wheels in relation to torque at the flywheel…
@OP, here’s a good video that will give you the precise answer you’re looking for:
TL;DW: for most cars, shift at redline and you’ll be in the ballpark
It is poiintless now to teach someone until the telemerty is fixed.
Thanks for the feedback! Can anyone else inform me on the precise amount I should let power drop?(ex. -15hp after peak)
Generally I’d go with shifting when the power and torque starts to gradually fall off, you’re likely to then be at an optimal power/torque level in the next gear (Providing the ratio’s aren’t too wide or narrow).
For instance, the V8 swap in stock form generally runs out of power after around 6100 rpm.
The best way to have to so you are at most power is to match the power you have just before you shift (after max power) is the same power in the next gear (before max power) just after you shift up.
Sentenza, reread my post I said shift points are going to be BETWEEN min and max TQ, not AT min and max TQ.
Instead of using my 30+ yrs experience in the automotive mechanical field and get all technical I was just trying to keep it simple minded.
Have a good-n