Yellow996

I love these quarterly soap operas. As soon as this thread was posted, I knew we were in for another Battle Royale!!!

NYoutftr

That's funny

Some topics here on the racing forum, may seem very elementary, but there are a lot of us folks who are trying our best to learn the most we can.

We learn from the experienced racers/instructors here on Rennlist.

This is forum is a huge help, so we can get the most out of our DEs, as some of us can only budget for two or three a year.

So a big thanks to everyone that helped and contributed to this thread.

David

mark kibort

you definitely can learn from the discussion, and we all learn from others mistakes , on the track and with a calculator.
Ill leave you with your own custom shift point chart, so you can make decisions of where you want to shift. (power vs engine wear considerations)
as you can see, with your flat HP curve , you dont lose too much, but if you are going for a hot lap , be closer to redline, than not. if you look at the graph, if you short shift at 6500rpm for example, you might lose 50hp for a couple of seconds.. so for DE'ing, that is a small price to pay. racing, it becomes about losing a position over it. it's all about hp-seconds...look at the average over any period of time and thats the cost or advantage you might have.
Have fun and be safe
mk

StoogeMoe

Did anybody link this YouTube video in before?


It's better than reading all this bickering back and forth. The conclusion is what you'd expect. Take it to redline. Unless you have some weird engine that really drops off at the higher revs.

NYoutftr

It is pretty good,
I had to watch a second time so the torque being multiplied through gearbox I could get straightened out in head.
But really for students homework assignment between 2 day driving events.
One instructor, I think was my first DE, gave me the car contol limit circle for my over night home work.
LOL, but it helped

mark kibort

Yes, i provided this link to show the foundation of why you need to maximize HP. it already incorporates maximizing torque at RPM via the gearbox ratios
Also, you are spot on, until the last part of your statement. many cars drop off HP at the higher RPM and all engines lose torque ...... so even with an engine that has HP that falls in the "higher revs" you still shift at redline, unless you have a real close ratio gear box . Here is a 911 motor that has HP fall off in the higher revs. you can see the advantages of shifting at redline with a typical 2-3 shift. then i also show a close ratio 4-5th shift where in this case, you would want to short shift by a few 100 rpm for maximizing HP. STILL always shifting past max HP in all cases.

Ive also added a BMW e36 dyno run for Dave's education, (below the 911 curve) to show shift points to show the "meat of the torque curve" never being touched. (75% of redline RPM gear used)

Veloce Raptor

To the OP and others, the video Stooge posted is very good. Realize however that the S2000 is somewhat unique in its combination of engine characteristics and gearing.

My suggestion is that your mileage may vary. After you understand the power and torque curves of YOUR PARTICULAR ENGINE, test various upshifting timings on track and measure the results. It may be that Luigi's point of upshifting a tiny bit before actual red line is best for you car. And it may be that it's not. What works for a GT3RS may not be optimal for a Viper or a 996 Carrera.

Thundermoose

Dave - can you post a dyno graph example where shifting short of redline would be optimal?

Veloce Raptor

Not a dyno. But actual data sometimes show it is, depending upon engine and transmission characteristics. I care a lot less about a dyno chart than about actual results ON TRACK.

mark kibort

Dave you dont understand physics or math.. thats ok. There was a time that people thought the world was flat because that's that they THINK they saw or in your case "felt".
Actual data will always show that redline shift in all the cars you mention will maximize acceleration. I posted the shift points of the BMW for your enjoyment and education.
on track performance will always follow the dyno runs, an engine that has a peak HP point will always benefit the driver to shift beyond it to maximize HP available there is no "meat of the torque curve" that is ever taken into consideration by those in the know.

its real simple...........ALL YOU NEED IS A HP CURVE and GEAR SPACING. with that, you can determine shift points. its that simple. your on track data will correlate perfectly to this, and there is not a reason in the world it wouldnt.


remember, he said short or peak HP as well. btw, you are fooling yourself i you think he can produce anything logical to prove his point.

mark kibort

WellDave,you are in luck... Here is a GT3RS, a VIPER and a 996 carrera dyno sheet. is there any point on the HP/torque curve RPM scale where you would want to shift at any point before redline to maximize rear wheel forces anywhere on the track?? (straight line discussion)

Wild Weasel

It's probably worth mentioning that we're only talking about straight line acceleration here.

If we start getting into what to do all around the circuit, there are times where you don't actually want the most power available in order to keep the car under better control and going faster under different circumstances. Is it possible that's leading to confusion?

Veloce Raptor

You might be right. However, with several vehicles I have tested, quicker lap times have resulted upshifting just after the power peak rather than winding it out to red line. As I said, the only gauge or graph I care about is the stop watch and segment times.

mark kibort

I made a point to make that clear throughout the discussion . short shifting is often done in areas of the track where you are traction limited. we are strictly talking about shift points in a straight line where traction is not an issue. i dont think this is a confused point as dave has made it clear as he referenced shifting to get to the "meat of the torque curve" which points to some confusion on the actual physics.

there is no logical or practical reason to think that dave's shifting at max HP or just after max HP and losing 30-50hp for a few seconds , can help a lap time. if a lap time is slower, its due to something else.

Wild Weasel

Yeah. I was just trying to plant seeds of reconciliation. Playing peacemaker. But he's doubled down. I don't know what to say other than to just ignore that guy.

He's really determined to be right though, so I'd love to understand his logic beyond just "I've tried it and it feels faster". There's just no argument for it. It's a simple choice between having less power and having more power. He's chosen less power and is convinced it's faster.