Ritter v4.0

The longer this thread goes on, the better I feel about my 2:23.

p.s. Short shifting is not an option in my car IMHO- you gotta wring that 3.4's neck and keep revs north of 4500- or better 5k. With a 6800 redline that's a bit of a tightrope, but you do get a feel for it.

onefastviking

Here is a 3.6 996 dyno that I did recently.

sbelles

I was going to say at least you have another gear as I don't get to 5th at Sebring but the extra 1,000 rpms I have in my 3.4 probably makes up for it.

mark kibort

Wow, what is the big deal. GT3s on slicks are running 1:29s at laguna on slicks and so are WCGT porsches cups with all the motorsport upgrades, and the other players. (mustang, vets, vipers, etc).

maybe i should have been more clear. GT3 was GT3 cup. when i was talking about "street" version, i said " GT3 street".

mark kibort

So,I hope by looking at your dyno, you now understand what my point was.

Do you? for example, your 3rd to 4th gear shift, is a RPM level 80% of the pre-shift point. that puts you at 6000rpm. agreed ? any short shifting at all imeadiately loses near 40hp for the the time it would have taken to get to redline or 7600rpm where your dyno test stops.

mark kibort

Hey, dont shoot the messenger. I was just making a factual statement based on cars that have been in pro races, sometimes comparing their times on the same day. GT3 cups on Slicks with out the RSR total upgrades that the WCGT goes through, usually have those trade off which make those two platforms pretty dan close. I think I just saw the Street cup car driver that I raced against, his time at Sebring last year at 2:13 in 18th place or something as a fairly recent driver to appear on the scene. at laguna he drove his street GT3 conversion to a 1:35ish time and his first time at Laguna. It was about 3-4 seconds slower than the top drivers of the GT3cups of the same year model.


Anway, back to the topic,
Yes, of course ive looked at the dyno runs AND the gear charts. I posted them, do you not remember?? it showed a rpm level of 80% of the pre shift rpm.
So, unless you have close ratio gears (that 80% generally goes to 85-87%), I can always just look at a dyno run and see if short shifting is a good idea.

You can CLEARLY see that a short shift instantly kills 40hp for the time it would have taken to get to the higher RPM level. when it starts to fall, and based on the shape of the curve up top, it might make sense to short shift from redline, but those type of curves are generally pretty rare. 928 early models have such a HP curve by the way.

so, the "logic" is this:
your 3-4th shift or 4-5th shift, even with you or VR driving, has a drop from 7600rpm to 6000rpm. you go from operating at 300hp to down to 360hp.
"Logic" says, that running at that same speed at 300hp is BETTER than running at a post shift level of 360hp. And, the interesting part is this. like a BMW e36, with a flat peak HP curve like yours, if you think , like it seems like VR is thinking, you get to 300hp , its flat, torque is falling, so why not shift. After all , from (Dave's ) VR's perspective, its all "noise" right? wrong. Thats even MORE the reason to keep taching it out!!! you shift at 7000rpm for example, and your power drops from the same 300rwhp, down to 340rwhp. a full 60hp less. (warning, more logic). This hurts straightline acceleration when going for a fast lap time.

Now, granted the gears get closer at the top gears. (near 83%), so that 7600rpm shift goes down to 6200rpm, now, only a 20hp loss, but still there are those that would give away family members for less HP gain!

With all the technology you profess to use, you still dont undersand, do you ! all that "noise" is 20-40hp more than a post shift gear. tell that to your next student next time and see if he wants to short shift. Better yet, try and explain it to him as to why.

Veloce Raptor

David, please do not fall into Kibort's terminology trap. Viking and I are definitely NOT suggesting "short shifting". We are saying that sometimes--as in Brinkley's case--there may be very good power delivery & car stability reasons to upshift 200-300 rpm shy of redline instead of riding at redline until braking. This is most definitely NOT "short shifting" despite rhe repeated misuse of that term in this thread.

Mark, when you have actual on-track in-car data to back up your incorrect theories, please rejoin this conversation. As Viking correctly noted, dyno graphs are somewhat irrelevant on track.








Professional Racing and Driving Coach

PedroNole

Chad-

I think you've officially had your thread hi-jacked.... No good deed goes unpunished.

Ritter v4.0

Not the first- and I'd venture not the last

bobt993

As I spend more and more time looking at data it really comes down to trying both techniques as I am sure VR does with his coaching. There are so many variables taking place and you cannot assume available power is simply applying max throttle. If I am at the limit during corner entry that last thing I want to introduce is a mid-corner shift that disrupts the car balance and loses precious time. I always suggest try different gearing in critical corners and look at the results in the data. The important factor is your consistent when you do this. BTW I don't see the merit in throwing times out there to smack down a driver's progress.

Thanks for sharing your progress at Sebring and congrats on the results.

mark kibort

Dave, you are the spin doctor arent you. pretty funny, when called on an error , you gently massage it to fit your defense. I know , you are never wrong, after all, you are a "professioal racing coach".

Look knucklehead, you clearly said that the rpm above a certain point was "all noise". My point was specifically around straight line speed and acceleration. NOT (and i made this very clear) anywhere around areas of a track that was limited by traction . With that said, if you are ever going in a straight line, have a HP curve the shape of those posted by Viking or me, then it never pays to short shift, IF you care about lap time. you dont need motec data Aqu. to figure this out and YOU should know better!

Now, you say "incorrect theory" ? Hmm, why dont you for once on this list, make that point clear of how it is incorrect. (again, leave out areas of the track that dont require max acceleration. How does HP curves become "irrelevant at the track"? again, you made it a point to talk about the noise at the top of the RPM curves. you make it pretty clear to me that you are refering to the falling off of torque past 6500rpm. But, i just want to be clear that even though torque might be falling off, your butt dyno is sensing falling acceleration, that shifting to the next gear sacrafices 20-40hp as soon as you short shift. as long you can correct this, you have a point. If you cant. (again, not in areas of a track not limited to traction or control issues) we will listen and you will not have a point. doubtfull though.

Lets see you back pedal around this!

Lets also be cleaer on "terminology" anytime you short shift, you are shifting short of the engine and cars max potential to accelerate itself for reasons we both agree on. *(traction, car control capabilites, in areas of the track that dont require max accelation )

Mk

mark kibort

VR-Dave Scott,

here is your post. I dont think it takes a racing engineer to understand
what i had posted. its simply this: You are advocating shortshifting, and I disagree, unless its in a part of the track where max power at that speed, might upset the car. But, that makes no sense either, becasue usually a shift will upset the car more in those areas, rather than modulating the throttle in those critical track areas. So, what do you really mean? Nice projection about knowing what you are talking about here.
Face it, you dont understand the basic concept of maximizing acceleration at any speed by keeping the car at max HP regardless of what your butt dyno says. do the test. its basic physics here. Your data acqu. system will validate it. now, it wont gurantee lap time improvement, thats up to the driver and coatch.

Now, you take viking's dyno run. you short shift, (or as you like to say, "shift a little earlier by 300rpm" and what do you lose as far as acceleration. by anyone with a 3rd grade education in math, you lose near 20-40hp based on the graphs we have posted. (depending on the gear shift 3-4th or 4th to 5th).

PedroNole

Veloce Raptor

Good lord. Incredible, isn't it? Another Kibortion...another thread Kiborted.









Professional Racing and Driving Coach

TRAKCAR

Well stated

Kibortian; You ever read your own crap??