333pg333

Nice going. Sounds like that's a great time you achieved.
A couple of questions.

-You seem to stay in a higher gear through some of the corners which to the ear sounds like the car
labours out of the next corner a little. Was this done on purpose or had you downshifted in the past
and found it to be slower?

-What Hoosier slicks are you using?

-Agree with VR...you need some Sunnies or a tinted visor.

Veloce Raptor

Mark...are you aware that redline is not the HP peak in your graph? redline appears to be 7,600. The HP peak appears to be 200-300 RPM under that.

Pretty much what Viking and I said....know what I mean?









Professional Racing and Driving Coach

mark kibort

So, even with you 3.4, do you see the problem with short shifting even 2-300rpm?
If the torque is flat from 4400rpm to 6000rpm, that means the HP is rising at a 45 degree angle. so, as soon as you short shift, you loose 50hp, which is a reduction of acceleration, because you are in a taller gear now with less mechanical advantage.

[QUOTE=Ritter v3.4;8275075]

mark kibort

Sure. Im absolutely aware of that fact. So are you still thinking its better to shift out of the gear you are in as the HP starts to fall, or before hand to save the engine? I just want to be clear on what you are suggesting.

So, why are you rolling your eyes, even if the HP falls off as you pass THOUGH 7400rpm, it still pays HUGE dividends to carry the RPM to redline. Do you know why?
This is because shifting to the next gear gives you MUCH less HP at the same vehicle speed, thus giving proportional less acceleration. Do you not agree??
your seat of the pants "feeling" cannot be trusted. It might feel like you are not accelerating any more, but the next gear gives an even greater reduction in acceleration. make sense??? This is someting I counted on my BMW racers to "feel" so I would have a distinct advantage in our races. It wasnt until later when the races didnt mean as much , did I educated them on this common misconception. After much push back, they finally got it and the result, their lap times improved. Not a big deal for DE'ing, but if you are racing or wanting a better lap time, it is a big deal.


edit: I assume you are referring to the graph of the 3.6L 996 showing redline or end off the dyno run at 7500rpm.
Ill conciede one thing, it doesnt always have to be redline. redline is too general, lets just say its often well past max HP. Using seat of the pants wont tell you anything here, you need to know your engine profile (hp curve) if you are serious as a racer (Or coach) to optimize straight line speed anywhere on the track. It may seem like shaving hairs, but in this regard, its as important as braking zones, cornering and exit speeds and driving line. If dont KNOW it, and using seat of the pants or misinformation, you are guessing at what is best.

mark kibort

No, i never use the seat of the pants feelings to determine shift points. I always use dyno sheets, especiallly when racing a car of mine or someone else.

countless hours on dynos dont prove anything but helping maximze HP performance, and safety of their engines. I have minimal dyno tuning time each year, mainly to just make sure the engine is safe from itself. If I wanted to , I could spend the extra cash, optimize the power and pick up about 40 more HP by most approximations.

Now, to answer your other question, I visit the dyno 2 times a year, if there are no changes. More if I have changed something like a cam or intake mod. I dont "rely" on the web for any information I use in my racing. what do you mean by that? the point is, on the topic of maximizing acceleration, nothing else., it never pays to short shift, ever in a car equiped with an engine with a rising, peaking HP curve. Im lucky having a V8, its a very flat HP curve, so I have the luxury to short shift slighty, and have it not impact performance as much as it would, a flat or inline 6, generally. in other words, my short shifts
end up at near the same hp post shift as pre shift, but this is generally unusual.

so, my main point to you is that I am bashing the "seat of the pants" opinion. I can do this, by saying there is NO basis for it to be true. And can prove it very simply by common logic based on the common shape of the engine HP curves for the car in question. I also can give a reason to why it might feel faster or better to short shift, but those feelings are incorrect and certanly can be proved by data aqu. if a comparitive test is done. If you dont have the same HP at any given speed, you dont have the acceleration rate at that same speed either. just basic physics. By understanding this, VR would be a better coach!

Veloce Raptor

..

mark kibort

Now, we are going racing at High PLains Raceway, with you and a 300rpm earlier rev limiter.

Seriously though, Its still bugging me though. what did you mean, or does it matter with the 3.6 liter engine having the HP fall off 300rpm past peak HP. Help me understand the point.

deputydog95

Wow, I'm a *****. I have no business driving a GT3. Based on my lap times at Sebring I'm better suited for a miata

mark kibort

Remember when WCGT went to Sebring with the ""Cheater" Caddies. they broke into the 2:10 range, if I remember correctly. On DOTs none the less!
I forgot what tourng was doing, but they seem to be a good bench mark for cars we can at least relate too performance-wise. (I think 2:23 comes to mind)

Brinkley

Deputy Dog... you kill me!

Mark, now I don't understand your last statement about the GM Caddies, who according to you turned a 2:10, how is a fully tube-framed factory "touring car" eeeeerr racecar a good comparison to a showroom purchased, aftermarket modified street car? I lost ya...

mdrums

I was just going to type the same thing! Kibort whatcha smokin? I do agree a street GT3 on Hoosier or Yoko's or Cup slicks should be turning 2:23...r-comps 2:26. Chris Hall turned a 2:26 in my stocks Carrera S with me (240lbs) in the car on worn out R888's!

Deputy Dog...I've some some kiddie carts or a Big Wheel for ya!

mark kibort

The point was that a well tuned and driven GT3, on slicks should be pretty close to the WCGT times. GT3street, a few seconds behind that.

(at least its like that at Laguna seca for WCGT, GT3's, and GT3 streets)

The fact that the WC touring cars on 245 DOT toyos can run 2:22 with less than 300rwhp, sets the bar, right?

PedroNole

You're joking right... Wow, just wow

onefastviking

No, he really is serious, that's what I don't ever understand.


Mark, you can't say a short shift is faster or slower in X car with X dyno graph without also using a gear chart for the car to REALLY determine where the power will jump to. Then you could logically argue your point. The stock gear charts are readily available on the internet for you to play with.

I now need to go over the data from this weekend to determine some real world situations. Have a good evening.
Viking

Veloce Raptor

Seriously....









Professional Racing and Driving Coach