Jump to content


- - - - -

Revs / Power Bands, Etc


  • Please log in to reply
69 replies to this topic

#21 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Aug 31 2015 - 03:15 PM

Speedshifting is wrong in so many ways in a sim. It's great in games. :P

#22 John Woods

John Woods

    Be Somebody

  • Supporter
  • PipPipPipPipPipPipPipPipPipPip
  • 2,471 posts
  • Gender:Male
  • Interests:Too Much Fun
  • Sim interest:GPL

Posted Aug 31 2015 - 05:26 PM

From page 22 of Steve Smith's Four Wheel Drift:

"To Clutch or Not to Clutch:

The use of a clutch is new to auto racing sims, although most experienced players probably won’t recognize its absence as an aid (although I guess you could think of its presence as a “reality enhancement”).
Thirty years ago, a driver only needed the clutch at the start of a race, to get under way, after which a “crashbox” (a manual transmission without synchromesh) could be shifted all race long by just matching the engine speed to the speed of the gears (easier than it sounds)."

#23 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Aug 31 2015 - 06:17 PM

Not true. You forget i'm from that era.

Just one example.

https://www.youtube....h?v=JJDkZYhJR1E




Clutch, or no clutch they didn't speedshift as the term is used in GPL. Which means full throttle shifts.

Edited by Pete Gaimari, Aug 31 2015 - 06:21 PM.


#24 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Aug 31 2015 - 07:34 PM

A post by the son of the present owner of  the R2 Lotus 49. The same one I posted a video in another thread.





My Father owns the car now. This is chassis R2/11, which was Jim Clark's car for the Dutch Grand Prix in 1967. It was the car's first race, and Clark's first time racing the car (he hadn't even driven it before the race weekend), and he blew everyone else out of the water. An incredibly important part of Formula 1 history as this was the first F1 car to use the engine as a stressed chassis member. It was also the first race car to have sponsorship/sponsorship colors.
I wish Road and Track would have picked a driver who had ANY experience using an H pattern box, because according to R&T, Rossi has literally none. The ZF box that the 49 uses is very delicate and prone to breaking. It broke on my dad at the Historic Monaco Grand Prix twice. The key is to pause between coming out of gear and selecting the next gear.
<a class="expand" style="color: rgb(51, 102, 153); margin-right: 3px; padding: 1px;">[–]Ayrton Sennamattverso 6 points 2 years ago



Changing gear properly in that car would require significant use of the double-declutch and heel-and-toe techniques. Clutch in to shift to neutral, clutch out, back in, select gear, out again, while matching revs with your toe and braking with your heel.
It is the opposite of easy. It's also why most drivers these days have no idea how hard it used to be. I've wrecked the gearbox of more than one modern car trying to learn the techniques and I still haven't got it down. I can only imagine how short a time a classic Lotus's gearbox would last if you didn't know exactly what you were doing

Edited by Pete Gaimari, Aug 31 2015 - 07:35 PM.


#25 John Woods

John Woods

    Be Somebody

  • Supporter
  • PipPipPipPipPipPipPipPipPipPip
  • 2,471 posts
  • Gender:Male
  • Interests:Too Much Fun
  • Sim interest:GPL

Posted Sep 01 2015 - 07:43 AM

From Road & Track magazine website:
(article on history of Hewland)

At Lola's request, Hewland modified a VW Beetle's magnesium-case four-speed for strength and service. It also provided for a custom dog-clutch (read: unsynchronized) geartrain. The result was a five-speed manual that let you blitz through shifts without the clutch and allowed for complete ratio swaps in 20 minutes.

From sdt.com:

For a manual car the best method of acceleration is to rev to or just beyond peak power in the gear before up-shifting. After the change the engine will be right on, or just below, the point at which it develops maximum torque. By red-lining each gear the engine sounds like its making extra power but really you are only putting excessive stress on all engine component, wasting fuel and making noise.

Lewis Hamilton on the 2014 car, from BBC

"This year, the torque is much lower in the rev band and there is so much more of it. We also have a lot less downforce.

That means we use the engines very differently - we rev them much less, and we change gears much sooner, so at the same point on the track we're often in a higher gear than last year.

This is called short-shifting, and it allows you better control of the torque of the engine.

If we had as much downforce as last year, we would not have to short-shift as much. But we have lost a lot of grip, especially at the rear, with the restrictions on aerodynamics.

It's really difficult to put into words exactly how you judge when you need to short-shift, because it's all done on feel."

Edited by John Woods, Sep 01 2015 - 07:57 AM.


#26 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Sep 01 2015 - 08:44 AM

John...The Lotus 49 didn't use a Hewland. It had a syncro ZF tranny. Not a dog ring tranny. It needed the clutch for smooth shifting. It was also a sequential tranny that couldn't skip gears on downshifting. Hill hated that, because he was used to skipping gears going into a turn. Jim never complained about it. :)

Lets keep to 67 F1 cars, and the era they were driven. What Hamilton does in a modern F1 car is not relevant to this conversation.

#27 Fat Rich

Fat Rich

    Lazy Blipper

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 772 posts
  • Gender:Male
  • Location:Fallen out of the Karussell again
  • Interests:GPL has got me by the throat and won't let go.
  • Sim interest:GPL

Posted Sep 01 2015 - 11:02 AM

Steve Smith's Four Wheel Drift was a good read and a very nice addition to the game, but there's some stuff in it that I don't agree with... and some stuff that Lee's explanations of how GPL's physics code actually works suggest Steve Smith wasn't in possession of the full facts at the time of writing. As for clutches, people made a big fuss that Jim Clark won the '67 Mexican Grand Prix despite his clutch breaking early in the race, drivers could change gear without it but it wasn't something they chose to do.

Personally I often short shift the Lotus 49 as it sometimes has more torque than it has grip, I usually avoid 1st gear completely except for the start of the race, apart from the hairpins at Monaco or similar. Generally I short shift 2nd to 3rd, but hardly ever above that. I always try to avoid "speed shifting" (or flat shifting) although sometimes I miss-time my shift and do it by accident. Although shifting takes approx 0.2 of a second, it's not adding 0.2 of a second per shift to your laptimes.... it would only do that if the car was suddenly totally stationary for each of those 0.2s ;) Let's say you shift up to top gear while doing 145mph, while the clutch is in you'll only slow down fractionally due to wind and rolling resistance.

Edited by Fat Rich, Sep 01 2015 - 11:04 AM.


#28 John Woods

John Woods

    Be Somebody

  • Supporter
  • PipPipPipPipPipPipPipPipPipPip
  • 2,471 posts
  • Gender:Male
  • Interests:Too Much Fun
  • Sim interest:GPL

Posted Sep 01 2015 - 11:54 AM

Some may recall BRR's test at Reims yielded an average point-5 second slower lap time when on the .22 shift delay than when deleting it for purpose of test. So shift-time delay does effect lap time, but not 1:1?
This is the reason for Fairshift?

Pete, just guessing, Hamilton's comments about low end torque and short shifting would apply to any era?

This thread, reading the first post as literally as possible, does not limit the discussion to the Lotus 49 or the 67 season.

Did all 60s era F1 cars use the synchro'd sequential ZF?

Find lots of references to shifting race cars without the clutch, as Steve Smith notes, enough to assume it was very common going all the way back.

Powershifting and speedshifting at the same time, while not possible in Grand Prix Legends without using GPL Shift, seems theoretically possible, or just stupid fun, in "real life."

Like to try it someday with an old VW on snow.

Edited by John Woods, Sep 01 2015 - 12:08 PM.


#29 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Sep 01 2015 - 12:50 PM

Read the last sentence in the first post John.

#30 John Woods

John Woods

    Be Somebody

  • Supporter
  • PipPipPipPipPipPipPipPipPipPip
  • 2,471 posts
  • Gender:Male
  • Interests:Too Much Fun
  • Sim interest:GPL

Posted Sep 01 2015 - 02:29 PM

View PostRonnie Nilsson, on Aug 30 2015 - 01:21 PM, said:


principally


So he didn't specifically exclude an old VW on snow.
:)

#31 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Sep 01 2015 - 02:39 PM

True. :)

#32 David Wright Lo67

David Wright Lo67

    Denny Hulme

  • GTLW Crew
  • 443 posts
  • Gender:Male
  • Interests:GPL, GTL and P&G
  • Sim interest:GPL and P&G

Posted Sep 01 2015 - 02:41 PM

View PostJohn Woods, on Sep 01 2015 - 11:54 AM, said:


Did all 60s era F1 cars use the synchro'd sequential ZF?


No.  Lotus were the first team to adopt the ZF box with the Lotus 25, keeping it for the 33.  The 43 used a BRM box but the 49 reverted to ZF.  However, in 68 Lotus switched to the Hewland box for the 49B.  Cooper used a ZF box for the T-81, but went to Hewland for the T-86.

#33 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Sep 01 2015 - 02:43 PM

What's your opinion of using the clutch with the ZF tranny David? Was it used?

#34 Wozza_UK

Wozza_UK

    Denny Hulme

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 95 posts
  • Gender:Male
  • Interests:Sim racing, video games in general, fiction writing.
  • Sim interest:GPL

Posted Sep 01 2015 - 04:26 PM

I thought the idea was to shift up at 'peak bhp' then continue in that gear all the way to 'peak bhp' again, then change up again. The redline comes a little AFTER peak bhp and is to be avoided due to the risk of damaging the engine. It's the theoretical maximum revs the engine will take.

You short shift in order to either eliminate wheel spin in a low gear, or if it makes the next corner more comfortable, or if going downhill.

Where in Setup Manager does it give these bhp/rev limit figures? There are two graphs but I've never been able to make head nor tail of them apart from using one of them to get an idea of gear spread.

#35 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Sep 01 2015 - 04:58 PM

I've run full GP while shifting the Lotus at 9000 rpm. No damage I was aware of.

#36 John Woods

John Woods

    Be Somebody

  • Supporter
  • PipPipPipPipPipPipPipPipPipPip
  • 2,471 posts
  • Gender:Male
  • Interests:Too Much Fun
  • Sim interest:GPL

Posted Sep 02 2015 - 10:47 AM

Posted Image


This is a graph illustrating what is meant by "marginal returns." Often referred to as "diminishing returns" or "maginal utility."
(Its from economicconcepts.com).

A marginal return is apparent in the change in output between any two points along the line topping out at point C.
Easy to notice this coincides very nicely with a torque and horsepower graphs in Set Manager and Race Engineer.
There are lots of ways to apply marginal returns analysis to motorsport.

Validity of the marginal returns graph is proven by direct evidence of the torque and horsepower curves for an engine.

An easy way to think of it is if fuel or throttle is the variable factor, (or input).
Unit of fuel equals horsepower, torque, speed, (whatever).

The chart is divided into three stages.
Stage I yields the most output for a given unit of input.
   So speed is increased the most per unit of fuel input during this stage.
Stage II continues to yield more output than input, but the amount of gain is less for each unit of input added.
   So the car is still accelerating, up to maximum cumulative marginal returns at point C.

However, easy to see the rate of acceleration slows a bunch during Stage II, so maybe best to get back into the next gear's Stage I condition as quickly as possible, maybe somewhere a little past point B? But don't get back too far, maybe just down a bit before point A?

:)

Thus my earlier posts about shifting into the next gear's bottom of 90 percent output lines.

Edited by John Woods, Sep 02 2015 - 11:05 AM.


#37 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Sep 02 2015 - 12:12 PM

Bottom line is in drag racing shifting it done at redline. It gives the fastest acceleration. It's no different in road racing.

#38 John Woods

John Woods

    Be Somebody

  • Supporter
  • PipPipPipPipPipPipPipPipPipPip
  • 2,471 posts
  • Gender:Male
  • Interests:Too Much Fun
  • Sim interest:GPL

Posted Sep 02 2015 - 07:51 PM

Just wondering what is the definition of "redline."
Typical definitive keywords found: "set RPM," "recommended," "safe."
It refers to the maximum appropriate RPM the engine is capable of running continuously under load without blowing up.

It refers to some point well before catastrophic disaster...not an engineering/theoretical maximum ideal output like Point C at the top of a curve.
This isn't economics...its real racing and the car that first finishes wins.

Redline refers to a point before C, as determined by an engineer using mechanics, physics, machine science, and math to lock in the exact safe RPM that if set as the redline, with a given set of gears, would yield an appropriate rate of acceleration and run as close to flat out as necessary for the duration of a single race.

Redline is what an expert says it is. But we have ShiftR!
And we are, of necessity, our own experts.

Not really happy with definitions like "safe" and "recommended" decided to make an interpretation of a racer's redline, (GPL Lotus49 diagram below).

Attached Files


Edited by John Woods, Sep 02 2015 - 08:07 PM.


#39 Pete Gaimari

Pete Gaimari

    Jim Clark

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 3,536 posts
  • Gender:Male
  • Location:Colorado
  • Interests:Racing and Muzzleloader Hunting
  • Sim interest:GPL

Posted Sep 02 2015 - 07:56 PM

You know the Lotus 49 had a rev limiter? Safe to say it's redline.

#40 colepole

colepole

    Jack Brabham

  • Supporter
  • PipPipPipPipPipPipPipPipPip
  • 47 posts
  • Gender:Male
  • Sim interest:GPL

Posted Sep 02 2015 - 08:55 PM

As far as I am aware the limiters in use in those days reacted quite slowly, so, on a smooth track you can redline it ........ what kills the engine is sudden changes in rpm e.g going over jumps/bumps while flat on the gas. Holding a gear longer than you really want to is fine for short periods ....... just have to make sure the overall oil/water engine temps don't rise above safe limits.




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users

Sim Racing Links