Downside of Bike Engines and now car engines

[dannylt]

Yep - I had selector forks replaced in my busa box at the yearly refresh. The distance lost per change seems spot on to me.

[Jason Plato]

Minimum of 7 foot furtehr down the road per change

 

my calculations are that at Curborough I did : 16 gear changes in a double lapper .

 

Thats like 112 feet .

 

Now what I need is some clever buggar to calculate the time advantage that gives .

 

I'll be back in a few hours to see your figures 😬

 

Dave "slow ole shifter" Jacko

[dannylt]

Ah, but the bike gearbox was way closer ratios, so ends up being a lot more changes. Especially compared to a nice 200+lbft Duratec :-D

[Alex Wong1697456877]

With my quaife 5 speed, I did 4 gear changes in a double lapper at Curborough

 

With the Elite, I do up to 19 changes depending on whether I use first on the corners

 

The times are pretty much the same - With the Quaife and a slightly less powerful engine, I did a 59.08. With the Elite and a slightly more powerful engine, I was doing 59.8 - I think I packed the ratio's a bit too close together when I chose them!!

 

There is a tendancy to use 1st more often because you can - you can get carried away with the sequential shift - but I think I need to stop changing that far down, especially as my 2nd gear on the Elite is already shorter than it was on the Quaife.

 

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Edited by - Alex Wong on 4 Nov 2005 18:06:58

[andygriffiths]

My busa with a 3.14 diff makes no more changes around curborough than most car engine caterhams.eg at curborough i go 1st 2nd 3rd round to molehill 2nd round molehill and upto fradley and around fradley then 3rd and just snatch 4th then down to 2nd for seccond lap and stay in seccond all the way round molehill and fradley and then 3rd 4th and sometimes grab 5th and in general dont rev over 10k so this will give a good comparison.At somewhere like Aintree i would think everyone would be in top over the line.Ialso think that the overall time gains with flatshift are not as great as some of the manufacturers claim but it is still amazing just to keep pulling the stick with myfoot nailed to the floor.I remember picking my car up from Steve from SBD and he said take it for a spin.Iarrived back with a huge grin on my face, and i dont think i stopped grinning all the way home.Curborough was my 1st sprint last year and after my four runs on the saturday i could not remember how many gears i had used or where i had braked or turned in but after every run i just walked round like a cheshire cat even though i was slower than my old vx car.On the sunday i ended up about aeccond faster than i had ever been before even with a std 1300 engine and no flat shift then.The bec cars do take a while to get used to, but are mad when you start to master them 😬

 

GRIFF

[Peter Carmichael]

I've done some fag packet maths to look into the gearchange distance thing. I wouldn't care to hang my hat on any particular figure as the distance will vary depending on which gears you are swapping between and how much running you get in each gear after the change.

 

A swifter gearchange results in a higher speed sooner. My numbers suggest that an upchange advantage of 0.2s in 200bhp Sevens at 70mph will result in a 6 inch advantage by the time that both cars are in the new gear and accelerating. This advantage will continue to open as the faster gearchanging car will have established a ~4mph speed advantage.

 

That six inch advantage in itself is worth 5 thousandths of a second. By the time you have been in that gear for 3 seconds, accelerating up the straight, the time difference might be 0.1s and the distance will be >3metres.

 

So yes, the gearchange is worth something, but around Curborough where you really don't get too much of a run in any gear apart from up the straight I reckon 0.2s quicker upshifts are worth 0.2s on a double lapper.

[Peter Carmichael]

Oh, and I reckon it is quite easy to engineer the h-pattern shift down to sub 200ms shifts, although the 2nd to 3rd shift up the straight at Curborough always caused problems for my h-pattern six speed (witness the 1 second of coasting with a missed gearchange in August 2002, resulting in a 58.6s run and a second place by three hundredths to a Busa... No, I'm not bitter. )

[Gambo]

Andy , just out of curiosity, what were your times at Llandow with the VX on 1A's?

 

RED 2.0 HPC now on throttle bodies

[metal mickey]

Peter, that seems a very small time gain. I'm not doubting your calculations but if Griff is doing 9 gear changes and they are saving 0.2 sec each then surely the overall gain must be more than 0.2 sec. Also surely the increase in speed means the overall course will be covered in a lower time 🤔

[Richard Price]

Gambo,

look here

 

 

[Gambo]

*thumbup*thanks , that gives me reason for hope. 😬

 

RED 2.0 HPC now on throttle bodies

[andygriffiths]

Hi Gambo,as Richard i beat you to it Price has put i did 82.97 and this year in the busa 80.02 and a late 79 in practice.At curborough i didabout 62 secs and in the busa 58.59 in practice and 59.12 in timed so it is slightly quicker,but the vx was set up really badly as richard Price will agree 😬

 

GRIFF

 

Edited by - Andy Griffiths on 4 Nov 2005 19:57:52

 

Edited by - Andy Griffiths on 4 Nov 2005 19:58:44

[andygriffiths]

Forgot to mention that this year due to the cut switch was on the lever end not the engine side i had to increase my cut time to 1.2ms but next year it will be no more than 0.6ms. I think steve from sbd runs at less than 0.5ms in his oms.So next year my changes will be twice the speed which will be nice but at such small cuts it will probably be hard to tell the difference.

 

GRIFF

[Peter Carmichael]

On Andy's description of a double lapper at curborough...

 

1,2,3 then into paddock, so feathering the throttle and no advantage from the quicker gearchange. 2nd round molehill all the way to fradley.

 

2nd to 3rd 3rd to 4th up the straight. These are the gearchanges that count on the first lap. probably Griff isn't in 4th for long enough for it to count.

 

Back round to Fradley, 2nd all the way.

 

2nd to 3rd, 3rd to 4th up the straight Possibly 5th. These are the gearchanges that count on the lap 2. So in total 5 upchanges but probably only 3 with significant time spent under power following the change. 0.2-0.3s advantage if the changes are going in 200ms faster.

 

I don't believe Griff's numbers for the cut that hes just posted. Much more likely to be 120ms, aiming for 60ms. From the Proshift website, there is this quote:

At first trap with ProShift (after 5 gear changes), time = 19.04 sec. Without ProShift and time = 19.32 sec. Hill-climbs are won/lost on hundredths of a second so a 0.28 second improvement is very important.

 

... so I don't reckon I'm far off.

[andygriffiths]

Peter you are correct,decimal points are incorrect 😳.like you say 10ths and 100ths are very important

 

GRIFF

[Jason Plato]

regardless of the facts i have now added the gearchange to the Official list of drivers excuses (89th Edition/2006) .

 

"anything upto and over 4 seconds is lost as a result of happy jappy gearboxes"

 

That will do me 😬

[Mike Biddle]

Mark, the exhaust coating has suffered a bit from stone chip damage, the tail pipes in particular are taking on tht "sandblasted" look, but otherwise it's fine. The manifolds are still perfect, so no problem with handling the heat.

 

Metal Mickey, I don't have a definitive weight yet although British Airways did tell me that the total weight according to them was 625KG, with the standard shipping pallet it was sitting on weighing 125KG, so a provisional estimate is somewhere aroung 500KG including a box of spare parts, a spare radiator, and 1/4 tank of fuel (2.5 imperial gallons). There is still some work to do on the car, including a corner weight set up, so I will have definitive info at that point.

 

I have not set out to build an ultra light car, despite the carbon interior, I have just specced it the way I wanted it. There are some items which carry a weight penalty like the SV De Dion tube and driveshafts, rear wing extensions, Freestyle ultra wide front suspension, Chassis stiffening top and bottom in the engine bay, substantial stiffening around the diff mounts, quite a few standard instruments due to my dislike of electronic pressure/temp guage systems, preffering capillary tube analog ones, even though this duplicates some functions existing in the Stack ST 700 system.

 

DSL, Davey Bee, Re handling, I'll let you all know, once the car is finished. The Freestyle inboard front suspension has yet to be fitted due to time constraints, and the requirement to engineer the steering system around the suspension. It currently runs directly forward horizontally, through a 90 degree bevel gear and striaght down to the rack, which does not permit fiiting the inboard kit, which I feel is quite important bearing in mind the "super wide" front track which makes the standard inclinded suspension even less effective.

 

Re Curborough, I know that Russell has not paid enough attention to proper set up of the car, even to the point of running quite a high tyre pressure on the day, and if I'm not mistaken, Dave Jackson had very little time in the car prior to the event. That's a shame because the car is capable of much more, if understandable since they have been concentrating on engine and installation development.

 

Dave, both Russell and Chris agree that my car feels much better than the SV on the road, and I can assure you that it gets the power down very well, even at full throttle, at least on the roads in the USA which are not the best in the world by a long way. Rod Thonger was a passenger up highway one, I'm sure he would agree, as would Chris Beardshaw and one or two others who witnessed a fast getaway on a minor, poor quality back road somwhere in the middle of nowhere. Next summer when it's back in the UK and finished you are welcome to a test drive for the sake of comparison.

 

Maybe this has something to do with the very wide rear track (2" wider than an SV) with the new 245 Cr 500's and the fact that I did not even attempt to spec the spring rates and dampers, leaving that to Gary May. Thanks Gary, great job!

 

Now I'm not suggesting in any way that my car is the ultimate, and I certainly don't want to get into a pi$$ing contest with anybody, I'm sure for instance that there are plenty of car/driver combimations around here that could beat me in any form of competion, so lets not get into that, but if anybody want's to make sensible comments or ask questions please feel free.

 

I would add that posts on this thread so far have been entirely constructive, and it's one of the best for some time, very interesting.

 

 

 

 

 

 

 

 

 

 

 

 

Edited by - Mike Biddle on 5 Nov 2005 10:51:11

[Violet Elizabeth]

... so I don't reckon I'm far off.

 

Ah, but that is flatshift vs clutchless I would imagine, not comparing the same thing. Even without flatshift, a bike box can still be clutchless.

 

200 ms seems very low for the whole H pattern process of dip clutch,. come off accel. change gear, clutch up and back on power. Granted you could perhaps swap cogs in 200ms.

 

The 125 ms quoted for a flatshift is from full power to full power.

 

 

 

 

[Jason Plato]

just as a slide aside . Peters comment on the August 2002 Curborough event made me recall the thread . Its interesting to se how things have since moved on and cars developed- with soem of the drivers taking different routes since - Dave K in single seaters now, Pete = ski bum , brodie class 6 and me 1900K . As a comparison Class 5 record is currently 56.99

 

Class 5 was Dave K in busa , Peter C in his 253bhp K , me in my little 1600K on 32R's and Brodie in his fireblade on 32R's .

 

thread is here

 

Mike - your car sounds like a great package. A drive would be a great treat 😬 - maybe we should resurect the car comparison thread from last winter - where 6 of us were going to meet up and swop cars and write a report for LF ?

 

. I found traction to be a problem on the RSTV8 mainlay as a result of cold hard tyres and far too much power - the nitron dampers were probably fine 😬

 

Dave

[DSL]

Dave,

 

Talking of a blast from the past Dave K is the guy building my car & he seemed to be rather keen to take me up on my offer of sharing the Busa car at a couple of rounds next year to see what it will really do *thumbup*

 

Should be enough to extract maximun effort from Brodie for a change 😳 😳 😬 😬

[EFA]

When someone fabricates a decent switch for the Quaife seq box, can they get in touch please. Ta.

 

Wopulkd be best to design a two switch device so you can automate throttle blips on downchange.

 

Someone mentioned magnetic reed swithces. Are these necessarily accurate enough? - Perhaps a Hall effect transducer may also be an option?

 

Biggest problem is the lack of room in the chassis around the lever (unless you perhaps have a padded tunnel top?

 

 

[metal mickey]

Mike B - thanks, just interested in the overall weight.Would be very interested in the accurate weight when you have it on the scales.

Peter - thanks for explanation of calcs. I too was misinturpreting the decimal point and not taking into account that some changes are in fact down changes off the power, although im sure the increased speed/ease of down change is also a benefit.

Dave(dropped a cog) Jackson 😬- are you going to publish the 'excuse book' 🤔

[Jason Plato]

why do you think you will need it 😬 😬 😬 *wink*

[Peter Carmichael]

Noger,

 

The 200ms figure I quoted was from datalogs showing the dip in the longitudinal acceleration, so the 200ms involves the entire gearchanging process. I really do have a problem with the cross-gate shift from 2nd to 3rd. The best downshifts come in at 175ms including the throttle blip. I went to a lot of trouble to get the 5.5in clutch setup working well and giving rev drop rates to achieve this.

[EFA]

In my MBE 970 ECU, the min and max durations for power shift are 0 & 127.7ms respectively.

 

Peter is alos right in that you will need a engine with a very low moment of rotary inertia (read: a small clutch, and light rotating internals) to get this to work.

 

On that subject I saw a DKE "lighweight" steel crank for a K the other day - not very lightweight IMO as it has 8 counterweights. A bit strange when they can make the VX one with just 4.