NZ land speed record?

**Deano** · 28th July 2008, 10:01

Cliff Hanger Promotions are currently in the throes of organising a NZ speed record attempt.

Looks like it will be held in Featherston in early November.

**koba** · 28th July 2008, 15:14

Originally Posted by johan

Thanks for that link!

I couldn't see atmospheric conditions were mentioned.

It seems odd if timing devices with the resolution of at least one fiftieth of a second are required, but no measure of atmosphere is carried out.

As far as I know with the little aviation theory I've been studying, engine performance can change around 10% from day to day. It wouldn't be too hard to convert the speed to ISA conditions just to see how much it would differ, if it would make any practical difference.

Right atmospheric conditions really affect performance of the bike, at the sprint the VFR's top speed varied by 12 Kays or so, getting faster as the air got thinner.

BUT apart from wind how does it matter?

The idea is to cover a measured kilometer (or whatever) in an acuratley measured elapsed time, the atmospheric conditions dont change the constant of a meter or of a second.

Or do they...

Originally Posted by madbikeboy

Ok, is it just me, or does 307 not sound that fast?

Now, I'm not advocating doing anything illegal, but I worked out the gear ratios and final drive on my humble scoot, and it worked out about 310 (on the limiter in top). The speedo stops at 299, but they lie like politicians anyhow.

I would have thought a hayabusa would've gone faster given my experience with them.

I'm assuming that you can change gear ratios, and run taller back ends, and with the mirrors off...

307 should be achievable...

Anyone willing to give it a go (meaning loan me a Hayabusa for a day?). It'd be interesting to find somewhere and get the permissions to try it out. I'd be willing to give the 1000cc record a nudge...

I really isn't as easy as it sounds, getting two runs back to back seems to be the hard bit.
It seems litre bikes get to 290 REAL KPH relativley easy but after that every kay an hour seems a bit of a battle.

Thats not to say it can't be done, I would say it is somthing most people with a good modern litre bike could have a go at.

As dangerous says aerodynamics are very important, the rolling resistance (wheel bearings, chain etc..) on a bike doubles with a 2x increase in speed but the aerodynamic resistance increases exponentialy.
(I think)

**johan** · 28th July 2008, 15:35

What you're looking at is the density altitude. As you know, performance of a normal aspirated engine decreases with altitude opposed to a turbo equipped engine, where the higher altitude with lower temps work to its advantage.
We're not necessarily talking about air resistance; bike vs airflow, turbulence and drag. That's another topic.

The density altitude is a product of altitude, pressure, humidity (dew point) and temperature. So at a geographic location of 100 feet, as the atmospheric conditions are changing, the engine will perform as if it was at an altitude of say 5000 feet. Or it could be the other way around, density altitude decreases, and you'll get an increase in performance.

High density air equals to more horsepower (more air molecules in a given volume of air).

You also want to know the current figures to make adjustments to the injection for optimal performance.

Just like when you do a normal dyno, the operator should be very careful to enter the atmospheric conditions valid for that hour.

Here's an online tool. Play with it, as you can see, horsepower can change 10%. If you have a bike with 200 horsepower, that's 20 ponies up or down.
http://wahiduddin.net/calc/calc_hp_dp_metric.htm

Read this report where they are keeping track of the atmospheric conditions all the time.
http://www.cookedgoose.org/2001bonnevilles.htm

Looking only at the GPS for speed becomes more of a random number generator without taking density altitude into account.

I'm sure more knowledge people can correct me, I'm new to this, but the subject caught my attention.

Originally Posted by koba

Right atmospheric conditions really affect performance of the bike, at the sprint the VFR's top speed varied by 12 Kays or so, getting faster as the air got thinner.

BUT apart from wind how does it matter?

The idea is to cover a measured kilometer (or whatever) in an acuratley measured elapsed time, the atmospheric condidtions dont change the constant of a meter or of a second.

Or do they...

**madbikeboy** · 28th July 2008, 17:52

Allright, I'm going to be really serious for a moment.

Running on tarmac isn't like at Bonneville, most bikes at Bonneville struggle with the air and the lack of traction on the salt.

Now, on stock gearing, my bike can and does hit the limiter in top gear. Without doing the math on the increased circumference of the tire, because I have no way of measuring, I can extrapolate what the speed of the bike is based on final drive ratios.

I think, based on the way the scoot pulls at top end, that I might be able to add a tooth over stock, or maybe two, and still hit the rev limiter.

Doing the math on either of those puts the bike over 307, not by much, but that's not the point.

My bike has had a small amount of work

and there are other GSXR1000's on here with more power, surely one of those would do it. Then, take into account what sort of torque a Hayabusa has, and then the numbers don't look all that fast, meaning if my slow old gixer can do it, then a new Busa should be able to better it...

Doing two runs would be more about making sure the preparation is perfect, and that the bike was dialed in ahead of time.

Disclaimer: All speed runs on the limiter in sixth have been done on a private closed road or at a racetrack. I don't advocate speed, noise, wheelstands, or country music - they're all superbad, and should be outlawed in the same way clubbing baby seals is bad and should be outlawed. In fact, we shouldn't even be allowed to ride those contraptions with two wheels without someone walking ahead of us while wearing a safety vest ringing a bell warning passersby that we're coming - and we should have to wear bubble wrap and get nice cuddles from our PM.

**Forest** · 28th July 2008, 18:06

Originally Posted by Gremlin

Who said anything about a 1098R? They are talking about the desmosedici...

Sorry. Was posting late at night.

The Desmosedidi RR might be capable of 350kmh.

**Kickaha** · 28th July 2008, 18:08

Originally Posted by Deano

Cliff Hanger Promotions are currently in the throes of organising a NZ speed record attempt.

Looks like it will be held in Featherston in early November.

Will this mean any bike can enter and will be able to have a go at whatever the current record for their class is?

**koba** · 28th July 2008, 18:28

Originally Posted by johan

What you're looking at is the density altitude. As you know, performance of a normal aspirated engine decreases with altitude opposed to a turbo equipped engine, where the higher altitude with lower temps work to its advantage.
We're not necessarily talking about air resistance; bike vs airflow, turbulence and drag. That's another topic.

The density altitude is a product of altitude, pressure, humidity (dew point) and temperature. So at a geographic location of 100 feet, as the atmospheric conditions are changing, the engine will perform as if it was at an altitude of say 5000 feet. Or it could be the other way around, density altitude decreases, and you'll get an increase in performance.

High density air equals to more horsepower (more air molecules in a given volume of air).

You also want to know the current figures to make adjustments to the injection for optimal performance.

Just like when you do a normal dyno, the operator should be very careful to enter the atmospheric conditions valid for that hour.

Here's an online tool. Play with it, as you can see, horsepower can change 10%. If you have a bike with 200 horsepower, that's 20 ponies up or down.
http://wahiduddin.net/calc/calc_hp_dp_metric.htm

Read this report where they are keeping track of the atmospheric conditions all the time.
http://www.cookedgoose.org/2001bonnevilles.htm

Looking only at the GPS for speed becomes more of a random number generator without taking density altitude into account.

I'm sure more knowledge people can correct me, I'm new to this, but the subject caught my attention.

Right, but it is somthing that compeditors have to work with and tune to and isn't really somthing that should be considered in recording the attempt.

I'm finding it hard to explain what I mean....

If a bike does 310 average speed, both ways under the conditions set out in the MNZ rules under the perfect atmospheric conditions that have been tuned to by the racer/race team then the should have the record, in my opinion, the relative air density is just another part of the game that the smart tuner needs to be up with and doesn't constitute an "unfair" factor.
I guess "thats racing" applies.

I don't know for sure if you were asking whether air density ect should be taken into account - damn internet communication i really struggle with it sometimes!

Another factor would be that thinner air MAY (just guessing) create less resistance for the bike to push against, possibly offsetting some power loss.

Perhaps a given bike may be faster (due to less air resistance) at high altitude even if it puts out less power if the less dense air is allowed for in tuning?

Originally Posted by madbikeboy

Allright, I'm going to be really serious for a moment.

Running on tarmac isn't like at Bonneville, most bikes at Bonneville struggle with the air and the lack of traction on the salt.

Now, on stock gearing, my bike can and does hit the limiter in top gear. Without doing the math on the increased circumference of the tire, because I have no way of measuring, I can extrapolate what the speed of the bike is based on final drive ratios.

I think, based on the way the scoot pulls at top end, that I might be able to add a tooth over stock, or maybe two, and still hit the rev limiter.

Doing the math on either of those puts the bike over 307, not by much, but that's not the point.

My bike has had a small amount of work

and there are other GSXR1000's on here with more power, surely one of those would do it. Then, take into account what sort of torque a Hayabusa has, and then the numbers don't look all that fast, meaning if my slow old gixer can do it, then a new Busa should be able to better it...

Doing two runs would be more about making sure the preparation is perfect, and that the bike was dialed in ahead of time.

Disclaimer: All speed runs on the limiter in sixth have been done on a private closed road or at a racetrack. I don't advocate speed, noise, wheelstands, or country music - they're all superbad, and should be outlawed in the same way clubbing baby seals is bad and should be outlawed. In fact, we shouldn't even be allowed to ride those contraptions with two wheels without someone walking ahead of us while wearing a safety vest ringing a bell warning passersby that we're coming - and we should have to wear bubble wrap and get nice cuddles from our PM.

DO IT!

I See you understand that the gearing needs to be spot on for the intended top speed, I would reccomend having a few spare rear sprockets on the day just in case tho.
Also concentrating on aerodynamics would be a good way to start, esp if you already have "the easy" power mods, maybe single seat hump, real good leathers with a good speed hump.

**koba** · 28th July 2008, 18:33

Originally Posted by Kickaha

Will this mean any bike can enter and will be able to have a go at whatever the current record for their class is?

Some info on current records would be interesting, also really the purpose of this thread....
MNZs records bit on thier website seems poked.
I shall use the E-mail.

**johan** · 28th July 2008, 18:49

yeah, I see what you mean koba.

Simplified, it's the same as having a 100kph tail wind one year and the next year you have 100kph head wind. It's nothing you can do anything about, it might just work to your favour, or not.

Should this be taken into account or not when setting a record? According to MNZ rules, it's not a part of the measurement. Which is fine. I just found it a bit odd.

I shall stop my rambling now.

**k14** · 28th July 2008, 19:17

Originally Posted by johan

yeah, I see what you mean koba.

Simplified, it's the same as having a 100kph tail wind one year and the next year you have 100kph head wind. It's nothing you can do anything about, it might just work to your favour, or not.

Should this be taken into account or not when setting a record? According to MNZ rules, it's not a part of the measurement. Which is fine. I just found it a bit odd.

I shall stop my rambling now.

No it is not the same as having head winds, the winds are supposed to be irrelevant due to having to do one run each way within one hour (i think??) of each other.

Does anyone have a copy of all the records for all bikes? What is the 125 record??

**koba** · 28th July 2008, 19:30

Originally Posted by k14

No it is not the same as having head winds, the winds are supposed to be irrelevant due to having to do one run each way within one hour (i think??) of each other.

Does anyone have a copy of all the records for all bikes? What is the 125 record??

I've E-mailed MNZ.
Will post reply.
I know Ivan did a one way run of 204.08kph.

Sprints results at www.cliffhanger.org.nz makes for interesting reading.

**Kickaha** · 28th July 2008, 20:01

Originally Posted by k14

the winds are supposed to be irrelevant due to having to do one run each way within one hour (i think??) of each other.

I think the wind is not allowed to be over a certain speed for a record attempt

**madbikeboy** · 28th July 2008, 20:29

Originally Posted by Forest

Sorry. Was posting late at night.

The Desmosedidi RR might be capable of 350kmh.

If you threw it out of a Hercules maybe...

Plus, if you ran it, you'd need to get it started again for the second run. I own Italian machinery, it's not as much of a joke as you'd think...

**madbikeboy** · 28th July 2008, 20:38

DO IT!

I See you understand that the gearing needs to be spot on for the intended top speed, I would reccomend having a few spare rear sprockets on the day just in case tho.
Also concentrating on aerodynamics would be a good way to start, esp if you already have "the easy" power mods, maybe single seat hump, real good leathers with a good speed hump.

If they'll let me run, I'll be there. Yeah, the gearing is the key, too big, and the bike can't get on top of the gear, too small, and it's just over too soon. Anyone willing to sponsor me a nice new set of tires for the event??? Of course, aerodynamics is also the key - I spend time doing performance coaching for cycling - you'd be amazed at the small things that reduce drag hugely.

Can you provide the rules, can I remove mirrors and indicators? I don't think (from memory) that you can alter the shape of the bike for speed attempts, but a shroud behind the lid makes sense.

Seriously, if they will let me run, I'm in...