z4m sprint championship on going times/progression..

[original guvnor]

loving the Landy v8 doing a track day. Was that just one of the organisers having fun or a competitor?

Not sure I agree with your logic for the roof. :?

Having had the skin off my hardtop for repainting and seeing how it's metal frame is braced together and its mounting points for the car and how they lock into the mounting points.... Their is no one on this forum that can convince me that it won't a) have an impact on rigidity of the car however small it may be, and b) have an aerodynamic benefit with the spoiler on top.... Hell even the PDF for it says their is an aerodynamic benefit ....

With how this is clamped in place , and where it's clamped it WILL be twisting with the chassis .. BTW are you aware Porsche have 2 figures for rigidity for the boxster? one with the hardtop in place and one without.


I'd love someone with an engineering back ground to pop in and give some actual facts.
Where's Jon ???

interesting for sure either way.








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Basically, you need a coupe mate...

Also was the 130i in your class modded? They seemed to get a good time in!

I must admit after reading about how rigidity and aerodynamics is so important I did think the same thing! It's also (slightly) quicker round a track too.

 

[Beedub]

george on the zpost trying to keep up with a grand AM series race car in his blown z4mr.


love this guys videos and he wrote a really interesting piece about the aerodynamic benefit he feels with the top in place, in america i believe you HAVE to have a hardtop in place to run a roadster on a track but that may vary state to state???

take a look at his videos, if you get 20 mins, bloody awesome car!

https://www.youtube.com/watch?v=4k8P2KwsuOA

 

[Beedub]

Having had the skin off my hardtop for repainting and seeing how it's metal frame is braced together and its mounting points for the car and how they lock into the mounting points.... Their is no one on this forum that can convince me that it won't a) have an impact on rigidity of the car however small it may be, and b) have an aerodynamic benefit with the spoiler on top.... Hell even the PDF for it says their is an aerodynamic benefit ....

With how this is clamped in place , and where it's clamped it WILL be twisting with the chassis .. BTW are you aware Porsche have 2 figures for rigidity for the boxster? one with the hardtop in place and one without.


I'd love someone with an engineering back ground to pop in and give some actual facts.
Where's Jon ???

interesting for sure either way.








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Basically, you need a coupe mate...

Also was the 130i in your class modded? They seemed to get a good time in![/quote]


I must admit after reading about how rigidity and aerodynamics is so important I did think the same thing! It's also (slightly) quicker round a track too.[/quote]

The coupe Vs roadster argument is so boring i won't even enter into it tbh, I'm just stating my reasoning behind running the top on a circuit...

 

[original guvnor]

You're right it is, I've no desire to open up that old chestnut either, and it's cool you have a Roadster, but you sort of asked for it really by shooting the other guy down by placing such importance on aerodynamic efficiency and rigidity.

Those track times really show the importance of weight don't they? The Tiv's are what? 1,100kg with 350-450hp stock and Caterhams c. 600kg with 300hp? To get a Z4M anywhere close to them even with your amazing hp would be virtually impossible without shedding 200kg of weight.

Auto Express have just done a track video of M4 vs RS5 and the M4 was 2.3s quicker on a 70 second lap and was even quicker than the Cayman S. No coincidence that the M4's been on a bit of a diet and is now over 200kg lighter than the RS5 and now only about 130kg heavier than the Cayman. It will be really interesting to see how the trend goes in the next few years. Who knows we may see a 1,000kg M4 in the not so distant future.

 

[BMWZ4MC]

Some surprisingly good times set by cars you wouldn't expect. I've no doubt the hardtop adds to the rigidity of the MR (assuming it bolts soundly to the bodywork) and I doubt 30kg has a significant adverse effect on your lap time.
Shouldn't the Ultima be in with the supercars, especially given the other cars found in that class?
Can you post a link here when you've got something concrete for a Z4 day

 

[Adamski]

Didn't sixspeed lose 100kg from his? Isn't that about the max possible saving without getting silly and removing air con etc?


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[BMWZ4MC]

Didn't sixspeed lose 100kg from his? Isn't that about the max possible saving without getting silly and removing air con etc?


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Flatout certainly did with smaller cats, lightweight seats and different wheels. That still leaves the car at 2-3x the weight of a Westfield though with the inevitable consequence on rates of acceleration, be that cornering or changes in speed.

 

[Adamski]

Yeah I think it would need serious money and the inevitable loss of comfort to shed major weight from the Z4M.

If it was a track only machine, I could see the point. But for road and track use - meh


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[Beedub]

You're right it is, I've no desire to open up that old chestnut either, and it's cool you have a Roadster, but you sort of asked for it really by shooting the other guy down by placing such importance on aerodynamic efficiency and rigidity.

Those track times really show the importance of weight don't they? The Tiv's are what? 1,100kg with 350-450hp stock and Caterhams c. 600kg with 300hp? To get a Z4M anywhere close to them even with your amazing hp would be virtually impossible without shedding 200kg of weight.

Auto Express have just done a track video of M4 vs RS5 and the M4 was 2.3s quicker on a 70 second lap and was even quicker than the Cayman S. No coincidence that the M4's been on a bit of a diet and is now over 200kg lighter than the RS5 and now only about 130kg heavier than the Cayman. It will be really interesting to see how the trend goes in the next few years. Who knows we may see a 1,000kg M4 in the not so distant future.

no body shot down anybody??? i just see discussion and ideas being banded around, he asked why i had the top in place and i explained, i personally think this discussion and debate has been exactly what this forum seems to lack now-days, constructive debate about something that may or may not have an effect.

And on the weight theory?? yeahhh i agree to a certain degree and have always believed the same, but i think the 2 tonne GTR kinda blows out the argument/ laws of physics alittle! The guy posted that time in bone stock GTR on stock run flats, i have no doubt with proper tyres and a big brave lunge he'd nail a 1.22.. no doubt at all, it made it look effortless.. now with my car... no excuses but theirs some real limiting factors, street compound tyres being the largest one ( yes i should have checked the TWR before i had them fitted) street compound is 180 and the track is 120, and equally an important this was my FIRST outing on the new figure 8 circuit with has some decent speeds on some tight corners with scary cambers i just couldn't push any harder than i was doing, i just didn't have the confidence to do so. Theirs a low 1.2x in this car and i will extract it! This current time was set with me leaving some in reserve, and learning also.

the TIVs are like 1000kg with 450hp i think and with a cage, slicks, and some track mods they were very very competitive , they are my bench mark, i agree their power to weight can't be ignored and they way they change direction is something the lardy z4m will need a diet to do...

Tbh after seeing bone stock saxo with all interior gutted, a cage and some decent coil overs/tyres i was blown away at how those things perform... incredible , I'm guessing on a tight road most of us would see which way they would go!!

its going to be fun working on that time, class lead will be easy, getting down to the 1.23 mark will take more skill than maybe i have?? but ill try anyway.... i need to get better at braking, I'm braking way to early for the big stops... i can't tell you how much fun it is chipping away at the time.

 

[Beedub]

Yeah I think it would need serious money and the inevitable loss of comfort to shed major weight from the Z4M.

If it was a track only machine, I could see the point. But for road and track use - meh


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agreed, I'm nicely straddling the line between to two right now, and the car is a peach to just drop the drop and enjoy with my GF at low speeds too, its really a dual use thing, any more extreme and its time to look into caterhams.

 

[exdos]

The ultimate performance you can extract will essentially be a combination of: the power-to-weight ratio of the car, driver ability/bravery, handling characteristics of the car and grip of the tyres. So to test whether or not the addition of the hard-top significantly affects performance, by altering the handling characteristics from aerodynamic effects and possibly influencing rigidity of the car, surely it would be a simple matter of Byron doing alternate runs with and without the roof on the same day. If Byron ran a total of, say, 10 times with 5 times in each configuration, the times could be compared with and without the roof, and you'd see if there is any significant difference. Simples!

Removing the roof will certainly alter the power-to-weight ratio, so if there is a performance gain with the roof left on, then you could conclude that the roof has a positive effect greater than the weight penalty of carrying the roof. Whether that's from increased rigidity or aerodynamics would be impossible to say from running a figure of "8" track.

It's also possible that the addition of the roof gives Byron greater confidence to drive harder with the belief that the roof offers him some protection if the car were to leave the track, and from what he says, I think that might well be part of the story. I know that I certainly wouldn't have the same confidence driving a MR like I do my MCs. Yes, he should've got a MC!

If Byron keeps the hard-top on the car permanently, then how about removing all the soft-top parts to get some weight loss to counteract the weight of the hard-top?

The old adage: "To go faster add lightness".

 

[exdos]

and they way they change direction is something the lardy z4m will need a diet to do...

Progressively try reducing front geometry from toe-in to toe-out, and you'll find the car will be more than willing to change direction with toe-out. Likewise, increase the caster angle which will give you greater dynamic negative camber on the outer wheel (i.e. the only time you really need negative camber) and this will also give you greater self-centreing and straight-line stability, when you exit the corners.

 

[Beedub]

this is currently on my FIRST BUDGET semi slick too BTW... the nankang ns-2r , I'm truing to reduce the overall costs for the car and tyre has had to take a hit as well.

http://www.nankang-tyre.com/home.php?fn=eng/products_car_detail&lv1=1&lv2=7&no=12


Ive no driven the car with the roof off on the circuit for years tbh.... however me and my GF had a lovely 4 hours Rd trip in the roadster with the roof off , didn't once venture over 4.5k revs , we laughed, shades on, music loud, was great and thats the other side i LOVE about the car.. really gives me alot of joy on both sides of the spectrum however its become much more uncomfortable but still is able to be enjoyed.

 

[Beedub]

and they way they change direction is something the lardy z4m will need a diet to do...

Progressively try reducing front geometry from toe-in to toe-out, and you'll find the car will be more than willing to change direction with toe-out. Likewise, increase the caster angle which will give you greater dynamic negative camber on the outer wheel (i.e. the only time you really need negative camber) and this will also give you greater self-centreing and straight-line stability, when you exit the corners.

id love for US to do a DIY alignment on my car

 

[Beedub]

The ultimate performance you can extract will essentially be a combination of: the power-to-weight ratio of the car, driver ability/bravery, handling characteristics of the car and grip of the tyres. So to test whether or not the addition of the hard-top significantly affects performance, by altering the handling characteristics from aerodynamic effects and possibly influencing rigidity of the car, surely it would be a simple matter of Byron doing alternate runs with and without the roof on the same day. If Byron ran a total of, say, 10 times with 5 times in each configuration, the times could be compared with and without the roof, and you'd see if there is any significant difference. Simples!

Removing the roof will certainly alter the power-to-weight ratio, so if there is a performance gain with the roof left on, then you could conclude that the roof has a positive effect greater than the weight penalty of carrying the roof. Whether that's from increased rigidity or aerodynamics would be impossible to say from running a figure of "8" track.

It's also possible that the addition of the roof gives Byron greater confidence to drive harder with the belief that the roof offers him some protection if the car were to leave the track, and from what he says, I think that might well be part of the story. I know that I certainly wouldn't have the same confidence driving a MR like I do my MCs. Yes, he should've got a MC!

If Byron keeps the hard-top on the car permanently, then how about removing all the soft-top parts to get some weight loss to counteract the weight of the hard-top?

The old adage: "To go faster add lightness".

love the way you can add you piece to any debate. i agree with everything you say really...

 

[exdos]

id love for US to do a DIY alignment on my car

I'd be happy to help.

 

[jimmybell]

Great thread to read, thanks for all the contributions. I think with regards to the hard top it probably does add some rigidity, but also maybe even aero benefits, plus driver confidence, but how those benefits weigh up against the weight who knows (without doing some testing as per exdos suggestions).

A few questions:

Beedub - The passenger comment was interesting, especially cool from a westie owner.. do you run uprated brakes?
Any pics / layout of your new improved circuit?
How did your tyres fare against 60 laps? (trying to work out rough costs for an average day spent there)

also - how did you get in to the local circuit? It's a scene i'd absolutely LOVE to be involved with, but ive no idea really where to start, especially down here in wee ole London. The semi-private track day scenario is really appealing, seems like a great place to not only learn to drive, but also test out your mods in anger. I know you're talking about running your own day up there, i'd be keen to drive up for it.

I'd also love the opportunity to go somewhere in the wet and kick the rear out a bit for practice (and push the car enough to reach the point where the grip may slip..), i rarely feel confident with DSC off in the wet, and in the dry i just feel im burning dollar shaped holes in my tyres.

 

[tertius]

Great thread to read, thanks for all the contributions. I think with regards to the hard top it probably does add some rigidity, but also maybe even aero benefits, plus driver confidence, but how those benefits weigh up against the weight who knows (without doing some testing as per exdos suggestions).

A few questions:

Beedub - The passenger comment was interesting, especially cool from a westie owner.. do you run uprated brakes?
Any pics / layout of your new improved circuit?
How did your tyres fare against 60 laps? (trying to work out rough costs for an average day spent there)

also - how did you get in to the local circuit? It's a scene i'd absolutely LOVE to be involved with, but ive no idea really where to start, especially down here in wee ole London. The semi-private track day scenario is really appealing, seems like a great place to not only learn to drive, but also test out your mods in anger. I know you're talking about running your own day up there, i'd be keen to drive up for it.

I'd also love the opportunity to go somewhere in the wet and kick the rear out a bit for practice (and push the car enough to reach the point where the grip may slip..), i rarely feel confident with DSC off in the wet, and in the dry i just feel im burning dollar shaped holes in my tyres.

Slightly off topic, but from what you say I'd suggest a Walshy day (www.carlimits.com) at North Weald. Yes, it'll cost a lot in tyres but what you'll learn will more than make up for it.

Regarding the roof, I can't see it providing any aero benefits on a sprint circuit - what is the max speed you achieve? Confidence is the most likely benefit.

 

[Beedub]

Great thread to read, thanks for all the contributions. I think with regards to the hard top it probably does add some rigidity, but also maybe even aero benefits, plus driver confidence, but how those benefits weigh up against the weight who knows (without doing some testing as per exdos suggestions).

A few questions:

Beedub - The passenger comment was interesting, especially cool from a westie owner.. do you run uprated brakes?
Any pics / layout of your new improved circuit?
How did your tyres fare against 60 laps? (trying to work out rough costs for an average day spent there)

also - how did you get in to the local circuit? It's a scene i'd absolutely LOVE to be involved with, but ive no idea really where to start, especially down here in wee ole London. The semi-private track day scenario is really appealing, seems like a great place to not only learn to drive, but also test out your mods in anger. I know you're talking about running your own day up there, i'd be keen to drive up for it.

I'd also love the opportunity to go somewhere in the wet and kick the rear out a bit for practice (and push the car enough to reach the point where the grip may slip..), i rarely feel confident with DSC off in the wet, and in the dry i just feel im burning dollar shaped holes in my tyres.

Slightly off topic, but from what you say I'd suggest a Walshy day (http://www.carlimits.com) at North Weald. Yes, it'll cost a lot in tyres but what you'll learn will more than make up for it.

Regarding the roof, I can't see it providing any aero benefits on a sprint circuit - what is the max speed you achieve? Confidence is the most likely benefit.

max i achieve on this circuit is around 105mph down the back straight, clearly their is an aero benefit to the hardtop with the built in spoiler ( according to bmw anyway) however I'm unsure if its available at this speed???

 

[Beedub]

Great thread to read, thanks for all the contributions. I think with regards to the hard top it probably does add some rigidity, but also maybe even aero benefits, plus driver confidence, but how those benefits weigh up against the weight who knows (without doing some testing as per exdos suggestions).

A few questions:

Beedub - The passenger comment was interesting, especially cool from a westie owner.. do you run uprated brakes?
Any pics / layout of your new improved circuit?
How did your tyres fare against 60 laps? (trying to work out rough costs for an average day spent there)

also - how did you get in to the local circuit? It's a scene i'd absolutely LOVE to be involved with, but ive no idea really where to start, especially down here in wee ole London. The semi-private track day scenario is really appealing, seems like a great place to not only learn to drive, but also test out your mods in anger. I know you're talking about running your own day up there, i'd be keen to drive up for it.

I'd also love the opportunity to go somewhere in the wet and kick the rear out a bit for practice (and push the car enough to reach the point where the grip may slip..), i rarely feel confident with DSC off in the wet, and in the dry i just feel im burning dollar shaped holes in my tyres.

Love your enthusiasm

yes i run the AP racing 6pot front, 4 pot rear calliper upgrade, pagid race pads, uprated lines, AP racing fluids. The brakes are incredible, nothing less than incredible.

In terms of the circuit heres how it looks and how we drive the figure 8, so basically one lap then the figure 8 on the second lap , the new curbs are alittle aggressive .

https://www.youtube.com/watch?v=tL-76S2MYks

Hmmm the tyres, sadly big cost, hence the reason why I'm trying a budget semi slick, this will cost me time but i simply can't afford to keep burning through premium tyres like i am, i can be exactly but 1 whole day of sprinting seems to take a good few MM of the tyres, the front edge on the front ( towards the fender) takes a real beating hence the heavy camber i run to counter this , obviously the rear tyres on my particular car take a real beating.

On the day id planned I've found a better option, their is a company that i drive with called Sprint and track days, they were HAPPY to book a day for 20 people @ 60 quid per head, they do all the hassle of collecting the keys to the venue, they even provide fish and chips for an extra fiver, they are friendly and time the events properly, you can go as quick or slow as you wish and many choose not to be timed, only the few that are actually taking proper track vehicles to the event.

its a great place to slowly build up speed and try and post a decent time, its fun and as your on the circuit alone your car will come off looking the same (unless you bin it)

for me the sprinting scene is fun, fast, friendly and hugely competitive .. i love it and its definitely fuelled my love of the petrol world to new heights.