Project "Marginal gains..."
Turbo Mini Forums

Trial fit of the main hoop:

DSC_7843 by Aubrey Boy, on Flickr

It's about 4 - 5mm off the centre and a mm or so at the edges and the corner bends are very close to the trimmed headliner rails.

All to just give as much clearance as possible

Cheers

Edited by Aubrey_Boy on 3rd Jul, 2017.

Sweet

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Looking great

Cheers guys

I just wish there had been more going on, I've been doing plenty of simulations and revising plans but little has been converted to metal yet.

I must admit I have drawn to the dark side a little lately and showing an unhealthy interest in the 1/4 mile side of things and maybe letting that influence some of the choices on the car...

Cheers

Amazing attention to detail, been following this on here since the demise of vauxsport, Have you considered hiding or partially hiding the cage inside the b pillar? Like the viva van did?

Thanks

I'd like to do something like that, I've not seen the Viva van though, the problem with doing it on a mini is where the 'B' post is relative to where your head is and also the 'B' post isn't straight or deep enough to hide even a 38mm hoop which is as small as I would go.

If I end up adding a front half cage to the rear hoop then I will be pushing the 'A' pillar part of the cage as far into the dash rail and door post as I can to try and lose it and again help with the distance of any tubes from me.

What happened on VS? People just stopped using / boycotted it or something else?

Cheers

would a doubled up smaller tube work ? I sat in a WRC fabia once and was amazed at the amount of gusseting and amount of pipes they crammed in there. It would also be pretty bad place sit in without a helmet.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

I spent too much time sat in the metallic blue and yellow WRC cars... but seriously.... no I don't think doubled up small tube would work? Stiff in one direction but not the other...

Gusseting also adds little in terms of stiffness from my experience pretty as it looks, no idea what it adds in terms of strength, I never measured that? You'll notice the blue and yellow cars had very few gussets.....

Cheers

Edited by Aubrey_Boy on 1st Aug, 2016.

So due to a late change of plans I can't get to MITP to have a snoop around..

And the mini was never going to be ready for this year

So I have been doing a bit more chassis simulation, specifically standing starts / launches...

I have simulated several different configurations now and plan more but this is just a typical example for those that are interested in sim stuff, this looking at rear bump and rebound damping separately and can get the front vertical tyre force to be above the the baseline throughout the launch.

drag_launch_WCR_zpsuvlsjhbs by Aubrey Boy, on Flickr

The above graph is essentially front 'axle' lift just to show the sort of difference we are talking about in pitch change or front lift, the baseline setup lifts about 12mm (graph units are metres) and the combined rear damper and spring is at about 11mm, this is at around 0.6g peak longitudinal acceleration.

Obviously the outright or absolute figures for any of this depend on the coefficient of grip of the road or drag strip and the longitudinal / tractive force that the tyre can generate, but the model is useful to show the typical changes or deltas that can be expected and therefore where most effort is best spent.

I have only looked at the first half a second of the launch as it's just the transient stuff during the first 15 feet or so that I am interested in as this will dictate the 60 foot times

Well it's my excuse for not going in the garage and still feeling like I am making some progress....

Cheers

Edited by Aubrey_Boy on 3rd Jul, 2017.

interesting stuff , how about with a much stiffer front ?

Edited by robert on 18th Oct, 2017.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Robert,

I tried a similar percentage increase on the front as well as part of a general sensitivity exercise to see where I was and the front showed a similar improvement to the rear shown here but obviously it depends on your start point...

My baseline settings are how I plan to start with the car, the front is quite conservative as my target front ride frequency is only 1.9 Hz which is a sort of 'fast road' setting, the rear was already pretty stiff as a start point at 2.7 Hz (before this increase) which I thought could already be too stiff as far as handling goes.

In general terms I think it is just about stopping the centre of gravity rising, as the CofG rises then the longitudinal weight transfer increases taking more weight off the front tyres

Cheers

Edited by Aubrey_Boy on 1st Jan, 2017.

i wonder what solid front and rear would do ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Bouncing on it's tyres giving horrible load variation on the front and poor traction

It has been quite tricky to get the damping right to match the stiffer springs, too little damping and it's easy to get a sort pitching fore aft bounce mode which causes the front tyre load to oscillate, similarly too stiff in damping and it's starts to bounce on the tyres which also causes the tyre vertical load to oscillate.

I've seen it quite a few times with some of the FWD drag series cars after a burn out, a pitching fore / aft bounce which must be very easy to aggravate on the 1/4 mile itself.

But in my opinion it's definitely possible to be too stiff while not using stuff like wheelie bars

The biggest hole in my data is normal road tyres at low pressures and drag tyres themselves so trying to simulate the actual damping required is unlikely but it's useful to give some direction, there is so little real longitudinal tyre data available let alone at pressures outside of a tyres normal operating range.

But as with anything it would need some real world data to see how well the model correlates

Edited by Aubrey_Boy on 12th Aug, 2016.

That hoop looks sweet! Sits nice and close its going to be fun to weld lol.

I have started posting on Instagram also my name on there is turbomk1golf

Nothing is impossible it just costs more and takes longer.

Cheers Simon,

Yeah it would be impossible to weld in situ but the plan is to mock up the harness bar / strut top brace along with the main backstay tubes up to the main hoop, that way it will all be finish welded away from the car and then squeezed back in.

I had half a mind that I would be putting at least a rear cage in so it's the reason why I have held off putting a boot floor, seat back or finishing the rear panel off but the deciding factor was when I chose to start again with the side rear quarter panels it meant that the rear inner arches can move out of the way if necessary to give clearance, the cage will go in and out through the big hole in the rear end that all of the above panels missing leaves...

I've currently done away with the ally rear radius arm box section and plan to direct mount radius arms (If I'd listened to Robert from the beginning, I could have saved myself some work!) which I could only do having finally made the decision to put at least a rear cage in as the radius arm mounting points will tie in to the lower leg of the main hoop.

If I do end up putting a front cage in then a combination of holes cut in the floor to lower the cage and probably cutting the roof panel off will allow the rest to be properly welded, I've seen quite a few cars where the cage sections that meet in the roof area aren't welded on the 'blind' side which I couldn't be happy with, having decided to lug all the extra weight I want it to be able to do it's job properly. If a cage is mandatory for a specific class then any decent scruitneer run their finger around the blind side as there is always somewehere you can get around and it's easy to tell if not welded.

Cheers

Edited by Aubrey_Boy on 13th Aug, 2016.

Robert,

Regarding the rigid setup... This is a scaling factor of 5 times the original front and rear spring rates, I wanted to try 10 to say it was an order of magnitude higher but the solver was having trouble running the sim, I guess due to the high frequency undamped content.

x5_scaling_fr_and_rr_springs_x2_scaling_dampers by Aubrey Boy, on Flickr

I tried not to add any damping but had to add some as it was just all over the place otherwise, this config gave just 3mm of front axle rise, so not quite solid / rigid but not far off.

Between 3.2 and 3.3 seconds there is a 300N drop in vertical tyre force which is about 31kg per tyre and at this point slip ratio becomes massive (wheelspin) and even though it is followed the second half of the oscillation which sees a significant increase in vertical load the damage is already done as the wheelspin just carries on once started. I guess axle tramp is closest analogy I can think of and would probably feel quite similar.

Edited by Aubrey_Boy on 3rd Jul, 2017.

yup that looks like axle tramp , prob break something too!

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Mk1 sliding window kit fitted now, as shown with upper and lower seals, door catch/lock and standard door handle it's just over 7.2kg

DSC_7854 by Aubrey Boy, on Flickr

With the missing external waist chrome trim and the sliding catches it's just over 7.4 Kg, so not especially lightweight but hopefully helps to get under 600kg.

DSC_7861 by Aubrey Boy, on Flickr

The weight penalty for the Mk1 sliding windows and the related seals/trim/lower runner is about 1Kg, so with plain riveted polycarbonate and no seals it could be 6.4Kg.

So still got some work to try and lighten the outer door handle whilst still looking standard

I just don't like having the small sliders and how little air they flow, tend to feel a little claustrophobic.

Cheers

Edited by Aubrey_Boy on 3rd Jul, 2017.

Still chipping away at the doors, I thought I would have been able to get them lighter but they are now 7.1kg fully assembled with all handles, chrome trim, seals and mk1 perspex sliding window kit, this still has a completely standard chrome outer door handle, I'm not sure how I am going to get much weight out of it while staying chrome and looking standard.

The CF lower 'door bin' is 200g but when painted body colour or covered in thin vinyl I think it will look a little less obvious than without it, as looking at the inside of the bottom of the cut out inner door frame without it is just seems ugly...

What sort of weight have other people gotten their doors down to?

I'm sure I haven't but it feels like I am running out of places to save weight without incurring fairly big costs on the project as a whole, having said that a year or so ago this door was 8.4kg when I first fitted the aluminium door skins and the mk1 sliding kit and it didn't seem like there was much if anything I could save then...

Cheers

Edited by Aubrey_Boy on 6th Sep, 2016.

Where did you get the mk1 sliding kit from?

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

Can I make a suggestion for the simulation (if you can be bothered) a lot of FWD drag cars run wheeliebars, the idea being with the rear suspension locked solid (or near enough) when the front lifts it pushes down on the wheeliebars making the pivot point the car is rotating about aprx 1.5m behind teh rear axle, increasing load on the front axle, as effectively the whole cars weight is on it. If you can fit that into your simulation without too much hassle itd be interesting to see the outcome

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

JT,

The poly sliding windows were from Plastics 4 performance, I didn't get the full kit just the poly, I sourced the rest myself, I don't know that it was any better or cheaper but I had the catches already so I did it that way.

Denis,

Yes it would be interesting to see the difference in front axle loading with a wheelie bar, I hadn't considered doing it as I was just looking at stuff I was likely to try myself, damping, springs, CofG height and weight dist etc.

I know it won't be easy as it isn't part of a normal vehicle model setup but I'll look in to it, I could extend the wheelbase by 1.5 metres with a bit of work but it would still have tyres and the sort of stiffness / deflection you'd normally get... Thinking about it I could try and put some essentially solid value for tyre vertical stiffness in and see if that would solve? Just trying to think if that would be fundamentally different to the behaviour of a wheelie bar or not? Need to think about it some more....

Cheers

as a quick and dirty test i would keep all the data on the model the same just move the rear axle rearwards and make it solid as you can such that the natural CofG will bias to the front axle more, I have no idea how your moddeling is laid out, This is a bit of a selfish request as I have always wondered what effect these bars have on FWD cars

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.