4722 replies to this topic

[Doctor Ed]

Err that wings gotta be sitting at 10deg in these pics???

[Nev]

It's deceptive, as the profile is heavily shaped with an upward "flick" at the rear. Maybe it's more like 5 degrees, but on my driveway when I wash the car the water collects and stays on the top ( which is the only flat surface). My drive is about on a 5 degree angle. TBH it's hard to say which part to measure the angle from, I've assumed the flat part on the top is the pertinent measure point.

 

 

Edited by Nev, 26 March 2018 - 11:52 AM.

[Doctor Ed]

you include the 'flick' in the aoa

 

[Doctor Ed]

[font="arial, helvetica, sans-serif;"]Random chord profile [color=rgb(51,51,51);]Lift-Drag ratio C L /C D vs angle of attack α[/color][/font]

most profiles are about the same though, with 10-12deg aoa maxing them pretty much out

(ie, youre running a lot of wing)

 

Edited by Doctor Ed, 26 March 2018 - 01:43 PM.

[Nev]

I'll take a pic of it next time it's on the drive if you like.

 

Mine has 10:1 chord ratio, but the flick at the end is more than what it should be really IMO. I did some wool strand testing with a video camera on it years ago and it keeps fairly good laminar flow.

 

 

[Exmantaa]

Good laminair flow on both sides mean that your wing is not stalled,anywhere, so your probably running it somewhere near that optimum 8-12degrees AOA. Which will give you pretty significant downforce with that big profile.

(How's the front  grip?)

[Nev]

Good laminair flow on both sides mean that your wing is not stalled,anywhere, so your probably running it somewhere near that optimum 8-12degrees AOA. Which will give you pretty significant downforce with that big profile.

(How's the front  grip?)

 

In it's current configuration/geo the front does dig down at speed, by about 110 leptons the car become noticably more stable, by 150 you need noticable extra force to turn the steering wheel and I've measured the coilovers get sunk down by about 1.5 CM on the front and about 2.5 CM on the rear, so the whole car is dug in.

 

The best front end effects occurred when I experimented with the front spoiler 7 CM above the tarmac (almost on the coilover bumpstops!). This really was incredible, as you could feel the front downforce at just 70 leptons (ie 40 leptons earlier) and by 100 the steering needed two hands to turn. However, driving with so little clearance is just stupid on the road, so it's back up to 12 CM.

 

This is all without the rear floorpans installed BTW. If I put them back on things might improve further.

 

 

Edited by Nev, 26 March 2018 - 04:56 PM.

[Exmantaa]

That was with the integrated front splitter/spoiler at 12cm height as in your latest pics here?

Good to know and will check what I'm running currently.

[Mattyboi]

How did you measure the coilover height change when driving? I seen people video themselves driving past a camera at speed to check height changes.

[Nev]

How did you measure the coilover height change when driving? I seen people video themselves driving past a camera at speed to check height changes.

 

There are 2 easy ways:

 

Method 1: Put a small tie wrap on the coilover strut as a witness marker. As the coilover compresses it pushes the tie wrap along the strut and leaves it in the most compressed position. Obviously you have to be very careful not to go over bumps etc during your test, but you can get under the car to reset it and test once you are on some smooth flat tarmac.

 

Method 2: Use a tiny £10 micro camera mounted in the wheel arch to study the wishbone angles and coilover travel. This is very good for studying whether or not you are hitting your bump stops and in particular seeing if you reach max droop. Once I'd seen the footage of this on my old setup 6 years ago it made me get serious about buying the raised hub carriers, and I've now got a setup that is the best compromise between bump travel and droop travel.

 

The camera is the best method IMO, but getting enough light to make things visible needs a little forethought.

 

Once you do stuff like this you realise just how many lowered VX220s are handling so much worse than they could be. I've sent my Nitrons 40 back to the factory and demonstrated (with pics + video) what they need to change twice. Thankfully they were very professional and admitted the faults (to me at least) and did all the work for free and sent me some extra free stuff as way of saying thanks.

 

Anyway, the morals of the story for owners in general are:

 

1. Don't mess with ride height and geo settings unless you REALLY know what and why you are doing it.

2. Don't assume when you buy a set of coilovers that they are fit for purpose and will make your car "better", no matter how much they cost.

 

Edited by Nev, 27 March 2018 - 07:58 AM.

[Exmantaa]

Makes me curious to the bump/droop percentage on your current ride height. (Remember the rear shock length vs wishbone angle debate from a while ago...)

[Nev]

Makes me curious to the bump/droop percentage on your current ride height. (Remember the rear shock length vs wishbone angle debate from a while ago...)

 

My fronts struts are 50% exposed when the car is at rest (ie equal range for compression or droop). Not sure about my rears, but they have a lot more droop than compression available, so at a guess maybe 65% available to droop and 35% to compression. On the rears (as we all know) the compression is limited by the subframe, rather than the coilover.

 

Matt Bentley suggested 60% for droop and 40% for compression, but I found the car (in my case) slightly better at 50/50. Bear in mind my physical setup is very different from most peoples though, so not necessarily the best % ratios for you. Also I find myself bashing through a lot of potholes & dips on the roads I drive on, and bearing in mind I've already bent a wheel the compression range is important to me.

 

My Nitrons are valved with a 2.5 to 1 compression to elongation ratio BTW, others may differ and that will influence how you set them up too.

 

 

Edited by Nev, 27 March 2018 - 06:16 PM.

[Nev]

Managed to get out for a 160 mile run around last Sunday morning. Lovely weather, almost had to take the roof off at the end of the trip.

 

[Nev]

The other day when I went out, the car was occasionally hesitant at low RPM. A quick check of the spark plugs shows a fair bit of wear on the electrodes and the gap was up to 0.9mm on one of them.

 

I had a look at my log and they are only 2 years old so they've died quite quickly, but I also noticed that they are only a heat rating of 8. So I've bought a new set and plumped for the '9' heat rating (ie cooler running) in the hope these will survive a little longer.

 

Had a look down the spark plug holes with a strong light to see the piston crowns, although oily and a bit sooty there wasn't too much carbon build up which is good.

 

I also had a quick poke round my new crank case breather/separator and it seems to be in good order and working well. Checked the dip stick and the oil level is still high and doesn't need topping up even after 600 miles.

 

Off to watch the carnage and meet a few VXers at the Castle Combe Action Day on Saturday.

 

Edited by Nev, 03 April 2018 - 02:52 PM.

[chris_uk]

What did you originally gap your plugs to? I find that 0.711 seems to work quite well on stage 4 turbos at least.

[Nev]

Cracking day outside, bloody irritating to not have my spark plugs in and get out into the hills.

Edited by Nev, 05 April 2018 - 10:17 AM.

[siztenboots]

what is 0.711 gap , its an odd mm size and not even imperial either  , 0.65 , or 25 thou

[Nev]

Amazeballz! Not 5 minutes after writing that, the postie has just delivered my new spark plugs. Am off into the garage to shove them in and go for a tootle.

 

Brmm brmm.

[The Batman]

Im just about to go out and test the new throttle so hopefully cured the part throttle issues

[siztenboots]

I'm just about to go out and take the VX out in the sunshine and hopefully get a wide open throttle run logged.