Saxo VTS Track-Day Fun. - Page 2 - Saxperience

VeiRoN · 7th April 2023, 22:15

I've fixed up the chassis where i had to cut it to fit the BE gearbox,I also fitted the proper steel spacers to the rear rose jointed mount:

Added a support as the chassis leg was flexing too much:

Got a new smaller steering wheel:

Added some brake ducts as last track day i could feel the brakes getting hot and increasing the pedal travel:

Had to change the Powerflex purple as the driver side one acquired play and i could move the wheel side to side quite a bit

I thought they would last a bit more than that? seems strange,this time I went with the Black version:

Always wanted to try a decent size splitter that goes as far back as possible after the first "failed" attempt,this time i went with aluminium 2.5mm thickness,made in 4 separate pieces as i could only get 50cm by 1 meter,and bonded and riveted together (counted and there are 105 rivets lol),weight 9.5kg,eventually i will continue with adding a flat floor and diffuser at the back,so got a cardboard template first:

So to lift it up i can just use the sill mounts and then put axle stands in the original locations if i need to:

Also fitted a smaller pulley from Spoox to gear down the alternator:

I don't like bonnet vents too much but i thought i had to put some after fitting the splittter to get some air moving since it's all covered at the bottom now:

nuttysaxo · 15th April 2023, 10:15

Looks mean that bonnet , I thought the MK 3 fiesta rs turbo bonnet intakes would look nice , but cosmetically that is all .

sri_130 · 17th April 2023, 15:57

Vents would work when sat, but unlikely to do much when in motion. The low pressure under the car will pull the engine bay air out, as long as the splitter doesn't totally seal the entire bay off?

VeiRoN · 17th April 2023, 20:33

Yes it is all covered up as per picture above,there is only a few centimeters of space on either corners where the plastic arch liners ends but other than that it is all covered.
I dont pretend to know the physics behind but my thinking is I have a quite large space at the front for the radiator and the two smaller air ducts at each side of the number plate (and behind the number plate a few more holes that i could use on trackdays by taking the plate off) and I would hope some of this air gets pushed out of the vents.
Would be pretty cool to get some actual data to see if there is an actual air flow or not.

sri_130 · 19th April 2023, 11:46

You could do some tuft tests!

I've a slight concern for you, that you may hit some temperature related issues. I hope not. but this was why I halted my plan to use an air dam, in a similar way, many years ago. I don't know how to work out the maths - so you might be ok, depending on the aperture for the flow to exit the tray, but I can't make much out, on the photos.

The dam and under tray creates low pressure under the car, which in turn acts like a venturi/suction to pull the air out of the engine bay, at speed - as well as the primary job of downforce... But...if the rear of the tray is sealed, or the exit isn't good/big enough, for engine bay air to join the underside of the car, beyond this point... I think you may hit issues.

The air going over the bonnet is high pressure, so wouldn't be 'sucked' into the vents on the top, at speed - Unless, the low pressure isn't there - being fully blocked off from joining the underside rear of the car due to not enough exit space or it being sealed in. It could create some weird air flow actually and I think you may disrupt the flow enough for the radiator also, by needing all air to mainly traverse out of the top of the engine bay - where all the high pressure exists, it may not hit its efficiency.

I mean, I never got as far, into testing, so what do I know... But my final plan was to halt the under tray before the bulkhead, leaving enough of a void behind the engine for the flow to work - but still provide the many downforces I was expecting! lolz. I did research it, I promise. It was over 10 years ago though, so apologies.

Good luck either way. might be worth a quick post on other forums/threads like timeattack or something - just to make me look dumb, if nothing else and put your (or my) mind at rest.

VeiRoN · 21st April 2023, 18:37

Quote:

Originally Posted by sri_130

You could do some tuft tests!

Yes I've been trying to do this but couldn't get a clear answer lol,I think I will have to strap some go-pros to have a clear view of what's going on.

Quote:

Originally Posted by sri_130

I've a slight concern for you, that you may hit some temperature related issues. I hope not. but this was why I halted my plan to use an air dam, in a similar way, many years ago. I don't know how to work out the maths - so you might be ok, depending on the aperture for the flow to exit the tray, but I can't make much out, on the photos.

The dam and under tray creates low pressure under the car, which in turn acts like a venturi/suction to pull the air out of the engine bay, at speed - as well as the primary job of downforce... But...if the rear of the tray is sealed, or the exit isn't good/big enough, for engine bay air to join the underside of the car, beyond this point... I think you may hit issues.

The air going over the bonnet is high pressure, so wouldn't be 'sucked' into the vents on the top, at speed - Unless, the low pressure isn't there - being fully blocked off from joining the underside rear of the car due to not enough exit space or it being sealed in. It could create some weird air flow actually and I think you may disrupt the flow enough for the radiator also, by needing all air to mainly traverse out of the top of the engine bay - where all the high pressure exists, it may not hit its efficiency.

I mean, I never got as far, into testing, so what do I know... But my final plan was to halt the under tray before the bulkhead, leaving enough of a void behind the engine for the flow to work - but still provide the many downforces I was expecting! lolz. I did research it, I promise. It was over 10 years ago though, so apologies.

Good luck either way. might be worth a quick post on other forums/threads like timeattack or something - just to make me look dumb, if nothing else and put your (or my) mind at rest.

I can report that I don't have any temperatures changes,coolant or oil,luckily it's still all good,one thing that I had an issue with after fitting the splitter though.

I couldn't get past 90 on my "trackday",the front middle section wasn't solid enough and it was flapping around and making an horrible noise,so I've reinforced it with three M10 mounts just before the air dam and it can support my 80kgs no problem and no noise,tested until about 130 (on the trackday):

I do want to continue with creating a flat floor so ordered more aluminium,by having these sideskirts I can integrate the middle sections nicely,I don't have any actual numbers but I know it feels great in corners at speed.

VeiRoN · 21st April 2023, 18:49

I had an issue after doing the BE gearbox conversion specifically with the driveshaft on the driver side,I've found out that for some reason the driveshaft taper bottoms out before clamping the bearing properly and this would cause massive play in the wheel,I would press the hub back in again but the play would appear again after only a few corners.

What I've found out worked was to use a 5mm spacer on the driveshaft itself,this way it loads the bearing correctly,checked again and again and still all good.

I've worked out the thickness of the aluminium spacer by looking at the old CV joint,you can see the shiny mark and where the hub wasn't pushed all the way in on the driveshaft taper.

Also,added some cage tubing that goes to the rear axle mounts,I will do the same with the other two axle mounts in the rear seats compartment and eventually the front strut mounts too.

sri_130 · 24th April 2023, 20:29

Yeah for the tuft tests you will need either someone track side with a camera - as in, taking still photos at varying points - or some sort of sync'd go pro setup.
good luck

MartinObviously · 24th April 2023, 23:09

Your bonnet is an area of LOW pressure. you have massive pressure at the front of the car, going through the radiator, the low pressure going over the bonnet will draw the air out of the bay.

It'll be high pressure at the front of the car, and at the base of the windscreen.

Your louvres are a bit steep.

Most of your engine bay temps go under the car, but since you have a flat floor it'll now be going out your bonnet vents and wheel arches. The wheel arch ones will stop flow from attaching to the sides of the car. You can cut the wing and taper it in towards the engine by to reduce flow separation as the air leaves the arches.

didn't spot a picture, but your flat floor at the rear, you should probably avoid tapering it up more than 10-20 degrees and only at the back. flatter the better. Being a hatchback you want to reduce drag and not add downforce. I'd be tempted to remove the splitter element and just focus on the flat floor. the splitter will be reducing your top speed.

It won't be of much benefit unless you're consistently over 100mph on track or tootling about at 56mph trying to get maximum economy.

VeiRoN · 13th May 2023, 21:01

Went to Castle Combe on the 10th of May,I understand now I've added all the grip at the front with the splitter and the quaife (as that's the only two things i changed) and removed all of it at the rear lol,at low speed it's not really a problem but above 70-80 is quite scary lol,caught by surprise on the first lap and done a 180.

That was the only one for the day though,after I got a bit more used to it and managed to keep where i wanted it more or less,still at the end of the day after 140 miles on track I still wasn't confident enough to push it more,so really need to get some grip back at the rear,it definitely keeps you on your toes lol.

I also swapped the front Ferodo DS3000 pads to EBC YellowStuff as they were low,unfortunately they are very much a downgrade,was able to brake a lot later with the Ferodo

I am looking at some Carbon Lorraine RC8 that I might go for soon.

This is a little video of the afternoon laps.

https://www.youtube.com/watch?v=UWjY6TZCljw

Also I found it a bit strange that the passnger front tyre was pretty much gone on the outside and not much wear on the inside,perhaps need more camber? currently I only run -1 and always kept the tyre pressure around 30psi hot,I understand Castle Combe it's mostly right turns.

So swapped that straight away with the same Toyo R888R as the other side:

3 days before the trackday the water pump decided to leak (on a Sunday) so I quickly changed that over for a new one:

No holes to keep the cams locked on the Piper pulleys so made a quick tool for that,later I've welded the plate on for use next time:

Thought I should cover this,don't want air going above the undertray:

I have added a few Naca ducts to the splitter,the central one should suck the hot air from the engine out and the ones on the sides are supposed to help with downforce:

I have made the M10 mounts as close to the air dam as possible to help support the load,only got to 120mph on Castle Combe but experienced no problems and it stays all nice and solid:

still need to do the same on the driver side.

VeiRoN · 20th May 2023, 19:37

Must say I wasn't very happy when I've found out that the oil sump baffle I've fitted that's supposed to prevent oil starvation does the exact opposite and cuts oil pressure off.

Luckily oil pressure always stayed above 2 bars so no engine damage i can see,only noticed because I saw an oil pressure drop on my aftermarket gauge,guess the magnetic sump plug I have is useless against the pressure of the oil pump.

MartinObviously · 21st May 2023, 00:54

Most baffles I've seen are welded to the sumps, rather than bolted to the engine.

There's probably too much of a gap between the baffle and the bottom of the sump. so all the oil is just running underneath it?

VeiRoN · 21st May 2023, 11:01

Well I don't know about that,I only know that a piece of the baffle broke off and was cutting oil pressure partially.