Category: Engine

  • Thoughts on Development Direction

    Thoughts on Development Direction

    Introduction

    So the recent mods (see previous posts) are all in the car and have been tested at a shakedown at Thruxton Circuit in blisteringly hot conditions. In this post I review the work this far and how this has shaped future thinking for the car going forward. There’s some YouTube links below which show full runs at Thruxton.

    IL Motorsport Chasis Bracing

    In my New Bracing Goes In post I said that I was hoping to improve the rigidity of the chassis having notice some kick when changing gear under load having installed stiffer suspension.

    I can honestly say I didn’t notice any kick on the drive in (though this was pretty gentle) and not on the track so I’m going to say that adding the IL Motorsport Cross Brace and Rear Suspension Brace have improved the handling of the car.

    I was definitely pushing my limits further than before and my pace improved over my previous outings.

    BC Racing DS Coilovers

    I love these, they are a definite improvement over the old worn out Bilsteins. That is not to say I would not have loved new Bilsteins, which I did in my younger days on a different more rally-orientated car; or any other make of coilovers for that matter.

    When I drive on the road with softer settings they are comfortable in that role and when I set them much harder on the track there is less roll than before and there seems to be tighter control at higher speeds. On this occasion I drove in with them set at 1 click off softest, then started the sessions at 5 clicks from hardest in the morning and 1 click from hardest in the afternoon. I accidentally drove home with them set at track hardness and frankly it was not pleasant so note to self – change them back before loading the boot; and a learn from the experience.

    My spring rates are the 6 front and 4 rears which is the BC Racing recommendation for MX5 NC’s. I noticed at Thruxton that where I was pushing the car much more than on previous runs I was getting more roll than I had anticipated in the harsher corners like Campbell, Cobb and Segrave, which made me start thinking about anti-roll bars as a future option.

    The car was splendid through the chicane at Club so as I’ve already said above, I’m really happy with this choice.

    I’m not drawn to the idea of upping the spring rates yet (c.ÂŁ200) as the ride for road use is pretty good at the settings described above. I don’t really want to add harshness given my Grand Tourer objective, though this would change if the car was to become a track-only tool but I’d still need to upgrade the ARB’s anyway.

    Thruxton 2026 07 07 i

    Yokohama AD08RS

    These are the newer road legal spec and sometimes get battered for not being as good as the old spec. I’d pretty much decided that I wanted AD08’s as the start point for my track-focussed tyre choice.

    Since I’ve got them I really like them. My standard road tyre is Dunlop Sport Max which is a pretty good track day tyre for wet conditions. The Yokohamas were part of a tyre & wheel package from Wheelbase last year.

    On my last trip to Thruxton I did notice that the tyres protested the treatment they were being given by squealing pretty regularly on the tighter corners but the handling remained strong and I was doing 12 lap runs. I did trip the DSP once or twice when pushing harder than normal. I’d have no problem getting them again but I have not yet tried them against anything else.

    If I could afford them when the time comes and if they were available in my wheel size then I’ll try the Avon ZZR’s recommended to me by a very fast MX5 owner I met in June who raved about them, though at c.ÂŁ260 each for the Avons and half that for the Yokohamas that’s a couple of Track days so we’ll have to see what the budget will allow.

    Fox FX004 Wheels

    These Black 17 x 7.5’s are shod with Yokohama AD08 RS215/45/R17 came from wheelbase as a package and frankly I think they look fab .

    I don’t think they were a weight saving choice (Budget wouldn’t allow), but they look mean and that’s got to be wort 1-2 mph. EBC Yellow Stuff Brake Pads on standard discs and calipers

    Parked up at Silverstone Old Pits Paddock

    I love them they work well for me, though for the first time I noticed that they get better with a bit of heat in them. With good braking point selection they hauled the car down to

    BBR GTI Catted Manifold, Centre Pipe and GT Rear Box

    Again I love it it burbles nicely, makes a good noise when up and running and the car either is faster or feels faster. I added a Versatune standard NCU package ECU flash as a stop gap until I can get it on aRolling Road. Again Ive not been disappointed despite the cost.

    I fabricated a heat shield for the rear of the alternator until I can be sure the heat generated by an unshielded manifold won’t damage the black plastic ?? vent to channel cooling air into the alternator.

    Thruxton 20260707

    So Where Next…

    As the car does not over heat despite 30+C at a fast track where the car is up near maximum revs for a lot of the lap I’m not thinking an Oil Cooler is necessary at this time and have removed that from my development plan for the time being.

    I’ve been thinking that I’ll start getting together the parts for a clutch swap. With over 80+k miles on the clock I’m expecting the clutch to need replacing in the not too distant future. I’m also convinced that this car has been tracked at some point by previous owners again increasing the likelihood of increased wear. The car itself is not showing signs as yet. Its going well an is eager to go faster when the load button is pressed.

    I’m thinking I’ll be going for the Bofi Stage 2+ kit on the premise that it will cope well with heavy track use and a lightened flywheel to make it a little more eager.

    The other possible development direction might be Aero with a splitter at the front, some underbody air flow smoothing and wing at the back and probably done in that order. But that’s a cerebral exercise for now as the car is going well and I’m probably still less competent in my driving than the car’s capability.

    Finally there could well be the option of doubling down on my BBR GTI upgrades and going for the Cam upgrade to take the car to 200 BHP.

    I’m back at Thruxton next month so if you see me come over and say hello.

  • MX5 Suspension & Exhaust Upgrades Begin

    MX5 Suspension & Exhaust Upgrades Begin

    Introduction

    May and June saw the process of preparing the car gathering pace ahead of planned trips to Silverstone and Thruxton circuits.

    Planned works included BC Racing DS coilovers in the corners, a sound-pipe delete and a new catted BBR GTI Exhaust System. Also plans included installation of adjustable seat runners on the passenger side and new EBC yellow stuff pads for the season ahead.

    BC Racing Coilovers

    Choosing the suspension has been the most stressful decision about the car so far. I wasn’t sure I even needed to upgrade and it was pretty good already with the Bilsteins which were standard on this spec of car.

    The choices I thought about were – should I stay with the Bilsteins’ or try something else; and if something else then what; should I run with the pack and fit Meisters or try something else like Yellow Speed Racing, Ohlins, or similar.

    At Thruxton I’d hit the bump stops at Campbell on more than one occasion last year when trying to conserve speed so this had made up my mind to try something new. I was looking for something firmer, and with 88k on the clock I thought the Bilsteins’ were probably past their peak.

    In the end, after much humming and harring I chose the BC Racing DS range as I wanted something that might be more plush for the road bumps and stiffer for the track day undulations. I elected to stay with the softer 6Kg/mm front 4 Kg/mm rear springs as BC racing had strongly suggested this starting point so I elected to run with it and upgrading springs if necessary in the future would not be that expensive.

    Installation

    I measured the ride height of the car (hub centre to top of wheel arch) prior to starting and decided that my target would be 245mm for the front and 250mm for the rear once the new suspension was installed.. This would give a little rake for loading and acceleration squat and I gambled that the stiffer springs would not squat so much with fuel and passengers on board, It will be easy to adjust the height once the car had settled onto its new suspension should this not be enough.

    I having jacked up the car. I removed the wheels then the bolts on the suspension upper mounts and also removed the turret brace bars. These bolts are not torqued up very much and were easy to remove.

    The front left was the first to succumb to change and took me a little longer than I had anticipated. I ended up accidentally disassembling the whole original shocker on the car having misunderstood what I was looking at when I was looking down at the top mount as the top of the Bilstein mount which had a black shiny metal cap was nearly the same colour as my car and looked like a permanent part of the car. having understood the issue the remaining mounts proved much easier to remove.

    I also removed suspension upper wish bone bolts, brake line fasteners, anti-roll bar and drop-links to allow for the necessary wiggle room and it all came out nicely. The only pig was the strut bottom nut and bolt which was super stiff and took plenty of work with a breaker bar to get out.

    To be fair the new struts are pretty boring to look at but are super clean and have no rust (unlike my rusty Bilsteins which had definitely seen better days).

    When refitting the top suspension mount brace to the BC’s I took the opportunity to drill the brace top and fit 11cm extenders to the front suspension adjusters and 25cm extenders to the rear. these facilitate rapid adjustment of rebound on track days. I wound it all up to 5 clicks off max hardness all round for the test period

    The sound pipe has been deleted and a Mk3.1 air pipe replaced the original. Also the suspension adjustment is blocked by strut brace
    Sound Pipe Delete and new suspension fitted

    New Exhaust System

    Whilst the car was up on the jacks I took the opportunity to instal a new exhaust. This was a the BBR GTI catted manifold, mid section and Grand Touring exhaust. Removing the old manifold was the most trickiest operation with rusted in bolts catching on the body work despite angling the engine over on one side as seen in the Turbo installation YouTube video from Flying Miata.

    The purchase of some swan neck ring spanners proved very useful in both the removal and installation phases for managing the manifold bolts.

    I also gave some thought to he absence of heat shields on the BBR manifold and fitted some gold reflective tape to the pipes and cam cover and existing engine bay shield and fabricated a shield for the back of the alternator where there appears to be a black plastic air duct.

    Heat shielding over new exhaust, also suspension adjustment extenders fix the problem of fouling caused by strut brace.
    Heat shielding and suspension adjustment extenders.

    Versatune

    Also while I was at it I opted to remap the ECU by flashing it with a vesatune basic upgrade.

    Impression

    So the weird thing is that the suspension feels a little stiffer but not massively different at urban speeds. The engine note is exactly what I wanted with a little burble and more open bark under acceleration and is not any more intrusive at motorway speeds than OEM.

    I had dialled the suspension up to five clicks from hardest all round and have noticed that under hard acceleration there is now some kick in the straight line direction upon gear change and I think this may be because as yet I have not had the tracking re-set. though it may also be chasis flex, but tracking will be the first step.

    Anyway despite this anomaly it was more or less ready for Silvestone and Thruxton and the seat runners would have to wait for another day…..

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