MX5 throttle body conversion update

MX5 throttle body conversion

I’ve had a few comments and questions sent to me recently about my throttle body setup and it occurred to me that the most recent post and photos that I uploaded here are quite out of date.

Black crinkle paint for the cam cover
Black crinkle paint for the cam cover

There’s not a great deal to add, but I’ve now fitted an airbox (Pipercross 600 series) over the throttles, tidied things up a little, given the cam cover a lick of black crinkle paint and refined the fuel and ignition maps plenty more.

I was having some issues with rough running at very low TPS and RPM values, I think the very short intake trumpets I’m running due to lack of space was causing turbulent airflow at low revs. The airbox appears to have the effect of lengthening the intake tract and smoothing things out a little. The car definitely runs a little smoother with it fitted, although that great ITB sound is muffled a little unfortunately. Whether it robs the car of any power at the top end is up for debate. Perhaps a bhp or two, but I can live with that.

Nangkang NS2R
Nangkang NS2R

I’m also running some more aggressive, track-biased tyres now. As the car only gets used in the dry or for the occasional track day, I figured I may as well get something suited to those conditions. In the dry they’re great, plenty of grip and very controllable at the limit. I wasn’t so keen at Snetterton circuit earlier this month though in cold and soaking wet conditions. Part of the problem was that I forgot my tyre pressure gauge and was running far too much pressure. Either way, there was lots of this going on…

Slip slidin' away
Slip slidin’ away


Snetterton trackday

Here’s a few laps of the Snetterton 300 track from a couple of weeks ago in the MX5. As usual, the video makes it all seems a lot slower and more sedate than in real life.

CartoDB and track days

Here’s a very quick and dirty attempt at taking some data logged (on an iPhone) at a track day I did a while back and using CartoDB’s excellent web mapping tools to create an interactive visualisation of the data. Hover over the points to view speed, lateral g (cornering) and lineal g (acceleration/braking). Click, drag and scroll as usual to pan and zoom around the map.

Note that the iPhone can only gather GPS information at 1Hz, which is why the data is pretty coarse. I’m at Snetterton in a few weeks so I’ll do a bit more data logging and analysis then.

MX5 interior refresh

Last night I finally got around to finishing off a little bit of retrimming in the Mazda. I’d got fed up of the bulky interior door handles encroaching on the already pretty cosy interior, so decided to ditch them. To cover up the holes left behind, and also to improve on the dated vinyl door covering, I have recovered them in some cheap faux suede that I found on ebay. A small strap, screwed to the back of the door release lever, serves as the new door handle.

MX5 door pull strapThe cabin feels a bit more spacious now and has a nice minimalistic feel. I also added a layer of 3mm scrim foam underneath the fabric to give it a soft, slightly less cheap feel.

MX5 door pull strapThe blue matches nicely with the stitching on my gear lever and handbrake gaiters.

MX5 gear lever and handbrake gaitersThere’s more to come on the throttle bodies conversion too. I’ll update here as soon as I’ve taken a few pictures.