Mapping by Skuzzle Motorsport

Soon enough, Thursday arrived which was the day it was booked in with Skuzzle Motorsport near Winchester for mapping. I’d already filled the tank (and a 10l jerry can) with fuel, and also on the fluid front I chucked in some extra coolant and oil just in case.

Getting to Skuzzle is an hour long motorway/dual carriage way effort, with a couple of miles of country road at the end. I plugged in the laptop, started VE Analyze Live and let it map itself on the drive down. Unfortunately this wasn’t entirely successful as the lead fell out of the ECU before I’d even gotten to the motorway. I popped it back in at the next services and it happily stayed there for the rest of the journey. I was glad of the road mapping done earlier this week as although the lead wasn’t in for quite a few miles, I knew that the tune was at least ok to carry on.

When I arrived they were busy finishing off previous work but soon had it cleared out of the way. We got it on the rollers and removed the bonnet to save damaging it from heat. Whilst the rolling road fan would sufficiently cool the radiator it wouldn’t provide the airflow required to expel the heat of the turbo. Hopefully real life does!

Then came the messing around. We spotted a few drips of oil under the drivers side of the engine bay, looking like it was coming from the oil pressure sender/takeoff/filter area, so one of these joins:

We cleaned it up then ran the engine again and it was dripping slightly from the pressure sender. It was pretty tight but managed to get another quarter of a turn out of it without it feeling like it was going to break. The leak was still there though, so we removed the turbo oil feed and tightened up everything. The ‘T’ piece was probably the culprit as we got nearly a whole turn out of that one. Everything reassembled and the leak was cured. Mapping commenced!

Lots of turbo-ey sounds later and it was at 165bhp @ 7psi, then 170, then 185, then I popped out for some fresh air to come back to 195, all at the wheels. Nick (the tuner) then asked if I wanted to turn the boost up. Now, this is where I stupidly thought yes, let’s see what it can do so I said I was originally aiming for 12psi as a finger-in-the-air figure. Conveniently forgetting that my mythical 12psi figure was to achieve a target that I was probably already at with 7psi.

Cue some more turbo sounds and he returns with quite possibly the biggest grin a man can have. It had made 229bhp at the wheels at 11psi. There wasn’t much room left in the injectors though so turned it down to 10psi, which was 217bhp.

MX5 1.8 TD04 Power Chart

There’s a bit of a peak at 3.5k which he offered to dial out but I didn’t think it was big enough to notice so left it as it. It’s not the smoothest of curves I’ve seen in my life but should be quite predictable in the track zones. It’s making more torque at 2,000 rpm than the throttle bodies ever made anywhere, so it’s going to be a different beast to drive. I suspect I’ll be in a higher gear around some corners.

I took it for a road test and could instantly tell it was even quicker than when I arrived. The turbo was also much more noisy! I made my way down the road, using small amounts of throttle but at the same time using the torque to build speed rather than outright power. The road was a bit bumpy so I didn’t fancy deploying everything then spearing off into the scenery! On the way back, on a straight bit I opened it up a bit more and it was seriously quick. Then the hose from the turbo to the intercooler popped off. And it was slow.

Popped it back on when I got back and vowed to replace a hose that I’d cut a bit too short which was putting undue strain on the hose that popped off. Nothing major, just a niggle to iron out.

I paid up and left with my dyno chart, and proceeded to catch some sun burn on the way home. Had to stop off on the way and put in the fuel from the jerry can, it’s not exactly as frugal as it once was…

Will take it to work tomorrow, may be a bit braver and deploy some more of the new found horses on some roads that I know, but can’t see me ever putting the my foot to the floor on public roads. Perhaps I’ve ruined it a bit in that respect? I can always reduce the boost to wastegate pressure (7psi) if I feel that way after a few drives.

Track day next Friday, can’t wait!

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