Saturday, 16 July 2016

Rolling Road Day

It was time to take the Sprint for a Rolling Road setup of the Microsquirt.

I thought that I had set it up quite well using the autotune - I hadn't !

The ignition map which I had copied from the Sprint Distributor settings was pretty close, but needed more advance at mid range rpm

and the fuel map was still too rich, but ended up like this

We didn't do a before and after run, but the end result was 137bhp and 131 ftlb at the flywheel (yes corrected I know, but I am happy with this. The factory were managing 127 bhp


Interesting when you took at the torque curve, it clearly shows where the cam starts to "work" at 2300 rpm, and torque steadily increases to 5200, which is why a Sprint is so nice to drive, as you mostly drive it on the upslope of the torque curve.

This is a decent result considering I used standard unleaded at 95 octane ( in their day they wanted 5 star 98-100 octane) AND its a tired engine with 79000 miles on it. Also the cam timing is off, as when I had the head skimmed I didn't have a vernier cam pulley, and a mistimed cam does affect the Sprint's power output significantly.

I can now decide on a cam for the new engine that I am building - to keep the tractability I think a mild cam would be best, probably giving power at about 2500, as the increase in capacity of the new engine will pull back the point at which the cam starts to work.

I do wonder how little power the engine had before I started this work, as the car is significantly faster now - where do all the horses go ?

Anyway I can completely recommend Chris at - he's based in Runcorn, and works on most ECU's Omex, Emerald, Microsquirt  etc etc - if you want a rolling road session give him a call - reasonably priced too ! I am very pleased with the result

Where am I?