Forged engine build – mapping

So with running in done it was time to prepare the car for being mapped. I drained the old oil out and set about replacing bits and bobs… somehow not dropping them into the oil. First off was the injectors. I wasn’t a long way off the limit of the RX8 injectors I was using and wanted a bit of flexibility. I ordered a set of 700cc Deatschwerks injectors for £260. I think the Deatschwerks injectors are remanufactured Bosch units.


Deatschwerks 700cc injectors

Photographing them in situ is easier said than done!


Another job I had was to replace the battery. It has been using a Varley Red Top 25 ever since the Mazda one tried to fall out on a track day a few years back. Unfortunately it’s gotten a little old now and wasn’t cranking particularly well, as mentioned in an earlier post. I was unable to find the Powervamp PVR20 battery but did find what must be its replacement, a Powervamp Clubsport EP. This is the same size as the Red Top 25 but with 16ah capacity instead of 20ah. It had 600CCA though which is plenty.


Slots into the same bracket nicely and cranks the engine at a much more suitable speed! I updated the ECU with the new injectors settings and it fired quickly… then cut out. With all the messing around trying to get it to start on the old battery I think I’ve taken too much fuel out so added some more by telling the ECU the injectors were slightly smaller than they actually were.

Oh, and this happened whilst I was running it in:


Westfield steering wheel failure

Thankfully a cable tie got me home and a friend has leant me a nice OMP wheel for now.

Mapping day came along so in the morning I took the trip down to Skuzzle Motorsport… stopping once to check I wasn’t leaking any fluids. And again because I only had 3l of fuel left. That’ll teach me for patching a cold start issue with more fuel globally! I wasn’t very convinced I was going to make it to that petrol station!

Anyway, here are the results of the mapping. All figures at the wheels unless otherwise stated.

20psi dyno_s

This was the results of ‘seeing what it could do’. It’s at 20psi and you can see we’ve encountered the same problem as the TD04 just at higher power. There’s really little extra power to be had from 5.5k. The turbo is just becoming inefficient at those kind of flows. With the big figures though, we had plenty of scope to tune the shape and make it more drivable. We went for a rising boost rate to reduce that big slap of torque from 4k onwards.

17psi dyno_s

This is where we left it, with boost rising from 11psi to 17psi. In terms of headline figures we’ve sacrificed a few bhp and a fair amount of torque but there’s still way more than enough for a Westfield! Here’s the two charts overlaid:

20psi vs rising boost_s

So the green is at a steady 20psi and the red is the rising rate. It shows better just what a difference that’s been made. It should be something in the region of 335bhp using a conversion factor of 1.2, which even with 620kg is 545bhp/ton. That’s more than enough!

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