Engines and power…
I wrote a blog at the end of 2021 and you can read it here , but where are we today - late July 2024?
Since I wrote the above we have moved forward a long way with understanding the Bosch ECU, making the race cars give good power for the whole race and developing the turbo.
Let’s start with the turbo. The S260 had an 11 blade exhaust wheel, swapping to a 9 blade gave something like a 5% increase in power with an even better spool up – the S260 was dead, long live the S260A. Matt at TT had designed a K04 version of their Fiesta turbo with good results, so he grafted a K04 core into the S260 exhaust housing – it was brilliant and we called it the S300. We then thought to try a 9 blade exhaust wheel it was even better but the ECU couldn’t cope, we were too far off the end of maps and the extrapolation didn’t work. The race guys couldn’t wait and fitted stand alone ECUs to control their S300Rs.
We persevered and found that by altering the axes of the torque maps we could bring the S300R under control with the ME7 ecu. We also managed to taper the torque curve so that we stayed below the design torque for the 5 speed gearbox, which we believe to be 225lbft (300Nm). As an aside, what we did with the ME7 Euro 5 ecu we found that we could do with the ME17 Euro 6 ecu.
A combination of the S300, our bespoke race cooling package, fuel pump booster and more revs and we have a happy 320bhp car. The race guys with their bespoke ecus are winning with under 300bhp, they have mega boost but no ignition advance and aren’t letting the engines rev to the 7500 that we have found safe with a stock engine.
What this tells us is that by getting the hot exhaust gas out of the engine we let more cool air in and reduce the detonation, so we can run more ignition advance and have a more efficient package.
Then TT ran out of exhaust housings! We knew that they were low in October but we were continually told 2 to 3 weeks for more, finally last week somebody admitted that they were completely out and needed to find a new foundry.
I had an idea that we could have a problem and wanted to try something bigger so I bought one of the new generation Garrett GBC22-350 turbos, designed for small engines and up to 350bhp. It was a B**** to fit, the adaptor has three angles on it, the wastegate arm had to be rotated and a new actuator mounting made, but it is on without any body mods… It is big.
My worry was that with it’s size it would never spool up and it might be third gear before it started to go. Well, Mr Garrett has done his homework and it starts to spool at 1700rpm, much earlier than an S260A, BUT we are back to the ‘off the maps’ problem. The first proper run we did it got to 306bhp at 7500 on pump fuel. A couple of changes and we are at 317, but there is more to come, at the moment it isn’t holding boost over 5800, we need to re-write the programme in the ME7 and it will take us a week or more.
The idea of the GBC22 was as a race turbo, there is a GBC20-300 and a GBC17-250 – just slightly smaller but with the same footprint. We have done the design work with both IHI and Garrett manifolds in mind and with the TT situation perhaps it is the way we have to go.
Now what we need is a crystal ball to know what the quantities might be – do we get the complicated adaptor cast? Do we ask Garrett to make us a batch with the correct angle on the wastegate arm? So many questions – we would love some feedback.
My calculations tell me that we are getting close to the flow limit of the standard throttle body – but who wants more than 325 GENUINE bhp – it is too fast for a road car.