The way l view tuning is it's a bit like painting a picture, you start with a clear idea of what you want to paint, but it helps to focus on filling out different areas of the canvas in stages. One must then accept the full picture will only be revealed at the end of the process, and when every section has been completed.

In the case of Monty, the Stage 2 tuning process took the engine to a genuine 173hp fairly easily, all Monty really needed to make this number and produce excellent torque was a better exhaust manifold, the FF inlet, a pair of Phase 2 cams, and a re-flash of the standard ECU. However, I choose to fit an EMU Black ECU, but only because I knew I was going to take things further.

For those of you who want to extract a meaningful amount of additional performance from their Duratec Plus 4, and for the least outlay, I'd say the stage 2 recipe would be the way to go. I'd also suggest you could probably achieve similar results while saving the cost of the FF inlet by simply using the standard plastic Ford inlet, well assuming you remove the restrictive swirl flaps and blocked off the ERG path.

Stage 2 as I'm calling it instantly gave Monty another 30hp and a big uplift in torque in the mid range, Stage 3 has built on these increases with more low down torque, more mid range punch and even helped Monty's Duratec hold onto peak torque and especially horsepower for a lot longer. So our painting is now very nearly complete, all that remains is to fill in is the sky (the top end).

However, the real trick we need to pull off now is to get that horsepower line climbing as it should from 5,500rpm all the way out to 8,400rpm and deliver Monty's true 213 - 220hp potential, but do so while retaining all the low end and mid-range gains we've worked so hard to create. To achieve this what Monty really wants is the current setup including the FF inlet up to 5,500rpm, but a way of then augmenting the airflow going through the FF inlet with a set of ITBs that only start to open above 5,500rpm.

Fortunately most motorcycles run drive by wire ITBs these days, and controlling when they open based on TPS, RPM and engine load is easy with my EMU Black ECU. The idea is to use a set of the drive by wire motorcycle TBs not to replace the standard 60mm single throttle body, but to use them to give Monty the air he's clearly craving over 5,500rpm, but not before!

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The good news is such drive by wire motorcycle ITBs are cheap if bought used, they also have quite small chokes as they are only designed to feed air to relatively small cylinders. The ones I have my eye on are only £120.00, they are off a 2023 Kawasaki Ninja ZX 400 so each choke is only supplying air to a tiny 100cc cylinder, as the 60mm cable TB remains these drive by wire ITBs should be big enough to give Monty the extra air he clearly needs from 5,500rpm to 8,400rpm.

What we're creating here is the best of both worlds, all the pulse charging ram air effect of the FFs lovely long runners that deliver such good low end and mid range torque, but then the short runner 'straight shot' of additional air at higher rpm that a set of ITBs would deliver.

Of course the idea is nothing new, the history of variable length inlet manifolds goes back to Porsche's VarioRam system and before. While Porsche was an early adopter of variable intake technology first featuring a simpler variable geometry design on the 1992 964 Carrera RS and later the multi-stage VarioRam in 1995, several other manufacturers beat them to production. In 1983 the legendary Alfa Romeo Busso 6 received an early system with the Alfa 75 (Milano) featuring variable length intake tracts.

Adding the motorcycle ITBs to the cylinder head end of the FF inlet is just a bit of fabrication work, I'll give the project to Matt at Fusion Fabrications as I know he'll be right onboard with the idea, and obviously he built Monty's inlet in the first place. However, the idea is only viable because the motorcycle ITBs are drive by wire, and my EMU Black ECU can easily control them.

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Wish me luck chaps, but I'm very confident the idea will work, so 220 horsepower here we come happy3

Last edited by Montegue; 21/06/26 12:30 PM.