HPI Savage X 4.6 Ignition Conversion – Initial Carburettor Settings & Module Mountings

Ignition Module Mount
Ignition Module Mount
Ignition Module
Ignition Module

The engine now with it’s required ignition sensor, it is now mounted back on the chassis of the model. I have replaced the stock side exhaust with a rear silencer, so I could fit the ignition module in place next to the engine.
For the mounting, I fabricated a pair of brackets from 0.5mm aluminium, bent around the module & secured with the screws that attach the engine bed plate to the TVPs. The ignition HT lead can be routed up in front of the rear shock tower to clear all moving suspension parts, with the LT wiring tucked into the frame under the engine.
In this location the module is within the profile of the model chassis so it shouldn’t get hit by anything in service.

Rear Exhaust
Rear Exhaust

New exhaust silencer fitted to the back of the model. This saves much space on the side of the model & allows the oily exhaust to be discharged away from the back wheel – no more mess to wipe up.

Kill Switch
Kill Switch

The ignition switch fitted into the receiver box. This is wired into channel 3 of the TF-40 radio, allowing me to remotely kill the engine in case of emergency. I have fitted a 25v 1000µF capacitor to smooth out any power fluctuations from the ignition module.
The radio is running from a 11.1v 1Ah 3S LiPo pack connected to a voltage regulator to give a constant 6.5v for the electronics. I found this is much more reliable than the standard 5-cell Ni-MH hump packs.

Fuel Tank
Fuel Tank

The stock silicone fuel tubing has been replaced with Tygon tubing to withstand the conversion to petrol.

High Speed Needle
High Speed Needle

High speed needle tweaked to provide a basic running setting on petrol. This is set to ~1.5mm below flush with the needle housing.

Low Speed Needle
Low Speed Needle

Low speed needle tweaked to provide a basic running setting on petrol. This is set to ~1.73mm from flush with the needle housing.

As petrol is a much higher energy density fuel, it requires much more air than the methanol glow fuel – ergo much leaner settings.
The settings listed should allow an engine to run – if nowhere near perfectly as they are still rather rich. It’s a good starting point for eventual tuning.

 

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