Another rusEFI K4M build, 1986 Renault 4 swap

[Crazy Striker]

Hi everyone !

Here to present my second RUSEFI project running a Renault K4M engine (https://en.wikipedia.org/wiki/Renault_K-Type_engine) using Proteus board. Proteus is way way overkill for this project but I have one spare so why not use it ?
So the engine is currently experiencing maintenance as I bought it in a highly unknown state. What I planned to do so far is disassembling head to check what cylinders looks like as I have a "stuck" valve, replacing timing belt because it is in bad shape, replacing water pump, checking what's inside oil pan, cleaning everything inside with diesel fuel and do standard maintenance like plugs (1 of them is corroded because water was sitting inside the plug well).

K4M engine from the side, after sitting for a month in my living room

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On the electrical side of things, I strpped the engine completely to rebuild a custom harness using a main engine connector to allow for easier engine swapping inside the car. I retained OEM coils as I had the chance to find Nippon-Denso unit on the engine instead of the faulty SAGEM ones. Only culprit being these coils are "dumb" units with very little seriesresistance (.5 Ohms) that I'll drive using custom coil drivers i already proved was working on the original R4 engine.

Custom ignition module using IGBT

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The trigger was a bit tricky due to the available choice of flywheels and the fact timing belt pullies are free floating when not tight. I decided to go for 180mm and then 190mm RENIX flywheels found on Cléon-Fonte engines from Renault 5 Alpine and Renault Super5. These are 44-2-2 symmetrical pattern flywheel and thus need a cam sensor to even have wasted spark capabilities. Cam sensor will be mounted using a modified Renault Energy engine distributor that I'll also use to drive alternator from the flwheel side. Both trigger sensors are Cherry-ZF hall units, GS 1005 and GS 1007.

I also made a custom fuel rail to install nippon-denso injectors taken from my NB2 miata (265cc/min) instead of standard marelli units because I broke one during dissasembly (brittle plastic and shitty design). This rail is made of universal fuel rail extrusion from Aliexpress and will be capped with 1/4" NPT threads to accomodate for the feeding line on one side and regulator on the other. The fuel is originally pumped by a mechanical driven fuel pump, and will now be raised into a 1.5L surge tank using membrane pump and then feeding a 155LPH "high pressure" external fuel pump up to the rail.

OEM lower manifold with temporary yellow RX8 injectors (420cc) and custom fuel rail

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As for the swap candidate, it is a 1986 Renault 4 GTL, better known in France as the "Renault 4L", very iconic car that lived from 1961 all the way until 1992 when emissions regulations killed it. I originally bought it with a friend to participate in a raid in Marrocco and decided to keep it as Ifound it very fun and rewarding to drive. The original engine is a 1100cc Cléon-Fonte unit producing a whopping 34hp at the crank, currently equipped with a Renault 5 GTL distributor and carburetor that push it to 45hp.

Renault 4 shitbox having unprotected sex with my NB2 Miata

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A gearbox swap has to happen soon too, as I'll be using a 5 speed gearbox from a Renault 5 Alpine Turbo (NG5), along with custom front axles and upgraded suspensions. Some chassis work is needed to fit both the gearbox and the engine, the damper pulley on the K4M interfering with the cabin and the nose of the gearbox being 10cm in front of front member.
A full cage has to be fitted for my own safety and to stiffen the car a bit, considering how filmsy the cabin is and especially how easy it separates from the chassis in abnormal conditions.

Will keep this thread updated with how this build goes, starting with some engine on a bench and then moving into the car.

For very good info on K4M and RUSEFI see this thread from JPh : https://rusefi.com/forum/viewtopic.php?f=3&t=1673

See you soon

Gwendal

[Crazy Striker]

First meeting with my future chassis, which needs some work but is in a very nice shape considering its price tag.

Got the engine out on a stand to disassemble it and see what was inside. I bought it in unknown condition and unknown mileage, and I was worries it was just a piece of crap.
Opened the head to discover sand in cylinder n°1 and n°2, not like a few sand grains but a whole shovel. But it seems cylinder walls did not suffer as honing marks were still visible. Almost no soot inside cylinders, no metal shavings in oil pan or.on oil pump pickup. Only issue is corrosion related as the engine sat with some coolant in it for a long time, nothing a pressure wash can't get rid of.

180mm Renix flywheel was mounted to the engine for a test fit and works like a charm.
Still waiting for parts to rebuild it and it should be ok and on its way for a test run outside the vehicle, but still on RusEFI.

[JPh]

Hello Gwendal,

You should swap your exhaust manifold from the cast one to the welded one.

You save weight and all cast ones crack. Do it before adjusting an exhaust because I'm not sure they are exactly the same profile.
I'm not sure about your injector choice, they will be way to big for the naturaly aspirated engine.

[Crazy Striker]

Hi !

I'm not sure about any manifold yet as space is a bit restricted on a R4, I might need to use a R5 alpine exhaust or similar to make it fit under the hood. The R5 alpine engine is a cleon bloc too with 85mm spacing, only issue being the round exhaust ports.LAst option is cutom tubular header, either steel if I still don't get my TIG soon or stainless steel if I can buy it long with some welding skills.

As for injectors, the 420cc yellow on pictures are just there to check that everything fits, they will be replaced by 265cc units that were mounted on my NB2 miata and power a 145hp engine on 98 RON, so they sould be about right for a 110hp engine on E85.