Thread: More from a S2A 4-cylinder?

Originally Posted by Brisso57

OK. Let's assume we have a S2A 4 cylinder petrol engine in good condition and nominal tune.

What can be done to extract greater power?

* Let's leave aside the "obvious" tricks, such as thinner engine oil.

1. There's balancing and blue-printing;
2. There's porting the head;
3. A more "hairy-chested" cam maybe?
4. An exchange to a better carbie?
5. Dare we suggest turbo-charging or supercharging?

What is the "known art" with this engine?

Doug

Good set of extractors, twin 1 1/2" SU's or one x 1 3/4" SU. Adaptor for this last is easy to make and an SU from an Austin 1800 does not need a needle change. Get a reputable cam grinder to recommend a mild cam that will not greatly affect low speed output. Port match the manifolds. An electronic ignition kit that uses the existing points as a trigger and with the wiring arranged so the electronic kit can be disconnected if it fails and you can hook up to run on points. If you have to fit new valve seat inserts, then you might as well ger bigger valves at the same time.

Rebuilt olmates 4 cyl engine last year. Basically she was machined with heploite (oversized) pistons, rebuilt head including new stems / inserts and oversized valves with a slight shave, has Lukey headers, runs a new stromberg carby with a cleaned up inlet manifold and elect ignition.

She does pull better and runs a lot smoother / quieter but is still just the Landy 4 cyl. However, I should get a heap more years out of her; thats if fuel prices dont force olmate into the garage for good first.

Street Machine mag did an article a few years ago on getting more HP out of the blue holden 6 - the same things apply to any naturally aspirated carby donk. The first few things they tried got pretty decent results - lose the fan (replace with thermo fan) and ditch the factory air cleaner, there was about 14kw just there... they got a bit carried away towards the end, but the article shows a good range of typical mods and what the effect is on output.

Link to the article Find used cars and new cars online - CarPoint Australia - CarPoint Australia

Before starting anything, the thing to do would be to make sure that it is fully up to the original manufactured standard - carburetter in perfect condition, all ignition bits in perfect condition and correctly timed, valves and piston rings sealing properly, no carbon build up, camshaft unworn and chain and sprockets unworn, tensioner working properly, and timing correct, and tappets correctly set. Thermostat correct and it and the rest of the cooling system working to keep the engine at the correct temperature. Fuel pump working properly and no partial fuel line blockages or leaks, manifolds tight, sealed, and matching the ports in the head.
And for the vehicle itself, wheel bearings correctly adjusted, brakes not dragging, gearbox, diff and transfer case bearings correctly adjusted, right size tyres correctly inflated.

The simplest improvement is probably to shave the head. Most four cylinder Landrovers sold here were 7:1, and provided the head is a later one with a square boss next to the carbie, it can be raised to 8:1 or even higher to advantage. This will modestly improve power and economy with virtually no adverse effects.

Beyond that there are a number of things that can be done as suggested, basically all involve improving the breathing (inlet and exhaust), which will increase the maximum power available, but if more than very minor changes are made, particularly to the camshaft, this is likely to be at the expense of driveability at low rpm. One of the attractions of this engine is the way it pulls strongly from idling.

I remember reading many years ago of this engine being supercharged, and this may well be a suitable approach - as it was designed originally as a diesel, it should stand a significant boost, and this may be an easier modification than turbocharging.

On the other hand, I would be very dubious about increasing maximum rpm significantly, as I would expect this to be likely to lead to all sorts of problems - it is already a high revving engine by the standards of its time.

John

Originally Posted by akelly

<Snip> The first few things they tried got pretty decent results - lose the fan (replace with thermo fan) and ditch the factory air cleaner, there was about 14kw just there... they got a bit carried away towards the end, but the article shows a good range of typical mods and what the effect is on output.
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OK. Definitely the fan gets changed for the Thermo jobbie.

The air cleaner is no doubt great for its intended (design) environment, but realistically a lot of 2A's are now hobby vehicles ... that don't run in aggressive environments, so it does make sense to swap the air cleaner for a higher flow conventional type. Does anyone have a suggestion of a widely available replacement, something that could be sourced from a wreckers?
(Holden/Ford/Toyota/ etc) ? It'd be great if the mounting flange was the exact size.

Doug

When I built my 2.25P I fitted 0.020" oversized pistons (but you can go up to 0.080"), and shaved the head to about 9:1 compression.

The above combined with extractors and a zenith, and it went like a freight train.

A mate had about 9.5:1 compression, 0.080" OS pistons, slightly strroked, and a bunch of other mods (was an engine builder). His motor had much more power again, but it pinged like a ba$tard on normal fuel, drank like a fish, and broke series 3 gearboxes every other week. He eventually swapped for a Stage 1.

I have gone back to the std aircleaner and have noticed the power drop off from when I had a paper filter fitted. As I have a thermo fan fitted I spose I should just get rid of the std fan and then the ol girl will be as good as she is going to be.

Now I have something to do after work tomorrow.

the 2.25 does reveal a smattering of cheap extra power if you do the aircleaner and fan as suggested but also goto the effort of port matching the manifolds and gaskets when you replace the exhaust manifold with extractors.

Thats pretty much the limit without pulling things apart but if your pulling it down Id suggest a bit more muscle on the cam, port n polish the head and up the compression to at least 8.5:1 and nearer to 9 I dont reccomend doing this by head shaving but by hightopp pistons.

There ends the relatively cheap mods and the ones that dont destroy the engine's longevity.