Why new engines make more power than old engines

If you've been watching the build of our sleeper Hilux you'll have seen us throw the old single-cam carb-fed NA four-cylinder in the bin, in favour of a turbocharged 2.7-litre DOHC 2TR four-cylinder from a modern Toyota commercial vehicle. People have been impressed with the power this pretty simple engine has made (SEE THE VIDEO HERE) and this is partly due to how modern engines are designed. 

So, why do modern engines seem to make power much easier than older engines? There are several reasons for this, but it mostly comes back to engines being far more efficient, and better controlled.

While we think of overhead-cam EFI turbocharged engines like the Nissan RB and SR, Toyota JZ, Ford Barra, Honda B-series as "modern", engine design has evolved massively since they hit the market. Most of these engine designs date back 40 years or more, so today they're as old in tech as the carby big-block V8s they took over from. Feeling old yet?

The computing power and amount of data capable of being read by modern ECUs has allowed engineers to design better engines as we understand far better what is actually happening inside these engines as they run. Think of the ECUs used in 90s cars as only being able to see 24 colours, but modern ECUs see in 4K resolution, and now replace "colour" with "data" and you get an idea of how far ECUs have come, and how modern engines are so finely timed and fuelled.

If you know precisely what the engine is doing you can extract every ounce of power out of it, and this allows engineers to put the engines together with much finer tolerances.

Tightening emissions laws have driven manufacturers to chase more efficient engines, which has benefitted enthusiasts as these engines make power easier than old school engines which had to fight for every horsepower they made. If you look up the specs of a lot of modern cars you'll notice a lot of modern engines have high compression ratios and run quite thin synthetic oil, and these both help enignes be responsive and spin more easily.

Lower compression ratios make for a lazier engine and thicker oil will drag more than a lightweight oil. However, with old tech ECUs (or mechanical injection and carburettors) people couldn't tune engines precisely like they do today, as they didn't have such fine-control over fuelling and ignition timing, while wideband sensors were rare and MAP-based tuning was just a concept.

All of a sudden our modern engines can spin faster, safely, and the oil technology has improved to match with it. But so has the technology in fuel systems, coil-on-plug ignition systems, the low-resistence serpentime multi-rib front-drive belt systems, and the big one: turbochargers.

If you're not deeply invested in the automotive aftermarket you might not realise how much turbo design has evolved in the last 15 years alone. To put that in perspective, I'm talking SINCE 2010. 

Lightweight billet compressor and turbine wheels, better blade angle design, wastegate efficiency (and precise electronic control), and better bearing design for the centre cartridge have revolutionised how fast turbos spool and how much power they can make. All of these improvements mean the (now more efficient) engine doesn't have to push as hard to make a single PSI of boost, improving performance. We're doing more with less. 

Modern piston and con rod design has also evolved as thinner, lighter piston/rod combos are no longer the domain of race engines, while piston-to-bore clearance, bearing clearances, and even more tightly controlled piston-to-valve clearance have all improved engine efficiency, which benefits emissions but also allows engines to work easier; they're not big, lumbering dinosaurs anymore.

With modern ECUs being able to read more data and have more control over an engine's operation it has also allowed engineers to push technology like active cam control and cam phasing, as well as valve and timing changes, and even adjustable intake manifolds. All of this helps enthusiasts enjoy more potent engines that make a wider spread of power.  

The metal engines are being made from has improved out of sight. We've had aluminium engines since the 50s (and in some rare, super-exotic cases, even earlier) but modern metal processing and engineering means the blends of aluminium alloys used in modern engines offer far superior tolerance to heat cycling, high cylinder pressures, vibration, and strain from RPM. 

Some of our favourite turbo hero cars use cast iron blocks as this was the only way to hold the cylinders in their correct shape when dealing with boost. Only 15 years ago it was fundamentally understood any turbo all-aluminium (barring super exotic aftermarket block/head combos) were on a borrowed timeline as, eventually, the cylinder pressure would oval the bores, lift cylinder heads or fatigue the block and break the crank. 

SImilarly, manufacturers now design deep-skirt blocks that put the whole crank tunnel in the block itself radically stregthening the main cap area.  Look at the pic above to see the difference between a typical 1960s passenger V8 (Holden 308), and a late-90s passenger V8 (5.7 LS1); we've now got dense, light alloy blocks (vs cast iron), 6-bolt main caps (vs 2), better cylinder head sealing, and that's ignoring priority mains oiling and other race car tech which has found its way into production engines. 

Honda's K-series backs up these claims. These storied transverse four-cylinders make rude power NA, let alone once they're fed delicious turbo boost, and they're able to do so thanks to the engineering progress we've made over the last 30 years. And it it isn't just the quality of the design and the parts being used.

Production tolerances, thanks to improving the quality of the design, the quality of the parts being used, and the precision of the machines building the engines, have all been tightened up out of sight compared to old engines. 40 years ago it wasn't uncommon to hear of someone having a lemon car where the engine suffered catastrophic failure through some silly manufacturing mistake, but this has largely been eradicated today.

All of this is great news for people at home wanting to build fun, fast street cars at home. We can turbocharge common, easy-to-source NA engines, control them with precision, and make more power than supercars had in the 90s.

And we can do it ourselves as the base equipment the manufacturers are giving us are so much better designed and built than they used to be.