It's hard to say why the acceleration is off and why it's not terribly efficient considering but gearing could be a big part where it's gearing happens to be poor for the testing they did (for instance maybe 45-65 instead of 50-70). The power band and the driving impressions I've read indicate that it's a lot livelier once you get moving and that it's a bit of a dog down low.
It actually sounds a lot like a diesel (slow standing acceleration), only they traded some of the benefits of diesel (efficiency, reliability) for a small packaging size so it's ok-ish but there's some tradeoffs.
The Elise has more power, less torque, and is more peaky:
Oh forgot to add output for the weight of the engine. The other thing I'd like to know is packaging size, and that's something small engines like this will be hard to realize right away (as in just slotting them into cars that normally use a larger 4 cylinder).
Kinda like how Hyundai was able to design the Sonata differently by only going with 4 cylinder engines, it might take a new generation car built around that to realize the full potential.
Wonder how longevity will be on such a highly stressed engine. 150 HP/L sounds good, but how will it fare after 100k miles?
It's got a cast iron block so the bottom end should be fairly robust, but there's quite a bit else to wonder about (has dual cooling channels so that they can let different parts of the engine heat up at different rate to help efficiency).
This engine has been out in the UK for a while.
Scary numbers of reports of head gasket failure at low miles. One case of someone having 2 head gasket replacements during the 50k mile warranty, and then a 3rd failure just out of warranty leaving them SOL.
This engine runs crazy boost (20 psi), and the head and cooling system is so small that you get significant heat-soak just climbing a hill.
EGTs are so high that there isn't an exhaust manifold as such - the manifold is part of the head casting so that it can be water-cooled.
Disappointing, but it is a pretty new engine so hopefully things they can get worked out. I do wonder if they didn't overengineer it to the point where they'll make problems for themselves.
The high boost might explain some things (standing acceleration for instance) if it takes a while for the small turbo to build proper boost. The preview drives have mentioned it's a dog starting out but once you get going it livens up, and so it's possible it's more of a freeway hauler. It actually sounds a lot like the way they started tuning diesels in small cars (where they focus on them having passing power at highway speed).
Another thing that's fairly concerning is that real world MPG doesn't seem to be living up to the EPA numbers, largely because to keep this engine in the power range you've got to flog it pretty decently.
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