I’ll preface this by saying that yes, I know Automation isn’t meant to be a hyper-realistic sim, and no, this thread isn’t meant to be complaining even if it might happen to sound like it. I just want to understand how/why Automation notably differs from reality.
Anyway, I’ve been noticing that a lot of engines I’ve been reading about (in particular, pre-EFI era) have considerably higher torque and compression ratios than a copy built in Automation, and I’m curious whether anyone knows what would be the culprit. Even if I set the valve timing very aggressively and run maximum richness, which presumably a non-sporting engine wouldn’t, I still can’t get close without switching to high octane fuel and cranking up the quality sliders quite a bit.
In terms of American cars, before 1972 engines were rated by SAE gross output which is the engine output at the crank without the alternator, power steering, water pump, or air conditioning compressor installed. Naturally, without all those power sapping components, the horsepower and torque ratings are significantly larger than they would be in a production car. After 1972, engines were rated by SAE net which was the power output with all those components attached and thus the outputs were much closer to what was actually getting to the tires.
The Automation valvetrain tech, pushrods in particular, aren’t always good approximations of real life. For instance, pushrod engines even in the 1960s were able to easily achieve 5000 to 6000 RPM, yet in automation you can’t usually get them to those ranges without abuse of the quality slider. This is a well-known incongruity.
Carbureted engines are known to run rich because of the problem of manifold lengths. Cylinders at the far reaches get less fuel than those near to the carburetor because the long runners reduce flow rate and allow for fuel vapor to condensate. EFI engines which inject fuel at the intake valves or directly into the cylinders do not have this problem. Thus if you try to run a carbureted engine lean, you will get poor results and Automation shows this.
Thanks, that explains most of it. Is Automation engine power gross or net? (doesn’t account for power steering?)
The thing that is most out of whack from what I can see, besides the under-performance of pushrods, is much lower compression, which presumably leads to some part of lower torque. Low torque tolerance until late years and somewhat low RPM limits on the internals don’t help either, along with somewhat low power limits on carbs, meaning big block American engines can’t be replicated (e.g. 7L).
Is this for gameplay reasons? Or is it just something that can’t be rectified without excessive rebalancing effort?
As for the OHV problems, there are a bunch of changes planned to the engine designer (which Killrob made a video about a while ago) that should hopefully make those engines a lot more useful for performance applications.
The new intake manifolds might also help with low end grunt.
A big part of this is that IRL, engine designers have a far broader toolkit. This is especially true and helpful with parameters like valve, combustion chamber, and piston geometry, spark plug placement, and metallurgical choices. These are the kinds of things that we don’t really have control over in Automation but that strongly contribute to available compression ratios and thermodynamic efficiency.
I understand that, but if (hypothetically, haven’t researched this thoroughly) most real engines perform above what they can in Automation (by the given common metrics; displacement, valve train, fuel system, etc.), then maybe Automation’s generic engine components should be given a performance boost to meet the average.
Just as an example the 426 street Hemi was rated at 425hp gross, only 350 net not sure how much the net torque dropped but I would guess it was about a 18% drop to around 400lb-ft. While car makers to this day play with the ratings, cough BMW, it far more honest.
For American muscle cars with gross rating subtracting 18% will get you a decent ball park rating of Net HP. You just have to watch out for the really hot engine and engines like the L88 which was rated at a low rpm well below it’s peak.
I think using the quality slider is a fair way to reasonably account for some the high performance engines with better heads and such, after all these cars did use higher quality parts and things like solid lifters, high rise intakes and aftermarket carbs. What you can’t account for is that in the US during that time you could get from 102 and and in some locals has high as 109 octane at the pump.
I feel the level of realism is pretty high in Automation; and will only improve with the future design options we will have. There definitely needs to be changes; such as increasing the hypereutectic pistons’ tolerance to high-rpm, and maybe a similar improvement for the pushrod speed tolerance.
Flow-wise everything seems where it should be. Valvetrains where the valves are vertical (OHV and OHC) have a narrower power-band than their better-flowing counterparts (SOHC and DOHC) with broader power-bands.
Horsepower ratings should always be taken with a grain of salt. Automation tends to rate engines with more conservative numbers than SAE / NET, not even mentioning Gross. Though the likelier case is that real-world manufacturers up-rate their engines to look more attractive on paper, rather than Automation measuring horsepower inaccurately; though a mix of the two is always possible.
I mostly look at 0-60 / 0-100 times compared to the weight of the vehicle, reasonable approximation of gearing, and engine displacement with general technological advancement. I tend to match real-life acceleration times with less horsepower than their real-life equivalents in Automation. The difference is I’d say about 10% less power required on average. For example; if I were to replicate my Altima in Automation, I can get the same acceleration out of a 138hp engine in Automation, compared to the real 150hp KA24DE of the same displacement.
As for 102 and 109 octane… that’s news to me. I know of 110/130 octane aviation fuel being used in race, or heavily modified cars; but that would never be sold from the factory. WWII era aircraft couldn’t idle for longer than a full minute before their sparkplugs were fouled because of the lead content of those fuels; at over 1.12 G/L… I have a manual for the P-38 Lightning somewhere, and if I remember correctly they were instructed to run the engines to 2,000rpm (or less than maximum allowed sea-level manifold pressure) after every 45 seconds of idling to clear the plugs. I remember the long streaks of lead behind the exhausts of old warplanes, lol.
Holley750cfm on australian ford clevelands, holley 640cfm centre squirters on tunnel ram optioned fords etc etc. Easier to buy bulk carbs than manufacture them
Still factory fit. Not aftermarket. Brother’s XC 302 had some huge unit on top, still factory fit. My ED fairmont had the XR8 body kit on it, option; still not aftermarket.
That is correct; (though some sources say 143hp) the KA24DE used in the Frontier and Xterra had a lower, 9.2:1 compression ratio and different cams.
Nissan was always a bit murky on their horsepower ratings for KAs. I know the KAs in Altimas had a different cam practically every other year, yet officially output only changed once during the 2000 refresh… which is also rather hard to believe that it gained 5hp while cutting the intake cam duration from 240 to just 224.
109 was definitely possible with leaded gasoline but not common, 100-104 was more likely. And keep in mind this is all RON, not R*M/2 like modern American ratings. As for “aftermarket carbs off the production line”, that would be a dealer option under a special contract with Ford, Chevy, or Chrysler. You paid the dealer extra to get high-end Holley or Weber carbs installed at the dealer with a factory warranty, like the DCOE option in Automation.
