Just tried to get back into playing this game again, and was immediately disappointed to discover the enormous nerf, especially related to exhaust. With the Kee version of the game I was able to accurately recreate the Chrysler SOHC V6 3.5L/3.2L engine, right on the dot. Needed some small quality bumps, but reasonable. Now I can’t come even close to that. I’m consistently 25 HP and ft-lbs of torque short of my previous numbers, and the exhaust size needs to be much larger. What’s going on here?
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Depends, don’t use dual reverse flow mufflers or you’ll need a lot more pipe diameter to not completely choke it. Engines make MORE power now without exhausts than they did before. We have not changed much else that would change power generation, so maybe it is a matter of not being familiar with the new systems and your need to “git gud” again after your leave? 
When making engines with VVL, I’ve noticed when you go to the car stats overview the octane is wrong (98.9 RON instead of 98.0 in this case) and when I exit back to the main menu and go to edit the car, going back to the compression/cam profile page, the cam profile has lowered (in this case, from 74 to 59)
in this case the engine is a 2002 V16, AlSi block, 80.0mm bore, 74.5mm Stroke, DOHC-4 with an AlSi head and VVL, Billet Steel Crank, Titanium conrods, Lightweight forged pistons, 12.0:1 compression, cam profile 74, VVL profile 99, VVT all cams, +7 quality on cams, Normally aspirated, Direct Injected, Twin throttle, Performance intake, 98 RON fuel, 15.0 fuel mixture, 75 ignition timing, 10000rpm redline, Long tubular, dual w/bypass valves exhaust, High-flow cat, and 2 straight through mufflers (all QPs at 0 except cams)
I’m not making more power with mufflers and cats off, everything else identical, but it is within about 4 percent. You guys know better than me, I was just curious what was up, thanks! Overall I am enjoying the UE4 engine (minus the multi-minute load times, but I see you guys are working on that).
(In case that is applicable) For carby engines you need to tune the power bulge position, that just came to mind as something pretty big that has changed, it’s a new game mechanic. That can easily lead to a few percent power difference. Cheers!
If the power is on the minus what does it mean, that the engine actually takes power from wheels instead of powering them?
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No it means your engine is dead
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Nah, it’s an MPFI engine. I did notice carbs seemed different in scenarios though, wasn’t sure exactly how. Thanks!
Not sure if this has been mentioned, but moving/placing certain fixtures is very CPU-intensive. Spoilers, grilles, license plates, gas caps, and especially spoilers, are all very laggy.
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Seen that too. Worked great once, now it should too 
The sealed beam light glass material (the one with grooves) is broke now. If it’s the default material on a fixture, it works fine, but trying to select it for anything else does nothing. And if switching the material on something that has it set as the default, it doesn’t switch back.
Negative net torque - interesting. I wonder if the drop continues at that rate. If so, it might be worth revving that thing to 5,700 or so, flick in reverse and slam the throttle to see what happens…
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It this a problem that has only just started happening with this update, or has it been happening in UE4 all along for you?
Also what are your PC specs.
I’ve had the high CPU usage problem just like @MWisBest for a while, mostly for the mods. I’ll double check and try to get a screenshot too.
Hmm if it’s for mods, maybe someone has made some excessively high poly mod meshes?
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That is why I hadn’t mentioned it until now, but it is also why I was going to double check and see if it was any of the stock parts.
@Daffyflyer I just finished rechecking the stock fixtures and I can’t seem to find one that has this problem for me anymore, however, the stock wing is still quite jumpy for me when trying to place it. The screenshot below shows the CPU graph and the period of slightly higher CPU usage is when I was moving the stock wing around before I placed it. Some of the more detailed mod wings move smoother for me when trying to place them with about the same CPU usage.
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Found this today. If you go to headlights/tail-lights and use the release year filter, they all disappear. The fixtures themselves show the year range backwards (20-40).
I can’t say when it started, I only just began using the UE4 version within the past week or so. No mods. My system isn’t particularly powerful, AMD A8-3500M @ 2.7GHz plus a separate dedicated GPU. Basically an Athlon II X4 638.
CPU usage moving the fixtures I mentioned is insane, jumps up 30% (maxing out a core plus some overhead on the main thread I assume) and the game lags like crazy, which kinda stinks because it’s hard to get those fixtures exactly where you want them. Surely this can be profiled on any system? Doesn’t seem right for moving a round gas cap on the car to lag the game so much when it runs so smoothly otherwise. And as @one85db mentioned the stock wing is very very bad too.
Deforming fixtures as they’re moved is among the more CPU intensive tasks the game performs for sure, and is single threaded, so you’d expect it to consume an entire core pretty handily on a low end machine. And if anywhere is going to show up a lack of single thread performance it’ll probably be that. Although I’ve never seen it being too much of a problem on low end machines I’ve tested it with.
I suspect the problem here is that, if I’m reading the benchmarks correctly, an AMD A8-3500M (at least at stock clocks), in single thread performance, is sitting right between a 3.2GHz Pentium 4, and an Athlon 64 3800+. So really surprisingly slow. (It’s like 4x faster than those CPUs at Multithreaded work, of course, but that won’t save you here)
We’ll of course continue to try and improve performance wherever possible there, but I think your machine might be a bit of a weird edge case where it has plenty of multithread performance, enough GPU and RAM to run fine, yet a real lack of single thread performance that makes that one task run slowly.
Though I do wonder if there is something weird going on specifically for you, as one of our other players has an A6-7310 (which is a bit faster single threaded, but not hugely) and they’re getting good performance with dragging fixtures around.
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After further testing, the lag varies significantly depending on the car model. The 1965 coupe body (2.4mm wheelbase one) is perfectly fine for example, the most CPU usage spike I can get is about 10% with the wing, but the 2005 hatchback body is TERRIBLE for fixture lag! Perhaps your other player has not tested other models?
I do understand this hardware is aging and single-threaded performance is fairly bad on it. Without overclocking I would’ve had to upgrade years ago for sure. (For reference, the effective stock clock is really 1.5GHz, so the overclock makes it better than that A6-7310) I don’t expect miracles here, I just wanted to make sure you’re aware of it. But yeah, going to need an upgrade soon, maxing out the GPU for 40 FPS in Automation now >_<
Now an actual bug I just discovered, is that mirror fixtures do not appear if Shadows is set to Low or Medium.
Edit: Also, having Environmental Detail on Medium makes engine blocks look awful from a distance.