73k for so much hp is kind of cheap, relatively speaking. Not that you will see on every corner, but all things considered, it is.
It's a good value for that kind of performance, in the same sort of spirit as the Corvette, but a different audience clearly.
It is simple engine, old design, and add supercharger on such displacement and you extract so much hp. It requires oil that it requires because it is simple.
Well, that depends on how you look at it. DOHC engines have been around almost as long, Ford was producing DOHC hot valley engines in the 60's for example (Ford Indy Cammer) but for practicality, the pushrod engine's simplicity won-out. We see Ford doing a bit of backtracking on that right now with their new 7.3L pushrod engine in the Super Duty trucks, after introducing the big SOHC mill that also originally powered the Raptor.
A pushrod engine is far more compact and less complex. Yes, you are limited by only being able to advance or retard camshaft timing as a whole, rather than doing intake separate from exhaust like you can on a DOHC mill, but it isn't really any more limited than an SOHC one. Valve arrangement on your traditional wedge chamber has required larger bores (vs an OHC arrangement) to mitigate shrouding, but that's less of an issue on engines like the HEMI where the valves are oriented like on a pent-roof SOHC design.
Putting a blower on an OHC engine achieves the same function (see the 5.4L 2V in the F-150 Lightning and Harley trucks or the 4.6L DOHC engine in the 03/04 Cobra for example, or the 32V 5.4L engine in the first gen Ford GT), but because of the pushrod engine's compact size, you can put more displacement under the blower for less real estate, and that's an advantage in producing something that isn't super stressed, despite making some eye-opening power figures, because in terms of power density, it really isn't that high. Of course that ties into it being easy on oil, as does the use of a supercharger with its own oiling vs sharing the engine oil. The 03/04 Cobra and Lightning did not have exotic oil requirements for example, for the same reason, despite being OHC.
Yes, this also has the benefit of being less expensive to produce, all things considered.
No, as I said, the Viper had a DOHC V10, it has nothing in common with the Hellcat engine.
SRT etc. all of them have this design bcs. it is cheap to utilize existing engines
The 6.2L wasn't an existing engine though. Yes, it's based on the existing HEMI architecture but the reason they didn't just slap a blower on the big bore 6.4L is because they didn't feel it would have the durability under boost at the power figures they were looking for (840HP in the Demon). So, they set out to make a specific version that would, that's how the Hellcat mill came about. Yes, they can use the same camshaft blanks, rockers, lifters...etc, so there's lots of cost savings in parts that will transfer over, but many of the parts are also engine specific.
bcs. generally, these companies are not bothering with other aspects of performance: balance, handling etc. SRT might have a lot of hp, but it is not going to win any handling competition.
Eh, there are enough SRT-specific parts underpinning the SRT vehicles to have me contest that. They are all rolling on existing platforms, but then so is the M3, M5 and AMG 63 cars. They get their own suspension components (control arms, bushings, struts, tie-rods, hubs, brakes, axles, differentials...etc). The limiting factor is the platform itself and with the Charger/Challenger, that old Mercedes platform is very long in the tooth, same with the WK2 underpinning my Grand Cherokee, which was a joint development under Chrysler/Mercedes.
Now, do I think the Charger RedEye receives the same level of handling refinement, even given its proprietary suspension bits, that say an M5 or M6 gets? No, but the price reflects that. But they are definitely improved, and receive attention, beyond what the regular cars get, or did while SRT was still its own separate group, be interesting to see how that goes under Stellantis.
The Viper was always a capable handler, but it would kill you if you didn't know what you were doing. The Demon isn't meant to handle, it's setup for the 1/4 mile.
You might find this video amusing, it's a 2016 stock Hellcat on the 'ring: