Replacement engines are they inferior

I had always heard that 400 Mopar was inferior to 383 Mopar it replaced. Though I know the 400 can be made to scoot I've did it in a Cordoba. Is it a step down compared to 383 which obviously made a lot more horsepower from factory. The same for 400 Ford which replaced 390 in all cars and 360 Mopar which replaced all 340 Mopar powered cars? Now I know all the engines made less hp and had lower compression a lot of that was due to emissions,gas crunch and insurance rates. But the question remains though they had a lot going against them are they also just not as strong or well built? Thanks guys..

My opinion is yes and no. Using the small block chevy as an example, the engine performance peaked in the 1969/1970 era and quickly went downhill as emissions and gas mileage came to the front. The result was the engines were modified to have thinner wall castings (weight savings), lower compression, lower emissions (run hotter to lower emissions), more cast parts than forged, etc. HOWEVER, things like fuel injection started to make inroads....for emissions reasons at first. The result was better efficiency, more power, better engine control, etc. A performance engine today is miles ahead of the 1970 engine design. A good example is the Vortec head on a chevy..... much better than the old LT-1 head on a 70 Z/28. I think you have to take the different eras into consideration....if it's the 70's or 80's then yes, the engines are a step back.

Thank you I thought so also. Let me give you some real life examples. I had a 1971 340 Duster and 2 Mopars with 360 a 1975 Roadrunner and a 1978 Magnum. Though the Duster was a stick and that gave it a little advantage off the line it was far quicker than both of them .Well I changed almost everything. cam,carb,intake, distributor, low 3:54 gears in one 3:90 in other,headers,head work,etc... on the 360's. And I eventually got them both to run quicker than Duster but why did it cost so much to do it?

Next example my friend had a 1967 Polara with a 383 Magnum I had a 1976 Cordoba with 400/4 barrel and dual exhaust. He kicked my ass for almost a year,before I could beat him at a cost of 3,500.. Why?

See it is mostly true. Inferior maybe not,under powered and anemic definitely. You can fix but it ain't cheap. I never had any problem with reliably like breaking down over heating or internal. or block failure so their not that weak. But they are power challenged.

Anything made after '72 in the US got hit by the CAFE regulations, and the engineers were throwing everything they could think of on the engines to meet the new limits. We got EGR to lower the temp of the burn in the cylinders to reduce NOX, retarded timing, lower compression, and every kind of vacuum switch they could dream up in '73/74/75 and on. Things didn't get much better until the mid-80's when the OEM's started clawing back ground, ala the Fox Body Mustangs and the Gen 3 Camaros. That's why the traditional "last of the muscle cars" is said to be 1972.

Your are so right. Thanks again.