Originally Posted by Southern-Nupe
I see nothing wrong with an engine which is reliable, runs to 7 grand, posts great torque/ power numbers, and weighs less than some 6 cylinders and most v8's. I'm usually more interested in the engines output, rather than the actual technological design, however the fact the LS7 is composed of titanium, aluminum and has the compression ratio of a highend supercar ....makes me all the more impresssed. Maybe you can find some cons (outside of older technology), but I can't think of too much wrong, with the LS7 design.
....and remember, inline engines are a fairly old technology dating all the way back to Ford Model A's. I do agree about inlines being better balanced, however they barely make great applications for performance cars, because of their size and weight (the Supra and M3 are the only exceptions).
The overall weight isn't a problem. The problem is the length. A longer engine means you have to either have a really long bonnet, or put more of the weight over the front of the front wheels, which makes the balance worse. You always want your engine as close to the center of your car as possible.
Another reason they are not being used as much anymore is because it is harder to make them meet pedestrian crash regs (due to the long, tall engine being closer to the front being more likely to cause injury).
The final reason they are not used so much anymore is because you can't easily make them into a FWD application. A lot of sports engines share a heritage with a consumer engine, and if you can't make it front wheel drive nobody will buy your car (with a few exceptions). Not to mention if you're already designing V6s, you already know the pitfalls of those engines, and are more likely to 'stick with what you know' and not start from scratch on an inline 6 sports engine.
As for Inline 6s being 'old tech', that's not true. They're a layout, not a technology. You can update a layout with new technology.
There are a few more examples than you mentioned too! Just some off the top of my head:
- Nissan RB20, RB25 and RB26 engines, the RB26 being included in the Skyline GT-R, one of the leading sports cars from Japan.
- TVR Speed Six engine in the TVR Cerbera, Tamora, T350, Tuscan, Sagaris and Typhon.
- Inline 6s were used in Formula one from 1947 to 1960.
- Ford Australia's DOHC Turbocharged I6
Also, the ones you did mention: The Toyota Supra 2JZ-GTE is considered by many to be the BEST turbo engines ever developed. It's solid, reliable, and can make LOTS of power without exploding (1000+hp models are almost common). And the M3 is the best, longest lived sports coupes ever. The old M3 engine was brilliant. So you can't tell me they don't make good sports applications.
An inline six not used for ease and convenience, not because the engine design is bad.