Wednesday, July 14, 2010

Why the hate for V's...not because it's an american trend....

Some people (well, a lot of people, actually) asked me "why do you hate V engines?"
Tired of explaining everything over and over, I decided to post an explanation.

To understand-me, first you have to understand my brain. I look at an engine (every one of them) from an application/efficiency point of view.
That kinda placed everything in view.
Since I consider only 2 kinds of vehicles: The sports car and the family car; I immediately place engines in 2 categories: Petrol engines for sports cars, diesel engines for family cars.

With this in mind, it's easy to understand that if you are requesting torque, that you move 2 tons of car + people, so you should go diesel.
On the other hand if you need response and pack as little weight as you can, go petrol.

On this front then, the petrol engine is supposed to revv and be light. Light also means on it's internals. So A V engine will have to either have a central CAM with push-rods, or 2 sets of overhead CAMS... now that's twice the drain on power to move the cams, valves, fight the springs, chains, etc comparing to an Inline Engine.

For some reason, V engines (apart from the caparo T1's unit, some ferrari's, some Bmw's and some AUDI's) rarely reach 100Bhp/liter. Since we have InLine units going over that mark with ease, why the hell going V?
The only acceptable response is compactness. But still, only if you save weight.

The truth is that an InLine engine, if needed to grow beyond it's physical location capacity, should become either forced induction, or replaced by a wankel.

To summarize, efficiency is accomplished by reducing the engine's internal loss and my making it work more (increase revvs).
To all those "there's no replacement for displacement" people out there goes a simple figure: try to use your calculator and quantify how many liters of air does an 4.0 v8 running 1minute at 4500rpm pumps out... and just how many liter does my 2.0 Inline4 running 1 minute at 9000rpm pumps.
The same goes for all the turbo and compressor fans. A 2.0 turbo running at 2bar (1 bar of boost) will be the same as a 4.0 atmospheric engine, admitting that it's intercooler had a 100% efficiency (it doesn't and probably will have something near a 3.0 to a 3.5).

So clear your thoughts on displacements, turbos, compressors and get to the raw engine power figures.. and that's called Specific Power output... or Bhp/liter.
Anything below 100Bhp/liter is (nowadays) pure garbage (unless it's diesel and it's meant for your family car).

Leveling things down this line of thought and you'll soon understand that, the less moving weight, the less power drain, the more revvs and consequently, the best Bhp/liter.

Through my viewpoint:
a light RWD sports car needs an IL4 or IL6 atmospheric 10.000rpm rev-monster.
a heavy RWD sports car needs the same engines but with a compressor on it.
a AWD sports car needs an IL4 or IL6 turbo or twin-turbo.
and if the IL4 is not enough and the IL6 too big... go the wankel way.

Anything besides that is for saloons and saloons should run on diesel with loads of torque to cope with all that weight.

When I look at people drooling around a Corvette Z06... I honestly laugh my pants out! That silly thing has chariot-like rear suspension and a MONSTER engine with 7.4liters and a compressor... and does what? 76bhp/liter... 84 maybe? pffff that's nor even a car to my view since it doesn't reach the 100Bhp/liter mark. (caustic I know.. but that's just me)

Feel my drift?