the flat 4 engine

[nicolas]

i have been asking myself what the benefit and the downside is of a flat4 engine? i know porsche used them for a very long time and eventually stepping up to a flat 6 and later to aircooled V engines. (because of emmissions???) anyway it looks like our little flat4's have been developed into 200+ HP beasts, but can it be achieved with 4 in-line engines, or other types? what is so good about the vw engine that others don't have? or is it simply something that an old idea that stuck for almost 5 decadedes?
(please feel free to move this to the off topic section if it is way out there...  ) but it was something that i have been asking myself

[Jim Ratto]

GOOD topic!

I think the boxer motor is best for balance of, but with VW we don't have either enough main bearings (look @ 911 crank or WRX crank) OR the journals of VW crank are too wimpy and need to be more robust.
There are lots of other 4 cylinders (some boxers!) that make prodigous amounts of power and live too....

Carrera 4 cam motor, will make power for its size and live but is fussy and only 3 guys in the world can make them work right

The old Ferrari TR500 variations of four cylinder F2 motors from 1950's...again, very stout, makes power but super exotic for its time

The Alfa Romeo four cylinder post-1900cc motors....finally, a layman's motor in this list, but while they may be plentiful, their construction and materials used were about as exotic as any other Ferrari or Maserati motor (or more so) of its era. Lightwight elektron castings, huge, finned oil sump, DOHC, big valves, hemi chambers. Tuned for race, these motors in 2000cc will easily exceed 200hp (i.e. Autodelta) not only that but the motor was used in almost every Alfa since what, 1955...unitl late 90's??

Ford Pinto motor: don't laugh....the Ford motor is very popular among tuners around the world, 200hp with mods, curiously, these things seem to have same cam and lifter wear issues like us guys

the British Leyland Austin/MG  1275cc, i.e. Mini Cooper motor.

Subaru WRX boxer motor in all its guises since 1993-4 or whenever it came out. Some guys mistakenly thumb their nose at the Suby motor, disdaining it as a "ricer car motor"....too bad. Forged crank with mains between every rod throw, super stiff closed deck alloy block, 16V pent-roof, DOHC heads with high rev adjusting shim/buckets, huge oval intake ports, lots of boost, huge charge cooler, in STi version forged rods, forged pistons.... yeah right, the WRX is a cafe racer, right? 

Great topic nicolas....I LOVE talking motors....any motors.

[Peter]

HEHE, i know boxers are thirsty,
and they make a bitchin sound

[louisb]

I am thinking the original reason that Dr. Porsche went with the air cooled flat four had more to do with economy and meeting the performance requirements, heat, cold, driving distance at a specific speed than any performance values as we know it. It was cheap and easily produced by 1930s standards. I seem to remember that an early version of the motor only had 2 cylinders.

Porsche used the aircooled flat six up to the 90's if I remember right. The main reason for going to the current water cooled engine had more to do with emissions than performance.

--louis

[Udo]

Subaru WRX boxer motor in all its guises since 1993-4 or whenever it came out

I have seen they make a boxer Diesel now 

Udo

[Jim Ratto]

I am thinking the original reason that Dr. Porsche went with the air cooled flat four had more to do with economy and meeting the performance requirements, heat, cold, driving distance at a specific speed than any performance values as we know it. It was cheap and easily produced by 1930s standards. I seem to remember that an early version of the motor only had 2 cylinders.

Porsche used the aircooled flat six up to the 90's if I remember right. The main reason for going to the current water cooled engine had more to do with emissions than performance.

--louis

noise restrictions.

they had to dial back tune of motor in 1974 or so, when they ditched plunger injection, wild 'S' and 'E' timing, in favor of CIS flapper injection and tame cams... until 1984 when they went to 3.2 and Motronic.  to keep performance levels up, they had to resort to higher CR, twin plug, engine management, two distribuotrs, and with 993 they switched to hydraulic adjusters for noise and service reasons. Anyway, that's a six cylinder.
Completely different creature than the VW or VW-derived 4 cylinders in 356 and 912

[nicolas]

oh yes there is indeed the Subaru's, how could i forget those, my friend has a 2006 WRX Sti and that car is very cool, engine sounds good. but that is a turbo, not exactly the same idea as a VW engine (initially   ) but why did they opt for the boxer? and do they use 4 cams as well?

and yes when the beetle was designed it had been done in a very set idea, but every bolt and nut was changed (except for one) in the beetle yet the engine configuration stayed the same, even later with type3's and type4's it stayed a flat4 and aircooled. others did not go that path frequently so that engine setup has to have some benefit over the lets say 4 in-line engines from BMW.

thanks for thinking along guys.

[Jim Ratto]

oh yes there is indeed the Subaru's, how could i forget those, my friend has a 2006 WRX Sti and that car is very cool, engine sounds good. but that is a turbo, not exactly the same idea as a VW engine (initially   ) but why did they opt for the boxer? and do they use 4 cams as well?

and yes when the beetle was designed it had been done in a very set idea, but every bolt and nut was changed (except for one) in the beetle yet the engine configuration stayed the same, even later with type3's and type4's it stayed a flat4 and aircooled. others did not go that path frequently so that engine setup has to have some benefit over the lets say 4 in-line engines from BMW.

thanks for thinking along guys.

Subaru adopted the boxer layout from their aircraft ancestry. Reasons the Subys of today run boxer motors....low hoodline, low center of gravity, balance of harmonics, compactness, weight distribution.
Of course, boxer motors cost more to produce. 
Yeah STi and all WRX's are turbo.
Secretly I have always wanted to take one, raise CR, make some wild cams and top it with some IDAs 

[Jim Ratto]

oh yes there is indeed the Subaru's, how could i forget those, my friend has a 2006 WRX Sti and that car is very cool, engine sounds good. but that is a turbo, not exactly the same idea as a VW engine (initially   ) but why did they opt for the boxer? and do they use 4 cams as well?

and yes when the beetle was designed it had been done in a very set idea, but every bolt and nut was changed (except for one) in the beetle yet the engine configuration stayed the same, even later with type3's and type4's it stayed a flat4 and aircooled. others did not go that path frequently so that engine setup has to have some benefit over the lets say 4 in-line engines from BMW.

thanks for thinking along guys.

good thinking on why VW "stuck" with the flat air cooled 4.... was it because that was what they knew? Marketing? Solid engineering ideas that worked? 

oh yeah all WRX and STi are 4 cammed.

[louisb]

So, there are really no inherent design flaws with a four cylinder boxer motor, its just the way they were designed for VWs. Well that and they are still aircooled. (Subaru's being water cooled.) With all the CNC tech that is floating around today, it should be possible to overcome those issues in a street motor. Of course, there is always the type four as an alternative.

--louis

[louisb]

oh yes there is indeed the Subaru's, how could i forget those, my friend has a 2006 WRX Sti and that car is very cool, engine sounds good. but that is a turbo, not exactly the same idea as a VW engine (initially  ) but why did they opt for the boxer? and do they use 4 cams as well?

and yes when the beetle was designed it had been done in a very set idea, but every bolt and nut was changed (except for one) in the beetle yet the engine configuration stayed the same, even later with type3's and type4's it stayed a flat4 and aircooled. others did not go that path frequently so that engine setup has to have some benefit over the lets say 4 in-line engines from BMW.

thanks for thinking along guys.

good thinking on why VW "stuck" with the flat air cooled 4.... was it because that was what they knew? Marketing? Solid engineering ideas that worked? 

oh yeah all WRX and STi are 4 cammed.

Probably more to a philosophy of not fixing what was not broken. VW believed in incremental changes as opposed to clean slate engineering. A very conservative mentality.

edit:

Plus until the rabit came out, it would have required a complete redesign of their car structures and drive train design.

--louis

[Prowagen]

A friend of mine had a 2lt Turbo Subaru motor in his bug, went quite well hooked up to a rancho freeway flyer it ran 13's in stock form.
I helped him strip it down once and I must admit i thought it looked a bit like a Type 4 motor when it was down to the short block.

He told me that Subaru bought designs or pattents from volkswagen for  the flat4 in the 70's anyone know if thats true?
Also it seems that the subaru also has the inherant problem of No 3 cylinder being a weak link once tuned.

Personally I prefer the idea of things being aircooled, would love to play around with a Tatra aircooled V8.

If I were to be into any other cars other than the beautiful aircooled VW, it would have to be the early RX's from mazda, wankle rotary engines now they are amazing!

Rob.

[Rick Meredith]

Ford Pinto motor: don't laugh....the Ford motor is very popular among tuners around the world, 200hp with mods, curiously, these things seem to have same cam and lifter wear issues like us guys

My Mustang has a "Pinto" motor in it 235hp at 2300cc. 

[Rick Meredith]

I seem to remember that an early version of the motor only had 2 cylinders.

--louis

There was a prototype motor that was a 2-Stroke 4 cyl. with 2 cyl. supercharging the other 2.

[alex d]

a light alloy flat4 makes sense when you have an engine hanging behind the rear wheels, lower center of gravity and less polar moment than an inline-4, of course using swing axle suspension with a very tall roll center takes all the advantages away, but that's another story 

another successful flat 4 engine is the Alfa Romeo one, used since the 70s in the Alfasud, Spint and later the 33 and up to the mid-90s in the 145/146, it was designed by Rudolf Hruska, who had worked with Porsche in the 30s.

[Rennsurfer]

Bayerisch Motoren Werke has been using horizontally opposed aircooled engines in their motorcycle division for years. Long before their cars, I would imagine.



Lycoming has been producing flat four and six engines for aircrafts for decades. These things sound awesome when tuned, by the way.



But then again... any boxer engine sounds magnificent in my opinion. Always been fascinated by them. Another even older concept is the Pratt & Whitney radial opposed engines that powered many famous airplanes.



Probably my favorite sounding aircraft engine. (I used to fuel private, commercial, and military 'planes in the '80s. Also detailed many of them and got to fly them. Being boxer powerplants, I was naturally in awe.)

Of course, the flat twelve in Ferrari's cars cancels out the need for a radio in the cabin. Just open up the throttle and listen to the sweet harmony.



If you're into model building many modelers are huge fans of the boxer realm, as well.



Let's face it... Dr. Porsche was years ahead of his time when he was asked to manufacture/produce an engine that didn't require water (cooling), got good mileage, was durable, and could run long hours, light, and efficient.

Long live flat engines!

[Jim Ratto]

a light alloy flat4 makes sense when you have an engine hanging behind the rear wheels, lower center of gravity and less polar moment than an inline-4, of course using swing axle suspension with a very tall roll center takes all the advantages away, but that's another story 

another successful flat 4 engine is the Alfa Romeo one, used since the 70s in the Alfasud, Spint and later the 33 and up to the mid-90s in the 145/146, it was designed by Rudolf Hruska, who had worked with Porsche in the 30s.

yeah the Alfasud, where a lot of guys got their Dellorto carbs....cool thinking

[Zach Gomulka]

A tuned VW engine sounds great (of course), but a tuned Subaru sounds like a dune buggy. I think those things need an equal length header or something.

[Jim Ratto]

A tuned VW engine sounds great (of course), but a tuned Subaru sounds like a dune buggy. I think those things need an equal length header or something.

people have commented that my Legacy sounds like water cooled 911

[Zach Gomulka]

Is it a 6 or 4?

[Jim Ratto]

Is it a 6 or 4?

2.5 turbo 4

[Zach Gomulka]

Hmm... same motor as my mom's Subaru Baja! Funny looking, but fun to drive- expecially with the 5 speed