Flat 8 engine


knightjp
02-02-2012, 12:47 PM
I know that boxer engines were used by VW on the original Beetle and is currently being used by Subaru and Porsche.
Going through wikipedia, there is a mention of flat engines with a range of cylinders from twin or 4 all the way to 12 cylinders or more.
I know Subaru and Porsche use flat 6s, but is that the biggest engine used in the cars...
To quote wikipedia... "Boxer engines of up to eight cylinders have proved highly successful in automobiles..."
I did a search, but there isn't a mention of a flat 8 engine used in a car. Does anyone know of any?

And while we on the subject, I know that Flat / Boxer engines are known to be well balanced engines which vibrate lesser than conventional V or inline configurations. But how does the Flat/Boxer engine compare with the Rotary engine, which is also known to be well balanced; in terms of power, torque, etc..?

MagicRat
02-03-2012, 12:39 AM
Flat 8's? They're pretty obscure.

For cars: Porsche 908 and 910

Race boats: Miller 148
http://www.milleroffy.com/Miller%20148%20Flat-Eight%20Marine.html

Aircraft: Continental and Lycoming made lots of flat-8 aircraft engines.

knightjp
02-03-2012, 04:10 AM
Thanks MagicRat for the info.

However you didn't answer the other question. Which of the two on the poll is better???

knightjp
02-04-2012, 09:36 AM
It would appear that there aren't many fans of the Mazda Rotary engine around to comment on the comparison.

Moppie@af
02-04-2012, 06:00 PM
Ferrari made a few boxer 8's as well.


The difference between a flat/boxer engine and a V engine and an inline engine is very small.
For a given displacement and number of cylinders they will generally all produce similar levels of performance as they all use pistons, connecting rods, a crank and valves in a cylinder head.

A rotary engine is a very different way of converting chemical energy into mechanical.
It has no valves, no pistons or rods, few moving parts at all.
Its power delivery is very different and there isn't even a way of comparing displacement directly with a piston engine.

knightjp
02-04-2012, 09:26 PM
A rotary engine is a very different way of converting chemical energy into mechanical.
It has no valves, no pistons or rods, few moving parts at all.
Its power delivery is very different and there isn't even a way of comparing displacement directly with a piston engine.
It must not be a very efficient engine otherwise it would be used more. Or manufacturers prefer to stick to something known for cost purposes.

I hear that its fuel efficiency isn't all that great and it doesn't produce that much torque. Also in cold countries, people have faced problems of it not starting up during winter and it uses quite a bit of engine oil.
The later I think isn't a problem but a sign of bad maintenance.. However the fact that a naturally aspirated engine only getting its power high up the rev range doesn't inspire much confidence. Sounds like a Honda. LOL

So far according to wiki, its merits are the fact that it is a very smooth engine and sweet sounding engine and its got a good mid-range power delivery.

Anymore information on the rotary engine would be helpful...

knightjp
02-08-2012, 04:15 PM
I've been doing quite a bit of reading up on these two engines... So far from what I've gathered, these are no V8s but their sounds do turn heads. With quite a few awards each in terms of design and testimonials on based their reps, these engines have proven themselves, when compared to the normal straights, inlines & Vs...

Choosing between them based on their merits and exclusivity is frankly proving very hard. I'm probably going to be happy with either one in the car, but I just thought I might choose based on their sound. So I chose a videos with both engines having the same aftermarket exhaust system.

Mazda Rx8 Borla Exhaust (http://www.youtube.com/watch?v=pZyDLNpL-jI)
Porshe 997 Borla Exhaust (http://www.youtube.com/watch?v=ATTPBexFmZI)

The flat 6 probably has its flaws, but I haven't found a single one yet. The Rotary has one major flaw.. its torque figures when naturally aspirated. Its fuel efficiency also questionable, but not much of an issue with me.
OK... the Rotary in the video is no 3 rotor, but I think I'd be happy with a Renesis.

thummmper
02-20-2012, 11:54 AM
they have called it in general--the boxers self balance, but eat a big square hole out of the area that suspension usually is. control arms to valve covers is real tight--
8 cylinders self balance in any configuration--so the six and four really benefit from the boxer config.
I didnt have the room to set a boxer in between my rear control arms, so I wedged a new gen v6 in there-[vanagon] and it conceals nicely.
It directly relates to what you want, and the room you have to house it. the laws of physics define the selection. bad initial equipment choices will plaque and even kill a project.

Lanos Driver
02-20-2012, 09:57 PM
I remember reading about rotary engines many years ago, mostly in Car & Driver magazine. Their testing revealed them to be very smooth, but dirty and thirsty.

knightjp
02-21-2012, 09:17 AM
I know rotary engines works with the four different jobs namely intake, compression, combustion and exhaust. It's a kind of having a dedicated (cylinder) for each of the four jobs, with a piston continually moving from one to next. It is also a hydrogen-fueled rotary vehicles.
Boxer engines can be mostly seen in Subaru vehicles. It uses each pair of pistons that moves simultaneously rather than alternately.

I'll go for Rotary engines.
I've opened another thread to discuss the advantages and disadvantages of the Rotary and Boxer units...
Flat/Boxer vs Rotary (http://www.automotiveforums.com/vbulletin/showthread.php?t=1075569)

knightjp
04-18-2012, 05:02 AM
I remember reading about rotary engines many years ago, mostly in Car & Driver magazine. Their testing revealed them to be very smooth, but dirty and thirsty.
Do you have a link to that article??

ApexR7
04-18-2012, 03:49 PM
Yea, I was going to say.. the Porsche 908 came to mind... You don't see those everywhere though..

Lanos Driver
04-22-2012, 09:13 AM
I remember reading about rotary engines many years ago, mostly in Car & Driver magazine. Their testing revealed them to be very smooth, but dirty and thirsty.

Do you have a link to that article??

As I stated, that was several years ago, in the 1980's as I remember. Maybe a search of C&D archives?

thummmper
04-23-2012, 12:35 AM
in the sand car community the rotary is known as the jackhammer on transmissions. especially the 3 chamber engines. their power pulsations are different from piston engines, and they spool up very smoothly.

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