Ruf's 8-cylinder Porsche 911

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Porsche tweaker Ruf makes an 8-cylinder 911, the mighty 542bhp RGT-8 supercar Courtesy of Evo.com

http://www.evo.co.uk/news/evonews/249388/rufs_8cylinder_porsche_911.html

Ruf took this rather intriguing RGT-8 to the Geneva motor show. And while most news coverage from the Swiss show glossed over the Porsche fettler’s produce, this is a pretty key car: an eight-cylinder 911.

Not quite a V8, it’s an eight-cylinder engine with a 180 degree ‘flatcrank’. The engine boasts a 4.5-litre displacement, producing 542bhp at 8500rpm and 369lb ft at 5400rpm.

There’s no word yet on what performance the RGT-8 achieves, but its construction is from lightweight materials. Aluminium is used on the door and boot lid while the engine cover and rear spoiler are made of carbonfibre. There’s also a set of light 19in forged alloy wheels (wrapped in Michelin Pilot Sport Cup rubber) which shroud ceramic brakes.

It should be plenty quick, then, but the big news surrounds the shoe-horning of an eight-cylinder engine into the back of (what is essentially) a Porsche 911. Flat-sixes have been a mainstay when it comes to 911 power, but the use of a high-bhp, naturally aspirated eight-cylinder in this Ruf could signal a new dawn for Porsche’s supercar when the 998 iteration is launched in the next few years. The RGT-8 produces more power than the most recent 911 GT2 but without its twin turbos.

We should get to sample the Ruf RGT-8 in the not too distant future, with sales set to be underway by 2011.

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How does a flat crank make it not quite a v8? It makes it an awesome-sounding v8.
 
It makes it two four cylinders strapped together, is what it does...

In a V configuration, just like all other V8s. For a second I thought it meant it had one of those "flat" Vs, which are not quite "V"s. :lol:

Is there any video of this thing? I bet it freaking hauls.
 
In a V configuration, just like all other V8s. For a second I thought it meant it had one of those "flat" Vs, which are not quite "V"s. :lol:

Is there any video of this thing? I bet it freaking hauls.
If it's got a 180 degree V, surely that makes it flat...
 
It's a flat-V8?

I'm wondering:
  • Where did the engine come from? It would cost a lot to design an engine for one limited application.
  • When do we see Porsche ditch their current V8s for this one? I think it'd be awesome to have the Cayenne and Panamera using flat-8 power, sorta like the 911 ish.
 
If it's got a 180 degree V, surely that makes it flat...

You'd think so, but I'm sure there's some technicality with engines like that that makes it a "V" still, even when it's blatantly not V shaped.

It's awesome though. Even if it didn't have a special engine the thing looks great inside and out.
 
A flat 8 is not a V. A flat-plane crank V8 still isn't a flat 8.

Wonder who built the engine for them, and what base engines they sourced the two four-cylinders from? There are outfits building Siamese V8s, but this one doesn't look familiar.
 
Might as well stick it in a Porsche Cayman. I think it would work better as a mid engine or maybe they are waiting for the 918 Spyder bodies.

 
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Duuuuuude this is veery interesting! And it's a RUF! Not a Porsche, a RUF which might mean...:drool: It may be in GT5 :drool:. Thanks for sharing it.

Also, can someone please explain me why a 180 degrees V8 isn't considered simply a flat 8 (or B8)? Don't they have the same basic shape?
 
A flat 8 is not a V. A flat-plane crank V8 still isn't a flat 8.

That makes more sense. I was wondering how they managed a flat-8 with a crank at the bottom and the heads/exhaust at an angle higher up.
 
@ CarBastard: Indeed mate, that's why I posted it ;)

15-ruf-rgt-8.jpg


Apparently it's an in-house engine, definitely looks like a V to me! A flat plane crank (like Ferrari use) has 180 degrees firing order rather than 90 degrees like a Rover V8 (While production V8 engines use four crank throws spaced 90 degrees apart, high-performance V8 engines often use a "flat" crankshaft with throws spaced 180 degrees apart. The difference can be heard as the flat-plane crankshafts result in the engine having a smoother, higher-pitched sound than cross-plane (for example, IRL IndyCar Series compared to NASCAR Nextel Cup, or a Ferrari 355 compared to a Chevrolet Corvette)

I'll let the man explain, English speaking guy starts at 55 seconds



Also

 
Stunning looking car, I'm sure it'll go like stink too. Can't wait to hopefully get hands on this in GT5! Thanks for posting, and the videos too.

Also, it was funny to hear Alois Ruf drop in a little broken Japanese at the begining of his speech in the first video.
 
Ohhhhh sort of got it now, thanks ;). It's basically defined by the shape the engine has on the lower bit, because this one really still looks like a V8 and not a B8.
 
That car looks stunning!! To fit any 8 cylinder in that engine bay is an achievement in itself and props must go to RUF for taking a chance and doing this car.

10/10 from me for execution....can't wait to see vids of this thing running around a road or track somewhere in the near future. 👍
 
Ohhhhh sort of got it now, thanks ;). It's basically defined by the shape the engine has on the lower bit, because this one really still looks like a V8 and not a B8.
No, it doesn't have anything to do with the shape of the engine.

This engine is a 90 degree V8. You can clearly see the V shape. The pistons point in a V shape, and if you measured the angle between the V it is 90 degrees.

That has nothing to do with the crankshaft itself. The crankshaft is a 180 degree crankshaft. That means that the 8 journals on it stick out 180 degrees from each other, 4 pointing one way and 4 pointing directly opposite.

The article's writer is confused.
 
The writer isn't confused. He said it has a 180 degree flat crank. The cylinders are of course aligned at ~90 degrees.
 
A flat 8 is not a V. A flat-plane crank V8 still isn't a flat 8.

Thanks for clarifying. I didn't take much notice of the article, nor (strangely) the pictures of the actual engine, so peoples' talk of flat engines had me confused. It's a flat-plane crank V8, in the same manner that Ferrari uses a flat-plane crank V8 in the 458/430/360/355/348 etc etc.
 
The writer isn't confused. He said it has a 180 degree flat crank. The cylinders are of course aligned at ~90 degrees.
You're right, he's not confused. He's an idiot. He thinks this 90 degree V8 is "not quite a V8".

Thanks for clarifying. I didn't take much notice of the article, nor (strangely) the pictures of the actual engine, so peoples' talk of flat engines had me confused. It's a flat-plane crank V8, in the same manner that Ferrari uses a flat-plane crank V8 in the 458/430/360/355/348 etc etc.
Exactly. Speaking of which, I want to hear this thing run. I bet it sounds amazing.
 
You're right, he's not confused. He's an idiot. He thinks this 90 degree V8 is "not quite a V8".

Oh, right. Forgot about that part.

The engine designer also designed the engines for the 917 and Mercedes Group C. This car is like a wet dream.
 
Too bad that being a flat-plane crank it will most likely sound crap like modern Ferarris, but I'd still like to see this thing in action.
 
Too bad that being a flat-plane crank it will most likely sound crap like modern Ferarris.

Whatever crack you're smoking Paulie bro, I want your dealer's number to get the same quality!! :odd: Modern Ferrari V8's sound awesome, from the 348, 355, 360 & 430, not to mention the California!! 👍

Not everyone likes to hear a Chev V8 you know. :D
 
I like the idea of never having to replace an engine belt. Bet it's freaking expensive to change out the AC/Alternator/Whatever though.
 
Whatever crack you're smoking Paulie bro, I want your dealer's number to get the same quality!! :odd: Modern Ferrari V8's sound awesome, from the 348, 355, 360 & 430, not to mention the California!! 👍

Not everyone likes to hear a Chev V8 you know. :D

It's the 360 onwards I dislike. Terrible sound.
 
A Vee has shared crankpins - piston pairs reach TDC one half revolution apart. A flat has separate crankpins - piston pairs reach TDC whenever you want them too, but usually the same time.

Boring, but technically correct. 180-degree Vee != Flat


Moving on, this 8-pot clearly has two banks of cylinders at 90 degrees. Sadly, that's not relevant. If the crank has 4 crankpins, it's a Vee. If it has 8 crankpins, it's a flat. I don't care enough to find out, but other flat-plane crank 8 pots - Esprit V8, TVR AJP8, most V8 Ferraris since ever - are all vees.
 
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:lol: :lol: Evo.com have pulled the news article possibly to rewrite it to clarify the engine layout. I must admit when I first read the article I did assume it was a boxer even though the cylinders didn’t look horizontally opposed and only realised it was a vee when I was looking for other articles on it.

Hopefully Evo.com will come good on their promise to get a test of it soon and post a video

Just found this post from another forum that explains it better than I ever could if anyone’s interested.

(http://www.team-bhp.com/forum/techn...letely-different-american-v8.html#post1177392)

Ever wonder why a Ferrari V8 sounds completely different from an American V8???

Well you've come to the right place if you have

So the Ferrari F430 uses a 4.3L V8. The V8 block configuration is the same as any Ford or GM V8 - 90* V8. So why does the engine sound so incredibly different? It seems that the answer is in the crankshaft:

Regular V8s use a cross-plane crankshaft (X) but the more exotic cars use a Flat-plane crankshaft (-)

CROSS PLANE CRANK:
Notice that the nodes are setup in an "X" or "+" configuration. The crank pins are 90* apart.

131490.jpg


Considering the illustration.

131491.jpg


Assume the counter weight in vertical position is heavy enough to balance the crank throw, con-rod and pistons. When the crankshaft rotate 90°, the counter weight is repositioned to the right, but the piston doesn’t go to the left, and the con-rod just partially moves to the left. Only the crank pin moves completely to the left. Now you can see the system is not balanced. The counter weight will generate a net force towards the right.However, for 90° V8, when such a heavy counter weight moves to the right, the piston from another bank will cancel it completely, because their movement are exactly opposed at this moment. (see illustrations below) The same result can be found for the counter weight moving to the left. Therefore 90° cross-plane V8 employs full-weight counter weights can achieve near perfect smoothness.


DISADVANTAGES: The disadvantage of cross-plane V8s is also about the counter weights - not only increase the weight of engine, they also contribute to rotational inertia, thus making the engine less responsive and less revvy, dropping upper rev limit and top-end power. Moreover, the larger counter weights usually requires a larger crankcase to house them, thus raising the height (and more important, center of gravity) of the enigne


FLAT PLANE CRANK:
Notice that the nodes are setup in an "-" or "|" configuration.
The crank pins are 180* apart.

131492.jpg


Flat-plane V8 is named according to the shape of the crankshaft, which is in a flat plane. It is very much like two inline-4 engines mated together. In particular, it achieves end-to-end balance because the first piston and last piston of a bank is exactly in the same position, so are the center two pistons. This is just the same as straight-four engines, therefore the sound of flat-plane V8 is usually somewhat like a pair of four-pot engines screaming simultaneously, unlike the rumble-bumble of cross-plane V8s. As both banks run like an inline-4 engine, there is second-order vibration. For a 90° flat-plane V8, the sum of second-order force generated in the 2 banks is - by simple vector analysis - 1.41 times (root-2) of the force generated by each of the inline-4 it consists of. And the direction of vibration is left-right instead of top-down. In other words, while displacement increases 100% compare with the inline-4, the second-order vibration increases just 41%. That makes the flat-plane V8 more refined than an inline-4 although it is not as smooth and quiet as cross-plane V8.

To exotic sports cars, less refinement is not a big problem. Especially they usually employ short stroke and light weight pistons / con-rods, the second-order vibration is greatly reduced.

BORE X STROKE:

To reduce the second order vibrations and to give the engines a high degree of it's rev-happy tendency, the engines are usually over-square. The bore is much greater than the stroke.
An F430 engine has a 3.62" Bore but only a 3.19" stroke. Compare this to a 4.125" bore and an almost equal 4" stroke in the GM LS7.


Awesome video explaining the two:


Keep in mind that this video is actually an infomercial and is very biased and pro-crossplane since thats what they're trying to sell.

I hope this info helps

SOURCE:
http://www.autozine.org/technical_s...ine/smooth4.htm


EDIT: Evo.com news article now back up with flatcrank reference completely removed :lol:

Ruf took this rather intriguing RGT-8 to the Geneva motor show. And while most news coverage from the Swiss show glossed over the Porsche fettler’s produce, this is a pretty key car: an eight-cylinder 911.

It's a 90 degree V8 that manages to fit snugly into the space normally occupied by a flat-six unit. The engine boasts a 4.5-litre displacement, producing 542bhp at 8500rpm and 369lb ft at 5400rpm.

There’s no word yet on what performance the RGT-8 achieves, but its construction is from lightweight materials. Aluminium is used on the door and boot lid while the engine cover and rear spoiler are made of carbonfibre. There’s also a set of light 19in forged alloy wheels (wrapped in Michelin Pilot Sport Cup rubber) which shroud ceramic brakes.

It should be plenty quick, then, but the big news surrounds the shoe-horning of an eight-cylinder engine into the back of (what is essentially) a Porsche 911. Flat-sixes have been a mainstay when it comes to 911 power, but the use of a high-bhp, naturally aspirated V8 in this Ruf could signal a new dawn for Porsche’s supercar when the 998 iteration is launched in the next few years. The RGT-8 produces more power than the most recent 911 GT2 but without its twin turbos.

We should get to sample the Ruf RGT-8 in the not too distant future, with sales set to be underway by 2011.[/QUOTE}
 
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The question is... how will it sound?

It's an interesting development, and probably needed... I don't know how much bigger Porsche can make the cylinder bores in its flat sixes... so it will need to add that extra set of pistons sooner or later.

Though RUF has apparently beaten them to the sooner part...
 
Now everyone's saying this is the path for the future of 911s, yet, all the rage in the industry is about turbocharging smaller engines for fuel efficiency. Then again, many would believe the 911 has reached the absolute max potential for its current ethos, rear-engined RWD flat-6, so perhaps something else is needed for the sake of moving forwards.
 
I agree with Paulie - turbos appear to be the easy way forward for fuel efficiency, but then again, RUF are a small manufacturer, I'm sure the size of their engines won't cause too many furrowed brows.

I'm stoked that someone has finally put 8 cylinders in the back of a 911! Couldn't really care how it sounds, it can't sound any worse than a flat 6...

;)
 
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