Doyle Engine

[George inMinneapolis]

So where does the transmission attach? Having difficulting seeing how this works exactly.

http://www.youtube.com/watch?v=lJ1kxbtsBSU

Would this be good for motorcycles?

George

[chasbmw]

Drive probably come out the opposite end to inlet and exhaust.

Lots of pistons, modern car engines see to be going down the Twin cylinder route to reduce frictional losses, eg fiat twin air engine and the adoption of twins by both BMW and Honda for high efficiency bike engines.

[Major Softie]

Lots of pistons, modern car engines see to be going down the Twin cylinder route to reduce frictional losses, eg fiat twin air engine and the adoption of twins by both BMW and Honda for high efficiency bike engines.

Uhm, "flat twins?" Do you mean parallel twins? Boxers are "flat twins."

Edit: AH, FIAT twin! Sorry, on my home monitor it definitely looked like "flat." Perhaps if Fiat had been capitalized....

[chasbmw]

The FIAT 500 TWIN Air engine, can give 105 BHP in a turbo version, I have heard that owners have not got the fuel efficiency claimed by Fiat.

Review below

But as soon as you turn the ignition key, it's clear that there's a very different powerplant under the bonnet. Fiat describes the TwinAir unit as a manifesto for its latest engine technology. So as well as being smaller, it is the first engine to be developed from scratch to make the most of Fia's MultiAir system.

It uses electro-hydraulic control of the inlet valves, rather than a conventional camshaft, to manage the amount of air entering the engine. This allows more precise management of combustion, reducing fuel consumption.

As well as boosting efficiency, the managed air flow improves low-down torque, while the more constant flow of air keeps the small turbocharger spinning, pushing power up to 84bhp.

At idle, the engine chatters into life, making a noise similar to a diesel but with a more breathy character. It's quiet, especially in the cabin where you’d be hard pressed to notice that you weren't sitting in one of the other petrol units in the range.

But once you move off the sensation is quite different. Below 2,500rpm, the engine feels just like a conventional four-cylinder. It pulls surprisingly well too, helped by short gearing to make the most of the unit's power and 145Nm of torque. The gear ratios are widely spaced, which means you need to use the engine revs more to make good progress, especially if you press the fuel-saving ECO button which restricts torque to 100Nm.

But above 2,500rpm the soundtrack changes, sounding more like a small motorbike than a car and in tune with the Fiat's original 500 which was also powered by a two-cylinder unit.

What's surprising is that although the engine note is unfamiliar, the refinement is impressive. Thanks to a balancer shaft which counterweights the action of the cylinders, vibrations are well isolated. Were it not for the characterful soundtrack, the unit feels similar to an equivalent 1.4-litre four-cylinder unit.The icing on the cake is fuel economy of nearly 70mpg and thanks to CO2 emissions of just 95g/km, owners taking delivery later this year will be able to enjoy road tax-free motoring.

[Garnet]

It uses electro-hydraulic control of the inlet valves, rather than a conventional camshaft, to manage the amount of air entering the engine. This allows more precise management of combustion, reducing fuel consumption.

And who is going to adjust those?

[Major Softie]

It uses electro-hydraulic control of the inlet valves, rather than a conventional camshaft, to manage the amount of air entering the engine. This allows more precise management of combustion, reducing fuel consumption.

And who is going to adjust those?

Why, electro-hydraulic engineers, of course.

I fully understand the advantage of variable intake timing - especially as infinitely variable as a electro-hydro system would be able to accomplish, but I had no idea how the Fiat system worked, so I Googled.

Car and Driver has a nice page explaining it. They even have a nice set of photos and cutaway diagrams.


http://www.caranddriver.com/features/fi ... -explained

This one shows the basic layout, with conventional cam operating the exhaust valves. Since changing exhaust timing can also provide some benefits to spreading the torque curve over a wider range of rpm, I find it interesting that they found that the exhaust wasn't worth bothering with the cost and complexity of this system, even when they've gone to the trouble of utilizing it for the intakes. Apparently the cam has one lobe for each exhaust valve and one lobe for each cylinder's intake valves. The intake lobe pushes a hydraulic plunger to actuate the intake valves, and the electro part is bleed-off valves that can bleed off hydraulic pressure to change when and how much the valve opens, but only within the maximum defined by the intake lobe. So, you can design the cam for maximum peak power at the expense of low-end power, and then "detune" that cam with the electro-hydraulic system the rest of the time.

If you go to the Car and Driver website, the photos in the slide show are much better. Hit the "zoom" control and they will be nice and big.

It's ingenious, but it also looks like a bleedin' nightmare, if you'll pardon the pun.

[chasbmw]

My alfa twin spark hengine from 2000 had a mechanical variable cam timing that seemed to be fairly reliable as long as you changed the oil regularly, it also sported variable length intake trumpets inside the air intake system, all this worked very well to create an electrifying little car. Pity that at that time they had not really sorted out the rust issues.

Charles

[Ken in Oklahoma]

It's ingenious, but it also looks like a bleedin' nightmare, if you'll pardon the pun.

On every vehicle I own, If I break down on the road because the vehicle won't go, I'm pretty much reduced to opening the hood and wondering what the hell can be wrong.

Except, of course, for my airheads.

Personally, I've given up. I now carry a AAA card, a credit card with enough credit to handle a tow and repair, and a cellphone.

Now most of my worries have morphed to whether I'm in range of a cell phone tower, if my cell phone is charged up, and how long will it take for my checking account to recover.



Ken, carded in Oklahoma

[chasbmw]

But when was the last time a modern car let you down?

[Major Softie]

And, when's the last time you had to bleed your valve-train?

(did nobody get my joke?)