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Discussion Starter #1 (Edited)
Now perhaps this may be a bit of an if not when type scenario, but today I want to talk about a rarity in the automotive world, they call it the straight 5.

See Audi has always been a bit of an oddball, well maybe not now as they've grown into a fully fledged stock broker, but during their rebellious teenage years Audi was open to many, many things. One of those things turned out to Audis straight 5 the debuted back in the 80's, 30 years later it is still having its impact.

So where did this engine come from? I'll tell you if you stop interrupting with these questions, SHEESH! The Straight 5 was bred for the magical land of Group B rally, where the cars fly, the engines spit fire and the drivers were martians. This is the sound of a silky revving flat five boosted to within an inch of mechanical life (paradox?)...


Now imagine that engine in your Q3, now imagine that you're not dreaming... Yes I'm insane but what does that have to do with your day dream? See Audi was never content to just use that engine for competition, no that engine is quite alive and kicking despite the industries plea for cookie cutters and cup holders.

In a 2.5L guise outfitted with a turbo and high pressure injection Audi's straight 5 has stared in the diminutive RS3 and TT RS, now these mad man have decided to stick it in your grocery getter.


*female not included, get your own daughter

Meet the RS Q3, featuring the aforementioned 2.5L Boosted straight 5 complete with hi po injection and an intercooler that could house a family of 4. It has been detuned from its use in the RS3 and TT Rs, but no matter you're still getting a mill that was born and bred for WRC and after a few wrong turns accidentally found its way to suburbia. I mean we're talking 306 horses and 309 lb-ft on tap that motivates the RS Q3 to 62 in 5.5 seconds. Hows that for a drive thru weapon?

So whats the point you might ask, and despite the show I've made at avoiding questions I'll tell you. The RS Q3 is for people who want pace and space, I stole that but it sounds so good I don't care. By no means is the RS Q3 comfortable what with the typical RS low pro tires tires that are all to happy to skitter over mildly rough surfaces, plus the stiffer suspension and 25% lower ride height. No mater you might be able to pull down 15 mpgs if you're lucky.

If the RS Q3 does make it to North America I just ask that you try to keep your pants on, as it will be one big bargain, no matter the price tag, to get your hands on a legendary piece of Group B history ;)
 

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more pics of the daughter please.

kidding.

inline 5 huh... i will raise you one inline 7 engine that does not exist yet. going to patent it.
 

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more pics of the daughter please.

kidding.

inline 5 huh... i will raise you one inline 7 engine that does not exist yet. going to patent it.
x2 on more pictures of daughter :D



6cylinder engines and 8 cylinder engines sound amazing, i wonder what 7 would be like.
 

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I am just curious to take a inline 5 out for a test drive. I want to feel what it is going to feel like to drive. Has anyone had the pleasure of being able to drive one?
 

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Discussion Starter #5
I am just curious to take a inline 5 out for a test drive. I want to feel what it is going to feel like to drive. Has anyone had the pleasure of being able to drive one?
go test drive a volvo...

I5's are like any inline engine, however their one big advantage is the overlap in power cycles. An I4 fires sequentially every 180 degrees of crank rotation, but an I5 fires every 144 degrees of crank rotation. However an I5 fires in the order of 1-2-4-5-3 to keep it from rocking front to back. You will notice an I5 lays down power much smoother than a 4.

as for driving five-cylinder engines abasically combine the benefits of four- and six-cylinder inline engines. They generate more power and torque than four-cylinder engines, while maintaining better fuel economy and response than six-cylinder engines. However I5s are not inherantly balanced like an I6, necesitating the need for balancing shafts.

In short just listen to the sound and you'll know why we need more I5s :D
 

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Discussion Starter #7
Any idea what other car makers had 5 cylinder engines? Must be very uncommon.
well volvo uses straight 5's almost exclusively since the early 90's, the volvo 5 was used in the last gen Focus ST and Focus RS

Honda used to use a 5 cyl in the Vigor, Inspire, Ascot and TL

VW used a straight 5 in their euro van, they also have a derivative of the audi 5 that is supposedly going to make its way to NA in the Jetta, Passat and Beetle. Plus Vw does have a V5 engine, which is just straight ODD.

FIAT has an I5 kicking around that gets used sporadically in the larger alfas, but I think thats done now.

GM used a straight 5 in the Hummer H3 as well as the old Colorado.

Not to mention the copious uses of 5 cyls in diesel applications. The most common is the ford Duratorq in the Transit and global ranger...
 

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well volvo uses straight 5's almost exclusively since the early 90's, the volvo 5 was used in the last gen Focus ST and Focus RS

Honda used to use a 5 cyl in the Vigor, Inspire, Ascot and TL

VW used a straight 5 in their euro van, they also have a derivative of the audi 5 that is supposedly going to make its way to NA in the Jetta, Passat and Beetle. Plus Vw does have a V5 engine, which is just straight ODD.

FIAT has an I5 kicking around that gets used sporadically in the larger alfas, but I think thats done now.

GM used a straight 5 in the Hummer H3 as well as the old Colorado.

Not to mention the copious uses of 5 cyls in diesel applications. The most common is the ford Duratorq in the Transit and global ranger...
Not too bad, more than I originally thought. Is there good reason for going 5 cylinders? Since it hasn't been used often something has me believing it's not.
 

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Discussion Starter #11
those answers are a little misleading. They make it sound like there is copious engineering of components that needs to go into keeping an I5 sane. Its not, its a simple balancer shaft. I won't act like its easy but its not TERRIBLY difficult especially for professional powertrain engineers.

You want to know the real reason we dont see more I5's, its because of modular. Companies like to spread components over the maximium amount of vehicles to improve scale. An I5 has limited uses, eith to LARGE FWD/AWD applications or RWD applications with a long nose.
 

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i think the reason i5 isn't very popular is just because they arent as smooth as i4 or i6

even though you can still balance it - by nature its still not perfectly balanced. and i'm sure there is lots of engineering involved

nothing is easy when it comes to engineering combustion engines.

or we would all be doing it :)
 

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Discussion Starter #13
i think the reason i5 isn't very popular is just because they arent as smooth as i4 or i6

even though you can still balance it - by nature its still not perfectly balanced. and i'm sure there is lots of engineering involved

nothing is easy when it comes to engineering combustion engines.

or we would all be doing it :)
its easier to balance an I5 than it is to balance a V6. on a V6 you essentially have two independant banks of I3's. From a driving perspective an I5 essentially combines the best aspects of I4's and I6's. 5's generate more power and torque than four-cylinder engines, while returning better fuel economy and response than six-cylinder engines...

A five-cylinder engine gets a power stroke every 144 degrees (720° ÷ 5 = 144°). Since each power stroke lasts 180 degrees, this means that a power stroke is always in effect. Because of uneven levels of torque during the expansion strokes divided among the five cylinders, there are increased secondary-order vibrations. At higher engine speeds, there is an uneven third-order vibration from the crankshaft which occurs every 144 degrees. Because the power strokes have some overlap, a five-cylinder engine may run more smoothly than a non-overlapping four-cylinder engine, but only at limited mid-range speeds where second and third-order vibrations are lower.

For a four-cylinder engine, 720° ÷ 4 = 180° so there is a power stroke every 180 degrees, which is two power strokes per revolution of the crankshaft
 

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so why go for an i5 over an i6 if the i5 is just as good as the i6?

why not just go for the i6?

v6s are hard to compare. they are around because of the compact size. there are some SMALL v6s out there

i would imagine i5s are a tad bit longer.
 

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I would not go for an i5, it's not as likely to be used in a number of vehicles as an i4 or i6 would be. So at least in the long run you can expect maintenance on the engine to be within a decent price range with easy to find things for it
 

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Discussion Starter #16
so why go for an i5 over an i6 if the i5 is just as good as the i6?

why not just go for the i6?

v6s are hard to compare. they are around because of the compact size. there are some SMALL v6s out there

i would imagine i5s are a tad bit longer.
because modular, I said this a few posts up. I5's are harder to repurpose throughout the lineup. BMW is lucky with the I6, well maybe not lucky, but because everything they make is RWD the I6 works in every single model they sell to date, go look you'll find it.

V6's I4s and I3s work for most companies because a V6 can be used horizontally or longitudinally same with an I4 and I3 if you have to, an I5 will not fit horizontally, so therefore less companies use them because they cant multiply use cases, except for in RWD or rear bias AWD's...
 

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Being harder to repurpose is an issue from how I see it with the way the industry is going these days. i think it's a bad idea
 
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