Avoid the Audi S4

[12,000 RPM]

Parts for the 2.7T are probably cheaper, and much more widely available.

Time to drop the engine and reengineer it isn't though

One swap I've seen that makes sense is the 4.2 V8 from the A8 into B5s. It has a timing belt, but the belt is at the front of the engine and you don't have to drop the motor to change it. That process is fraught with problems as well though too.

http://www.clubtouareg.com/forums/f73/diy-timing-belt-4-2-v8-34691.html

And in the end, you have a car that weighs more than an RX300, with the weight balance of an OG Saab, the reliability of a late 90s VW and the performance of a bolt on G35 

For the same $$$ Id prob just get a 1G CTS-V

[GoCougs]

Coyote has considerably simpler chain routing.  The Audi's chain routing looks like it was penned by Daedalus himself.

But four chains nonetheless - I just couldn't resist .

Perhaps simpler "routing" but all in all the Audi has a simpler chain system as it uses only three chains to drive the cams (the 4th chain is used to drive some sort of accessory - probably the oil pump) whereas the Coyote uses four chains. The Audi V8 was also the more demanding motor - higher red line (much higher in the RS4 - 8,200 rpm) and 5 valves per cylinder such that shorter (stiffer) primary chains (i.e., chains that actually drive the cams) were likely beneficial/necessary.

[MX793]

But four chains nonetheless - I just couldn't resist .

Perhaps simpler "routing" but all in all the Audi has a simpler chain system as it uses only three chains to drive the cams (the 4th chain is used to drive some sort of accessory - probably the oil pump) whereas the Coyote uses four chains. The Audi V8 was also the more demanding motor - higher red line (much higher in the RS4 - 8,200 rpm) and 5 valves per cylinder such that shorter (stiffer) primary chains (i.e., chains that actually drive the cams) were likely beneficial/necessary.

It's total chain length that drives the "stiffness", not the individual chain lengths.  Two 10" chains will have as much stretch as a single 20" chain of the same link geometry.  Hard to scale from a photo, but I doubt the Audi's total chain length (ignoring the accessory chain) is much less than the Coyote's from crankshaft to camshaft.  Plus the longer chains running between intake and exhaust cams introduce potential for more intake/exhaust variation on a given cylinder bank than the Ford's shorter cam-to-cam chains.  Not that chain stretch is that much of an issue with modern motors...

The intermediate "idlers" on the Audi design will also introduce additional friction and rotating mass into the valvetrain, which is perhaps more pertinent than the slight differences in overall chain length.

I'd also wager that the new Voodoo engine, with its rumored 8000+ RPM redline, will use the same cam chain layout as the standard Coyote.

[MexicoCityM3]

Well, the S4 joins the M5 (among others) that I will never own, despite their affordable entry fee on the used market, because the cost to repair is prohibitive. Other cars on my list are any car with a turbo and any car with a DCT.

The M5's engine isn't as bad as this. The major are the rod bearings and it's a 2K preventive maintenance thing. Also, it's a 500hp V10, much more exotic than this Audi's 340hp V8.

[Payman]

My brother is toying with the idea of buying a certified pre-owned Gallardo, using the pro "it's got an Audi V10". Hmmmm. 

[Char]

LOL, I've been saying this on the board for a while now. Nothing on that car screams (we thought this out) From the shit engine, the the garbage AWD system - Audi/VW has always been a fashion brand for pretenders and always will be.

[GoCougs]

It's total chain length that drives the "stiffness", not the individual chain lengths.  Two 10" chains will have as much stretch as a single 20" chain of the same link geometry.  Hard to scale from a photo, but I doubt the Audi's total chain length (ignoring the accessory chain) is much less than the Coyote's from crankshaft to camshaft.  Plus the longer chains running between intake and exhaust cams introduce potential for more intake/exhaust variation on a given cylinder bank than the Ford's shorter cam-to-cam chains.  Not that chain stretch is that much of an issue with modern motors...

The intermediate "idlers" on the Audi design will also introduce additional friction and rotating mass into the valvetrain, which is perhaps more pertinent than the slight differences in overall chain length.

I'd also wager that the new Voodoo engine, with its rumored 8000+ RPM redline, will use the same cam chain layout as the standard Coyote.

Actually, it's many things that define "stiffness" (which is a layman's term for linearity = stiffness, backlash, bandwidth, hysteresis, response, etc.) such as mechanical design, material, and application (i.e., tension/loading).

Said two ganged 10" chains will not have the same "stretch" as a single 20" if they are they are tensioned differently. And two 10" chains will likely have far higher natural frequencies than a single 20" chain, plus the designer can tailor each chain to its local application - one chain to be beefier and higher tensioned for example.

What Audi did is fairly common in industrial applications - in general, the more chains/longer the chains, the worse the "stiffness" (linearity) of the system. Not saying the Coyote is flawed it's just that the the Audi chain layout is inherently the better dynamic system - fewer chains, less total chain length, equal length primary drive chains, and the ability to tension each chain differently to suit the localized application.

[Char]

Actually, it's many things that define "stiffness" (which is a layman's term for linearity = stiffness, backlash, bandwidth, hysteresis, response, etc.) such as mechanical design, material, and application (i.e., tension/loading).

Said two ganged 10" chains will not have the same "stretch" as a single 20" if they are they are tensioned differently. And two 10" chains will likely have far higher natural frequencies than a single 20" chain, plus the designer can tailor each chain to its local application - one chain to be beefier and higher tensioned for example.

What Audi did is fairly common in industrial applications - in general, the more chains/longer the chains, the worse the "stiffness" (linearity) of the system. Not saying the Coyote is flawed it's just that the the Audi chain layout is inherently the better dynamic system - fewer chains, less total chain length, equal length primary drive chains, and the ability to tension each chain differently to suit the localized application.

Audi is the Fox News of Cars. If it were true before, it becomes False as soon as they start doing/saying it. You cannot predict the way the will fuck up the simplest of things.

[GoCougs]

Hmmm. A bit of research says Ford is behind the curve in using all these chains. In fact I wasn't able to find an example of a modern DOHC engine using 4 chains. Just a small example:

BMW S65 4.0L V8 - two chains:



Nissan VQ V6 - three chains:



GM 3.6L V6 - three chains:

[MX793]

Actually, it's many things that define "stiffness" (which is a layman's term for linearity = stiffness, backlash, bandwidth, hysteresis, response, etc.) such as mechanical design, material, and application (i.e., tension/loading).

Said two ganged 10" chains will not have the same "stretch" as a single 20" if they are they are tensioned differently. And two 10" chains will likely have far higher natural frequencies than a single 20" chain, plus the designer can tailor each chain to its local application - one chain to be beefier and higher tensioned for example.

That depends very much on the machine.  I don't believe that is applicable here.  If I take a single-speed bicycle and replace its single long chain with 2 chains (and an idler sprocket shaft to connect them), I do not decrease the "slop" in the chain drive (in part because I actually increase the overall chain length by doing this).

What Audi did is fairly common in industrial applications - in general, the more chains/longer the chains, the worse the "stiffness" (linearity) of the system. Not saying the Coyote is flawed it's just that the the Audi chain layout is inherently the better dynamic system - fewer chains, less total chain length, equal length primary drive chains, and the ability to tension each chain differently to suit the localized application.

I'm not sure there's less total chain length with the Audi configuration vs the Ford configuration (removing physical size differences between the motors from consideration).  I'd have to draw it out, but my gut is telling me that if there is a difference, it's negligible.  Ford's "primary" drive chains are likewise equal length from crank to exhaust cam, and each chain in the Ford, as with the Audi, has its own independent tensioner.  The Ford configuration likewise has the option of using different gauge chains (heavier for the long primary chains, lighter for the secondaries).

The biggest advantage of 3 chains with idlers sprockets that I can see is that it permits smaller sprockets on the cams (and therefore a potentially more compact head) since you can do all of, or part of, the gear ratio work via the idlers.

[12,000 RPM]

Cougs is on a tear here, this is hilarious

[GoCougs]

That depends very much on the machine.  I don't believe that is applicable here.  If I take a single-speed bicycle and replace its single long chain with 2 chains (and an idler sprocket shaft to connect them), I do not decrease the "slop" in the chain drive (in part because I actually increase the overall chain length by doing this).

I'm not sure there's less total chain length with the Audi configuration vs the Ford configuration (removing physical size differences between the motors from consideration).  I'd have to draw it out, but my gut is telling me that if there is a difference, it's negligible.  Ford's "primary" drive chains are likewise equal length from crank to exhaust cam, and each chain in the Ford, as with the Audi, has its own independent tensioner.  The Ford configuration likewise has the option of using different gauge chains (heavier for the long primary chains, lighter for the secondaries).

The biggest advantage of 3 chains with idlers sprockets that I can see is that it permits smaller sprockets on the cams (and therefore a potentially more compact head) since you can do all of, or part of, the gear ratio work via the idlers.

I'm not a fan of the word "slop." There is a lot more going on in a drive train be it gears, belts, chains, etc., as mentioned, and I'd already mentioned the advantages of decreasing individual chain length, as well as decreasing the total # of chains. It's unlikely a coincidence that pretty much no one else uses four chains. I don't see any counterargument to Audi having the inherently better cam drive design.

[SVT666]

The M5's engine isn't as bad as this. The major are the rod bearings and it's a 2K preventive maintenance thing. Also, it's a 500hp V10, much more exotic than this Audi's 340hp V8.

The M5's transmission is the really scary item.

[FlatBlackCaddy]

The M5's transmission is the really scary item.

I've always thought BMW's manuals were pretty decent? Never heard about any big issues with them.

[Char]

The M5's transmission is the really scary item.

Transmission and all, I would take the M over the S4 GOLF GTI.

[12,000 RPM]

I've always thought BMW's manuals were pretty decent? Never heard about any big issues with them.

Its not the manual to be worried about.... the SMG is the problem

IF someone could put the DCT from the F10 into the E60 theyd make the perfect M5

[FlatBlackCaddy]

Its not the manual to be worried about.... the SMG is the problem

IF someone could put the DCT from the F10 into the E60 theyd make the perfect M5

Ohhhh, I don't consider the SMG M5's of that generation to be an actual purchase option. I don't know why anyone would since we(in america) were given the REAL transmission will the rest of the world got stuck with the SMG.

Why would anyone even want an M5 with the SMG?

[12,000 RPM]

Why would anyone even want an M5 with the SMG?

http://www.caranddriver.com/comparisons/not-quite-up-to-pacing-page-2

MW responded with a six-speed manual-gearbox option, which we've been anticipating for a year. Yes! This'll push the bad-boy Bimmer a big step closer to perfection. We thought.

Uh-oh, not so fast. This M5's shift-for-yourself six-speed is consistent with others we've experienced from BMW. In fact, it's the same six-speed employed in the previous-generation M5. And therein lies the rub. The new M5's V-10 was designed to be allied with the seven-speed SMG. Bolting the same engine to the six-speed entailed a proviso. With the SMG, the driver had the option of disabling the dynamic stability-control (DSC) system. When you opt for the manual, you don't get that option. A little dashboard button labeled MDM — for "M Dynamic Mode" — raises the DSC intervention threshold, but unlike the SMG version, it can't be completely shut down and is always on guard. When wheelspin is detected, DSC goes to work, damping the throttle, sometimes squeezing the big cross-drilled brake rotors.

Would you be surprised to hear that this doesn't have a positive effect on acceleration? Or lap times on the Streets of Willow? Or making a hot exit from a slow corner? Of course you wouldn't. Because that's precisely what happens. This M5 was a half-second slower to 60 mph than the SMG version we tested in January 2006 — 4.7 versus 4.2 — and a half-second slower through the quarter-mile: 13.0 seconds at 114 mph versus 12.5 at 118. DSC also inhibited lane-change performance (60.8 mph versus 65.6) and skidpad results (0.83 lateral g versus 0.89).

All of this is attributable to product-liability issues, specifically, concerns about axle tramp, a.k.a. wheel hop, during full-throttle launches, which could break expensive drivetrain bits and irritate the well-heeled owners BMW would prefer to keep happy.

Strange, given that the E39 made the same amount of torque, and IIRC had the same gear ratios. Not so strange, given the fact that the 1G CTS-V used to lunch rear ends on launched, and the aftermarket had to step in to save them.

[Cookie Monster]

I'd still get the 6MT version. It's not a racecar. I want more fun.

[MexicoCityM3]

http://www.caranddriver.com/comparisons/not-quite-up-to-pacing-page-2

Strange, given that the E39 made the same amount of torque, and IIRC had the same gear ratios. Not so strange, given the fact that the 1G CTS-V used to lunch rear ends on launched, and the aftermarket had to step in to save them.

The DSC issue was fixed on later manual cars it can be fully disabled. I'd have gotten the manual if it were available here.

I'd only consider the SMG in the US at significant savings vs a manual car.

[FoMoJo]

Hmmm. A bit of research says Ford is behind the curve in using all these chains. In fact I wasn't able to find an example of a modern DOHC engine using 4 chains. Just a small example:

GM 3.6L V6 - three chains:

I'd be concerned about all the tensioners and guides in this setup...as with the Audi S4.  Much risk of wear, as proven in the S4, as well as additional resistance.  Better to go for a simpler setup, even if it means strapping the cam drives together with a chain.  No chance of "slop" developing there and zero guide wear and resistance.

[MX793]

I'd be concerned about all the tensioners and guides in this setup...as with the Audi S4.  Much risk of wear, as proven in the S4, as well as additional resistance.  Better to go for a simpler setup, even if it means strapping the cam drives together with a chain.  No chance of "slop" developing there and zero guide wear and resistance.

GM's 3.6 also has a history of timing chain failures and stretching or tensioner issues...

[FlatBlackCaddy]

GM's 3.6 also has a history of timing chain failures and stretching or tensioner issues...

Do you actually think he will acknowledge that?

[GoCougs]

I'd be concerned about all the tensioners and guides in this setup...as with the Audi S4.  Much risk of wear, as proven in the S4, as well as additional resistance.  Better to go for a simpler setup, even if it means strapping the cam drives together with a chain.  No chance of "slop" developing there and zero guide wear and resistance.

Again, the Coyote has the more complicated setup owing to the use of 4 chains =  Coyote has more tensioners (4 vs. 3; each chain needs one) and at least as much chain guiding (and probably more - wow, look at all that black) vs. either the S4 V8 or the GM 3.6L.

[GoCougs]

Hmmm. Maybe the Coyote folks should have taken a queue from the Ecoboost team - 3 chains (= 3 tensioners) and less chain guiding (but really not - the Coyote is a derivative of the 20+ year-old Modular, so Ford was hamstrung a bit):

[hotrodalex]

Engineering superiority.

[GoCougs]

Imagine an LS7 with 10 years' worth of advancement, esp. direct injection and pooprod VVT. I sure hope GM has the guts at some point...

[FlatBlackCaddy]

Id rather they fix the top end so it doesn't blow apart before 50k. LS7 is possibly the least reliable ls, dont know why you are so obsessed with it. Id rather have a nice modded ls3 that will match the hp of the 7 without being a 15k dollar boat anchor in a few years.

[hotrodalex]

Id rather they fix the top end so it doesn't blow apart before 50k. LS7 is possibly the least reliable ls, dont know why you are so obsessed with it. Id rather have a nice modded ls3 that will match the hp of the 7 without being a 15k dollar boat anchor in a few years.

You think a modded LS3 making the same power as an LS7 will somehow outlast it?

[FlatBlackCaddy]

You think a modded LS3 making the same power as an LS7 will somehow outlast it?

A: General motors sells a crate ls3 with more power than the ls7

B: the ls7 issues seem to be related to rocker arm geometry (or so i gather according to the vette and aftermarket community) the ls3 has no such issues.

So yes, id have more faith in a 500hp ls3(modded or factory crate) over a stock ls7.