CodeRedR51
Premium
- 55,296
- United States
I quite like how this thing sits.
2015 Ford Mustang - General Discussion
- Thread starter CodeRedR51
- 6,247 comments
- 419,842 views
- 13,281
- GTPlanet
- Street-King-07
- Quattro Saltire
I quite like how this thing sits.
I thought pornography wasn't allowed on this site.
Seriously though, I also really like the stance on it.
Gives it proper presence.
- 6,425
- KCCO
Sitting high up in my truck when I was driving on I85 the other day I really liked watching one of these go by with the rear splitter the same color as the body, but when level to it not so much...
- 2,121
- Chicago
- mustang622006
I would like how it sits much better if it were sitting in my garage 👍
- 8,721
From the above video at 2:22
That's different!
No wonder I couldn't quite reconcile the sound. It also makes sense of the exhaust manifolds.
So they went with a configuration that still visibly requires crank counterbalances (although only about 2/3rds the size for a given piston mass), and also produces a second-order (and up) vibration.
I wonder why they didn't just use the standard flat-plane crank: no counterbalances required, just the second-order (and up) inertial vibration.
It doesn't look like it'll benefit from the overall torsional characteristics of traditional flat-plane cranks (I'd have to check), and it's torsion that is the real killer in cross-planes (mainly due to the uneven firing in each bank, mind you). The pin-to-pin torsion from the piston motion looks like it might still be lower than in cross-planes, though, which potentially means the crank can be slightly lighter.
Crank torsion is why cross-plane engines run rougher than flat-plane engines (especially at high speeds and high specific outputs), despite being inherently better balanced. Of course modern ignition, fuelling and variable valve timing can help here.
And the firing order is sequential: 1-2-3-4 (or reversed) in each bank! That's great for intake charging, but not for torsion (again). I had to question whether this was genuinely a picture of the GT350's crankshaft!
What a strange beast; weirdly, I approve - it shows we're just about mastering the internal combustion engine to the point that we can do what the hell we like with it!
That's different!
No wonder I couldn't quite reconcile the sound. It also makes sense of the exhaust manifolds.
So they went with a configuration that still visibly requires crank counterbalances (although only about 2/3rds the size for a given piston mass), and also produces a second-order (and up) vibration.
I wonder why they didn't just use the standard flat-plane crank: no counterbalances required, just the second-order (and up) inertial vibration.
It doesn't look like it'll benefit from the overall torsional characteristics of traditional flat-plane cranks (I'd have to check), and it's torsion that is the real killer in cross-planes (mainly due to the uneven firing in each bank, mind you). The pin-to-pin torsion from the piston motion looks like it might still be lower than in cross-planes, though, which potentially means the crank can be slightly lighter.
Crank torsion is why cross-plane engines run rougher than flat-plane engines (especially at high speeds and high specific outputs), despite being inherently better balanced. Of course modern ignition, fuelling and variable valve timing can help here.
And the firing order is sequential: 1-2-3-4 (or reversed) in each bank! That's great for intake charging, but not for torsion (again). I had to question whether this was genuinely a picture of the GT350's crankshaft!
What a strange beast; weirdly, I approve - it shows we're just about mastering the internal combustion engine to the point that we can do what the hell we like with it!
- 22,551
- Arizona
- HamiltonMP427
@Griffith500 Are you saying you didn't know that it had a flat plane prior to that video? If you go through the thread that's all we really talked about with this new GT350, there are tons of other cools things about it if you look through the thread. It's quite an interesting car. 👍
- 8,721
It's more that I didn't realise Ford were crazy enough to reinvent the wheel:
That is the "flat-plane crank" as we knew it.
EDIT: Below is the GT350's crank
/EDIT
I'm surprised there's so little noise about it (well, that I can find, at any rate).
Last edited:
- 22,551
- Arizona
- HamiltonMP427
It's more that I didn't realise Ford were crazy enough to reinvent the wheel:
View attachment 470713
That is the "flat-plane crank" as we knew it.
I'm surprised there's so little noise about it (well, that I can find, at any rate).
Well Ford said they didn't want to sound like the European cars, and still have a distinctive V8 gurgle, and more so be different overall and get the same attributes by going this route instead of just using the Coyote.
- 8,721
But they could have done all of that with the "normal" flat-plane V8 crankshaft, is my point.
In fact it would have sounded even better!
- 22,551
- Arizona
- HamiltonMP427
But they could have done all of that with the "normal" flat-plane V8 crankshaft, is my point.
In fact it would have sounded even better!
What is "normal"* and "better"**, considering how relative that all is. I gave the reason why Ford did this, which actually answers this retort you've posted. I get your point, but Ford didn't want to do that and I actually like the fact they went out of their way to do this. Clearly it wasn't an expensive endeavor because if it was, this car should be Z28 money, not Stingray or Hellcat money.
*I assume European and Japanese V8s
**Not sure how this is fact, in fact I'd say this sounds better than those
- 8,721
Why so defensive? I like it as well.What is "normal"* and "better"**, considering how relative that all is. I gave the reason why Ford did this, which actually answers this retort you've posted. I get your point, but Ford didn't want to do that and I actually like the fact they went out of their way to do this. Clearly it wasn't an expensive endeavor because if it was, this car should be Z28 money, not Stingray or Hellcat money.
*I assume European and Japanese V8s
**Not sure how this is fact, in fact I'd say this sounds better than those
- 22,551
- Arizona
- HamiltonMP427
Not defensive at all, thought the emoticons were enough indication I'm joking along. Just trying to make sure you understand what I'm getting at as well. See I've even contradict myself with the double asterisk quote for humor, see, please say you see it!!!
EDIT: Oh I see the counter balance, now that you've posted a good picture. Good eye.
- 8,721
I don't understand what your reason for commenting was at all, then.
I commented because Ford have made a totally new engine configuration. It is neither "cross-plane" nor "flat-plane" as it is commonly intended to mean. Please say you see it now? Or is this not new at all?
- 22,551
- Arizona
- HamiltonMP427
I commented cause I was surprised that this was news, since there is an entire thread dedicated to this info. I wanted to make sure I understood you right, and you more or less confirmed. Then went on to say it was surprising, so I thus posted in an effort to jokingly and nicely inform you, since you didn't seem to know this info prior or at least to the extent the video showed.
And now we're here.
- 8,721
I see; any chance of a link to the thread?
- 22,551
- Arizona
- HamiltonMP427
- 8,721
Well I don't recall anyone mentioning the unusual crankshaft. But meh, sorry for my enthusiasm.Sure, just scroll to the top of this page and read the title. Can't miss it I'd say
- 22,551
- Arizona
- HamiltonMP427
Indeed, sorry indeed.
Too be honest it's no problem, but us enthusiast like to make sure other enthusiast are informed. I'm still curious as to what sounds better and I think @Eunos_Cosmo or someone went into detail about the cross plane and its differences with others.
- 11,826
- Marin County
I have a feeling the counterweights are in place due to the sheer size of this engine compared to, say, a Ferrari engine. This engine has a 93mm stroke, compared to the largest ever Ferrari flat plane @ 81mm stroke. That is a pretty huge difference, and the engine speeds are not that far removed either. Consequently, the Ford actually has considerably higher piston speeds.
Ford piston speed: 84ft/s @ 8250rpm
Ferrari piston speed: 80ft/s @ 9000rpm
My bet is that the NVH or crankshaft torsional loads (or both) were something awful and counterweights were used to reduce the problem.
Ford piston speed: 84ft/s @ 8250rpm
Ferrari piston speed: 80ft/s @ 9000rpm
My bet is that the NVH or crankshaft torsional loads (or both) were something awful and counterweights were used to reduce the problem.
- 8,721
The thick counterweights are there purely because this engine is not balanced, just like a cross-plane engine - no other reason. Look closely at the crankshaft: it is UDUD, not UDDU (Up; Down).
The front and rear pistons in each bank form a rocking couple (one goes up, the other goes down), but the inner pistons offset that slightly (by about a third), hence the reduction in required counterbalance mass over the cross-plane (ULRD). A normal flat-plane crank has what are called "mirrored pairs" (one goes up, the other goes up; the mirror being the midpoint of the crank), to eliminate rocking entirely (see also straight six, some straight eights).
Mean piston speed is a useful heuristic (and bragging tool) but it can hide certain things; better to focus on the real concern (ignoring piston rings, oil and bores), namely: peak and RMS piston accelerations - but there's no easy formula for that! That long stroke will be the reason for limiting high-rpm running to 8 seconds, for sure.
- 11,826
- Marin County
I didn't notice that the center two rod journals are on the same angle. That is kind of strange. Won't that mean there will be two ignition events right next to each other on each bank simultaneously? I would think that would create all sorts of cooling problems in the middle of the head.
- 8,721
The firing order is sequential all the way down the bank, hence the sound. I knew something was up when I heard it!
And I'm still surprised this isn't a bigger deal at this point, too.
EDIT:
But it's not entirely new:
Investigating the source...
- 11,826
- Marin County
I misread your post. So if a normal flat-plane V8 sounds like 2 sets of 4 cylinder engines, then I guess the Voodoo sounds like 4 sets of 2 cylinder engines.
- 8,721
The first thing to remember is that a four-stroke engine only has each cylinder ignite once every two rotations: 720 degrees.
From there, we can figure out that a four cylinder engine needs ignitions every 180 crank degrees (720/4) in order to be smooth-running. Hence the 180 degree separation in the crankshaft. An 8 cylinder needs 90 degree intervals; hence the 90 degree crank and / or 90 degree bank angle, of which there are numerous permutations.
The UDDU and UDUD cranks would sound identical with an equal length 4-1 exhaust, for reasons I know you understand (based on your other posts). What matters, and what you went to great pains to explain in this thread, is how you group the pulses in the exhaust (and intake).
So either type of flat plane V8 engine could sound like any other (4-stroke) 8 cylinder engine, just as a cross-plane V8 could, depending on what they breathe through.
This particular combination of firing order and exhaust layout results in something very similar to the McLaren V8s, but just different enough to be noticeably unique (even discounting all the rasp and particular filtering in the name of different "sonic targets" for each car).
The resulting sound could indeed be considered to be the combination of 4 sets of 2-cylinder engines, but that two cylinder engine must have the 270-450 firing order; i.e. a 90 degree V-Twin, or 270 degree parallel twin (the intake on the latter really screams like a V8).
Voodoo.
- 11,826
- Marin County
Looks to be a DIY 180* crank kit for small block chevy V8.
http://forums.hybridz.org/topic/70271-diy-180-degreesingle-planeflat-plane-v-8-crankshaft…/
See post #11.
- 8,721
Great find, thanks!
So that UDUD crank is really how the crossplane crank is cast / forged before it's heated and twisted into the form we usually see it. From that "flat" initial shape, it only needs a 90 degree bend at each end, in opposite directions, to achieve the desired result. Casting and forging is generally easier (/ more successful / cheaper) if the object is as planar as possible, for separating the moulds / dies etc.
This is clever because it means Ford can reuse some of their existing tooling for what will be a low volume engine, keeping costs down. So that explains why it is the shape it is, and modern CAE and manufacturing has made it a viable production item, instead only being suitable for a hot-rod. Pretty cool.
- 8,721
So they couldn't split the intake, necessitating a change in FO, hence the UDUD crank and its required balance masses?
I'm not fully convinced by that. I still reckon they chose the UDUD crank first for simplicity (cannot be twisted at its midpoint without new tooling), then made it work with what they had. There are only 8 firing orders for that crank configuration, time to see which ones offer the best intake charging with the existing intake packaging (compared with the traditional flat plane and the Coyote crossplane orders).
The whole video is dripping with the effort of Ford's marketing hand, but it was still interesting and enjoyable.
I'm not fully convinced by that. I still reckon they chose the UDUD crank first for simplicity (cannot be twisted at its midpoint without new tooling), then made it work with what they had. There are only 8 firing orders for that crank configuration, time to see which ones offer the best intake charging with the existing intake packaging (compared with the traditional flat plane and the Coyote crossplane orders).
The whole video is dripping with the effort of Ford's marketing hand, but it was still interesting and enjoyable.
