Variable compression engine

http://www.msn.com/en-us/autos/news...8/ar-BBvCcdn?li=BBnb4R5&srcref=rss&ocid=iehrs

Interesting concept. Compression can be varied from 8:1 to as high as 14:1

8:1 when running max turbo boost..and 14:1 while cruising.

I read about this a few months ago. I'm not really sold on it. I'm skeptical of the reliability especially in any high horsepower configuration. But I was skeptical about VTEC and variable cam timing when they started messing around with it a couple of decades ago.

It's like valvetronic for the crank,

Variable cam timing is an elegant solution.

The variable compression system looks like a total kludge.

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We will just have to wait til Sept 29....for the Paris auto show. If it works as advertised, Infiniti will get the last laugh.

If Ford was smart, they would introduce a direct inject 5.0 L engine.

Sky Render said:

Variable cam timing is an elegant solution.

The variable compression system looks like a total kludge.

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Valvetronic isn't timing...

https://www.youtube.com/watch?v=DKfcV7hITYI

I'd argue against DI on a gas motor until Ford sorts it out.

80k and heads were being trashed.
I attribute 40% to El Paso shitty ownership.
The rest, I hold the system in question.

I recall VW added an injector or two to spray purely for cleaning the valves.
I've not heard of long-term issue there.

Just my .02 on Ford's GDI setups from working at the dealer.

I think it's a move in the right direction.
Everyone knows how efficient diesel motors are compared to gas.
But it's going to take time.


I personally feel like the auto makers make the cars as "burners"
As the trend of always buying something else once A: it's paid off or B: warranty expires.

While that may or may not be the case.
Like I stated "personally"

DesertStang06 said:

I personally feel like the auto makers make the cars as "burners"
As the trend of always buying something else once A: it's paid off or B: warranty expires.

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Agree with you 110%, there are definitely mileages in mind where they would rather have the vehicles crapped.

The electric car thing will help us with this. Less crazy archaic bs... I mean seriously, crankshafts, we're barely out of the steam era here....

I used to work on/test (blow up) Stirling Cycle motors 24yrs ago. We had variable stroke. That shit didn't work, LOL!

Kaboooooommmmm!!!!!!!

Department Of Boost said:

I used to work on/test (blow up) Stirling Cycle motors 24yrs ago. We had variable stroke. That shit didn't work, LOL!

Kaboooooommmmm!!!!!!!

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Would the vastly improved processing power of the control computers fix the issues you found?

MechE said:

Would the vastly improved processing power of the control computers fix the issues you found?

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Only some sort of materials breakthrough would have helped.

The actual variable stroke worked great. We would start them at zero stroke and as they warmed up we would add stroke in until they were maxed out. But when the RPM's went up they just came apart. Too much mass. And we were using some pretty trick lightweight stuff.

It was supposed to be solved when the second generation motor was done. It was much smaller motor we called "Jr.". It made about half the required RPM before everything came apart. It wasn't even close to right.

I tried to google my way into a pic of what it looked like in the crankcase, but either my google-fu sucks or that stuff was never put out there. I suspect the latter.

DesertStang06 said:

I'd argue against DI on a gas motor until Ford sorts it out.

80k and heads were being trashed.
I attribute 40% to El Paso shitty ownership.
The rest, I hold the system in question.

I recall VW added an injector or two to spray purely for cleaning the valves.
I've not heard of long-term issue there.

Just my .02 on Ford's GDI setups from working at the dealer.

I think it's a move in the right direction.
Everyone knows how efficient diesel motors are compared to gas.
But it's going to take time.


I personally feel like the auto makers make the cars as "burners"
As the trend of always buying something else once A: it's paid off or B: warranty expires.

While that may or may not be the case.
Like I stated "personally"

Click to expand...

What are you seeing with the Ford DI motors? Carbon build up on the valve tops?

I have a 2012 Focus with DI that's been great. It's hard to believe that a 12:1 2.0 motor can run on 87 octane and make 160hp. That's more than the 350 in my 71 Chevelle made.

How about the Ecoboost motors? They are all DI right?

Direct injection would be the ultimate for forced induction. No fuel "waiting for the spark" to pre-ignite, which should be way more controllable!!

BruceH said:

How about the Ecoboost motors? They are all DI right?

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Yes

skaarlaj said:

Direct injection would be the ultimate for forced induction. No fuel "waiting for the spark" to pre-ignite, which should be way more controllable!!

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That's one of the reasons the EB motors make so much power for what they are.

Variable compression sounds cools but an engine that has variable boost levels essentially has variable (dynamic) compression. Now on a NA engine I could see the variable compression having more merit.

s8v4o said:

Variable compression sounds cools but an engine that has variable boost levels essentially has variable (dynamic) compression. Now on a NA engine I could see the variable compression having more merit.

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I was told is that lower static with higher pressure inlet air is less likely to pre-ignite than compressing a larger amount into a smaller area in one motion. Not sure if it's true, but it makes sense to me. Compress the air with a pinwheel, throw it through charge pipes and intercooler to bring the temp down, then compress it again in the cylinder.

If carbon is the issue with DI, stop putting EGR through the intake. Pipe it in seperate. Think EGR injected. Or don't EGR. Find a new way to deal with it.

BruceH said:

What are you seeing with the Ford DI motors? Carbon build up on the valve tops?

I have a 2012 Focus with DI that's been great. It's hard to believe that a 12:1 2.0 motor can run on 87 octane and make 160hp. That's more than the 350 in my 71 Chevelle made.

How about the Ecoboost motors? They are all DI right?

Click to expand...

Again, this may be mostly lack of care rampant here.

But yes.
2.0, 3.5, a few 2.3s.

The F150s that I serviced were city, records showed timely maintenance, But at 110k, when the heads were off.....it was atrocious.

The other ecoboosts I had to R&R were in the late 80 range.
Valves were sludged.
The chamber's themselves were caked.
Pistols were very crusty.

Now was that purely the cheapest 86 they could find?
Possibly, won't rule out owner habit.
But we had far too many earlier through 2013 range ecoboosts in with toasted heads.

Not saying it's a bad platform.
But having seen it, I'll pass.

But again, environment, owner care, etc wasn't ruled out when I said this.

I'm still willing to bet my heads look better.
When I motor swap/rebuild or whatever.
I'll make sure to look.

My 5.4 had 337000 when I tore it down.
Nowhere near as bad.
Rings had started to go, so I knew it was time.

And yes, Ford uses DI on their ecoboosts.
The plain Jane 3.7s in mustangs, trucks, and Lincoln's are still use sequential port injection.

Mostly saw those for water pumps

tjm73 said:

If carbon is the issue with DI, stop putting EGR through the intake. Pipe it in seperate. Think EGR injected. Or don't EGR. Find a new way to deal with it.

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I could be wrong.
So this is just one of those IIRC statements.

I recall the issue was more along the lines of placement vs spray.
When you have conventional spraying. Everything gets some, and burns.
DI doesn't.
While for economy and output it's a plus.
You lose the inherit gas, and the detergents that flow around the valves.

Not advertising, But go to a shell, and look at their little picture of a "shell" fueled valve.
Basically you don't get that cleaning effect.

Now as stated VW added injectors for that sole purpose.

But again, I claim no vast knowledge, So I could be wrong.

So...my .02, egr would alleviate, but the core issue persists

BruceH said:

What are you seeing with the Ford DI motors? Carbon build up on the valve tops?

I have a 2012 Focus with DI that's been great. It's hard to believe that a 12:1 2.0 motor can run on 87 octane and make 160hp. That's more than the 350 in my 71 Chevelle made.

How about the Ecoboost motors? They are all DI right?

Click to expand...

My 2011 Fusion is 2.5L, 175 hp on 87 octane, no DI, superb gas mileage with the 6 speed auto, both in town and on the hwy. Good enough for me.