Nissan's Variable Compression Engine Technology

[balactm]

http://autoweek.com/article/technology/v...i-near-you

Maybe this is old news, but to be honest, its the first I've seen or read about it.

During our senior project working on the ethanol powered Harley in ISAT, I spent a LOT of time researching alcohol's and their effects on engines. For example, a "flex-fuel" vehicle can operate on mixtures of ethanol/gasoline. The inherent problem was the compression ratio though. Ethanol requires a higher compression to burn efficiently. So while flex-fuel vehicles can "run" on mixtures of ehtanol/gasoline, they don't necessarily run well on anything but pump gas because the compression is always geared for more a heavier gasoline mixture.

I had spent countless hours trying to figure out the control system for an electronic wastegate that would alter the boost levels of an engine based on the alcohol content of the fluid in the tank. Turns out the only piece I was missing was Nissan's "multilink."  Hey, 20 years of research led them there, I was just stoned off my ass trying to figure out to make it go faster and use alcohol more efficiently...

The thing that shocks me the most about everything I've read so far, is that all the articles focus how it's going to replace the 6 cyl and provide more power. I see this as a huge step towards getting off of gasoline all together (I know this at the bare minimum will strike up conversation) and allows more efficient combustion of alcohol/gasoline mixes.


Let the debates begin...

[JPolen01]

Was Paul Tutel Jr involved in your project? I remember seeing his truck at ISAT and wondering what he or his company was working on.

[rherold9]

Yes, old news and I believe this is much cooler: http://www2.mazda.com/en/next-generation/technology/

[BLINGMW]

Maybe the article title meant to say this will be the first *mass produced* variable compression engine, but it's certianly not the *first*:

https://en.wikipedia.org/wiki/Saab_Varia...ion_engine

I'm sure either approach is pretty difficult, and I certainly don't want to be the first to buy one....

I'm also a little unimpressed by the numbers.

27% better fuel economy than a 3.5L V6?
Yeah, ok, any 2.0T has that down. 

268HP and 288lbft of torque? 
The Honda Accord's 2.0T makes 252HP and 273lbft of torque, so this variable nonsense gets me 6% more? WHOOOO sign me up. 

I definitely agree with the article that the 2.0T has replaced the 3.5L V6 though, that's my new van and my old van exactly.

As far as Mazda and their SkyActive whatever, they're trying to get above 50% efficiency. Not sure exactly what they have up their sleeves, but that's a huge jump.

[ScottyB]

Chan beat me to it. Saab was the first with an engine that literally had a hinged block that would alter the distance of the crank from the head.

with the advent of electric power on the horizon in the next 10-15 years, from a R&D standpoint the most effective thing to do is figure out how to make typical gasoline engines more efficient with the infrastructure we have. alcohol is just not a feasible fuel and ethanol blends will never dramatically change in the future because so many cars don't have fuel systems that can handle the corrosive nature of stuff like E85.

skyactiv is the future for now, and i see most manufacturers following suit until the hybrid/electric model starts taking over.

[balactm]

All interesting points.

I was aware of the saab engine, but I also knew it wasn't really tested and manufactured like the nissan one. Definitely should have been more clear.

Totally agreed on 4 cyl turbos replacing the v6's.

The main thing I see from this nissan engine is the ability to burn alcohol/gas mixtures more efficiently. Or hell, any fuel for that matter. You could just as easily adapt this technology to a gaseous based fuel system. Take the Old Honda civic gx from the 90s. ran on propane. If you were able to use this same variable compression technology on that, you could theoretically burn hydrogen gas as well, since hydrogren requires a much higher compression ratio to burn efficiently compared to propane.

Scotty,

Electric cars are actually much more cost prohibitive to bring to the market, because our infrastructure currently has a liquid distribution system. Yes, we have an electric grid as well, and adding a couple chargers here and there is certainly not the hardest to do, but if you're talking about a major shift from gasoline, it seems to me that another liquid form of fuel would have the least effect on our current distribution methods.

Out of curiousity, why do you think alcohol isn't feasible? I feel like changing some of the fuel fittings in a new car to copper fittings to fight the corrosive nature of ethanol would be a fairly easy change on the manufacturing side of things.

[GTBrandon]

Very cool technology, wonder why they didn’t use it on a 4cyl application for more efficiency to compete with these other 2.0’s. Big thing for me is reliability and way more parts to fail. They said this engine has gotten way more miles of road testing than any other engines they made, but still would worry about that.