Live data from Hacker News

“Inside-out Wankel” rotary engine delivers 5X the power of a diesel

newatlas.com

1–10 of 211 posts

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#4
post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

I understand this too, however, the technology might be worth revisiting with modern techniques, I understand the power output is 'smoother', which can reduce vibration, some applications might need that?

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#5
post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

They also have issues meeting emissions targets - both because of the basic design (there isn't the ability to actively control valve timing events), and also because they typically need some sort of lubrication for the combustion chamber. They are similar to two-stroke engines in these respects.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#6
post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

My near-mint condition 2009 Mazda RX-8 never had a Wankel engine problem (over 100k miles). It would have easily lasted another 5 years without a doubt or hiccup.

Wankels are usually excluded from all engine comparisons, because it's a considered a different class...for piston engine marketing reasons.

I sold off my RX8 in 2018 because my fiancee and I moved to Seattle (passing emissions testing wasn't anything special). We needed the money and we had her car, which was more functional. I do miss it.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#7
post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

They also have issues meeting emissions targets - both because of the basic design (there isn't the ability to actively control valve timing events), and also because they typically need some sort of lubrication for the combustion chamber. They are similar to two-stroke engines in these respects.

Running them at a pre-determined RPM constantly can resolve lack of VVT, but that limits their applications. New materials for apex seals being researched could alleviate their longevity issues too. But, I have a big soft spot for rotaries and would love to see them applied more :(

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#8
post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

The folks in the article seem to have figured some of the longevity problems out.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#9
post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

They're not great, at all. They have very few moving parts and they are very smooth because there are no reciprocating parts.

Other than that, they have emissions like 2-stroke engines because of the incomplete combustion and we have never been able to devise any kind of material to make the apex and side seals last anything like as long as piston rings.

Piston engines are a terrible way to power vehicles, but everything else we've tried is worse.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#10
A non-turbo diesel is an interesting choice of competitor. The big selling point of the Kohler motor is that it's almost silent - even the valve train is belt-driven to reduce noise.

Not sure a rotary engine screaming at 6500RPM is comparable here to a diesel with a peak torque at 2000 and peak power at 3600.

> LiquidPiston has been working on these X-engines for nearly 20 years now,

I'm guessing they will never actually release a commercially viable product. 20 years to design an ICE is...too much.

Post reply on HN