guess the engine

[dieselgeek]

This engine's been around (in production cars) since the early 70s. It has a loyal following.

It's tiny - under 100 cubic inches, still came with as little as 100hp in early versions, and as much as 250+ hp in later turbocharged versions. All under 100 cubic inches.

Younger 'rodders are pumping them up to 500+whp on pump gas. Drag racers have taken them out to 1000+hp.

What is it?

[STINEY]

Subaru boxer.

[dieselgeek]

Did they make boxers that small? While it's not the engine I was thinking of, I am pretty sure this one has THREE MAIN BEARINGS! (haiku to follow)

[STINEY]

[Barry Donovan]

Did they make boxers that small? While it's not the engine I was thinking of, I am pretty sure this one has THREE MAIN BEARINGS! (haiku to follow)

subaru common into any power is 108ci and beyond..
there is smaller, never hot rodded into big numbers, short stroke screamers.
I found one for scca cone thrashing, little stroke, less than 100 cubic inches.ea71 or 61.

there is the fiat 850 of youtube user fiatnutz, that has 3 main bearings... but he did alot of machining just to get it to handle its tiny size as it is, also a cone thrasher.

I could not guess the answer.

maybe 1595cc of alfa romeo? only found that to 250hp.(which is in fact amazing)
I am stumped.

did not mention internal combustion... maybe a riddle of something else.

[dieselgeek]

subaru common into any power is 108ci and beyond..
there is smaller, never hot rodded into big numbers, short stroke screamers.
I found one for scca cone thrashing, little stroke, less than 100 cubic inches.ea71 or 61.

there is the fiat 850 of youtube user fiatnutz, that has 3 main bearings... but he did alot of machining just to get it to handle its tiny size as it is, also a cone thrasher.

I could not guess the answer.

maybe 1595cc of alfa romeo? only found that to 250hp.(which is in fact amazing)
I am stumped.

did not mention internal combustion... maybe a riddle of something else.

barry you are on the right track. It IS an internal combustion engine - and you can even buy a brand new car with a version of this engine today.

[Ron Ward]

Wankel rotary engine. Commonly found in Mazda RX series cars (think RX-3, RX-7 RX-8 etc) and Rotary pickups.

Ron

[Barry Donovan]

barry you are on the right track. It IS an internal combustion engine - and you can even buy a brand new car with a version of this engine today.

rotary/wankel?
no mention of torque.
a boxer question never forgets the baseline torque exceeding all tiny hp air fuel combinations since the dawn of japan runting them.

final guess: rotary.
with 3 foot pounds.

[dieselgeek]

WINNER!

the sound would give it away, but here's us doing a little warm start tuning last night on a 13B Mazda with a big single turbo, should be good for 400-500whp on the dyno in a week or two.

Some interesting facts, the manufacturer doesn't consider it a two stroke but I sure do! and so does the EFI computer that we put on it.

They actually inject some of the lubricating oil into the combustion chamber to keep Apex seals lubricated. One of the first thing the guys building them do, is ditch the oil injection and simply mix 50:1 two stroke oil directly in the tank!!

Getting one of these engine timed properly for start up can be an exercise in frustration too. They're weird. They have a Cam Angle Sensor, but it spins at Crankshaft speed.

[Barry Donovan]

I have only seen one in real life.. in a mazda rx7.

did alot of rocking, like an oscillation. the seals is a big thing with those to stay almost wobbling evenly..
even sound two strokish.

that car (private owned mazda) was in maine, believe it or not. didnt last long..enthusiasm died off quicker than the seals.
interesting none the less.

[Ron Ward]

Oddly, I had never thought of the Wankel as a two-stroke, but ya know... it sure sounds like one.


Ron

[Bob Holmes]

Cool. I know they used to use a little Nitro to help deal with the oil in the fuel.

Only Japanese manufacturer to win at LeMan was Mazda with a four rotor.

The things spin to the stratosphere, and can be just about ear-splitting.

[dieselgeek]

The one above has an aggressive port job.

Porting these engines is more like changing a cam profile in a typical piston engine, just like many two stroke piston engines, the port shape directly affects intake/exhaust event timing and duration.

I think they're pretty stout motors, I see a lot of kids building, breaking, and improving them.

I'm tuning THREE of these this week - one of them is a super rare 20B Cosmo engine (with a big single turbo). The 20B has three rotors and N/A can do well over 500hp with simple mods.

The turbo version should be well over 1000. Definitely will take video of that.

These things put out subtle low frequency vibrations that are known to make some people motion sick.

[squirrel]

They had little miniature AFB looking carbs on them in the early days. Seals didn't last long. They got lousy mileage too. It's definitely not a "two stroke", but it does have 3 "cylinders" per rotor. Which is a strange concept.

It's good to see materials science has progressed to the point that they can get that much power out of them. It's definitely a very efficient engine as far as power vs. weight/size

[dieselgeek]

They had little miniature AFB looking carbs on them in the early days. Seals didn't last long. They got lousy mileage too. It's definitely not a "two stroke", but it does have 3 "cylinders" per rotor. Which is a strange concept.

It's good to see materials science has progressed to the point that they can get that much power out of them. It's definitely a very efficient engine as far as power vs. weight/size

THere's a spark and combustion event for every single TDC. I fail to understand how that's not a two stroke, especially since air is moved in and out of the cylinder by ports exposed when the "piston" travels a certain distance.

The computers that run them have to do it in two-stroke fashion. I guess it depends on an individual's definition of "what exactly is a two stroke"

they do get TERRIBLE mileage. Because they are so inefficient! They put a TON of combustion heat into the exhaust (a big reason they're so inefficient) but that is what makes them work good with turbochargers.

Guys that run N/A 13B engines with carburetors, often do it with large carbs. I saw one with a Holley 750 carb - they flow even more air and fuel for a given power level than piston engines. ALl based around their inefficiency from what I am told. On this car, we'll be doing good if we can beat 12mpg.

But it hauls ass and it's cheap to hotrod. So I see a handful of them still in action.