The rotary engine is eligible for LeMans again

Please delete if already posted.

The Facebook algorithms actually put something together that grabbed my attention, and showed me the Jalopnik article here.

I doubt Mazda is going to put forth the cash to go to LeMans, but maybe some very wealthy fan would put forward a private team?

Can someone (Pete?) explain the reasoning behind this?

5.8.1 No fuel injectors are permitted downstream of the exhaust valves or of the exhaust port inlet on a rotary engine.

Wait I see they are just pointing out the rotary doesn't have an exhaust valve.  Now can anyone explain why a fuel injector would be an advantage in the the exhaust?

In reply to Stampie (FS) :

Only reason I want fuel after my cylinder head is if i'm trying to ignite it to spool up a turbo, usually before launch (Anti-lag).

Can't imagine that's it though.

ALS or cool exhaust flames. 

Stampie (FS) said:

Wait I see they are just pointing out the rotary doesn't have an exhaust valve.  Now can anyone explain why a fuel injector would be an advantage in the the exhaust?

When downshifting or in neutral you can dump fuel into the exhaust.  The ignition of it turns the turbo into a mini-jet engine and keeps it spooled up.

I forget what its called, but it is very common in rally cars

Stampie (FS) said:

Can someone (Pete?) explain the reasoning behind this?

5.8.1 No fuel injectors are permitted downstream of the exhaust valves or of the exhaust port inlet on a rotary engine.

I'm gonna call "not it".

The only reason I could think of, for ANY engine, for a FUEL injector downstream of the engine, is to help spool up a turbo.  But help spooling a turbo is the absolute last thing a rotary needs.  For those familiar with turbine housing sizing, rotaries generally like turbine housings 3-4 sizes larger.  Like where a piston engine making X horsepower might like a T3 turbine in the .63-.82 range, a rotary might prefer, for the same compressor, a T4 turbine in the 1.0-1.32 range.  And have faster spool in the process.

Hell, the biggest downside a rotary has is that a certain percentage of the fuel going into the engine goes right out the exhaust port unmolested by combustion.  For a race where you are alloted a certain amount of fuel, wasting even more fuel would seem to be a negative.

Mr_Asa said:

Stampie (FS) said:

Wait I see they are just pointing out the rotary doesn't have an exhaust valve.  Now can anyone explain why a fuel injector would be an advantage in the the exhaust?

When downshifting or in neutral you can dump fuel into the exhaust.  The ignition of it turns the turbo into a mini-jet engine and keeps it spooled up.

I forget what its called, but it is very common in rally cars

It's generally only air that gets injected into the exhaust, fuel is introduced "naturally" via the intake.  With direct injection, you don't even need to do that: just keep the throttle open a certain amount and change the fuel injection timing to inject after compression TDC, and ignite the spark later. 

Mr_Asa said:

Stampie (FS) said:

Wait I see they are just pointing out the rotary doesn't have an exhaust valve.  Now can anyone explain why a fuel injector would be an advantage in the the exhaust?

When downshifting or in neutral you can dump fuel into the exhaust.  The ignition of it turns the turbo into a mini-jet engine and keeps it spooled up.

I forget what its called, but it is very common in rally cars

Anti-lag is what you're referring to..


grassroots version in action on the Big Bad Wolf S2000 a few years back.

https://www.facebook.com/TheBigBadWolfLives/videos/1886082281622137

At one time I was enamored with them, not any more. That said, I know someone who has a 4-rotor version... boy does that get the imagination going, noise and mileage be damned.

kb58 said:

At one time I was enamored with them, not any more. That said, I know someone who has a 4-rotor version... boy does that get the imagination going, noise and mileage be damned.

The noise is the main draw!

Brett_Murphy (Ex-Patrón) said:

kb58 said:

At one time I was enamored with them, not any more. That said, I know someone who has a 4-rotor version... boy does that get the imagination going, noise and mileage be damned.

The noise is the main draw!

This video rolling around online is like 95% of why I wanted an RX-7 when I was a teenager.

Older ears tell me he was using a standard, unmodified Holley on a Racing Beat manifold, so it was loading up/flooding after letting off the throttle, but still.  Not just "the sound", but also the feel, like the engine just wants to SING and it is skipping across the high spots while it is waiting for you to nail the happy pedal.

I thought kids grew out of this once they tired of putting playing cards in the spokes of their bike wheels... but I stand corrected, given the number of Harley riders...

A buddy has an RX-7 when he was a teen and when he'd meet up with his buddies in a parking lot on Saturday night, he'd rev it waaaay up, kill the ignition, but keep his foot down. Everyone would run for cover, knowing what was coming, raw fuel sitting in a near-red hot exhaust... a tremendous BOOM.

They make great noises. I have had quite a few of them and would pick up another RX if the price was right.