Jim Downings R26B 4 Rotor Race Car Idles (Side View)

Jim Downings R26B 4 rotor Mazda-Kudzu DLM race car idles from the side. Filmed at Rotary Revolution 2005.

Category:

Autos & Vehicles

Tags:

• jim
• downing
• 4rotor
• r26b
• race
• car
• mazda
• kudzu
• dlm
• rotary
• revolution

[JudgeItoRx3Sp]

jim is a legend.. awesome

[d00df00d]

It's not 4-rotors that don't like idling, it's all rotary engines set up for big power.

You could have a 4-rotor that idled smoothly if you wanted. It just wouldn't make as much power.

[aaroncake]

@Vince62965 There's something to be said for the silky smooth nature of a stock port rotary, so much so that Mazda has had to include an over-rev joy buzzer in all their rotary cars. Though, there is also a lot to be said of a 4 rotor peripheral port race car!

[d00df00d]

@JD0x0 I appreciate your detailed response, but you misunderstood me.

I was responding to a comment that "4 rotors just don't like idling." I basically said the same thing you did, i.e. that the design features required for the power output are what's causing the lumpy idle, not the simple fact that it's a 4-rotor. To illustrate the point further, I then said it's theoretically possible to make a smooth-idling 4-rotor IF you're willing to sacrifice power.

FYI.

[Vince62965]

A smooth running Rotary? no thanks

[aaroncake]

@JD0x0 Exactly. And just to add one thing, but Mazda rotary engines have had variable porting since the early 80s. First seen in the 6 port 12A (very rare) and then made standard on all NA 13Bs since '84. Aux ports with much later closing times open up above about 3800 RPM and work with a Dynamic Effect Intake which uses the closing pulse from the opposite port to produce about 2 PSI of positive pressure at port opening. In '89, all NA 13Bs also got variable length intake manifolds called "VDI".

[JD0x0]

@d00df00d Any engine making big power, the idle suffers. Even piston engines, the large cam overlap makes for a choppy idle. The problem mostly lies in air velocity. Engines tuned for high RPM power like to have bigger ports to let more air in. This means the air, especially at low rpm, has less velocity to atomize and mix with the fuel. This is one of the reasons for the VICS systems in mazda engines as well as the variable porting in new rotarys, which give you more of the best of both worlds.

[d00df00d]

@mootsfox ...I didn't say anything about torque. I was talking about the quality of the idle.

[mootsfox]

@d00df00d What? The R26B does 700+HP while rev limited. Torque is only an issue at low RPMs, which don't happen much in a race anyways.

[sircygnus]

im happy i live in atlanta and walking distance from mazmart and downing atlanta.

[arbpotatoes]

These 4 rotors just don't like idling don't they... it's either gun it or fuck off!