RX-8 friend

"How much HP increase does Stage X give?" is the question most often asked. A more relevant question would be "how can you increase the engine HP without modifying it physically?"
A simplified set of answers follows.

Without engine modifications (machining etc) you can:

1. Improve intake and exhaust flow. The more air/fuel you can get into the engine the greater the "push" it generates. Reducing exhaust restriction leaves more room in the engine to get more air/fuel in.

It appears the RX-8 intake is just fine restriction wise. The exhaust may start to be restrictive up around 8500-9000 RPM, but we're not sure about that just yet.

2. Run at stoic. all the time. I'm talking of perfect air/fuel ratio, about 14.5 to 1 air to fuel. This is very difficult to do in the "real world" where the ambient temp. varies, the humidity varies, the altitude and even the base air pressure varies. Your engine also has variables such as physical "timing" (when the rotor is at "TDC" - which is difficult to measure), the compression ratio can change if gunk builds up in the engine. The heat flow through the engine metal/air/coolant interface can change.

All these variables mean it's difficult to control exactly when and how the intake charge burns. This control is essential to avoid detonation, the death rattle of a rotary. So the engine is set up to run a little rich, which evens out the variables. Rich mixtures are very detonation resistant, but you loose power.

This is the method Stage 1 employs, and it uses control of fuel and timing to avoid detonation prone areas of operation.

3. Increase RPMs. Higher RPM operation means more power pulses per second, which translates to more HP. I think most of us understand the physical limits this can impose, but for limited life engines (racing) this is the main technique used. Therefore we see F1 engines operating at 18,000 and up RPM!

4. As per #1 above, stuff in more air/fuel. This is done by compressing the intake manifold, either by a supercharger (a pump mechanically driven off the eccentric shaft or by an electric motor), or a turbo charger, which is driven by the exhaust gases.

This brings in many control issues, as the intake air pressure can now vary over a range 10-30 times as great as a "normally asperated" engine. Great care must be taken to control the air/fuel ratio.

Something to consider in our quest for more.

IKnowNot'ing

Point 2 :

Stoichiometric fuelling has nothing perfect with regards of performance or economy. Running stoich on modern petrol (gas) engines is down to emission legislations wich impose to simultaneously reduce (as in reduction, the chemical reaction) NOx and oxydise HC and CO in the catalyst. This can only be done with staying close to a stoich AFR and slightly (less than +/- 3%) fluctuate in rich (for reduction) and lean (for oxydation) operation.
For max torque (hence power), AFR must be slightly rich. That's what most engines do at WOT.
For best fuel economy, a lean mixture is prefered, but it must be kept away from the engine's lean limit (= no / poor combustion).
However, to lean out at part throttle would be a nice way to improve the 8's fuel economy. I'm seriously thinking about this.

The engine management system (EMS) is fully capable of adjusting the mixture to the operating conditions (ACT, ECT or CHT, lambda, catalyst temperature...) throughout the engine life. The EMS on the 8 is fitted with knock control and a linear, wideband lambda sensor which gives a very acurate AFR metering in all conditions (lean, stoich or rich).

The presence of this linear lambda sensor probably means the engine works in CLOSE LOOP operation at all times (bar cold start, when the sensor still heats up to its functional 600°C).

MP3Guy

Ah, for the days of rejetting a carb in the morning, running the hell out of it all day.

Omicron

I believe this is something CanZoomer is working on as well.

emailists

First you get the money.

Then you get the women.

THen.. you get the power........




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read about my MTV video
https://www.rx8club.com/showthread.p...threadid=22619

Winning_BlueRX8

hahahha Scarface. Good stuff, good stuff.