Highest power exhaust for GSX-R750 L1 2011-2023?

[ptuomov]

It's even possible an exhaust system that should be symmetrical will run like it isn't.
I don't think you will have to worry about that, but, it happens a lot more than people think.

Why would a symmetric and even-firing engine run very differently in different cylinders because of the exhaust? Is it because it's really not exactly symmetrical and at low rpms the empty pipes can do counterintuitive things?

[Rick!]

It's even possible an exhaust system that should be symmetrical will run like it isn't.
I don't think you will have to worry about that, but, it happens a lot more than people think.

Why would a symmetric and even-firing engine run very differently in different cylinders because of the exhaust? Is it because it's really not exactly symmetrical and at low rpms the empty pipes can do counterintuitive things?

How does one even measure that and then trace the issue back to the exhaust?
Killing cylinders on a dyno are one way but that's not a part throttle study nor a low rpm full throttle thing, is it? NASCAR Dr. guy made the presentation on that for individual cylinder timing but I don't recall chasing down exhaust system mods in that presentation.
Going backwards for a moment, the inline 4 cylinder design I have witnessed on a few engines is that a target RPM and power level get defined and then the head and intake tract are modeled to find the total intake length that gives the target hp at the target rpm. So the observation made that the intake length affects mostly the high rpm power is correct interpretation. This is why one sees (used to see?) super bikes with motorized intake trumpets.

[modok]

To detect the presence of resonances out of time with the engine you can use the pressure transducers located on either side of your head.
And keep track of if these resonances have any correspondence to how the engine runs.
If it has IR carbs you could watch it on a dyno and use your optical sensors to see if the reversion clouds are all even under all conditions.

With a very good crank sensor and computer it is possible to sense the power balance in real time.
In an engine laboratory you could be looking at the actual cylinder pressure trace variations.

[Rick!]

Thanks for the explanation, modok, much appreciated. I have witnessed the fuel cloud above a set of Webers on a V8 below peak rpm on a dyno, just forgot to attribute reversion to possible exhaust issues.

[ptuomov]

Wired up:

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[ptuomov]

Current state on P1 WRX gasoline:

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[Rick!]

I don't think a gixxer 1000 is allowed in Extreme Kross Kart. The other two numbers for runs 128 and 130 are the 750.

[ptuomov]

I don't think a gixxer 1000 is allowed in Extreme Kross Kart. The other two numbers for runs 128 and 130 are the 750.

This is with gas station pump gas with 5% ethanol and 98 Euro octane rating:

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The ramp up in the torque curve is where the operator fully opens the throttle. The driver doesn’t use the car under 10k rpm.

[ptuomov]

Any opinions about how to best track the cooling system efficiency for the GSX-R750 engine?

[Rick!]

Any opinions about how to best track the cooling system efficiency for the GSX-R750 engine?

You need to know 3 fundamental quantities:

1. A water pump map of flow vs RPM, (SAE-2004-32-0084 does have pump flow rate for a 600cc bike engine in an FSAE car, otherwise pull the pump off and drive it externally connected to the cooling system with pressure taps and a turbine flowmeter)
2. Fuel flow vs RPM vs power - the ECU should be able to output in pph vs RPM vs MAP/VE/TPS; the goal is to calculate the rate of fuel energy going into the engine,
3. Engine water inlet temp and engine water outlet temp - this gives the engine deltaT and the cooling system deltaT depending on which way you are looking.

The cooling system should be removing 14%-20% of the fuel energy going into the engine at WOT. If a steady state water out temp is not reached during a lap, more heat needs to be rejected.
You get extra credit for measuring radiator airflow deltaT in the circle area under the fan. Determine if mdot x Cp x deltaT(coolant) = H x A x deltaT(air) (BTU In = BTU Out)

[BLSTIC]

Water pump flow is variable if there's a thermostat, so it can't really be used that way unless you know it's open all the time. If you have relatively constant temp coming out it's probably varying flow. So without some kind of flow meter it's going to be difficult to estimate. Can you measure *pressure drop* across the core during racing and compare that to a bench test with known flow?

There's also the thermal inertia of the engine and coolant to consider, you won't have real time fuel-to-coolant heat transfer under conditions that aren't steady state, so the best you would be able to calculate is lap average, even if you had coolant flow and temp in/out data for the radiator.

Is the vehicle overheating, or is this a curiosity thing?

If it were me I'd probably stop at measuring in/out temps and air pressure across the core, and working with that data. But I don't race at the level where I'm concerned about efficiency (so air can be diverted to other things) rather than just "not blowing up". Air pressure is a neat thing to screw with and surprisingly few grass-roots level competitors do anything with it.

[ptuomov]

Thank you, will digest.