TUNE VS POWER! HOW MUCH TIMING SHOULD I RUN ON MY TURBO MOTOR? WHAT A/F RATIO SHOULD I RUN (9:1?)

HOW MUCH POWER IS TIMING WORTH ON MY TURBO MOTOR? WHAT IS THE BEST A/F RATIO? WILL MY NA MOTOR RUN A 9:1 AF? WHAT HAPPENS IF MY TUNE IS OFF? WILL MY MOTOR STILL RUN? CHECK OUT THIS SERIES OF TESTS RUN ON AN NA 383 SMALL BLOCK CHEVY, WHERE WE (ACTUALLY THIS TEST WAS RUN FROM ENGINE MASTERS-THNX DAVID FREIBURGER) VARIED THE A/F RATIO BY MORE THAN 3 FULL POINTS, FROM 12.5:1 DOWN TO A VERY RICH TO 9.1:1. WHAT HAPPENED TO THE POWER? WE ALSO TESTED IGNITION TIMING ON THE SMALL BLOCK, FROM 36 DEGREES (WHERE IT MADE BEST POWER) DOWN TO JUST 11 DEGREES!
I ALSO INCLDED TESTING RUN AT VARIOUS TIMING LEVELS ON A TURBO 4.8L! HOW MUCH TIMING IS NOT ENOUGH AND HOW MUCH IS TOO MUCH?

Richard is the man, great stuff. I’ve seen this tuning on the street and I “intuitively” believed it to be the acceleration rate of the engine increasing/better efficiency. The other possibility would be lower EGTs creating less boost. It would be interesting to see this with EGT, IAT, & airflow data.

Assuming the accel rate was the same for both tests maybe this supports EGT variation being the driver?

[bdugle]

Boost change on the 4.8 turbo motor was across the rpm range going to 24°, but the timing was only above 4500 rpm. That tells me it’s something other than timing!

[PANTYEATR]

Timing blew piston rings in at least 3 cylinders in my Ford 427. I made a EFI tuning mistake which locked ignition timing to 10°, instead of following the timing map. I street tuned my car like this FOR 6 MONTHS! The car felt strong, but wouldn't pull all the way to redline. My friend suspect this caused the piston rings to get brittleb and break from late combustion flames which then caused oil dilution, combustion in the crank case, the ceramic coating to dull on my headers, cooked a wideband O2 sensor and oil blowing out the tail pipes. I had every negative symptom of a bad PVC, but once i found the error in the computer my friends and i suspected what happened. The leak down test suggest broken piston rings. I have yet to open the engine to see the damage. 😔

[malamri]

I never thought learning can be this much fun.

[Fktd]

Boost drop rpm from timing is an effect of back pressure in the exhaust. Containing more of the combustion by advancing timing as you said increases efficiency and useful work while less heat/work goes out the exhaust. Less heat in the exhaust means less gas expansion means less back pressure which in turn lowers boost pressure.
That’s at least what I feel is happening here.

[reedhanson]

more timing = less enthalpy available to spin the turbo. more of the heat energy from the fuel is converted to work (more hp) and more fuel energy would be transferred to the piston and cooling system. this would show up as less boost, so your data does make sense. having a turbine inlet thermocouple would have shown this too.

[Jkk.protuner]

well .. boost is just a measure of restriction to flow... with the added timing, the engine flows better thus lowering the observed boost.
Just like what happens when you added timing at idle, and then the rpm gets higher and makes more vacuum.

[kennethpowers]

Agreed the timing dropped the boost curve. With more timing in the engine it became slightly more efficient at producing power therefore the boost dropped slightly. It does make sense.

[BowTieSS]

The change in boost in my opinion is from some other factor than timing. Timing may play some part, but in particular for the 24 degree run, you said you only changed the timing after peak torque. If that's the case, it should overlay the 22 degree boost curve until the point that you added the full 24 degree and then diverge. The fact that it is offset for the whole rpm sweep leads me to believe there is some other factor involved besides timing.

[johnsheetz]

Black holes, FTW now that one made me laugh 😂

[spdnotch]

Yes a vacuum small vacuum leak can definitely throw you off. Pretty annoying

[obbyjep]

I think a bit of ex still burning is helping spin the turbo, keep it hot. With a diesel retarted injection timing defenetly helps spool a bigger turbo as compared to advanced although usually they make more power addvanced

[GTRliffe]

i wish i could have your life

horsepower, dyno, educate others…

Good life man! Good life!!

[bcbloc]

Additional timing advance lowers EGT's that drops the turbine drive power so boost goes down.

[startrek]

My assumption on the boost drop would be due to allowing more of the combustion reaction to happen in the cylinder by advancing the timing thus creating less back pressure in the exhaust.

[justRD]

The fuel releases a given amount of heat. The timing on a turbo engine effectively determines how much of the heat is turned into mechanical work by the engine and how much heat is sent out the exhaust as waste energy the turbo recovers.

[michaelblacktree]

Richard, I like the subtle changes you made to the video format. 👍

[deanbryan]

Don't know why there was the boost drop.
Do know boost is good, timing makes boost better (till it doesn't lol)

[aaronliddell]

I want the Black Hole tune! I wonder where the Event Horizon is in the exhaust tract ?

[dalelockett]

My take on lower boost pressure would be increased exhaust gas velocity from the increased dynamic compression force due to the increased ignition timing creating improved exhaust higher in RPM the better this gets thus the power response.