I’m looking for a little help on figuring true rwhp. I have a 2002 base model. I installed an A&A supercharger and a Corsa exhaust and it put down 530rwhp. Went back in for a built tranny diff, 3200 stall converter, cam, headers and catless cross pipe and put down 602rwhp and converter was able to lock. This all on the same Dynojet. I then dropped to a 3.6 pulley and added meth it put down 545rwhp on a mustang dyno (1st shop doesn’t like tuning with meth) converter wouldn’t handle power so unlocked. Then dropped to a 3.4 pulley and it put down 580rwhp on a Dynojet (I moved out of state) this with converter unlocked as it wouldn’t handle the power locked. So with this being said I come up with a corrected 680rwhp if the converter could be locked based on previous runs? Am I correct? Just looking for a double check. TIA

 

A locked converter at most 5% power adjustment. I would expect to see maybe 20 or 30rwhp from a 600rwhp combo locking a triple disc.

20rwhp is about 15,000Joules/second. If the transmission fluid volume circulating is around 11 Liters, transmission specific heat capacity 2.1J/g*C, ATF density maybe 0.85g/mL so 9.6kg of fluid total circulating (generous), thus 9.6kg times 2.1Joules/g*C is 20,000J per degree C for 11L.

20rwhp will therefore (power / total heat capacity) rise the temperature of transmission fluid in this condition at a rate of (15kW/20kJ/DegreeC) = ~0.75Degree C per second

Locking a converter for wide open throttle is not considered desirable or even necessary. A properly built converter should be faster unlocked. A high profile company such as Yank do not recommend locking the converter at wide open throttle, even though they are meant to stand the abuse more or less. It will still last longer without the abuse. Of course it is desirable for efficiency and in some situations MPH but a locked converter should not be seen, generally, as a necessity in straight line forms of racing environment with unlimited class (no rules).

While a locked converter may be more efficient, the time while the converter is in the process of locking can generate enormous strain and heating depending strongly biased to how the mechanical of the valve body is setup and tuned, meaning not all converter locking mechanisms in all types of transmission will behave similarly and care must be taken to set up the transmission for the type of locking event duress.

 

Thanks for your reply. It seems like my dyno numbers would point to more than a 20-30hp gain. I wish I could have ran the car on the same dyno each time. The converter is a Precision Industries Vigilante single disc. By my figures with a base of 600whp then 2 pulley swaps and adding meth I thought dropping a pulley size was 40ish whp for a total of 680 with results slewed do to the converter slip? I agree it should never be locked at wot just trying to compare apples to apples.

 

If you want to make comparisons I recommend only using dynojet. It is most reproducible standard measurement technique we have available.

When trying the power calc, we prefer measurable and comparable airflow and fuel flow mathematics, because power to the tires or crankshaft (dynometer) does not capture the full picture of where energy is flowing. Try starting with where on the compressor map at each rpm breakpoint. From the point on a compressor map you work backwards through IAT, manifold pressure, and fuel flow to determine whether the fuel use and intake air temp match what your compressor flow calculations represent @ whatever friction intercooling. This is essentially your bridging the gap between BSFC and parasitic losses of driving an aux air pump and cooling airflow with respect to its advantageous kinetic energy investments as measured by your engines conversion of fuel and air into useful measurable work, the rest is lost. Some units have compressor wheel speed monitoring that is mostly for turbo situations, supercharger is easily to calculate wheel speed by engine rpm and drive ratio assuming no slip. Find wheel speed you look at IAT and fuel flow like I said and then, brake specific fuel consumption, tweaking variables which influence BSFC and parasitic losses, for example injection end of spray angle and boost leaking. You would perform a full pressure test to from compressor through to engine intake system to eliminate leaking, air molecules that leak out cost power. End of injection timing can work for or against airflow and fuel mixing. Friction elements and transmission transfer and all of that also matters but I am getting too far. The point is that perception of power in terms of tuning efforts and understanding of how an engine works are made visual and conceptual through quantitative mathematical reasoning about the use and conversion of fuel to useful work and where the rest of it is going to wind up and whether or not that is going to be a problem and at what point it will happen.

 

I have a Yank single disc SS3600.

I tune the car and I ran the dyno when the testing was done. That was my job at the time.

It’s NA and the dyno was a Dyno Dynamics eddy current unit.

I tested both unlocked. I set the load rate to the lowest setting so as not to hurt the lockup clutch.

Power difference was on the order of 30whp.

When you run the converter unlocked you don’t get a true torque reading. You also don’t get any useful data below the stall speed. In my case, starting at 3500 rpm, it simply goes immediately to 5000 and sits there until the rollers catch up with the engine. Can’t do any tuning below that

With the converter locked I got a wonderful curve from 2000-7000.

With your power, you really need a triple disc clutch.

Our Dyno Dynamics reads 14% lower than a DynoJet.
I believe a Mustang is approx 12% Lower.

More than a few customers left our shop pissed at the power numbers. So off they headed to a local DynoJet. Then they were more than happy.