Dyno Testing & Downshift

[2000StreetRod]

Dyno data files

this is a great thread, im also on similier line of tuning mine up, would you happen to have the dyno print outs so i could compare with mine? ill post them up here when i get the photo copier working.

The scan below is of my stock SOHC pulling in 4th gear which is speed limited at 105 mph.

The scan below is of my stock SOHC pulling in 2nd gear to obtain a wider rpm range and avoid downshifting.

The scan below is for 2nd gear pull with a mod to eliminate slack in the throttle cable.

The scan below is for 2nd gear pull with the throttle cable mod and an Akimoto Racing high flow air filter.

 

[SB98UKexplorer]

well heres mine, i ended up taking a photo of it. but it shows i have fueling issue after 4500 rpm to the limit of 6250, all done in 2nd gear on the shifter.

 

[2000StreetRod]

dyno problems

The shop owner where I used to get dyno testing sold his machine but he referred me to the shop owner who bought it (One Stop Auto Shop in Taylors).

Today I spent an hour or so on the dynamometer but there were ignition sensing problems and dyno speed problems. I wasn't able to get a good plot with accurate readings but after reviewing the files I estimate a max power of about 168.5 rwhp @ 5055 rpm and a max of about 186 rwtq @ 3055 rpm. Todd, the shop manager, is very interested in my supercharger project and was extremely disappointed I did not get several clean runs to establish a baseline. He went right to work on troubleshooting the machine as soon as I left and will call me when it has been repaired. He didn't charge me and I will use him for the post supercharger installation testing. The engine tear down will start as soon as I get a good baseline plot of torque and horsepower. Jame's dyno tune worked great. I was able to slowly accelerate thru the gears using light throttle until the shift into 4th speed (1:1) and then pull at WOT from 1500 rpm to the PCM limited 6250 rpm.

According to my datalog the engine coolant temperature climbed to 214 deg F but the trans temperature only reached 163 deg F. My new top speed on the dyno is 127.5 mph since James removed the PCM speed limit. Air/Fuel ratio at 3000 rpm was about 11.5:1 and slowly increased to 12.3:1 at 6,000 rpm.

EDIT: I found a Dynojet installation guide online and learned that two secondary rpm pickups are needed for a waste spark ignition system like mine. One pickup encloses one plug wire from a coilpack section and the other pickup encloses the other plug wire from the same coilpack section.

For example, one pickup on #3 and one pickup on #4 plug wires. Then the dynamometer is set for spark spacing of 360 degrees instead of 720 degrees. That may be why one run showed a max engine speed of 4,000 rpm and another showed a max engine speed exceeding 9,000 rpm. Also, the vehicle ground and the dynamometer ground need to be connected.

 

[2000StreetRod]

stock performance

I found an online Dynojet software user's manual and read it last night. I learned a lot more about the viewer software. I looked at my stock dyno files and realized that several of the runs also had ignition sensing problems because Mark (the dyno owner at the time) did not hook up both secondary rpm sensors. Below are plots of the only good run in 4th gear (1:1) with the stock engine confirguration.

The plot drops off at 4700 rpm because the PCM vehicle speed limiter was set to the stock 103 mph. However, the power had already peaked at 152.6 @ 4400 rpm and the max torque was 192 @ 3790 rpm.

I reviewed again my recent corrupted dyno data and have decided that the new max power is 174 rwhp @ 4920 rpm and the new max torque is 197 @ 3900 rpm. That means that the power increased about 21 rwhp due to the improved intake and exhaust system and that I didn't lose any torque (actually gained 5 rwtq) due to the 3 inch diameter exhaust. I suspect the Dynomax VT muffler is responsible for maintaining the low speed torque. I'm anxious for the dyno drum speed sensor to be fixed so I can get some accurate and repeatable performance plots. Then I can get started on the supercharger installation.

 

[SB98UKexplorer]

when you reached 127 mph, at what rpm did you reach?

 

[2000StreetRod]

engine speed limiter

when you reached 127 mph, at what rpm did you reach?

I did not have James remove the engine speed limiter since the power rapidly drops above 6,000 rpm and its a good safety device to prevent engine overspeed should I get distracted. The stock PCM limiter is set for 6250 rpm which was 127.5 mph in 4th gear (1:1) with my 3.73:1 rear axle. I was a little concerned about exceeding the speed rating of my tires but I raised the pressure to 35 psi before getting on the dyno and I was only above the tire speed rating for a few seconds on each pull.

 

[2000StreetRod]

determining torque & power

The dynanometer does not need to know the transmission gear ratio, rear axle ratio or tire diameter to determine torque and power. It measures how fast the drum is rotating and how fast the engine is rotating via the ignition pickup sensor. Using those parameters it calculates an overall gear ratio to determine torque and power. But I noticed the numbers were higher when pulling in 3rd speed than 4th speed.

After reflecting on the above for a while I realized that a vehicle with a 4.11:1 axle ratio will accelerate faster than a vehicle of the same bhp and weight with a 3.73:1 axle ratio. Also, a vehicle in first gear will accelerate faster than a vehicle in second gear. And finally, a vehicle with small radius tires will accelerate faster than the same vehicle with larger radius tires assuming there is adequate traction. If a dyno merely measures the acceleration and velocity of the drum to calculate power and torque then lower overall gearing would result in greater performance. I searched online for a formal definition of rear wheel horsepower and only found the basic horsepower measured at the wheels.

According to the Dynojet WinPEP 7 User Guide:

"Power, in mechanical terms, is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of one foot in one second. In everyday terms, it would take one HP to raise a 550 pound weight up one foot in one second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second). Dynojet’s inertia dynamometer measures power just in this way. The dyno calculates velocity by measuring the time it takes to rotate the heavy steel drum one turn. The dyno measures force at the surface of the drum by indirectly measuring the drum’s acceleration. Acceleration is simply the difference in velocity at the surface of the drum from one revolution to the next. The force applied to the drum is calculated from acceleration using Newton’s 2nd law, F=MA, (F)orce equals (M)ass times (A)cceleration. Power is coupled to the drum by friction developed between the driving tire of the vehicle and the knurled steel surface on the drum of the dynamometer.

TORQUE
When an object rotates around a point, the object’s speed of rotation depends on both an applied force and the moment arm. The moment arm is the distance from the point of rotation to where the force is being applied. Torque is the product of the force and the moment arm. For example think about trying to spin a drum by wrapping a rope around the drum and then pulling on the rope. If the rope is wrapped around a drum of one foot radius and pulled with 550 pounds of force, the resulting torque is 550 foot-pounds. The torque on the dyno’s drum can be calculated by multiplying the force applied by the drum’s radius. However, engine torque is not equal to the dyno’s drum torque because the gearing through the drive train changes the moment arm. The change in the moment arm is proportional to the ratio of engine speed to drum speed. Therefore, tachometer readings are necessary to calculate and display engine torque."

There is a formula to calculate power from torque:

HP = TORQUE x RPM ÷ 5252

From the above a plot of torque and power vs rpm should cross at 5252 rpm. If not, then one or the other or both are bogus. I have read comments on the internet that Dynojet inertia dynamometer numbers are inflated compared to loading dynamometer numbers. That is one reason I wanted to stay with the same Dynojet for accurate relative numbers. However, I have read that for estimating purposes rwhp for an automatic is typically only 80% of the bhp. The Ford advertised power for my SOHC V6 when new was 205 hp at the flywheel/flexplate. 205 * 80% = 164 so my stock rwhp of 152 seems quite reasonable for a 13 year old engine with 150K miles on the odometer. I plan to use the HP to TQ equation to spot check some of the stock plots.

 

[pbnj22]

did you add any mods to see if you could find any gains!?

 

[2000StreetRod]

improvements

did you add any mods to see if you could find any gains!?

As stated in post #24 the 21 rwhp and 5 rwtq increase is due to an improved intake and exhaust system:
Low restriction cone air filter
Lightning 90 mm MAF sensor
75 mm racing throttle body
Custom tune for above
Enlarged downpipes
Enlarged high flow cats
Enlarged Y pipe
Straight thru 3 inch dia Dynomax Vt muffler
3 inch dia tailpipe
3 inch dia Vortex turndown tip

I doubt that any further improvements to the intake or exhaust system would result in any significant performance gain. That is why I'm going to install an intercooled supercharger to significantly increase low engine speed torque.

 

[pbnj22]

As stated in post #24 the 21 rwhp and 5 rwtq increase is due to an improved intake and exhaust system:
Low restriction cone air filter
Lightning 90 mm MAF sensor
75 mm racing throttle body
Custom tune for above
Enlarged downpipes
Enlarged high flow cats
Enlarged Y pipe
Straight thru 3 inch dia Dynomax Vt muffler
3 inch dia tailpipe
3 inch dia Vortex turndown tip

I doubt that any further improvements to the intake or exhaust system would result in any significant performance gain. That is why I'm going to install an intercooled supercharger to significantly increase low engine speed torque.

oh snap.. missed that post after work.. sounds similar to what im going to do with my exhaust but i have a 5.0 if be pumped with those kinda gains after exhaust.. im doing headers, cutting out the cats and doing duals 3 inch in 3 inch out but not sure what muffler yet.. i should also do a dyno like you but i would probably only do it after as i dont want to spend too much money on a dyno... how much did that guy charge you? per hour or what?

 

[2000StreetRod]

V8 headers

oh snap.. missed that post after work.. sounds similar to what im going to do with my exhaust but i have a 5.0 if be pumped with those kinda gains after exhaust.. im doing headers, cutting out the cats and doing duals 3 inch in 3 inch out but not sure what muffler yet.. i should also do a dyno like you but i would probably only do it after as i dont want to spend too much money on a dyno... how much did that guy charge you? per hour or what?

The stock V8 headers are fairly restrictive and in need of flow improvement. Many members post that the Torque Monster headers provide measurable gains. Unfortunately, unless the body is lifted there is not adequate clearance for what I consider high performance headers. That's one reason I changed my mind about installing the V8 and decided on the supercharger.

It is not necessary to eliminate the cats to achieve a high performance exhaust. After market high flow cats are available and not expensive. They also are good to eliminate the harsh exhaust sound. Dual 3 inch mufflers and tailpipes are not needed for the Torque Monster headers and a normally aspirated 5.0L. I would only consider going that route for a supercharged or turbocharged V8. It just adds weight and takes up space for virtually negligible max rpm performance gain and potential low rpm torque loss.

The first set of 13 pulls cost me less than $100 because the shop owner was interested in what I was doing. The second set of pulls cost me nothing because I didn't get any useful plots. The advertised shop dyno rate is $105 per hour which I will be glad to pay when I return after the dyno gets repaired.

 

[zpn_by]

...Dual 3 inch mufflers and tailpipes are not needed for the Torque Monster headers and a normally aspirated 5.0L. I would only consider going that route for a supercharged or turbocharged V8. It just adds weight and takes up space for virtually negligible max rpm performance gain and potential low rpm torque loss...

Agreed. From my days with my 5.0 Mustang, a dual 2.5" setup is the best way to go for a naturally aspirated engine. Your truck will fall flat on its face at low RPM if you open the exhaust too much. I once tried running 2.5" full-length with no cats and Flowmaster 40-series mufflers - what a mistake - I had to rev the snot out of the car (figuratively speaking) to take off in regular driving in traffic. that was with a lightweight mustang which was 3400 lbs with me in it. A 4500 lb truck wouldn't be able to get up a hill except at the top end of first gear. I ended up putting my original h-pipe back on the car but left the 2.5" cat-back and the flowmasters, and was much happier with the car. Plus I could take off at idle again too.

 

[pbnj22]

The stock V8 headers are fairly restrictive and in need of flow improvement. Many members post that the Torque Monster headers provide measurable gains. Unfortunately, unless the body is lifted there is not adequate clearance for what I consider high performance headers. That's one reason I changed my mind about installing the V8 and decided on the supercharger.

It is not necessary to eliminate the cats to achieve a high performance exhaust. After market high flow cats are available and not expensive. They also are good to eliminate the harsh exhaust sound. Dual 3 inch mufflers and tailpipes are not needed for the Torque Monster headers and a normally aspirated 5.0L. I would only consider going that route for a supercharged or turbocharged V8. It just adds weight and takes up space for virtually negligible max rpm performance gain and potential low rpm torque loss.

The first set of 13 pulls cost me less than $100 because the shop owner was interested in what I was doing. The second set of pulls cost me nothing because I didn't get any useful plots. The advertised shop dyno rate is $105 per hour which I will be glad to pay when I return after the dyno gets repaired.

I have the torque monster headers. i did not know that 3 inch would be too big. i know you need some "back pressure" in order to not lose low end torque but i thought if you got a custom tune that problem would go away. Guess i will go 2.5 inch then. Or would i be better off with just one pipe and doing that 3 inch? but for 105 per hour at the dyno that seams fair, I think ill call a few shops on my area

 

[2000StreetRod]

Dynomax VT

The main reason I selected the Dynomax VT muffler is because of the spring loaded valve that controls low engine speed exhaust pressure.

Even with the high flow cats the 3 inch dia. straight thru muffler is too loud for me but I'm rather conservative. The 2.5 inch dia. Dynomax VT (17956) flows 841 cfm @ 1.5 inches of Hg. That's probably more than your 5.0L will ever output without forced induction.

 

[Kiliona]

After reflecting on the above for a while I realized that a vehicle with a 4.11:1 axle ratio will accelerate faster than a vehicle of the same bhp and weight with a 3.73:1 axle ratio. Also, a vehicle in first gear will accelerate faster than a vehicle in second gear. And finally, a vehicle with small radius tires will accelerate faster than the same vehicle with larger radius tires assuming there is adequate traction. If a dyno merely measures the acceleration and velocity of the drum to calculate power and torque then lower overall gearing would result in greater performance.

These two cars, one with smaller gears than the other, would have the exact same horsepower at the crank (as you said) and the same torque. The reason the car with bigger gears would accelerate faster is because the bigger gears make for more torque AFTER the gears (but the same at the engine). It's making the "momentum arm" longer.

A similar example would be having a person use the same force to push on a one foot wrench compared to a two foot, at the persons arm (engine) the force is the same, but on the nut/bolt (wheels), the torque is doubled (effectively).

Horsepower generally isn't as important as torque for doing work, since work is your kinectic energy times the distance moved, you can move something farther with the same kinectic energy by using leverage (torque).

BUT the two (power and torque) are related by the equation power = work divided by time.

Just figured I'd show you how to factor torque into your logic

EDIT- I just reread what I said a while ago, dont even remember writing this, but I noticed I said something incorrectly. Torque may multiply applied horsepower... but you are sacrificing distance moved (you move that 2 foot wrench further than the 1 foot wrench) and the distance and force is directly proportional. If you increase torque you decrease distance and so work goes unchanged (makes sense, since you arent adding any energy, just applying it differently, so same work done). Just thought I would correct myself. the reason torque is important is because its the application of power, not application of work, same work done, power is just used more efficiently.

 

[QueenCitySleeper]

Why are you running 12.3:1 air/fuel? Seems overly conservative for natural aspiration.

 

[2000StreetRod]

air/fuel ratio

Why are you running 12.3:1 air/fuel? Seems overly conservative for natural aspiration.

My Bosch Fuel Injection & Engine Management manual states that maximum power is achieved at air/fuel ratio of 12.6:1 (0.86 lambda) and that was my requested target for the custom tune with the Lightning MAF sensor and 75 mm throttle body. James came very close to meeting that target over most of the performance band. However, that was using high octane gas with no ethanol which is no longer easily available in my area. It was also with a fuel pressure at the rail of 62 psi. With the Stealth 340 fuel pump my intank fuel pressure regulator now limits the rail pressure to 67 psi (an increase of 8%) which results in an 8% richer mixture when the PCM is in open loop.

The stoichiometric AFR of ethanol is 9:1 and the stoichiometric AFR of gasoline is 14.7:1. For E10 ethanol-blended gasoline the stoichiometric AFR is 14.7*.9 + 9.0*.1 = 14.13:1. My wideband O2 sensor reacts to the amount of oxygen in the exhaust. The corresponding output voltage is converted by the meter into AFR assuming a certain type of fuel which is set for 100% gasoline. An AFR of 12.1:1 is a lambda of .82 (12.1/14.7) for 100% gasoline. An AFR of 11.6:1 is a lambda of .82 (11.6/14.13) for E10 fuel. So the lambdas are essentially the same assuming 10% ethanol.

I know that my A/F ratio meter will display lambda but don't yet know if it will output the value on the analog channel for data logging. If it will I will switch to lambda for the supercharger tune to simplify things. Especially since I have no way of knowing how much ethanol is actually in the fuel I purchase. Some days it might be 10% and other days it may only be 6%.

 

[2000StreetRod]

3rd speed crossover

The plot below is a segment of my 3rd speed (2nd) gear run in the stock configuration shortly after I purchased my Sport.

Notice that the torque and power plots cross at 4468 rpm instead of 5252 rpm (where they crossed in 4th speed) indicating that one or both of the numbers is bogus. The max torque is 200 @ 4100 rpm compared to 192 @ 3850 rpm for 4th speed. The max power is 179 @ 5250 rpm compared to 152 @ 4400 rpm for 4th speed. The 5R55E gear ratio in 3rd speed is 1.47:1. The max torque is inflated about 4% and the max power is inflated about 18%. The crossover point is about 18% low. It appears that Dynojet is independently determining power and torque in the manner explained in the manual.

According to the plot the power at 3750 rpm is 141. Using the formula:
torque=hp*5252/rpm > 141*5252/3750= 197 which is the same as the plot.
According to the plot the torque at 5000 rpm is 186. Using the formula:
hp=torque*rpm/5252 > 186*5000/5252= 177 which is the same as the plot.

So now I'm puzzled why the crossover is off.

 

[QueenCitySleeper]

Thank you for the detailed response. Here in Ohio we are known to be a dumping ground for bad/diluted gas. I run mine at 13.1 WOT not taking into account ethanol. Ill change to 12.6 and see how it changes power. Great knowledge here btw, and test data to back it

 

[2000StreetRod]

another dyno attempt

I went back to the dyno shop today for another attempt to get some good results forgetting it was Friday the 13th. Todd told me that last evening he got a good clean run on a BMW with no problems using a sensor around the primary wire of the ignition coil. We agreed that my main issue was engine rpm sensing but my coilpack primary wires are between the coilpack and the firewall and not really accessible. We tried using two secondary probes around a coilpack pair (3 & 4) of spark plug wires but the sensing was too erratic to attempt a pull. The dyno ignition sensor electronics automatically adjusts its sensitivity to improve noise immunity. I suspect the waste spark system varies in amplitude in a way that is incompatible with the automatic gain control. I thought about trying the primary sensor with the camshaft or crankshaft position sensor wire but suspect the dyno electronics is expecting a break of a much larger current.

Being aware that I will have to modify the PCM main wiring harness to avoid interference with the supercharger manifold I've decided to split it out now to gain access to the cylinder 1/5 trigger wire from the PCM.

I'll make sure the wire is still accessible after the supercharger installation.