DUI 170 Dyno Results - Interpretations Please.

[fxp]

You may remember I did a dyno run when I installed the headers, that showed some handy gains. http://fordsix.com/forum/viewtopic.php?t=39873

Well the next stage was installation of the DUI. Essentially the car is unchanged from the header runs, bar the dizzy. The run sheet is here below.

There's good news and bad news, that might need someone with a bit more knowledge to interpret. So I'll give you the bad news first. The peak HP LOST 2.3HP! Huh? Three runs in D and all the same result. Talking with the guy, the theory is that the stock carb just can't deliver the fuel. The results showed a lot leaner burn which you would expect.

Anyway like I said there is good and bad news. The loss at peak HP was in Drive. Everywhere else the results are startling. In Low the peak HP moved up from 41.4 to 51.5! (ie up more than 24%). The power comes on way earlier as you can see and gives a much flatter curve. There is more power than the old peak from before the original curve even showed up all the way past the original peak. Torque in low is insane. Up from originally measured 410 ft-lb to a peak of around 700 ft-lb! (70%). Again comes in much earlier and the curve is never below the original peak.

In D the torque is again improved with the peak going from about 315 ft-lb to 370 (17% gain). Again coming in much much earlier. The power curve in D isn't all bad news either. As with all the other results the curve comes in much earlier and flatter. It's making power through a much wider rev range.

As I said, on first look it would seem that the carb can't deliver the fuel, although seeing as the engine's doing the same revs in L as in D (just slower speed) maybe that ain't it at all. I'd be interested in the analysis of a few other more experienced operators.

Anyway that's the numbers. On the qualitative measurements you can feel the extra power and torque low down. The idle is smoothed right out. I can now set the idle down to 600, whereas with the points even at 750rpm it was rough. The next step for me is a weber carb, so I'm hoping that will help richen up the mixture and get more of the benefit of the DUI.

 

[addo]

It's odd. The falloff at your top end looks normal enough - perhaps some heat soak plus inadequate cooling, took the edge off your second time about it?

Is there any possibility the tranny is slipping to produce those wiggles? Just after the 96km/h point, the two curves look extremely similar (suggesting similar fuelling), but the later run is at lowered road speed...

If you can get a US small style C-4 bell shipped over, could try a new trans.

 

[inline300]

Average HP and TQ improvement are best vs peak, so it wasnt bad at all, just more to be had via tune, to get the peak back up.


If youve posted a graph or picture, I dont see it anywhere.

 

[falcon fanatic]

timing? Did you tweak timing while on the dyno for optimum power?

 

[blueroo]

Did I read you right? 51.5hp and 700 ft lbs of torque?

 

[rommaster2]

Did I read you right? 51.5hp and 700 ft lbs of torque?

I think that the torque is because of the gearing. Just like with my friends jeep when he puts in a new transfer case it will make the torque at the wheels in 4 wheel drive low somewhere like 3,000 ft lbs. Its all in low gearing though, so it can only go so far.

 

[addo]

Here's the graph - maybe our man's link is down.

 

[65coupei6]

Here in the states we use SAE but not down under. That is why the torque is so high.

 

[blueroo]

I know the measurements are different, but I'm used to seeing nm and kw for down under.

What would the SAE ratings be for the curiosity of the "dumb American" here.

 

[Bort62]

What is your rear end gear?

 

[66 Fastback]

The high torque numbers would be a reflection of gearing. I don't know what the 170 ci engine put out or what the gearing in the car is but the 200 ci put out 120 hp and 190 ft-lbs (gross). Assume the net torque reading would be 80% of the peak and the engine is putting out about 150 ft-lbs. In drive, I think a lot of automatics had a final drive ratio in the range of 2.80:1. That would give you a torque reading at the wheels of around 420 ft lbs before additional drivetrain losses. The 170 engine would put out a bit less, so readings of 360 ft-lbs would seem logical. First gear is going to have an overall gear ratio that is about double the final drive gear ratio with more efficiency losses. So 700 ft-lbs looks about right.

Unless I am reading the wrong curves, I find it interesting that the curves all shifted substantially to the left. Peak torque is in at a speed that is about 30 kph lower than it was on the prior dyno run. Basically you have more torque and HP earlier in the rpm band than you did before. Either that or they just recorded more low rpm readings this time.
Doug

 

[addo]

I think his rear gearset is 3.50:1. Either that or 3.20:1

 

[fxp]

Sorry, been away from the computer for a while. The diff is a 3.2:1.

66 Fastback is right about the raw numbers I suspect, he's also right about the comparison. The torque and power is coming in much earlier. The actual number I don't think is so important, it's the gain. The simple change from points to DUI has hugely increased the torque available, and brought it in where you need it for normal driving.

The power in high is the baffler. Falcon Fanatic - no didn't tweak the timing for power. I put the DUI in set it to 14deg BTDC @ 600rpm (no vac connected) and then took it for the dyno runs. Now this might also give us a possible explanation, as I subsequently found the engine pinged a little climbing hills. It was good on the flat - and the accelleration was . But maybe it was pinging on the dyno? (I couldn't hear anything). Would this drop the peak power? Strange if it was doing it in D and not L (or is this not so strange?). Ideas?

 

[ASMART]

Looking at the picture make me think that the torque reading is being taken from the wrong curve. Torque and HP is on the same grapch butthe curves for Torque are the ones near the bottom. The numbers are still unbelievably huge but closer to something you would expect. For example, the lower curve that matches the color of "Drive before" has a peak of 300ft lb.

 

[wallaka]

I think that you are correct. If you take the bottom curves (for top gear) and divide by the 3.2 differential ratio, you get reasonable torque numbers. About 115 ft/lbs for after and 90 or so for before. That sounds very accurate for a 170.

A C4 has 1:1 in top gear, so it is left out. First is something like 2.46. You could divide by 2.46 and 3.2 on the first gear numbers to get an approximation, but the fudge factor would make the numbers even less accurate than the guesstimations with the gop gear run..

Top gear has less friction as well, which affects the torque readings. Still, there may be up to 20% losses due to driveline inefficiencies. Actual torque at the crank could be about 140 lb/ft.

 

[Bort62]

I think you guys are correct. That makes a whole lot more sense.

IMO this looks like a Fischer-Price Dyno. I put my camaro on one once like this and the results were so convoluted it was worthless. If the guy can't clearly give you HP and Torque Vs. RPM, then there is a lack of compitence involved. I would go someplace else for your next attempt.

I do like the info however. It is great to see step by step what is happening.

 

[fxp]

Looking at the picture make me think that the torque reading is being taken from the wrong curve. Torque and HP is on the same grapch butthe curves for Torque are the ones near the bottom. The numbers are still unbelievably huge but closer to something you would expect. For example, the lower curve that matches the color of "Drive before" has a peak of 300ft lb.

No. The dashed lines are torque, the solid lines are HP. The different colours differentiate the different runs. Look at the original thread and you'll see the original run results (the before runs on this sheet).

It's not a Mickey Mouse dyno. Showing the runs as kph instead of rpm makes it easier to differentiate between the D and L. I'm not really interested in optimising the engine for a particular rev range, just measuring what happens at each point when you make a sequence of modifications. The kph and runs in D and L gives a better 'on the road' reading for me. I can estimate the revs pretty easy. I'll sit down tomorrow and do that.

I reckon the explanation of the 70% gain in L can be explained by the gearing (happy to be set straight if wrong). The L gear is (with torque converter multiplication) 4.6 - 2.3:1. The torque gain in L is about 4 times the torque gain in D (1:1), so that sounds about right for the same torque gain at the flywheel. The 17% in D divided by the diff ratio is a bit over 5% (not including gearing losses) which is far from an outrageous number, but still not too bad for a bolt on mod.

So that leaves the peak HP loss in D? Possible causes so far: fuel starvation, heat soak, tranny slip, pinging. Any other possible culprits?

The heat might be a factor Addo, but it wasn't overly hot on either run (mid to high 20's) and we had a big fan blowing into the rad. Tranny slip - why on one run and not the original? We ran the D three times and the three peaks were all within .2 HP. I'm starting to suspect ping, but I don't know enough to be sure. Would pinging drop the HP? - I'm assuming it must.

 

[addo]

Sure, pinging affects power.

I too, like the road speed indication - but it would be nice to see tacho correlation as well - certainly losses would be easily quantified. Also some exhaust sniffer readings for AFR.

 

[66 Fastback]

I have no dyno experience, but....
Pinging / detonation is an indication that the ignition timing is not at its optimum and the spark is occurring too early, so it is reasonable to assume that it would decrease the HP output.
Doug

 

[Bort62]

I still maintain that the fact that there is so much guesswork involved in deciphering the dyno is making this harder than it needs to be.

Every dyno run i've dealt with was performed in 1:1 gear with HP and torque Vs rpm. If you don't have the direct data you want, you lose a lot of the information doing exactly what everyone is doing right now... trying to figure out exactly what the dyno means.