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The Dyno Tells All

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Trick6

Trick6

Jedi Hopeful
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I just got back from the dyno. I did three pulls. The first developed 116 HP and 120 ftlbs at 5200 rpm. The AFR was 11.5, rich. For the second pull, we decided to remove some fuel to gain some HP. I backed out the three needles and the motor responded by loosing HP to 106 and 13.5 AFR. What a shock. The motor wants fuel and more RPM. So, we went back to rich and up to 5500 RPM it developed 118 HP at 125 ftlbs of torque at 12.25 AFR. This is quite a surprise to me. I thought that the motor would develop more HP getting closer to the 13.5 AFR area. Nope. It wants the gas, RPMs and more timing. I left the timing. I do not rely on the timing marks. I advance the dizzy until it pings and back off a degree or two until it stops. I should have asked what the timing was peaking at but I didn’t. No matter.

I think that this is all I can get out of this motor with the GP2 cam, carbs and exhaust manifold. I made the mistake of not having cam bearing installed during the rebuild so I am locked in with a fairly mild cam. It surely feels better that 118 HP. It is the 125 ftlbs of torque that is kicking.

I will have to be satisfied with this HP for now until I do a complete motor conversion which is in the programming/planning phase. Next year or so.

Please click on the link below for the components of the motor.
 
Bummer, right, but now Al knows for sure whats going on, gotta be worth something!

Tinkerman
 
Boy, 118 sure sounds good to ME right now! I think I'm probably kicking around somewhere down in the low 80's at best. I gotta git me one o' them new fangled souped up injuns! (or at least tune up my current set-up)
 
Tinkerman:
Right you are. I do know exacly where I am and can advise others. I must admit that I had expected a little more HP but the torque is what is moving the car. You've got to love the torque. I also know that leaning my engine makes it unhappy. So we don't have to go that route.

Now if one wants more than 120 HP or so from the TR6 motor, you have to consider FORCED INDUCTION. The motor has built in restrictions that are expensive to overcome.

IThe car is the geatest and right now it is fast enough, but I do want a little more HP. If I add 15% for drive train loos the HP is up to a modest 135 at the flywheel. Not too bad.
 
tosoutherncars said:
Not too shabby at all! HP sells cars... torque wins races! :smile:
Click to expand...

Not true. Read this to find out what is really happening.

Horsepower is a calculated figure using the torque curve over an RPM band. It takes time into consideration that the torque figure does not. The article cites of couple of cases including a water wheel from a grist mill putting out 2600 ft/lbs of torque and two Corvette engines with the same torque, but one has more horsepower...guess which wins out! I'll take the higher HP figure everytime.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Isn't Paul making more than that?[/QUOTE]

Don,

If you meant me as that Paul, I really don't know. I won't be getting into the Dyno for another month or so. I get to go with the local MG Club, so I wait for their scheduled day.

I'm going to guess that I'll probably be about the same as Al. I know that my car runs so much better (and it was never a dog) that I really don't care about the numbers from the dyne with one exception. The fuel mixture. I don't want to be too rich or too lean. The rest will work out.

Going in this time, I have my own A/F ratio meter. I know that the 90 degree angle in the TR6 stock tailpipe can cause some bogus readings, so I can now tweak the carbs between pulls. I'm currently showing that I'm at 11.7-11.8 at WOT, which is about .8 higher than I would like to be at full open. Oddly, my plugs look more like I'm a tiny bit lean, but I know that I'm at exactly 12BTDC at idle, 36 degrees total advance at 3,500 RPMS and the electronic ignition is working just fine.

I plan to run mine to 5,500 for the initial runs and then to 6,000 if I have enough miles on it by then.
 
I thought somebody did a dyno run already. I remember Alan did his Fueley,but I thought somebody else did too with HP #'s.
 
martx-5 said:
tosoutherncars said:
Not too shabby at all! HP sells cars... torque wins races! :smile:
Click to expand...

I'll take the higher HP figure everytime.
Click to expand...

I read through the whole page and what I came away with, for a real world situation car, is that you can't beat a high torque number, at a moderately high rpm, with a very flat torque curve. Since the HP number is derived mathematically you'll still get a high HP engine with the above scenario. But its torque at rpm that get you that HP number. But you have to be careful, high rpm and high hp engines have real world drive-ability problems that high torque and lower HP engines don't.
 
tdskip:
Last time I was at the dyno the motor was very fat (rich). Tweaking the needles did nothing as to changing the AFR nor HP. I checked the needles and found that all three were B1ARs. Using the nifty chart supplied by Rich Good, I determined that these were far richer than the stock B1AFs. So I found the stockers and put them in. The other thing that was a surprise was the motor likes the points better than the Petronix. It just seemed to like the dwell set right on the mark. So I now have a mechanically controlled dizzy and points. The motor seemed to respond with a smile and the car felt much better pulling into the higher numbers.

The plugs went from dark sooty to just right, and like Brosky, if not reading a little lean. I was happy with what I saw on the plugs. Time for the dyno again.

Now to answer your question, I was expecting a HP reading in the 120s. Seeing that I was still rich on the first pull (116 HP) today I felt pretty good yet a little puzzled because of the plug reading. But I happily adjusted the needles leaning it out a bit. I had to go back to rich as I stated earlier.

I now don’t think that there is much ore to gain with the set up I have. I am looking forward to Brosky’s pulls.
 
Two questions:

What sort of dyno - there is a big difference between a Mustang and a DynoJet when it comes to #s. If it wasn't the same type between runs then it's easy to get huge swings.

Were both sets of #s corrected? Properly...
The difference can be surprising on a warm day.
 
The dyno used was the Dynapack. This type of dyno replaces the wheels. The Mustang that you referred to is the roller type, as you know. It was hot (88 degrees) and humid (67%) in the shop. This does play a factor. There is more HP on a dry cool day. I hate it when it rains on dyno day.

Two years ago I went to two different dyno shops, this one with the Dynapack and another with a Mustang. I had a different motor/carb set up then. However, the runs were a month apart but the results were very close. I have the sheets for those results also. I prefer this shop because they allowed me to tweak things a little and do not rush me in and out.

Check them out at this link.
https://www.xxtuning.com/
 
Here's Al all hooked up!

AlDynoRear2.jpg


AlDynohub2.jpg
 
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