Dyno'd my Duster 340 how did I do?

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71blueduster

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Went with some other Mopar guys and dyno'd our cars on a Mustang Dyno. I put down 220 hp and 232 lb-ft which calculates out to 340 hp and 357 lb-ft at the engine. That's without tuning in the carb and the timing, which I know the timing can be optimized and they also said my converter is flashing too high and I'm losing some peak torque because of it.

Engine specs:
340 bored .030, stock x heads, Comp XE268, RPM air gap, 9.5:1 compression, 670 Street Avenger carb (which I swapped on the week before I dyno'd), headers, stock type electronic ignition

Dynosheet220hp.jpg


Dynosheet220hp.jpg


Dynosheet220hp.jpg
 
The torque is a bit low, thats the waviest dyno chart ive ever seen lol. Pretty good though, get it out to the track. my 318 dynoed 250rwhp/280rwtq uncorrected. They said it was 284rwhp corrected for whatever thats worth, should be around low 14s or so too. Go run it!
-Mike
 
It looks like you are a little on the lean side, there might be some more in her if you richen it up.


Chuck
 
Hello,
Great setup. It's similar to my current project. 1980 Volare, 360, Comp Cams XE262 cam, SpeedPro H116CP pistons, 596 heads topped off with a TQ carb and a 727 transmission with 2800 stall with 3.21 sure grip.
However, I'm caught in a dilemna. According to guys I've spoken to at swap meets, my intake manifold choice, an Edelbrock Performer, will not make the power I'm expecting. Having said that, I also have available a stock cast iron 1970 340 intake manifold, and a Weiand 8007. I've been told the stock cast iron 340 intake manifold will outflow them all. Any opinion will help with these final steps to completing my project.
 
I've never seena dyno trace like that that wasnt dismissed as "something's messed up with the dyno..." It should be a smooth trace, not a hueg sweap back and forth. Converting from wheel to crank is still an approximate. But the ratio is roughly 1 to 1.2 for autos, 1 to 1.15 for sticks. Or, 264hp, 278tq. I think that's low. that package should be closer to 325hp 380tq if what you say is in there and in right. I would try tuning it a bit. I cant see the number well enough to say what direction to try. Just that you should try something. That reading is low. Even if the dyno was stingy, that's low.
 
moper said:
I've never seena dyno trace like that that wasnt dismissed as "something's messed up with the dyno..." It should be a smooth trace, not a hueg sweap back and forth. Converting from wheel to crank is still an approximate. But the ratio is roughly 1 to 1.2 for autos, 1 to 1.15 for sticks. Or, 264hp, 278tq. I think that's low. that package should be closer to 325hp 380tq if what you say is in there and in right. I would try tuning it a bit. I cant see the number well enough to say what direction to try. Just that you should try something. That reading is low. Even if the dyno was stingy, that's low.
Click to expand...

I think all of the dyno charts ended up wavy for everyone that dyno'd for some reason. And when they gave the printouts, they said to estimate the engine numbers by dividing the whp by 0.65. This is to account for drivetrain losses and the fact that the mustang dyno reads 15-20% lower hp. Dividing the 220 whp by 0.65 gives approximately 340 hp.

A friend that had a built 440 with aluminum heads, and a Mopar 509 cam, and some other good stuff and put out 308 hp after they tuned it, so if you would only multiply that by 1.15 he's putting out less than a stock 440 should make, which is definitly not the case.

I know I need to get everything tuned in. They said I was losing peak torque, because my converter was flashing too high. The carb is still in the out of the box settings besides float level and idle mixture, ect. and the timing definitly needs worked on. All I know is I have the initial set to around 10 and I don't know how fast it advances or the total timing. I'll probably mess around with a better distributer and have them tune everything in on the dyno sometime in the future.
 
the 1/4 mile dyno is more fun, maybe cheaper. Take it to the track and lean on it and you can get a real world h/p figure. Plus you have time there to make some changes and see how they affect your et and your not under the gun like on someones dyno. JMO
 
As I found out - Mustang dynos are very stingy - thats why we don't race dyno #s.
 
Interesting. I learn something every day. I've never used a Mustang dyno before. I will say the power levels indicate in both cases that improvmetns can be made. You cannot anticipate power levels well unless every facet of the work is know. I know a lot of "400hp" engines that dont make over 320 because the sum of the parts is not the total of the magazine writeups. Race one of the cars on a track and post it. I'd be very interested in the results.
 
moper said:
Interesting. I learn something every day. I've never used a Mustang dyno before. I will say the power levels indicate in both cases that improvmetns can be made. You cannot anticipate power levels well unless every facet of the work is know. I know a lot of "400hp" engines that dont make over 320 because the sum of the parts is not the total of the magazine writeups. Race one of the cars on a track and post it. I'd be very interested in the results.
Click to expand...

When we built my engine, I followed the 400 hp 340 article I found, but I always figured my engine would probably make around 350. And with dynoing my car this time, and knowing it can be tuned better, I know I should be close if not a little above it.
 
I have the exact setup as you, other than a 750 holley and 1000 over stock converter (whatever that is? 2800 I guess) and I would be happy with 350 to 360 horses, I used the same article with mopar performance springs. Walt:hello2:
 
You do want to be careful following "recipe builds". Because you use the same parts, does not gaurantee the same power. The difference between two identical builds by two different shops, is usually quite dramatic. The better equipped/more knowlegable machinist will always make much more power than the guy who orders the parts and assembles it carefully but perhaps uses older equipment and older techniques together when the same parts are used.
 
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