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Is this dyno run odd?

2K views 8 replies 8 participants last post by  Racer 
#1 ·
Here is 2 seperate dyno runs on my old openchamber headed 351 before i went alloy heads. It was a bit of a missmatched setup, so didnt quite go as good as expected. The question is, does the first dyno chart seem wierd with the torque figures, and also i thought power and torque were supposed to cross at 5250 rpm or close to??
 

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#2 ·
I think its odd on the first one where the torque drops off but I am guessing thats the histall playing funny buggers. One of my dyno charts has a loop @ the start due to the histall. They forgot what size it was.

On the second one the power curve is amazing semi straight! Your A/F's close but something weird happens up high. Prob a mismatched carb?

The only thing I find ordinary is that a 351 did that poorly. I've seen mild 302C's with the same power.

Brenden
 
#4 ·
thats probably an excellent point falcon coupe, xdclevo, where did you go for the dyno run and how much did it cost, did you go to SSV? (lee hollman or something or other, that guy) hehe. Thanks
 
#5 ·
I have a query about the 850 ft/lbs of tq @ 2000rpm and even 600 @ 6000 on the 1st sheet, that HAS to be way out to lunch!! Than much torque would have launched you out the dyno shop!! Definitely ask him about that one.

With an A/F ratio eyeball average of about 12.7, you could probably go smaller on the jets, leaning up and getting more power. Ideal power A/F is about 13.2:1.

Depending on what carb you are running (eg 750HP Pro, not sure on others), the air bleed screws can be changed to let a little more air in and refine the A/F ratio up the RPM range.

Since water is not able to be burned, increased humidity means that this water will displace a certain amount of the oxygen molecules in the air which will reduce the amount of fuel molecules needed to maintain the air/fuel ratio. This will produce a weaker combustion process leading to a significant horsepower loss. ie: humid day = rich, dry day = lean, if perfectly jetted for an "average" day!

Cheers
 
#6 ·
XDman, the first was from Holmans and the second was Cape york autos. It seems most of the hoons have been going to the second, so its easier to compare apples to apples. The two were fairly close, as the first was about 220 at the wheels and i did get the jetting closer and a few other things, so they did compare pretty close.
The torque thing does seem strange, but it was a very torquey motor. I have raced 2 guys that had just under 300 hp at the wheels and had no trouble beating them. Our drivelines were similar, and one was a HSV 355 stroker with a supercharger on it, and i thought he kept missing the start, but then he come along side me and said he wont worry about anymore runs. It was one dissapointed holden owner. Strike another for the fords.
 
#7 ·
xdclevo said:
The torque thing does seem strange, but it was a very torquey motor. I have raced 2 guys that had just under 300 hp at the wheels and had no trouble beating them.
remember:

"Horsepower sells cars - Torque wins motor races"

Also, "Go the Cairns Henries!"
What does your XD look like? I may have seen it around
 
#9 ·
davis said:
Yes it is odd...to the point of complete disbelief. It shows that you are making 850 TQ at 2000 RPM. That's enough for me to be skeptical.

:davis:
I think "torque" on those things is supposedly rear wheel torque, which would have to be divided by the diff ratio. ie: about a third to a quarter.
 
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