Dyno Charts Thread

[scottj]

Originally Posted by AL427SBF

That's a little different, looks like your HP and Torque intersect at ~5600 RPM.

They intersect at ~5600, but the values are not equal at that point. At 5250 the values are equal.

[AL427SBF]

Originally Posted by scottj

They intersect at ~5600, but the values are not equal at that point. At 5250 the values are equal.

yep, I just noticed the HP & Torque scales are different on each side of the graph. Nor does your RPM scale follow normal convention (n x 1000), that is one funky dyno plot, but a dyno plot it is

[AL427SBF]

Originally Posted by tcrist

Well I was going to post them. Had them my photos and tried to post them but they were so blurry they were unreadable.

Screw it.

well, when you look at her curves what do you see ...

42-24-32
36-24-36
34-24-38

[tcrist]

Ok, Cropped them and that did help.

[AL427SBF]

I like your torque curve, pretty flat/smooth in the 3K-4.7K range, makes the mountain twisties manageable and fun. No Dolly Parton there, but I see a little Jennifer Lopez

[undy]

...found an old chassis dyno for the Cobra.

[AL427SBF]

That's a pretty interesting comparison between the two dyno runs. Peak HP and Torque virtually the same and from 4000 to 6200 the curves lay on top of each other. Below 4K it's a different matter. I'm assuming you did a carb tweak or something to improve low end torque at the expense of some low end HP? Hard to tell with the color resolution of the actual graphs (order of the runs). If it were me, the Torque ramp starting at 2200 is where I would have left things - the tune I would be looking for.

[twin turbo]

[tcrist]

Originally Posted by AL427SBF

I like your torque curve, pretty flat/smooth in the 3K-4.7K range, makes the mountain twisties manageable and fun. No Dolly Parton there, but I see a little Jennifer Lopez

Nothing wrong with Jennifer Lopez. Had a few Dolly Parton's before. Really tempermental. Especially the MENTAL part.

[AL427SBF]

twin turbo you have a real beast, incredible power and the torque looks down right scary. I'm sure 9's easy with a decent track, trap speed killer too.


tcrist, I would rather have J.Lo as my main squeeze

[undy]

Originally Posted by AL427SBF

That's a pretty interesting comparison between the two dyno runs. Peak HP and Torque virtually the same and from 4000 to 6200 the curves lay on top of each other. Below 4K it's a different matter. I'm assuming you did a carb tweak or something to improve low end torque at the expense of some low end HP? Hard to tell with the color resolution of the actual graphs (order of the runs). If it were me, the Torque ramp starting at 2200 is where I would have left things - the tune I would be looking for.

Carb tweaks and linkage adjustments...

I running twin Quick Fuel 750s on a tunnel wedge. I also think the go-fast pedal got mashed at different RPMs and the vacuum secondaries took a moment to open all the way. The larger CFM carbs causes the secondaries to be a bit more sluggish than, say twin 600s.

[AL427SBF]

Originally Posted by undy

Carb tweaks and linkage adjustments...

I running twin Quick Fuel 750s on a tunnel wedge. I also think the go-fast pedal got mashed at different RPMs and the vacuum secondaries took a moment to open all the way. The larger CFM carbs causes the secondaries to be a bit more sluggish than, say twin 600s.

Great example of some quick carb tweaks and how that can move the power around, those runs were about 10 minutes apart.

[scootter]

Here's mine after I rebuilt the Ford Crate 514 after 13k miles on the chassis dyno.

[AL427SBF]

RW numbers so pretty nice scooter, building power all the way up.
What do the 3 runs signify?

Run 1: Before?
Run 2: After?
Run 3: The Triangle Plot?

[scootter]

The triangle plot is supposed to be typical. I was surprised it made that much power as I changed the cam from roller mechanical, to flat hydraulic. The original cam was like 605/615 and if I remember right the new one is 590/605. Since those runs, I changed the carb from the HP4150 1050 CFM to the BG Demon 850. Can't tell much at the bottom, but sure can at top end.
Scott

[AL427SBF]

Definitely some sweet power there, with 1050 CFM I would think you were over-carbed, the BG Demon 850 makes more sense to me on your 514. In talking to some builders, over carbing these stroked motors seems to be a common thing. Throttle response doesn't seem to get due consideration along with the rest of it, many things to consider when selecting your carb.

[undy]

Just curious...

How many are posting standard numbers versus SAE?

[bobcowan]

This one was done a few years ago. The engine has gone through a number of changes since then, which have added power. The last dyno tune showed 510 peak hp. But I just made some big changes that probably decreased power a bit; but it hasn't been to the dyno yet. In any case I like this one because of the comparison.

The initial test was done with "Tea Strainer" filters on the stacks. Then we popped the air cleaners off and did another run right away. No other changes, just removed the tea strainers. The difference is nearly 100HP! Looking at the AFR curve, I suspect that you could gain some of that power back by leaning out the mixture a bit. But I doubt you'd get 100hp. I doubt you'd even get 50hp. Those filters are really restrictive.

[AL427SBF]

Very interesting Bob, the guys running stacks thinking and I bet the same may apply to any intake filtering. Wonder what the solution is, I have to believe those filters are already "hi-flow", don't think running your stacks open is the solution either.

[bobcowan]

On the track I leave the stacks open. On the street I use these 4 oval K&N filters. I'm sure they cost me some power, but there's plenty to go around.



Pierce Manifolds sells a SS mesh filter that they claim has "virtually no air flow resistance." One of these days, I'll spend the $200 for them, I like the look.