This thread has taken a bit of a detour....... but.....

572 I built, 918 on the engine dyno, 778 on the dynojet.

8.33@165, @2700lbs

Shows 930 on the moroso chart

yep slight detour, thats interesting, more hp than the engine dyno, normally reverse of that, but thats the BIG mph, light car doing that I presume, 165 would normally be 8 teens.....I made it 988.

That looks strange to me too. I would think smoking the tires on the dyno? Were you running street tires or race tires?

I was posting my results just to say not to get discouraged w/ low numbers from a chassis dyno. Always felt like my car ran a lot better than the chassis dyno numbers would suggest...considering the crap you see blasted all over the internet and magazines.

When it comes to racing and car stories I always try to remember the old adage about believe nothing you hear and only half of what you see

Here's an ancient sheet of mine from Jake's for comparison.

It would do me some good to head back there.

I don't really dig the spike in the curve from the original post, I have no idea what is going on with that but maybe someone does. If that was mine, that would be the first thing I'd point at and ask questions about.

That 5th Avenue big block sounds cool as heck, I'd really like to check that out sometime.

zippy, what converter is in your car?

It's a tighter than normal turbo action "J", 9". Originally it was custom built for a much more radical combination. Around 4400-4600 in this car, feels surprisingly tight on the street and can be easily driven normally without alot of slippage at light throttle, etc.

I know the dyno sheet can be configured differently than what the OP has shown.

I’d like to see a graph where the x axis is speed(mph), and another where it’s time(seconds).

Those should give a much better illustration of how the converter is behaving.

When the converter is pretty loose, and you’re using time or speed as the x axis....... the torque line will just go pretty much straight up at the hit of the throttle.....then kind of flat line until the driveshaft speed more or less catches up with the motor.

Thats interesting, that shows about 16% drop from moroso slide to wheel. & about 15% from dyno to wheel, all very close. very cool

Another thing to keep in mind when looking at chassis dyno results, from an inertia dyno, especially when a fairly high stall converter is used...... the data on the sheet starts when the button is pushed, which is often prior the gas pedal hitting the floor.
In that scenario, the numbers on the sheet below stall speed are at less that wot.

This is how you can end up with these oddly shaped graphs.

It’s not the same type of test as if there were a load cell and the throttle could be opened, the load stabilized against the brake, then released....... so that all data on the “run” would be at wot....... and the bottom of the run would start at stall speed(which could easily be at a higher rpm than where the motor makes peak tq).

Absolutely, send me a PM. I'd be game for hanging out sometime.

So the most likely culprit is the converter then. I'm open to opinions on what to run. It's a bit weird since I have a lock-up 46RH transmission in the car. Current gear is 4.10, but I wouldn't mind going back down to a 3.23 providing I can get that torque curve where it should be.

I'm looking at a track day next month also. I'll have time slips before I spend anymore money on parts.

Thanks guys.

See if Jake can email you another sheet or two where the x axis’ are speed and time.

Do you know if the button to start recording was pushed before or after getting to wot?

My “opinion” on it is...... if the motor were tested on an engine dyno, the numbers......as well as the shape of the curve....... would look very similar to the sheet I posted.

A drum-RPM vs Engine-RPM comparison could show if there's any transmission or tire slip on the dyno.

In what gear was the run made?
Haven't seen it mentioned but I presume it's not a manual valve transmission, so maybe the throttle linkage is/was adjusted back a little too much to prevent a downshift during the run?

low gears and loose converters can give lower than expected numbers.

This is a pretty good read:

https://www.google.com/amp/s/www.hotrod.com/articles/hrdp-0405-chassis-dyno-guide/amp/

I've had my Dart on a hub-mounted Eddy-dyno about 3 sessions already.
It at least takes out the possible tire-slip (not that the engine in the car would be able to spin the wheels on a regular dyno that is...).

The HP and torque cross at 5,252 - always, they're supposed to (if using std. notation).
What reason is there for violent peak torque at the same place: 5,252?
None I ever heard of - tht's very close to the point of maximum VE.
With that small a cam, torque should be nearly flat from 3,500 up (not 200 @ 3,500) and fade slowly after 5,000 (the curves after 5,252 look possible if disappointing).
I don't know what a bad (mechanically failing) converter will do, but I never heard of a converter that sucked up 50% of the power @ 3,500 RPM (200 vs. 400).

If you look at the runs zippy posted, the curve starts down under 3000rpm, and shows about 200ft/lbs.
Obviously that part of the recorded data is not taken at wot....... since the car has a 4600 converter.

Any data under the stall speed is not an accurate picture of the power at wot....... since you can’t be at wot and under the stall speed at the same time.

A quote from the article in the link: