psyber_0ptix

iTrader: (4)

Holy ****. that spacer makes things pretty interesting. It's piqued my interest now.

matrussell122

iTrader: (1)

And now this has my attention. Might have to go this route now. Numbers look really goodI wonder what it would look like when running 25+psi?

Colipto

Well.. attention = caught = buying after winter, wondering how e85 added into this mix changes things
I only made it to about 17psi before and made 350... Always wanted to try a yolo 25+ pull

phocup

Thanks. This is really good data. That 15PSI with spacer graph is what pique my interest the most. Looks like gains EVERYWHERE vs flat top with more boost.

ridethecliche

iTrader: (2)

Why couldn't you have done this before I bought a Squaretop!? 😂😂😂

Thanks for the data. This is awesome!

HmoobDude

Postcats! This has definitely piqued my interest a bit more. Thanks for the data and for doing this.

nitrodann

first run looks like a car that couldnt stay up on the front dyno roller vs a car that kept off of the rear roller.

Mudflap

What does that mean?

nitrodann

So on a standard roller dyno there are 2 rollers, and only the front roller reads your output.

When the car has enough wheel torque to pull itself onto the front roller and up off of the rear roller the car is only accelerating the front roller, the roller which measures the wheel torque and speed. The rear roller weights shitloads and the inertia causes the dyno reading to be lower if the cars driven wheels are sitting against it.

On a dyno dynamics a full bolt ons MSM only JUST has enough wheel torque to pull itself from the rear roller mid run and then falls back into the rear roller at 6000 rpm or so. When it falls back into the rear roller the power reading dramatically drops as the car now has to work against the inertia of the passive rear roller as well as push against the dyno brake on the front roller.

The first dyno run looks like a car which JUST makes it off the rear roller but then falls back against it after peak torque. The 2nd run looks like it has a tiny bit more torque up top, just enough to keep it off of the rear roller. On my dyno the rear roller inertia absorbs around 20rwhp.

For cars which fall back into the roller I always get a 2nd person to push the rear of the car forward to keep it from falling back and giving a false reading.

Check this clip, youll see that the car is off the rear roller and falls back on when the tuner lifts off the gas. If the car only JUST has enough torque to pull itself up it will fall back down on its own when the torque starts falling off up near the redline. This affects the dyno graph significantly.

(skip to 1.48)


Dann

Mudflap

Very interesting. So you are saying it looks like (the red plot, VCTS) is falling on its face at 6000-6200 (around 250). And you think a portion (or all) of that drop off is due to the rear wheel dropping back onto the rear roller?

But when I review all of the plots together, I'm not so sure. It looks like the two cases track very closely in power and then the VCTS falls on its face.

But on the other hand I can see how if the VCTS manifold trailed off slightly, that would then cause it to sit down and then record much larger drops in hp.

So if I can try and read way too far into your very simple initial statement, the VCTS may NOT be losing as much power as the graph shows (70-80 hp and torques)?

Ken Hill

I did not mention the type of dyno used in my first post. All runs were made on the single roller Dynojet at www.APTuning.com. One of the features of a Dynojet dyno is its repeatability. The power difference is in no way a function or fault of the dyno.

nitrodann

Gottcha, thanks for clearing that up.

Interesting results that I would not have predicted.