mk3cn4

iTrader: (3)

I am in need of some raw data to help our little Ls1 community.

I have a nearly stock 98Z A4 (Lid and Vig 3600).

PRIOR to the Vig, I took it to the track and logged several runs, including RPM, MPH, Shiftpoints, etc etc. This locks me in to what RPM my stock stall was at any given MPH. Did the same AFTER the Vig install.

I keep seeing opinions on how bad this Vig slips when running someone on a roll, nobody really has real data to prove it, and I think I can prove exactly how much is lost. But, I need some help.

The problem is that dyno runs measure HP@RPM. Stick with me here, I want to measure HP at any given MPH instead (AT THE REAR WHEELS, this part is important).

So, I am looking for a dyno graph (at the rear wheels) of a nearly stock Z28 WITH A VIG 3600 INSTALLED THAT'S NOT CORRECTED for having a stall. This is the only piece I need.

I can then do a "MPH ADJUST" and show that, say, on a roll at 50MPH at WOT I had X horsepower at the rear wheels (at a much different RPM than stock of course) for both stock and stalled, and graph HP at rear wheels throughout the whole 0-100mph run for both stalled and non-stalled.

This would solve the question once and for all EXACTLY how much is lost higher up with a VIG, and if it works out we can do the same with yanks etc etc...

So, is my logic valid, and does anyone have a non-Corrected dyno run of a nearly stock Z with a Vig3600 (to match up all my data)?

Opinions also welcome.

jimmyblue

iTrader: (11)

I believe the dyno could be made to output the data
you want but nobody asks for it. The roller HP is really
a derivative of the roller speed.

I have logged direct acceleration g across unlock / lock
which is another way to go. Can see that at 5000RPM
I'm still better off unlocked with my converter. It comes
down to how torque multiplication rolls off and efficiency
rolls on. Mine was spec'd for max efficiency and wide
range of torque mult (low STR taken as a result).

Just two back-back pulls and take the scan tool MPH
data, clip it for the same "starting" MPH (like say bottom
of 2nd, 40MPH) and scatter-plot the MPH vs delta-time
in Excel will show you the relative acceleration produced
if you don't have an accelerometer. Massaging for some
finer value like d(VSS pulses) vs MPH might give you more
of a clean plot (MPH will be "notchy" and any dMPH/MPH
have a lot of zero points). Getting to a dVSS/MPH scatter
should let you pick out the crossover point pretty closely.

An old model red-LED G-Tech may just be laying around
and make a fine "free" accelerometer that you can log via
analog cable or through something like A/C pressure port.
Then you'd have even cleaner data to compare. I put up
a post a few months back showing how to pigtail out the
G-Tech's accelerometer IC signals.

mk3cn4

iTrader: (3)

Is it possible that this was an illusion to you?

Maybe @ 5k rpm unlocked since your MPH was way lower, there was an effect almost like a lower gear? So stalled 5k appeared to have more "power" not due to lock/unlock but because it was way lower MPH when you measured it? Or wind resistance was lower? Not sure, but I bet the MPH's were pretty different stock to stalled.

This is what I am trying to weed out. I want to plot a full HP sweep of deep low 2nd up and past the 2-3 shift for both HIGH STALL and STOCK STALL but tying HP to mph, NOT RPM. I can then tie the horsepower @ any given mph to my 2 graphs of STOCK STALL and HIGH STALL and watch the curves of power at MPH.

Then, I might see at say 40 MPH (or whatever), say both stock and stalled are low 2nd gear, I might see a much larger HP at the wheels then as the MPH's increase the 2 lines approach each other and get a delta.

Actually, now that I am typing this and thinking it through, I'd need a plot of rear wheel TORQUE not HP to get this data correct, because HP is a function of RPM.

Wow, I guess I need to rethink this. I can't be the only guy who wants to know this information, right?

EDIT: Yes, I do need to just use the torque, because HP has RPM as part of it's calculation it will be skewed by the stall slipping. So, I am going to plot raw torque at any given MPH for unlocked stalled/unstalled, and that will tell the tale how much is lost on say highway pulls for example at any given speed.

STILL LOOKING FOR A VIG3600 STALLED NEAR STOCKER UNLOCKED DYNO GRAPH IF ANYONE HAS ONE. No dynos near me unfortunately.

Muerte_X

iTrader: (1)

I did the same comparison myself, before and after adding a converter. See this post for my graphs. https://ls1tech.com/forums/showpost....25&postcount=8


It's not a vig 3600, but a yank ST3800 (iirc, and it's no longer made). But you can see the differences in mph (how the hp is actually put to the ground) vs rpm (how much hp is made at a certain rpm). And see how a converter helps so much, because it increases your hp at a given mph through it's slippage (shift extension), even though the power at a given rpm is about the same. These were all done unlocked, I didn't have a tuner available to lock the converter, which I probably wouldn't have done anyway.

mk3cn4

iTrader: (3)

Wow, I didn't weed through all of your data yet, but that looks like EXACTLY what I was looking for!! Near stock (boltons) and a similar TC, showing Torque and MPH! Nice!

THANKS FOR THE POST!!!

When I get time I am going to take your second graph's MPH numbers and sit down and try to work it all through, I think you did most of my work for me in your post however.

Thanks again!

Muerte_X

iTrader: (1)

Yeah, before the converter I had a lid only, and after I added a cutout, and iirc I had the free mods done when I had the lid. I'm not sure how much a cutout adds, but i doubt it's much with the stock manifolds and cats in place.

I think the biggest difference you can see is that I "gained" as much as 40whp in some parts of the curve when you see it graphed in mph (which is how the power is actually being put down).