Mr. Blue Sky

iTrader: (1)

My VIAS is not broken(cup is firmly attached, doesn't spin freely, is that normal?), and I have warpspeed y-pipe, GAB, 2.5" mandrel bent piping from cat to my stock muffler. It has about 175,000 miles on it as well. What I find weird(besides the seemingly low numbers overall) is that the torque actually begins to drop at a pretty constant rate around 5000 RPMs( i though VIAS was supposed to prevent that, but I may be mistaken). This was on a dynapack chassis dyno, and since I don't know how much drivetrain loss these dyno's average on auto transmissions I can't tell if it is normal or bad. Any insight from those who know more than I, would be much appreciated. Left the image large so the the data on the right could be read correctly.

Grand_hustle17

iTrader: (22)

woooow!!!

Mr. Blue Sky

iTrader: (1)

No one knows? I am still stumped. Me and my father had done a full service tune up on the car (plugs, Transmission oil, etc). Maybe a clogged main cat is the problem?

ajcool2

iTrader: (43)

What kind of numbers were you expecting? I can definatly tell you your VI is working just by looking at the HP curve.

Grand_hustle17

iTrader: (22)

^^^ and i can tell you that is not the numbers he should be getting... no way shape or form a 2K with Y-pipe and catback only gets 168whp... my 2k could havegotten more than that, stock

shadyonedeath

iTrader: (10)

Roger, dont worry about it. Michael told me that dyno was running low numbers for everyone. They need a calibration.

Your curve looks normal. You definitely have the increasingly linear power band.

Gemner

iTrader: (4)

did you get an AFR reading? dynapack's read high IIRC, so on a DJ you likely would have dyno'd lower. however, if the dyno wasnt calibrated right then its all guesswork

Mr. Blue Sky

iTrader: (1)

my afr dipped below 13 only after 5,000 but stayed around 12.7. Rich, but not quite pig rich. A tune will get me better numbers, but I want to fix any other issues that could be causing this before I even think of tuning. I have heard that the numbers on a well calibrated dynapack are very repeatable though (get near the same numbers on repeated trips). The statement about the dynapacks reading higher is due to the way that church's automotives dynapack reads higher than any other(i heard it was due to the way they did their own type of calibration to it). Most other correctly calibrated dynapacks will read numbers close to other types of dyno's, or even lower in some cases(i have heard). But then again it is very hard to have the exact same numbers from any type of dyno(dynojet, mustang dyno, etc) due to all of the variables involved.


i kinda thought the same thing, since a modded is300(intake, headers, y-pipe, catback(with a high flow cat, I think), and I believe an exhaust cam timing retardation(which I believe the owner told me is a power adder)) only got 174hp on the dyno.

I was kinda thinking either the cat is clogged, the air filter needs some changing, or the transmission could be slipping ever so slightly(although i doubt it). The car was serviced about 10,000 miles ago, with the oil changed about 2000 miles ago(regular maintenance done on everything else).

assuming a 25% drivetrain loss for my automatic(seems kinda high, I am thinking about 20% is normal for auto's, I may be wrong), that would mean that I am only making 2.2hp above stock, and about 5 lb/ft of torque more than stock, which seems little for the mods.

Edit: One other thing that I just thought of, maybe the dynapack was calibrated to give numbers similar to a dynojet(conservative calibration, have heard of it happening before) I am not a dynapack technician, so don't ask me how. I have been reading about that happening in 370Z and other forums.

niceguy

Can you take it somewhere else and see what you get? Otherwise, if you don't have any codes,etc you could try a vacuum test to check for a clogged cat....as you rev, needle should drop IIRC...

Jeremy

Mr. Blue Sky

iTrader: (1)

I will have to save up some money to do 3 pulls at another place. I think I will wait till stillen's customer appreciation day in october. They have a dynojet I believe, which will give me numbers that I can compare to this dyno