BamBam

iTrader: (4)

Alrighty guys, I have a question for some of you knowledgeable Dyno Folks.

The following are graphs from 2 dyno sessions 2 weeks apart. The Dyno Jet was taken first and the Dyno Dynamics was taken about 2 weeks later or 1,500 miles. Even taking into account the difference between dyno systems, is there anything you could think of that could possibly account for the massive difference between the two sessions?

The boost had not been changed (9psi and 11psi) nor had the air/fuel maps.

The A/F appears to be drastically different much, much richer on the Dyno Dynamics and the power delivery curves are pretty different also.

Any thoughts..?

ZU L8R

iTrader: (84)

You know what I think

BamBam

iTrader: (4)

I guess I should add that both dynos were on 93 octane.

I know the second shop was new to the VQ35 engine, but do not see how that could effect the results. They had experience tuning DSM for a couple of years. By the look of their Dyno Dynamics machine, it looked pretty new also.
But honestly how hard could it be to set up a dyno to read properly? They dyno’d a couple of semi-stock 350Z’s that same day (Plenum Spacers, Intakes, Exhaust kits) and they ran between 215 – 225whp… so It seems to me the Dyno was fairly accurate.

Any thoughts… Anyone…?

booger

iTrader: (6)

Seems a DD dyno and Mustang dyno read pretty close to one another . Ive only dynoed on a Mustang dyno . I went in to check some changes I made in my tune . The operator forgot to change the Wt. put in for the car . It was set on 2800lb's instead of 3700lb's for my G35 . I was surprised my changes made a 30whp difference and the A/F was leaner than Ive seen it . Then we found the Wt. wasnt put in . He changed it and dynoed it again . The changes in my tune didnt make any difference and my A/F on the second run was much richer .
So going from a 1500lb' DynoJet roller to a load base dyno , set up with the Wt. of your car [ 3200 to 3500lb's ] will make that much difference .

BamBam

iTrader: (4)

Yea, I understand the difference in dyno should attribute about 17% at most. I believe they had properly factored in any relevant loads because the fairly stock cars all fell within the expected range.

I am having a problem understanding what accounts for the additional -100whp difference, the super rich A/F and the wild power curve.

I understand this could possibly happen if the Intake Sensor is bad or there is a vacuum leak? I do not see much of a change in the Boost level, but the A/F is just whacked. This could be caused by the Intake Sensor dying and the EMS adding fuel to compensate for the lost metrics..?
--B

NoahzBurnt

iTrader: (10)

Brent, gimme a call.

Alberto

iTrader: (14)

What I assume to be the AAM dyno is uncorrected. Your SAE or even STD numbers will likely be lower than the actual 520whp you made on that day on the Dynojet uncorrected, so its an unfair comparison right off the bat. I gained 53whp going from DD to DJ dyno, but the difference between both of my maps were identical from dyno to dyno-within hours of each other. Also if that is AAM's dyno A/F, I wouldnt even look at that thing as its been WAY off for my own personal car and many people I know who dyno'd there. Regardless, I doubt Mike would tune you so damn rich so it may be the DD A/F that's off. You have an Innovate right? What does it read? Those turbo's spool slow man, I build 10psi at 3300rpm's, I wouldnt run those big snails at such low a boost personally-kinda contradicts the fact that you upgraded....

BamBam

iTrader: (4)

Bert:
I realize those #’s to be uncorrected on the Dyno Jet, with the correction factor it was 517rwhp. I also realize there is a big difference between the two dynos, but even factoring in say a 17% (450whp) difference it is still off by 65whp. The main concern is the variation in the power curve between the 2 and the drastic difference in A/F. It would be nice if the DynoDynamics A/F was messed up, but how to explain the very lumpy power curve?

As for the Turbo spool, yes it does have more lag. The stock standard turbo’s usually start spooling around 2,750 rpm and build full boost about 3,500. These are a different turbos and have an expected 1,000 rmp longer lag in them. The current level of boost is temporary just to see how the turbos and engine handle the differing airflow characteristics.
--B

Alberto

iTrader: (14)

Only other thing I can think of is that the Dyno Dynamics wasnt set to 1.00 correction, maybe even under or not STD corrected at all...that would give lower numbers also.

Sharif@Forged

iTrader: (92)

Hey Brett,

Numbers aside, the main issue here is the massive AF drop to pig rich...sub 10.. Not sure what could cause such a drastic change...especially since you were tuned with an FCON, which is unlikely to change more than .5 AF points on any given dyno day.

Since you mentioned the stock Z's running 215whp'ish, this dyno operator obviously has his machine setup correctly, and he is not adding any "artificial" correction. So that said, i would add about 13% to estimate what you would do on a Dyno Jet....still way off. The reason your power is low, is because you AF is off the charts rich....rather than dyno operator error.

I think the FCON just needs a retune. Most FCON tuners will disable AF feedback under boost, becuase it would be too risky, in the event your wideband sensor malfuctioned.

Aside from the obvious vaccum leak, or fuel pressure problem...he FCON probably needs to be retuned. Maybe your correction tables need to be tweaked.

Chris Macellaro

First question would be if you had the car tuned on the dynojet in question?

Second what gear was the car ran in on the Dyno Jet?

Wow that does not add up with the DJ numbers at all. Something else to look at would be that the Dyno Dynamics numbers are (Shoot Out) estimated flywheel numbers. This would show an even larger difference between the DJ and the DD numbers (estimated wheel output (DJ) to estimated flywheel output (DD)). Someone was not telling you the truth my friend and it was not the Dyno Dynamics equipped shop.

The older Dyno Jet 248 (most common) are 15% to 17% higher than Dyno Dynamics. The Newer Dyno Jet products out on the market are 12% to 15% higher than the Dyno Dynamics numbers. Again as Sharif said assuming no one is being dishonest from dyno to dyno.



Chris Macellaro

BamBam

iTrader: (4)

Chris, Sharif,

Thanks for the replies... The original tune was on the Dyno Jet at 500+whp and the Dyno Dynamics tune was 2 weeks later. I agree something was weird with the A/F and was the major concern between the dyno differences.

The short answer is the engine blew a head gasket shortly after the Dyno Dynamics runs. So, something was definitely wrong, what it was is debatable.

The engine needs to be torn down, analyzed and the tune needs to be reviewed.
--B