Now that spring has come early to Toronto, I've got the car back on the road (man do I envy you guys who live down south) and am planning to get the mods I purchased through the winter installed. I'd like to dyno it pre and post each one. I have never had a car dyno'd before, have read plenty about it here but wondering if anyone has any suggestions. The place I'm looking at has a Dynapack chassis unit. It's a hub dyno. Anyone have any experience with that type of set up? I've spoken with the guy who runs the unit, he seems pretty experienced. I'm planning to have AFR done along w the usual hp and torque measurements.

 

Hey Curious,

Glad to see you are taking the proper initiative to do informative dyno testing pre/post every modifications, that's an excellent plan for your project. Its also good you want to careful as to which dyno you choose.

Personally, I am opposed to hub dynos as they tend not to be realistic, furthermore, you are constantly having to take the wheels on and off which just leaves more room for error of something going wrong.

Hub dynos also tend to show higher numbers because the drive-train loss is significantly less due to the entire wheel/tire assembly being removed. After all, you don't drive down the street without your wheels, so its not truly a REAL WORLD gauge as to how your car is performing. With wheel & tire changes you can actually see dyno numbers influenced, well with a hub dyno you are not able to see those changes or monitor them carefully so its actually less accurate than a typical roller dyno (whether loading or inertia based). The two best options are Dynojet or Dyno Dynamics, I prefer the later as it is load based so its the most realistic.

If you can find a local Dynojet or Dyno Dynamics dyno you would be much better off in my opinion over the long term than a hub dyno.

Good luck on your project, we all look forward to seeing your mod progress

 

Thanks for the info, v good advice. I looked around a bit and found a Dyno Dynamics-based shop locally that seems very solid (IIRC, the Dyno Jet system tends to overcall the numbers correct?). Will post numbers and experiences once I've got the whole project finished.

 

Sounds great, Mustang dyno is also a great choice as well. I would recommend using a 4wd dyno if you can because a 2wd dyno only spins the rear wheels and for some very odd reason on our Vantages get MPH speedo reading from the front wheels (very annoying). This makes it extra hard to get a proper reading.

Do you also have a Mustang Dyno local in your city?

 

I did find a couple outfits with Mustang Dynos in area but I like the guy I spoke with who has the Dyno Dynamics set up. Going to go and get a baseline done tomorrow I think.

 

ok, just make sure they can lock all 4 wheels in rotation together, Mustang does this automatically but sometimes Dyno Dynamics will only spin rears which is why I recommended mustang.

You may be better off doing it on a mustang depending on if they know how to lock all 4 rollers in equal rotation.

 

Would you be doing the dynos before and after with the wheels as well? I would love to see how the new lighter wheels improve power to the wheel numbers. The OEM's are like 5-7lbs heavier!

 

wheels should make an impact, especially on mustang dynos (which seem to measure drivetrain mass reduction most accurately).

 

So I ended up getting the Dyno Dynamics baseline done today. It was interesting. It was only rolling the rears. Initially the temp sensor was not in the right place so was reading v high and the numbers were high as a result (~345 hp peak) but once we fixed that it was in line with what I've seen from a non-Dyno Jet run (303 peak).

After that run however, we discovered that there may be an O2 Sensor or cat issue as an engine code got thrown which he was able to read with the software set up he had on hand - 'P0174 Fuel Trim, Bank 2, system too lean'.

We watched the numbers for each bank in real time for a bit to get a clearer picture of what's going on. I forget the precise units for the numbers (he's going to email me a screen cap with the comparison from R to L) but there was a 'real time' short term reading and a 'rolling average' long term reading for each bank. IIRC the range you want to aim for on the long term read out is around 0-5% or so and the right was reading 1-3% and the left was reading 14-15%. His assessment (and no he's not an AM tech but does have a fair amt of experience tuning cars for racing), was that this would likely represent a Cat or ECU issue.

We also did AFR in the pipe which was around optimal at the low end of the rev range (~14-15%) and got a bit rich at the high end (~10-11%). Will be interesting to see how the ECU tune changes that.

Anyway, with the code wiped, I drove home and it did not recur. Mind you I was not hammering it either. OTOH, I have not seen any engine codes since I've had the car and I have had it WOT a few times (albeit not in 4th lol). I'm wondering f I should pick up some O2 sensors in anticipation of installing the cats and just replace them when I do the job.

 

Just curious, why do you consider 14-15% optimal?

 

Sry, just what I was told.

 

Regarding AFR I think what A-C means is a Ratio, not a Percentage. That is 14:1 to 15:1 Air-to-Fuel Ratio, which is the best for normal Cruise, then dropping to about 12:1 for WOT. (10:1 would be too Rich IMHO).

 

I think the 14:1 to 15:1 will make you the most friendly to the enviornment but too lean for maximum power.

12:5 used to be considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal is now around 12.8:1-13.2:1. Or roughly 13 parts of air to one part fuel.

My car dropped to 13:1 with opening the cats, exhaust and remap and produced much more power. The first thing that was realized was the amount of power that could be gained on these cars just by making them more rich.

 

Hey A, got ur email..so I'll just reply here..

The 14-15% is not ratio but rather percentage of how much the vehicle is riching out the mixture over a long term..verus what some are saying is a/f ratio's.
..a/f is something different

The real numbers that should of been looked at are the short terms, to see if the lean mixture is actually present..second, if mixture on short-term was indeed lean, the tuner should have moved the cooling fan that he probably put in front of the vehicle more to the other side..the tuner did use a cooling fan of some sort right??

The cats and pcm are not at fault with this code..heck anything is possible in real world but these codes are not usual causes of cat's or pcm faults. The lean mixture is the vehicle is getting too much air or not enough fuel. If the vehicle had no fault prior and only on the dyno..my guess would be due to the front wheels not spinning, the pcm could not adapt for a change in "turning a corner"or a "gust of wind". The pcm is setup to compensate for gusts of wind to the left or right side of the vehicle. If a gust of wind occured to the right side and the right filter was forced of air, this would simulate a higher rate of air to the RH bank through the maf. This gust creates a circling air bend that carries over to the left maf....none the less, all this would take long to detail a theory, but this is just a little example for my theory..

So this theory is only based on tuners usually put a fan in front..The fan in front of the vehicle that tuners put creates a "simulated air" in front of the vehicle to help cool the powertrain. So say the simulated air is to much to the RH air filter inlet, RH bank now goes lean and with the front wheels not turning to help the PCM conclude a possible corner turning or a gust of window due to steering angle input..fault flags lean mixture..

If the codes were cleared..I just drive it and see if the fault returns..if the fault does not return..don't worry, but due find a proper dyno..aka mustang dyno or anything equal..4 wheel dyno's I would suggest as well as noted by 007 Vantage..the DB9's and v8v/12's do not not like to spin just the real wheels on a dyno..it can be done, but flagging faults are common on a 2 wheel dyno, hehe just spinning the wheels on my lift at work during testing flags faults at times, then once faults are flagged and are pcm related, pcm goes to open loop and reduced power can be present, so ur dyno number show under powered.

If the fault does come back after some driving, there could have been a evap hose that came loose or cracked during the dyno..this will also cause the lean fault..anyways, drive like you normally do and feed us back some input in a few days as to if the light came back on before jumping the gun on any faulty/damaged parts

hope this helps bud..

 

Irish, he states "doing the AFR in the pipe" is that not the same ratio that the dyno spits out along the rev range that was referenced above (see attached)? Thats what they did for mine.

Thanks for your expertise again, never had heard of the percentages and am trying to get that information!

Also-Curious, did you shut off the traction control for the dyno? I had issues/faults until it was shut off then there were no issues on the 2 wheel dyno.