Cam timing adjustments without dyno
 

Is it viable to make cam timing changes when road tuning?

Doesn't look like any local shops have experience with this platform so I might be SOL.

Very difficult to do any more than rough tune the cam settings unless you have a perfectly repeatable section of road to use for logging.

Once your in the ball park, the power variations with minor changes will be well within the error range for run to run variation. My suggestion is to get fuel and timing dialed on the road then go to the dyno to do cam timing and then touch up fuel and timing, if you are trying to save dyno time that is. Or better yet, start with a base map that is close to your setup.

Whats your parts list? If your stock then just use one of the oft basemaps and don't worry about dyno time.

Perrin filter and inlet hose, nameless DP catted and resonated, Nameless header here soon. Possibly the axle back with an extra resonator.

I will probably start with the OFT EL stg2 map but I'm sure the cam timing will be different.

I'm at 4500' so my fuel and base timing will be off as well.

i have a very simple method of tuning cams, whether on the road or otherwise. not very scientific, but it works.

log a few pulls... calculate ve... make a change... if it improved ve do more of that, if not do the opposite. with sd it's even easier... just don't change your ve map and see where you go lean/rich. fix the ve there to get the afr back in line the do more of the same.

I started this thread last week:
http://www.ft86club.com/forums/showthread.php?t=57662

How do you go about adjusting the timing... In groups like the stock is setup or individual load cells?

If you have a good basemap I'd just look at full throttle changes and then smooth out the map. Doing partial throttle just won't be possible on the road.

If Shiv's maps are the same as the others I've seen, the top load cells are the same throughout the RPM range.

I haven't looked at them.... Not real good with the program yet

Here's my post with stock vs OFT:
http://www.ft86club.com/forums/showp...0&postcount=19

Done my homework, 2 questions :

1 - I got a higher value of 123% of VE at 4083RPM, and most of the time over 100% : not bad for a NA ! Are my numbers right ?

2 - Load curve is quiet similar to VE one, is it a good approximation ?

I have a simple formula to calculate VE approximately for NA in metric :

VE approx = ( MAF / 1.2 ) x 60 / RPM

MAF = mass air flow (gram/s)
/ 1.2 = 1 liter of air weight 1.2 gram at 10°C
* 60 to convert in minutes -> real number of liter inhale / mn
/ RPM (cause a 2 liter engine theoretical deplacement is 1 liter / round !)

On the graph, VRE with complicate formula for pressure correction, VRE approx describe below, and load comparison

https://drive.google.com/file/d/0B2J...it?usp=sharing
https://drive.google.com/file/d/0B2J...it?usp=sharing

123% seems a bit extreme for an na car.

123% would be really hard to do, that's like giant air funnel snorkeling in volumes of air to your intake, WS6 Ram-Air style.

Some smart arse gave me this formula to use to calculate VE:
[MAF in g/s] / (([MAP in kPa] x 1000)/(287.05 x ([IAT in C] + 273.15))x1000))/(121.9254 x [RPM]/3456x0.0283/60)x100


MAP can easily be converted from bar to kPa by multiplying by 100 if that's all you've logged.

Just check to confirm that all the input data is reasonable. I.e. You didn't have one NaN cell for iat or something.

There's no standard calculation of volumetric efficiency. It's a term that's thrown around all the time and it's hard to compare one set of numbers to another. Generally speaking, it's the amount of air entering the engine relative to some reference condition. Put another way: it's how much air is entering the engine now, compared to how much engine "should" enter the engine based on its displacement.

The sticking point is usually the reference temperature and pressure. Is it referenced to intake manifold conditions, ambient conditions, or SAE standard conditions? Even in an n/a engine, manifold pressure actually drops as rpm increases due to restriction.

And the result is... More than I've calculated with my complex formula ! :bonk:
123.18 instead of 122.99...
My formula :
[MAF in g/s] / (([MAP in bar] x 1000) / (287.058 x ([IAT in C] + 273.15)) x ( 1000 x [RPM] / 60 )) * 1000

My measures with Ecutek :
Mass Airflow (g/s) = 99.63
Manifold Absolute Pressure (Bar) = 0.97
Intake Air Temperature (°C) = 11
Engine Speed (RPM) = 4087

It shouldn't be grater than 110% according to HP Wizard :

http://hpwizard.com/volumetric-efficiency.html

A view of my calculated VRE :
http://i57.servimg.com/u/f57/16/17/22/66/vre210.jpg

I'd just look at it as a comparison rather than being 100% accurate. As you have the constants, the variables should give you a picture at what's going on so you can see whether things are improving or getting worse.

I know that @nelsmar had some cam timing optimization already. I'm just not sure that when he loaded it onto my ecu it was from a dyno baseline or from road tuning. Either way, it's been done.

Folks have commented already how my stock exhaust already has a different note to it. All readings have been good, so it looks like cam timing was nearly spot on.