once the motor is tuned
If i change to a different style intake or header or cams
Is there a way to tell if i get increase in power by the fuel demand?

For example i start from a stock itr motor then change to performer-x and increase fuel in 6000-7500 rpm range. Im assuming it means that the engine has increased air intake and requires more fuel.

its pretty expensive to go to a dyno every time. I was wondering if i can get it tuned once and then swap the intake and exhaust componenta to find the best combo and the get a final tune once its done.

 

If you use Virtual Dyno it will actually get you a much better idea than just guessing. The only hard part is consistent runs but you run into some of those issues on a dyno anyways.

 

yeah it can work like that. last summer thats all i did swapping around intake manifolds and intake tube lengths. (be careful to keep it clean if you keep swapping parts i dropped some random dirt or **** in my cylinder and scored the walls).

keep the testing conditions the same like load, temperatures etc so you can really compare. from this i realized all the hype over portmatched p30 im vs sk2 proseries is nonsense. no richening of afr down low and it certainly needed more fuel up top.
both manifolds liked a different vtec xover so thats tougher to do on the road no dyno

 

I second this......OP, I'm using it now, just have to be consistent and have the right tools, also be sure to make runs either at a track or a desolate road that's flat.

I'm using the android tunerview app to record my runs which will generate the data in to a CSV file needed for VD.

You'll only need the timestamp, and TPS for the calculations data off the CSV. Take note of your transmission gear ratios and build a custom profile with the gearing to match your tranny then get your car weighed with say a 1/4 tank of fuel or on E. 1 gallon equals ~6lbs.

Take your approximate vehicle weight (fuel volume calculated) + your weight and take note of the barometric readings outside during your run. You can also average the IAT temps off the CSV to get the avg temp during the run as an adjustment factor.

Generally its been said that with this app it can be reasonably accurate if done right, it has smoothing factors just as other real wheel based dynos do so generally if your WHP output at smoothing correction 6 is within 15 whp of the max which is smoothing correction 1 than the calculation is presumably accurate within 5 WHP.


Here's a run I did off a recent tuning adjustment with all these factors considered during the run.... this motor was originally dyno'd on a DynoJet @ 255 and I've been working out some tuning kinks since so its a neat tool to consider as a cheap Dyno alternative considering its free to DL. The program has three simulated versions and so the version simulated here is for DynoJet which is why its labeled so at the top of the graph

 

So how accurate are those virtual dynos? Worth it?

 

Its a reference point i guess.
to compare after each part swap
I tried to set it up from neptune datalog but it looked all fucked up.

How do i use it properly to get most accurate results?

 

I simply take the csv and delete the columns I don't need while saving the TPS ,timestamp, and RPM. You have to build a custom profile in the software with your gear ratios and vehicle weight is important as is making your run as you would on a dyno in 4th gear from 3k @ part throttle to instantly hitting WOT and holding it till you've hit your max rpm prior to redline.

I feel it's considerably accurate as long as you keep consistency in your runs while keeping variables in check.....ill check barometric pressure in the zipcode im making a run in too so this is factored.

For vehicle weight I took my car to a local metal scrap yard that has a scale and threw them $10 to weigh my car with 1/4 tank fuel which weighed in at 2600 lbs with the spare tire not including my weight which is also factored.

The thing to look out for is how much the power varys between the max smoothing and least smoothing....if the difference is 15whp or less than its considered pretty accurate.....I generally see this when running on a flat even road.

 

For the cost of nothing for VD + the datalogging bluetooth hardware ($45) and TV software ($5) its worth it I feel....

With the KnockSense + an isolated audio circuit I mocked up suggested from others here so I could listen for pinging + the android TunerView, ive now been able to concur ignition issues I was seeing on the high cam....btw with the isolated circuit for knock I got the KnockSense dialed in perfect at 3/4 pot so it only blinks when I heard a true knock, not my BOV or gear syncro, etc.....love these tools!

 

so back to my original question im trying to understand it better

why cant I use fueling graphs and lay them over after every part swap?

that will give me an exact graph of the fuel demand for each TPS/map position
that way I can see where its more efficient and where it lost efficiency compared to other intake not just at wot like virtual dyno would show.


or am I missing something.
because im thinking if I don't change ignition and I see an increase in fuel demand in certain rpm that would mean more power proportional to the fuel demand increase


because even after intake swap I can see much more demand at higher rpm
and same after I take out the muffler silencer

 

Yes, for PT tuning I would focus on datalogging the AFR changes so you can add/remove where necessary inorder to accommodate the part upgrade.

Virtual Dyno I dont feel would work very well for PT tuning accuracy which is why I really focus on throttle response (after AFR's are on point and with no pinging heard) along with fuel economy to make a judgement on the PT tune. In my case, when I make changes to the lowcam fuel or Ign thats a positive change for power this can sometimes affect the spool characteristics of my turbo when more torque is made and this also shows up on the datalog graphing.

When you do it everyday until you get everything where you want it you'll know when you've lost power or gained it.......**** my girl also drives my car and knows when I've made a PT change that's good for drivabilty.

 

**** man you got more girls like that? my girl doesn't even notice when I install full system with indash nav in her car lol

 

She Loves driving it and the fact that its quick (compared to most cars) since boosted, but she also hates it because anytime we both have free money to spend after the bills and kids are taken care of I tend to lean toward buying something for my car 9/10 times, so to her, its ALWAYS about my car .....they'll never understand why theirs always so much to do to get everything to our level of satisfaction with a build lol