Xyntax

Hi, has anyone Dynoed using the Canscan ?

I've been trying to figure out how to calculate HP using Excel spreadsheet by taking time, RPM, speed data from a log.

So far, no luck. I have been using Maniac's log for test values. I know his data was taken from 4 gears running WOT (possibly running the 1/4 mile).

I just received my Canscan today and I haven't plugged it in yet. I can't wait for lunch break!

smd3

we used to do this on our VW's using Vag-Com. It's not terrible accurate, especially with modified cars. You can find the formula to calculate hp on the web. It's HP = (RPMxtorque)/5250

You can set that up in excel and then graph it. You could try searching the vwvortex 1.8t or MKIV forum for more info. There may even be template excel sheets floating around. It's been a while since I've done one so I can't quote that by memory.

Xyntax

Thanks, but I know that formula. You can't really use that with the Canscan coz it doesn't provide Torque values. I will use that, however, to derive torque out of the calculated horsepower. By getting the speed and time from what Canscan provides and inputting the calculated weight of your car w/driver, Horsepower can be derived. How is what I don't have right now.

smd3

I'm sorry. I thought the Can bus on this car reported torque similar to the VW/Audi system.

zoom44

actual dynos measure the hp at the wheels and calculate T from that.

Xyntax

No worries, but that would have been cool if the RX-8 ECU actually reports torque to the Can bus.

r0tor

iTrader: (1)

you mean like i did? :D

Xyntax

^ Now I'm jealous :D

Mind sharing the spreadsheet champ?

Did you use time and distance to calculate everything? I have been playing with my Canscan for 4 hours and I couldn't find how or where to gather the distance.

Bob the builder

log the distance since last CLR

Best regards
Bob

Xyntax

oh that :D

Thanks! I'll check it out on my way to work.

Doomcue

The power curve seems to be almost linear until 8000 RPM. Why the drop-off at 8k?

-djb

zoom44

car cant breathe anymore

Xyntax

He probably cropped it from a logged run. Maybe the top end drop is when he upshifted. That's what I did to my data, I just trimmed it to a certain Gear.

Xyntax

By the way, that didn't work. That is for "Distance Since Codes Cleared". I just found that out now. My log for that field was 255 all the way. That's not even a zero, it means n/a.

zoom44

yeha you're right. it does look more like a shift than running our of air.

r0tor

iTrader: (1)

no it was all the same gear (3rd)... there appear to be some issues with the CANScan if you try to manipulate data logged at less then 1 sec - it just gets so noisy you really can't trust it a whole lot. That particular plot was my first logged at .1sec and it looked horrible so I ended up throwing out every 9 out of 10 points to get a 1 sec interval and then it looked pretty good exceot for that one spot

after several runs tonight it looks like somewhere around 1 sec is the best you can do for a log rate... no more noise or looking like my car took a dump! The data also appears to be pretty consistant from what i can tell as well... just gotta do a little more work on some things

Xyntax

Oh!!! And I thought my car was running strange! So the Canscan is causing those discrepansies. I have seen those on my logs too. I had to nitpick and delete them off to provide consistency along the lines. I'll try running 1 second intervals. Do you usually load 6 monitors (full) or just 4? I have not noticed these noises when I loaded 4 monitors only.

What was the formula you used to derive horsepower there? I have tried different ones and they still look funny. I can't trust the formulas I have used.

As far as AFR is concerned, I finally figured out how to get ratio numbers out of the log from O2 sensor. After reading the "Programmers' Guide" from Harrison's website, I used the formula (b1 * 200) to reverse the data back to it's bit response form. From there, I converted the result back to ratio numbers using the formula the pdf document provided (((b1*256)+b1) * 0.0000305) and multiplied it by 10 to move the period back. Here's what it looks like now:
B2: =B1*200
AFR: =10*(((B2*256)+B2) * 0.0000305)

Now my AFR lines seemed to draw out similar to Maniac's and Harrison's screenshots on the website.

I'm new to this, so please correct me if I'm going the wrong direction.

r0tor

iTrader: (1)

I have the Canzoomer model CANScan which actually displays a pretty good a/f ratio.


The power calcs are not very simple - its basically a kinetic energy equation but you have to add in losses like drag and others you get from actually having the car moving rather then sitting on a chassis dyno and then correct everything at the end for weather conditions like a chissis dyno would... its quite complicated

Xyntax

I see what you're talking about. I downloaded the Speed Scanner or something from Autoenginuity and they have the vehicle specifications and environment variables that needed to be setup.