Jump to content
CaddyInfo Cadillac Forum

Cadillac XLR Virtual Dyno calibration


Recommended Posts

Blog post: http://caddyinfo.com/wordpress/cadillac-xlr-virtual-dyno-calibration/

Using my initial and second (premium) run data captured from HPTuners, I did some Virtual Dyno Analysis (see my initial Virtual Dyno article here). First I needed a new custom file for the XLR:

Virtual-Dyno-XLR-data.png

I had run the test data with the top down (worse aerodynamics), and I used a back-to-back wind tunnel test of a different car (Miata) to model the degradation of top down as .06 CD. I will want to run virtual dyno tests with top up in the future?

I created a 2nd custom file to model the XLR with top down:

Virtual-Dyno-XLR-Tops-Down.png

I edited the .csv saves from Hptuners to only include the acceleration range desired, and loaded both runs.

VD-XLR-Setup-initial-Comparison-CD-adjus

I adjusted the SAE conditions for the pressure and temps during the test, 29.1 in/hg baro and 100F. The car intake air was actually a bit higher. I am not sure this adjustment is quite right — the reference site suggests a dyno adjustment of 4.5% for test conditions. The Virtual Dyno not-SAE – to SAE goes from 251 to 259 or a 3.2% increase. A 4.5% increase would be 262 whp, so not much difference really.

The results, 249 whp for the initial test, and 259 whp for the known-quality premium fuel test, seem consistent with expectations. 259 whp / 0.8 transmission losses = 324 hp. Cadillac rated the stock XLR LH2 V8 engine at 320 hp.

Read more:

http://caddyinfo.com/wordpress/cadillac-xlr-virtual-dyno-calibration/

Bruce

2016 Cadillac ATS-V gray/black

Follow me on: Twitter Instagram Youtube

Link to comment
Share on other sites


More baseline testing

http://caddyinfo.com/wordpress/cadillac-xlr-top-up-testing/

Virtual-Dyno-XLR-Tops-Down-comparison-ti

Update: the previous Virtual Dyno setup used 27.73 as a tire diameter, and I see from the calibration file it should be 27.24. This changes the results to following table:

XLR-tire-diameter.png

Which is less than expected. I am including both charts for now to document my confusion, and to assist in analysis. Yes, tire size has a significant impact on calculated results. With SAE adjustments for conditions the 320 hp rated LH2 should make approximately 256 whp; I am uncertain why today’s results are 226-236 whp.

Bruce

2016 Cadillac ATS-V gray/black

Follow me on: Twitter Instagram Youtube

Link to comment
Share on other sites

http://caddyinfo.com/wordpress/cadillac-xlr-virtual-dyno-conventions/

More work on tire diameters, frontal area, etc. I am going to stop trying to adjust for altitude, and just feed in the baro and temps the car sees and let the chips fall where they may.

XLR-close-top-updated-for-conventions.pn

Same data runs, today's settings. The 221 whp is the what I think of as the repeatable test area.

Bruce

2016 Cadillac ATS-V gray/black

Follow me on: Twitter Instagram Youtube

Link to comment
Share on other sites

Bruce

2016 Cadillac ATS-V gray/black

Follow me on: Twitter Instagram Youtube

Link to comment
Share on other sites

Bruce

2016 Cadillac ATS-V gray/black

Follow me on: Twitter Instagram Youtube

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...