Graphing HP Tuner Data

Although the HP Tuners scanner does a terrific job of showing both numeric and graphic data, it is helpful to compare results from different scans outside the tool.

The scanner allows export of the scan data in .csv, or comma delimited text format. This data file can then be imported to Microsoft Excel, and graphed. In this case, I exported from two different scan files, then added each as a worksheet within a single Excel workbook, added a calculated field, then graphed the two data sets together as x/y scatter graphs. It is helpful to use the ‘export visual’ option within HP Tuners to limit the data exported to the single WOT run in each case, or close to it.

HP Tuners did not export the calculated horsepower. I added a column to the data calculating HP = Torque x 5252 / RPM.

The chart above shows (blue and green) my current tune 3c2 scan for a single WOT run versus the stock tune on a different day single WOT run. This type comparison is inexact due to differences in variables (day, weather conditions, road used) but is helpful as a way to measure overall impact and to look for problem areas.

The data is uncorrected, and unsmoothed. Often dyno results will be corrected to STD or to SAE 1349, which help to match weather conditions. Smoothing also helps eliminate single peak max values. In this case the weather conditions were similar, and we are looking for trend comparison not peak comparison, but would be possible to make the same corrections and smoothing on the data within the data table prior to graphing.

The Blue torque after line compares to the red torque before line, and the green hp after line compares to the orange hp before line.

As expected, what I conclude is that the current tune is better across the board as compared with the stock tune

Cadillac STS-V Spectre Intake dyno test

I had a great time with my Cadillac STS-V this morning at True Street Motorsports in McKinney.  We did a baseline dyno run on my 2008 Cadillac STS-V, then installed a Spectre custom intake for the STS-V, and ran a new dyno for before/after tests.   The Spectre intake was custom ordered through Streetsideauto.

Cadillac STS-V on the Dynojet dyno

As soon as I arrived the True Street Motorsports crew got the Cadillac on the dyno and off we went.

A first casualty of the day were the batteries in my flip camera, so I switched my kodak to video mode and captured videos of the dyno runs:

True Street  Motorsports uses an in-ground Dynojet dyno.  A dyno reads horsepower at the wheels, after losses through the transmission and rolling losses.

One might expect an STS-V to put 360-370 hp to the wheels based on other results I have seen; my STS-V today did 356.8 whp and 350.2 ft-lb of torque, so a bit below average.

Once we had a baseline, the team started removing the intake and replacing it with the Spectre custom STS-V intake.

STS-V LC3 Engine Compartment with side covers and front cover on

This was the dirty picture from after I first removed the beauty cover to give an idea of the original intake tubing in place.

For the first run it was 92.9F 29.64 in Hg Baro, humidity 15%.  By the ‘after’ runs it was 99.4F.

Spectre intake parts ready to go in

Spectre intake parts ready to go in

The new intake parts replaced all the factory intake from the box to the intake pipes leading around the engine.

Spectre Intake installed STS-V

The OEM intake has baffles to reduce the supercharger characteristic whine; the new intake is lighter and has no sound baffles.

OEM intake piping with baffles

With the intake installed, coolant hosing routed appropriately, and fuel trims reset, we were ready for the AFTER dyno pulls

UPDATE: replaced the ‘after’ video with higher rez combination of the two video files.

This chart shows the before/after dyno runs on a single comparison chart:

2008 STS-V Before/After dyno runs

Lots of things to consider in these results.  First, I am happy with the Spectre Intake and the support from StreetSideAuto, and I had a blast at TrueStreet Motorsports, so thanks all around to everyone.  I’ll be doing more dyno runs at True Street Motorsports in the future.

The results were somewhat worse than hoped — I was hoping to see +40 whp before/after and we saw +19 whp.  If the 356.5 whp was 469 hp at the crank “before” (24% losses) under perfect conditions, then the after reading of 375.4 whp might equate to 493 hp at the crank “after” with only the Spectre Intake mod, or +24hp.

It was very hot here in Texas, and although the dynojet uses a correction factor to ‘standard’ conditions, that may or may not compensate adequately for the actual hp lost due to the hot air for a supercharged Cadillac.

HP vs Torque across all 4 runs exported Run Viewer

This chart is the same data done using the raw files and the dynojet viewer.   Click on the image for a larger copy, then hit back to return.

Next I want to wait a couple of weeks, then rerun a ‘check’ dyno, and swap the MAF to a different lot of the same p/n MAF and retest.


Good day, parts works, good times were had.