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.

Spectre Intake: boxes on the doorstep

Boxes arrived with the Spectre Performance intake system for the Cadillac STS-V LC3 4.4L Supercharged V8 today (Monday).   Sorry for the camera phone pics, but grabbed the snap while bringing my Wife home and running back to my next appointment.

Spectre Performance Intake

Spectre Performance Intake

The system is offered in two parts, the ‘bottom’ end from MAF to filter (?) and the ‘top’ end from throttle body to MAF.  I ordered both parts, so two boxes from StreetSideAuto.

Friday is the dyno/install/dyno test day at True Street Motorsports in McKinney.

Cadillac STS-V Spectre Intake Dyno Plan

Got the call from Jaime at StreetSideAuto that my Spectre Performance custom STS-V intake is on the way here; it appears to be set for arrival Mon/Tue.  I called and set my dyno day with Tim at True Street Motorsports in McKinney for Friday, August 5 beginning at 9:30 am.

The plan will be to dyno my 2008 Cadillac STS-V in stock configuration, swap on the Spectre Performance custom intake, get the STS-V back to the same conditions as start, then re-dyno with the intake.  We’ll be monitoring IAT, IAT2, and fuel richness among other things.

Dyno runs are normally done in the gear closest to 1:1 which in the STS-V is 4th gear.  In sport mode the STS-V can manually shift and hold gears, which is dyno friendly.

It is very hot in Texas this summer, and likely will be 103F still on Aug 3.  Stock 469 hp STS-V’s tend to dyno at 360-370 wheel hp, for a ~23-21% transmission & rolling loss.  So that’s what we might expect for the baseline.  Other users have reported as high as +40 whp, up to 410 whp, but there are very few controls on internet reports as to whose car is truly, strictly stock and not.  Judging by ‘normal’ automatic vehicles 20% transmission & rolling loss, that would put the V at 410/0.8 = 512 hp equivalent.

I am hoping to get to 400 whp, but the whole day is an adventure, so we’ll see.

As you can see from this view of the ‘back’ of the LC3 in the STS-V, the intake tubes run all the way around to the back of the engine.  That large box along the way is a silencer to remove or mute the sound of the supercharger.  The new intake is just straight flow, so the V will pickup a pronounced supercharger whine.

Then I’ll enjoy the car for a couple of weeks, and return to the dyno for a “2 week laters” test to see if the improvement is sustained.

What do you think?  Any advice?  Please add a comment!