Category Archives: STS-V

More Air Filter Testing – K&N on Spectre CAI Cold/Full

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I am gathering more test information using HPTuners and Virtual Dyno on my 2008 Cadillac STS-V across different modifications.  Today’s runs with a full tank of gas and nice weather after an overnight rain.  HPTuners shows the baro that the engine perceives, so I am using that for baro adjustments.

KN cold 2013-05-25 2 run comparison with weird midtorque run adjusted

This morning’s run in red vs the previous odd run in blue.  Today’s run showed the expected shapes — high torque at low RPM, high HP at high RPM.  Huge torque reading at low RPM today.  Not sure what additional variables the automatic transmission might be tossing in — these runs are in TUTD (touch up, touch down) mode with 2nd gear manually selected.  I have also adjusted yesterday’s run to reflect that it was with lower fuel before I filled up today.

hptuners for kn cole 2013-05-25 1300203

The Virtual Dyno is estimating wheel horsepower.  400 WHP with 20% drivetrain losses for an average automatic would equate to 500 hp at the crank.  HP Tuners estimated the engine was making 543+ hp at the crank for an instant at 6651 RPM, and above 520 from 6300 RPM on; 1- 400/520 hp  which would be a 23% drivetrain loss.  My goal for the STS-V was to get to a solid 400 WHP, which was reached with exhaust and CAI. Now I would like to get to a solid 425 WHP…

After the huge mid-RPM torque and low high HP run in the comparison above, I made an adjustment to ensure the engine wasn’t limiting boost.  In this theory, if the supercharger were breathing better and hit a higher boost point earlier than expected, the PCM might pull boost at high RPM.

Today’s run showed the engine is pulling and building boost all the way to fuel cutoff.  So either the previous odd run was just that, an odd dataset, or the new adjustments are working.

Here is a comparison of last night’s hot run vs today’s cold run:

kn cold 2013-05-25 comparison to kn hot 2013-05-24

Both of these are adjusted for weight, barometer, and temperature per the SAE standard, so they should read identically (within the error of the method used).  However, my STS-V is effected by heat to a greater degree than the standard adjustments correct so even with adjustments hot reflects lower results than cold.  This has added a dimension to testing.

 

Update:

Today’s graph had some data noise at the beginning of the run that caused the high torque spike.  With that removed the updated graph below is correct for today:

KN 2013-05-25 Correction

Re-test of K&N filter on Spectre CAI with Virtual Dyno

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This morning I ran some cold comparison tests for the K&N Filter in the Spectre CAI.

I changed my test method for these runs — same test route, but instead of starting from a stop, I started from a roll with the transmission manually selected to 2nd gear.  My thinking was that this would be less stress on the tires/drivetrain, and give better low rpm torque readings.

kn 2013-05-24 three run comparison cold locked 2nd pulls

The results are not what I expected.  We were looking for 376-380 whp so that part seems in range, with one runs at 384-388 whp.  The one run at 350 whp is odd.  The torque readings in general don’t seem to take the form one would expect.

kn 2013-05-24 hptuners

On the ‘green’ run in Virtual Dyno, I didn’t flip the transmission to auto-shift, so it redlined in 2nd gear getting to 6700+ rpm where the fuel cutoff is set.

Here is a similar graph with a previous 2nd gear sliced out of a 0-60 run compared with one of the runs from today:

kn 2013-05-24 cold to cold comparison

Red is today’s test; blue is a recent test in cool air with the Spectre filter in.  Today’s run appears to show much higher low end torque, and lower high end HP peak.

Next I will take the K&N filter off, check the installation, and re-install to see if there is something physical I am missing here.  Then I will re-oil the now cleaned Spectre and re-install it for testing.

Air Ducting to CAI DIY Mod #Motorama

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What benefit is there to routing air from the lower bumper to the cold air intake?

Spectre Performance 8746 Blue Air Duct Hose

I have a Spectre Cold Air intake on my 2008 Cadillac STS-V.  Today’s question is, what if we ducted cold air from the bumper to the CAI instead of to brake cooling as designed?

I shopped for this air duct by Spectre on Amazon.  It was available in a few colors, and the price differed by color, so I got the lower price blue one.

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This is a shot of the hose in the package as received.

photo2

The end pieces are rubber; the hose itself is plastic.  It stretches out like an accordion, and holds it shape once adjusted.

photo3

The coupler for the ducting is tucked into the brake cooling duct.  It is a press-tight fit, but I will keep an eye on it and see if it stays in place at speed.  I tested up to 45 mph or so and it was still there.  I would prefer to put a inner locking ring or similar to ensure it stays in place at speed.

The inner diameter of the brake duct on the Cadillac is larger than the outer diameter of the coupler on the ducting.  A 3.5″ diameter duct might be a better fit here.

photo4

This shot is looking down past the filter into the top of the ducting.  This is where the incoming air will blow out of the hose and onto the air filter.

Only had time and temperature for a short test run to make sure the ducting stayed in place.  I will be testing next available good weather day.  Stay tuned.

Do you have other hints or suggestions for this setup?

Update:

Ran a new baseline / test run this morning.  Weather was okay but ambient read 81F, and test area 76F.

2013-05-18 reset 1-2 added ducting

Virtual Dyno with 1st gear and 2nd gear together detected no improvement due to the new air ducting to the CAI.  The previous run Virtual Dyno vs HPTuners Delivered Torque Curve was at 379/345 hp/torque at the wheels.

comparison of virtual dyno runs

This shows a comparison of the two virtual dyno runs in 2nd gear side by side.  Technically 4 hp less for the ducted version.

hptuners more1-2 run 2013-05-18

HPTuners data shows perhaps a lower run-up in IAT2 max of 125F instead of 130F, but incoming air temp at speed would seem to have less impact on this — already cooler at that point.

comparison of maf readings

In an attempt to discern how to measure a difference, this chart shows the raw mass air flow coming into the intake.  This would show if we are presenting the engine with more air, regardless of what the engine is doing with it.  Although we might conclude given different days etc these are equivalent, it is notable that the ducted air is ahead of the unducted intake.

The ducting did stay in place through my test drive.  I plan to continue to test and evolve this setup.  I have a new replacement cone filter on the way also; mine is quite dirty.  I will put the new one on then clean this one and have it in standby.