1988 Monte Carlo SS
LS1/T56 Change-over page
2002 Project Updates
Cold Air Intake
As I begin the fine tuning process I have observed that my Intake Air
Temperature (IAT) as measured by the PCM using my ATAP software and laptop
typically reads about 25° to 30° above the outside ambient temperature.
This is not good! On cold days it should be cold and it really
isn't. I tried several approaches to resolve this:
- The first was to relocate the air filter pick-up location down lower from
it's current position which is just behind the driver's side
- I bought another 90° rubber 4" diameter elbow and this
view shows where the filter was relocated just in front of the left
front tire. I also had to place a metal baffle between the
inner fender and frame rail to prevent backwash from the tire soaking
the filter. And yes, the car is dirty in this pic! Please
remember, this is a daily driver, rain or shine! I had to
test this set-up in the rain to ensure that the filter stayed dry (and
- Unfortunately this really didn't change the air intake temperature at
- I concluded that the high pressure area in front of the air dam must
be enabling hot engine air to be drawn to the area behind the air dam to
offset the positive pressure created by the air dam.
- To test this theory I removed the left parking lamp in the lower
front facia so that cold air would be blown directly onto the air
intake filter at road speed.
- With the car engine cold I took the car out for a drive to measure
the IAT now and it was virtually at the outdoor ambient temperature
(about 25° cooler than before)!
- I did notice that as the car heated up that the temp would come up
only about 10°-15° above the ambient temp and cool down a bit
again under WOT.
- I reviewed several options for directing cold air into my air filter
system and settled on cutting a hole into the driver's side of the
sheetmetal box which connects the grille to the radiator.
- Here is a
view of the approximately 4" wide by 8" tall hole cut in
the sheetmetal using a die grinder with careful attention given to bend
the rear portion of the sheetmetal so that air would be directed toward
the air intake filter element.
- Next I had to isolate the engine compartment air from the air filter
intake. I used Crafter's
Supply non-air permeable 3/4" thick foam at a cost of 50 cents
a piece for an 18"x24" sheet.
- This view shows before
view without the foam and this view is after
with the foam box in place. To make this work I had to stop by a
local wrecking yard and buy a section of the front headlamp wiring
harness and splice this into my wiring to extend the wires to clear the
foam intake box.
- I took the car out for a drive and noticed good results in the IAT,
however, at slower speeds and idling it still drew in large amounts of
hotter air. I believed that hot air was being drawn through this
intake now due to the close proximity to the radiator.
- I mocked up a ram air
duct proto-type out of card board and duct tape up to the front nose
grille to isolate cold air so that it would only come from the grille
into the foam air filter box to see if this made a difference.
Took the car out again and sure enough, mission accomplished! Once
the car is warmed up the temp varies by less than 10° and cools down at
- Next, time permitting, I will have to create a fiberglass duct to
replace the cardboard/duct tape proto-type :>)
- On several dry near freezing days I road tested the car on the freeway
on-ramp at WOT and was able to break the tires loose from a 2nd gear 35MPH
roll due to the cold air intake! Love it!
I loaded up my software and deleted my trouble codes and everything
works great! I will be doing more fuel/air/timing fine tuning shortly.
Exhaust system components
I am still waiting for the completion of the merge collector fabrication
before I start the header fabrication to minimize vehicle downtime.
Hopefully the collectors should be available within several weeks. I also
ordered a pair of Car Sound
model number 93009 catalytic converters. These are one of the highest
flowing CATs available in 3" diameter flowing 482 CFM @ 20" water.
Click here to return to John Bzdel's LS1/T56 Change-over main index page
© 2002 by John Bzdel