|
Reprinted
from Turbo Gus' Webpage
Updated April 14, 2002
*Turbo Gus Mahon,
unfortunately, is no longer with us. He was killed in late
Summer 2002 in a motorcycle accident. He was quite an inventive
person and was able to propel his 2.5L Turbocharged Dodge
Caravan into the 13's at the dragstrip, frustrating many
musclecar owners to no end. We will be reprinting some of his
more generic articles mainly due to the great information they
provide. We are extremely sorry to hear about the tragic
accident that took his life, but will remember always the
contributions he has made to the hobby. The following is the
article in full along with how the results were derived.
Flow is not the end-all be-all test
for intercoolers, but it is VERY important! If your turbo has to
make 5 extra psi to hold your desired boost level, you are
overheating the air by about 55 degrees, which means your "high
efficiency" cooler may become "low efficiency" in short order.
These flow results DO NOT show the cfm flowed; they show how the
coolers were tested for flow IN
RELATIONSHIP TO EACH OTHER.
This relationship is *NOT*
LINEAR!
This means that an increase of one inch
H2O from 10" to 11" represents a
MUCH LARGER gain of backpressure than
an increase of one inch H2O
from 4" to 5".
Nevertheless, this test tells which cooler outflows which, and
allows you to go from there in your selection.
 
Isuzu
NPR
Supra
Here are the results of the test, starting with the best flowing
cooler, and descending to the worst flowing:
|
1. SPEARCO
intercooler |
32 short thick
wide tubes. |
4" H2O |
|
2. TALON
intercooler. |
42 short thin
narrow tubes. |
6"
H2O |
|
3. Supra
intercooler |
30 ultra-thin
wide tubes |
6.75" H2O |
|
4. Isuzu NPR
cooler (small version) |
16 ultra-thin
wide. |
8.25" H2O
|
|
5. FORD
intercooler. |
17 short
thick wide tubes. |
8.5" H2O |
|
6. VOLVO
intercooler. |
34 long thin
narrow tubes. |
9" H2O
|
|
7. MOPAR
intercooler. |
10 long thick
wide tubes |
9.25" H2O |
|
8. SAAB
intercooler. |
26 long thin
narrow tubes. |
10" H2O
|
The results of the NPR cooler were
just added. Because of heavier air (cool with higher barometer)
than at the last test, everything was reading ONE psi higher
than last test, so the NPR result was adjusted accordingly. It
flowed one full psi better than our stocker, but has a MUCH
better surface area and cross-flow properties than the stocker.
Here's how the results were derived:
As you can see, the abrupt change from over 3" ID to
a 2.5" pipe hampers flow. So we get 2" of backpressure from a
simple short straight 2.5" pipe. Therefore backpressure of the
coolers is measured in inches of water *above* 2".
EXTERNAL FLOW TEST
THIS TESTS THE ABILITY OF AMBIENT (OUTSIDE) AIR TO FLOW THROUGH
THE CORE OF THE COOLER, INTO THE ENGINE BAY. EACH EXTRA 5 MPH OF
AMBIENT AIR FLOW THRU THE CORE MAKES YOUR COOLER MORE
EFFICIENT. SPEARCO HAS CHARTS SHOWING DRAMATIC COOLING
EFFICIECY IMPROVEMENTS FROM BETTER FLOW.
I
have tested only 5 cores so far; here they are in descending
order of flow quality:
|
1. Supra
intercooler |
30 ultra-thin
wide tubes |
5.0" H2O |
|
2. Isuzu NPR cooler (smaller
version) |
16 ultra-thin
wide. |
5.75" H2O |
|
3. Spearco
intercooler |
11 long thick
wide tubes |
7" H2O |
|
4. MOPAR
intercooler |
10 long thick
wide tubes. |
9.75" H2O
|
|
5. Spearco
intercooler |
32 short thick
wide tubes. |
11" H2O |
Surprises? Yes! The NPR tubes are so thin, that
they look like they would not flow well. Apparently the internal
fins are designed for very little resistance, and the cooler
actually beats the stocker by a decent margin in INTERNAL flow,
and beats the stocker HANDILY with EXTERNAL flow!
The Supra cooler turned out to be just like the NPR cooler.
The thin tubes are very deceiving to look at. | 
