Looking forward to some new angles with this suction cup Contour Camera mount:
Contour HD on suction cup camera mount
It has multiple adjustments and looks like it is a perfect accessory to get my Contour out there in the action, or stuck right where we can see interesting video.
The Contour HD is a small battery operated video camera that captures video to a miniSD card. Also it is obvious I need a photo backdrop, but it’s the GEAR man!
Although the info shown is relevant for 4 Laminova cores in series, the Cadillac design does not have 4 in series but rather has A-B in parallel and C-D in parallel flow. I caused some confusion in the way I asked my question of Laminova as it turns out. I am leaving this for consideration, but the pressure head through 2 Laminova cores instead of through 4 cores would be different.
Intercooler coolant pumps are at heart 12v water pumps. Extra points if they are light and quiet, and very long lasting. They are rated in gallons per minute, or liters per minute, or liters per hour. However, with pumps one also has to know at what pressure. If an 8 gpm pump is pumping against NO resistance then it can pump 8 gpm of fluid. However, if it is pumping against some resistance, like the four cores of a STS-V intercooler, it has a harder job and the flow rate will drop.
Laminova was kind enough to send me this graphic showing pressure versus flow through four Laminova cores sized for the Cadillac STS-V application in serial:
Below is a graph with heat transfer vs. flow rate for a 4 x 39.5 mm cores in 392 mm length, coolant in series over the cores. (calculated with 350g/s 110ºC for the charge air, 30ºC coolant with flow from 10 to 35 l/min). As you can see performance continues to increase with increased flow, but at 35 l/min you have almost 1,4 bar pressure drop, then add the radiator etc. So be careful when choosing pump, normally there are graphs for flow vs. backpressure for the pumps available.
Laminova Cores bar of pressure vs lpm of flow
Let’s examine this graphic. First, a bar of pressure is a bit less than the English atmosphere (A), so 1 atm (atmosphere) = 1.01325 bar. Let’s stay in bar for now, as it is frequently used for discussion of our topic. But when you read bar you can think 14.5 psi if you prefer. A liter per minute is 0.2642 gallons per minute (gpm).
What the graphic shows is that as the coolant flow increases from 10 lpm (2.6 gpm) to 35 lpm (9 gpm) the pressure required to push the water through the 4 STS-V Laminova intercooler cores increases from 0.15 bar (2.1 psi) to 1.4 bar (20 psi). It takes a LOT of pressure to reach a 9 gpm flow rate. The good news is the heat transfer for the system of cores continues to improve right up to 9 gpm, flattening out after that rate of flow.
If we could increase the flow rate from 16 lpm (4 gpm) up to 35 lpm (9.2 gpm), the heat transfer will increase from around 16 kw up to around 22 kw, or 38% more intercooling at max rate.
It is inviting to think then, that the STS-V 8 gpm intercooler pump is about right on the money; unfortunately, that pressure it has to pump against lowers its output quite a bit. Let’s see how much.
The Cadillac STS-V uses a Bosch sourced 8 gpm (gallon per minute) pump. Here is a diagram of the Bosch pump output:
Bosch Intercooler Pump Flow vs Pressure
This diagram introduces new units again, but we’ll get through it. Along the x axis we have Volume of flow in liters per hour. Along the y axis we have delta pressure in hPa, which is hectopascals of pressure. 1000 hectopascals = 1 bar.
So this Bosch pump will flow 0 liters per hour at 0.5 bar, and up to 1800 liters per hour (30 lpm, 7.9 gpm) at no pressure. Good, as it is rated for 8 gpm.
Now, how do we determine how much a Bosch pump in our STS-V would flow against the pressure through the intercooler, hoses, and heat exchanger? We graph them together based on flow rates versus pressure and see where their graphs cross. That will be the point where the flow rate of the pump against the resistance in the system is equivalent.
I have included the Jabsco 50840-12 Cyclone aftermarket intercooler pump for comparison as well, reading off their flow graphic. This is a popular replacement intercooler pump for the STS-V.
| Laminova | System | Cyclone | Bosch Pump | |||
| FLOW L/Min | Pressure bar | Flow L/Min | Pressure Bar | Flow L/Min | Pressure bar | |
| 10 | 0.20 | 0.3 | 0 | 0.6 | 0 | 0.5 |
| 15 | 0.35 | 0.45 | 40 | 0.42 | 8.33 | 0.45 |
| 20 | 0.50 | 0.6 | 80 | 0.2 | 16.67 | 0.38 |
| 25 | 0.70 | 0.8 | 120 | 0 | 25 | 0.2 |
| 30 | 1.05 | 1.15 | ||||
| 35 | 1.30 | 1.4 |
This data table shows the resistance through the Laminova cores alone, then an equivalent resistance value for the whole intercooler cooling system. I don’t know a good value for this so I used 0.1 bar or 1.4 psi of pressure to represent the intercooler heat exchanger (1 psi), hoses (0.4 psi), etc. We can change it to another more accurate value later, and can model 2 heat exchangers, etc.
The data is really easy to relate to if we put each set on an XY graph, so let’s do that!
Cadillac STS-V Intercooler Flow Rate vs Pump Output & Pressure - Bar versus Liters per Minute
So reading from the graph, I find this tabular result:
| Liters/Min | Gallons/Min | |||
| Pump | Core Only | System | Core only | System |
| Bosch | 16 | 13 | 4.19 | 3.41 |
| Cyclone | 20 | 18 | 5.24 | 4.72 |
In other words, the 8 gpm Bosch pump will pump 4 gpm if it were only pumping through the 4 Laminova cores in serial (theoretical value), or 3.4 gpm through the whole system.
The higher flow Cyclone pump will or 4.7 gpm through the whole system, or 38% better than the stock pump.
A second FMHE (front mounted heat exchanger) might cost 1 psi and thus 2 lpm or 0.5 gpm of flow. Also notable is that the Cyclone pump with a 2nd FMHE still probably flows more than the stock pump and single FMHE. Heat transfer probably increases by 0.5 kw, or 38% of the increased flow rate of 1.3 gpm.
Design an experiment to test actual flow rate through the system. Ideal to me would be to add a flow rate indicator (gauge).
Source a replacement intercooler coolant pump that can pump 9 gpm against a 1.5 bar head pressure in order to optimize intercooler cooling. This is likely to need to be a positive displacement pump rather than a centrifugal pump.
See an error? Applause for the effort? Chime in via the comments section!!
The Cadillac STS-V (2006-2009) uses the 4.4L supercharged Northstar engine, making 469 hp and 439 ft-lb of torque. Can it make more?
Cadillac used a modified variant of the Magnuson MP122, or Eaton M122 supercharger, with a integrated intercooler using Laminova cores. The powerplant was designed specifically to be supercharged. The stock LC3 V8 uses 12 psi, or pounds per square inch, of supercharging. In other words, if atmospheric pressure is 14.7 psi, then air flooding into the LC3 at maximum pressure is 14.7 + 12 psi = 26.7 psi. In supercharger terms, it is at 26.7 / 14.7 = 1.82 pressure ratio.
As a rule, 1 psi of supercharging makes 4% more horsepower. Technically, 14.7 psi of supercharging would make 100% more power, or 6% per PSI. But, with inefficiencies, 4% per PSI is an achievable thumbrule. Looking at this backwards, one might find that a non-supercharged 4.4L V8 would have made 316 hp. This is very close to the 320 hp rating of the 4.6L VVT DOHC normally aspirated Northstar; no surprise.
So what would happen if we increase the boost level on the LC3 V8 from 12 psi up to say 14 psi or 17 psi? Notionally, in a perfect world the 469 hp stock would increase to 492 hp at 14 psi, or to 530 hp at 17 psi. However, there are issues to be considered such as the capability of the supercharger to make that much pressure efficiently, as well as the capability of the intercooler to take away additional heat produced.
A popular way to increase the output pressure of a supercharger is to substitute a smaller pulley for one or the other end or both ends of the supercharger pulley drive. For the STS-V LC3, the crank pulley appears to be 5.88″ outer diameter, and the supercharger snout pulley is 2.8″ outer diameter. Actually, I know the snout pulley diameter of 2.8″, and Cadillac said that the ratio between the two was 2.1:1. Also, when D3 created a 10% overdrive pulley, they chose to make it 6.47″ outer diameter, which is 10% more than 5.88″. This strikes me as an odd outer diameter, but note 5.9″ = 15 cm, so perhaps the crank pulley is metric?
Another choice is to change the supercharger snout pulley from 2.8″ to 2.55″. Remember our ratio — crank:snout pulley ratio so 5.88:2.8 stock = 2.1:1
If we change the crank pulley to 6.47″, then the pulley ratio changes to 6.47 :2.8 = 2.3. Now 2.3/2.1 = 1.1, or 10% faster, so 10% more boost, or 1.2 psi increase.
Likewise, a 2.55″ snout pulley would be 5.88:2.55 = 2.3 and 2.3/2.1 = 1.1 or 10% faster, so 10% more boost, or 1.2 psi increase.
Either way, 1.2 psi increase for 1.2 * 0.04 /psi = .048 or 4.8% increase. So a 13 psi LC3 might increase from 469 hp at the crank to 491 hp at the crank or 24 hp.
In an ideal world then, another PSI of boost would also add another 24 hp. For example, if we used a 6.47″ crank and 2.55 supercharger snout pulley for 6.47:2.55 = 2.5:1 ratio we could get to 2.537/2.1= 1.21 or 21% increase or 2.52 PSI. This would theoretically gain 47 hp and get from 469 to 516 hp.
A different approach is taken with the Stiegemeier Snake Bite kit. By modifying the internal gearing on the supercharger, and porting and cleaning up the flow paths within the supercharger, up to 17 PSI of boost is produced with the stock/OEM supercharger snout pulley and crank pulley. Theoretically this would gain 5PSI * 4%/PSI = 20% or 93 hp, boosting the LC3 from 469 to 563 hp. However, again with real world inefficiencies the actual gain would be expected to be less. I don’t see a claimed/measured gain on their website for this application.
So how do people get up to figures like 461 whp (wheel hp, or hp at the wheels on a dyno) or 576 crank hp (hp at the crankshaft on an engine test dyno) for the STS-V LC3? Through a careful combination of a variety of modifications.
The actual boost the engine pulls has to overcome the intake resistance. So add a higher flow intake and the engine effectively has more boost as a result. Add more intercooler cooling and the engine can make and sustain more power. Tune the engine for a specific car and environment and the engine can make more power. Through careful tuning and multiple dyno runs the community and Professional Tuners have slowly pulled higher levels of performance from the LC3.
With the CTS-V release and adoption of the LSA supercharged 6.2L V8, there is less market for LC3 tuning and the focus has shifted to the newer cars. That does not change the inherent goodness and balance of the 4.4L Supercharged LC3 engines, and I am having a great time considering and researching tuning approaches for mine.
See anything you disagree with? Did I get it ALL wrong? Do you agree and want to share your experiences? Put a comment up and join the conversation!
