Street Class
1) UnderdogSDA 13.3 (Nitrous)
2) S.Bretz 13.35 (Turbo)
3) Poc301 13.50 (Nitrous)
4) BoostedSL2 13.56 (Turbo)
5) Yardbird 13.59 (Nitrous)

Unlimited Class
1) Nefarious 12.26 (Nitrous)
2) LowSC2 12.4 (Nitrous)
3) 92saturnSS 13.33 (Nitrous)

DOHC
1) UnderdogSDA 14.21
2) Green Monstah 14.5
3) DonBaker 14.71
4) Applebit 14.8
5)SaturnMotorsportsOfCary14.84

SOHC
1) ProjectPhase1 16.61
2) Sh1FT 16.90
3) Wraith 16.98
4) jhsl1 17.2
5) SL_Sled 17.96

Ion
1) JGreen 15.48
2) schzzo97sc2 15.60
3) Chris 15.79
4) rascon11 16.06
5) IonJon 16.27

Updated 1/05

For the most recent list of the fastest five cars click here.

Intercooler Sizing

by: Titan

There seems to be a lot of misconception on intercoolers. Most people understand the basic function of an intercooler but no one seems to have any solid information on choosing the correct size for your application. If you ask someone the question "what size intercooler should I buy?" the normal answer is, "the biggest one that will fit". This kind of solution will work to an extent but if you're interested in pushing the limits of your car's power, it's the attention to details that will put you above the rest. A properly sized intercooler will allow you to increase boost levels while keeping turbo lag to a minimum.

There are two main types of intercooler cores on the market the bar and plate (BROKEN) and tube and fin (BROKEN). Between these two types I would choose the bar and plate because the core tends to be sturdier than the tube and fin design. In a front mount application the bar and plate core will stand up to the abuse of everyday driving better, improving reliability. Also, the extra weight of the core acts as a heat sink, which more efficiently soaks up the heat of stop and go traffic.

If you have been an avid reader of this website you may recall the two-part article titled deciphering turbo compressor maps. If you have not read this article than I suggest that you stop and read the article before continuing any further since there will be many references to that article. O.K. let's begin.

In part one of deciphering turbo compressor maps we found the airflow requirements of the 1.9liter Saturn engine in cubic feet per minute (CFMs). We then converted the CFMs to lbs/min and multiplied the result by the desired boost pressure ratio, which yielded the lbs/min of airflow a turbo produced at the desired boost level. In part two of deciphering turbo compressor maps we considered three additional variables that allowed us be more exact in our turbo calculations. The new airflow numbers from part two of the article are going to help us choose a proper sized intercooler for our power level.

Using the table from part one of deciphering turbo compressor maps I converted lbs/min to CFM by dividing lbs/min by .069 This yields the CFM output of Saturn’s 1.9 liter N/A engine.

Now take the CFM above and multiply it by the pressure ratio of your desired boost level.

Example:
171.16 x 2.22 = 379.98 CFM uncorrected*

This shows that at 6000rpm and 18psi the turbo is producing an uncorrected* 379.98CFM
*By uncorrected CFM I mean that we have not made adjustments for ambient air temperature, adiabatic efficiency (A/E), or air density ratio.

Now, using part two of the article deciphering turbo compressor maps find the air density ratio at an ambient temperature of your choice and multiply it by the turbo’s uncorrected airflow value.

Example:
379.98 x 1.49* = 566.20CFM (corrected*)

*Air Density Ratio using 80oF, 74% A/E, and 18psi

Corrected Turbo Airflow Output in CFM

80oF and 74% A/E

90oF and 74% A/E

You can see that there is a trend developing between the two tables. As the ambient temperature goes up less air is being pumped into the engine, which makes sense since air because less dense as the temperature rises.

Below is a graph of a Spearco bar and plate intercooler (part # 2-116). This intercooler has a flow rating of 645 CFM and can support 430 HP. The intercooler's dimensions are 13.6W x 11.75H x 3.5D. The data points below reflect 6000rpm values taken from the corrected turbo airflow table above (80°F and 74% A/E). The scale on the right hand side of the graph measures pressure drop across the core while intercooler efficiency at 5, 10, 15, 20mph is measure on the left hand side. On the bottom of the graph is engine size. The engine size may confuse you a bit. The Saturn has a 1.9liter engine but looking at the graph we did not plot any of our data points even close to that engine size. Turbo charging an engine artificially increases the CID of the engine. So, instead of focusing on the engine size it is more important to look at CFM.

In this example we will consider the green line which represents the efficiency of the intercooler boosting 15psi or 484CFM. On the graph there are two lines, a dotted line and a solid line. The intersecting point between these two lines, at the 90-degree elbow, is the corrected CFM data point calculated from above. Drawing a straight line down from this point will show approximate CID (220), Liters (3.7), and CFM (484) of the engine. The green horizontal doted line shows about a .9psi drop across the intercooler core at 15psi. The solid vertical green line is intersected several times by black lines each having a mph designation. These intersections show the core efficiency, on the left-hand side, at the given mph. At the intersection of these lines you can draw a line to the left and find the core efficiency. For example, at 10mph the core efficiency is .70 or 70%.

Solving for the corrected turbo airflow output of your turbo and then plotting the data on a graph will help you to reduce intercooler induced turbo lag brought on by a larger than required intercooler. By the same token it will save you from heat soaking to small of an intercooler.

I'll leave you with a few points to consider when choosing an intercooler
• Don't go overboard on the intercooler size. This can induce intercooler lag, which is created when the turbo has to fill the large space within the intercooler before it reaches the engine.
• Route the intercooler piping so it has the shortest distance between the turbo and the throttle body.
• Mount the intercooler where it can receive a fresh supply of air that passes directly over the fins.
• Make sure you have room for the intercooler. Measure everything before you order so that it will fit.
• Keep pressure drops across the core to a minimum. Anything under 1.5psi at full boost is considered good.
• It's better to have an intercooler with more height than width. This means that the flow through the intercooler is vertical not horizontal. (height is the charge side)

The turbosaturns.net forum has become one of the best resources for Saturn performance on the net. Our members are constantly pushing their cars to new performance levels. So, log in, share your ideas, and help push your car’s performance to the next level.

• Apexi Safc Install
• Turbo Tuning
• Cams 101
• Wastegate 101
• HP vs Torque
• Ian's Turbo F.A.Q.
• Oxygen Sensors
• DIY Fuel Regulator
• Taming Detonation
• Walbro Install
• Fuel Injectors
• Techedge Wideband
• OEM Fuel Pump Limits
• AVC-R Programming
• Dynosoft
• 220whp or Bust

Archived Articles

HERE

August 2005 TSN will be holding its first ever meet in Chardon, Ohio. Some of the fastest Saturns in the country will be attending. Activities will include drag racing, dyno, tech session, and BBQ. Look for the latest information in the forums.

Different Racing

Jeff and his team Different Racing have big plans on breaking into some really low quarter mile times this year. Last year he posted a 12.40 on a pretty healthy nitrous shot. This year he has a new turbo setup and some serious determination. Visit his website for the latest news and information. I expect we'll be seeing some low 12's from him by the end of the year.