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900 Turbo 8-Valve Intercooler Installation

Home | 85Intercooler in 83Turbo | Before and After | Parts Checklist | Getting Started | Assembly

Early 16V-T plastic grills added to airdam for more Intercooler flow, and some extra flow to the intake horn zone. Also note slit above bumper...has plastic grill on backside; also for more air to Intercooler.

85 INTERCOOLER IN 83 TURBO

by Kevin Kelleher

reprinted from NINES issue# 140, October 1985

Having decided to intercool my '83 Turbo I called and obtained brochures from three suppliers: Omni Cool, Turbo Car, and Calloway. Although all three provided quality products, I found some fault (in my opinion) with each.

The Omni Cool unit mounts on the hot side of the engine behind the right headlight. The manifold/turbo insulation provided may reduce some low speed intercooler heating, but it will also aggravate turbo bearing heat soak at shutdown.

The turbo car unit mounts on the cool side of the engine, behind the left headlight, with the oil cooler moved to allow more airflow. However, like the Omni Cool, it is fitted in an angled fashion with limited - if any - ducting to encourage efficient use of the airflow.

The Calloway unit mounts horizontally-flat behind the air dam, and it incorporates a lower air scoop. The plumbing is a bit long and the location vulnerable, but this is probably the most efficient unit of the three. Unfortunately, it costs more than the other two combined since it is sold as part of an elaborate "bump up" system.

I elected to undertake a more difficult alternative - retrofitting the standard '85 Saab hardware. To the joy of my local dealer, I ordered the intercooler assembly with all the related piping and hoses from the air inlet horn to the intake manifold flex-boot. Other main items included upper and lower intercooler mounting plates, lower radiator hose, and air dam and screen ports. On the '85s, the left port exclusively provides oil cooler airflow, but I feed half of this air to the intercooler, supplementing the normal slotted port flow. Since the '85s use the new compact "mass flow" injection system, the bulky '83 system required some repositioning, and the pre-heat system was sacrificed in the process. It is debatable how much cold weather preheating occurs, especially at high charge velocities. Also notable were the repositioning of the horn and oil cooler, and extensive use of thick rubber sheet pieces to direct airflow.

The total job took about 25 hours, cost $600+, and is not for the casual air-filter-spark plug changers. The results were an honest 12% increase in peak torque (based on uphill runs) with stock boost, and a very clean original equipment installation. Top gear roll-on times were taken during a a single, 70 degree F afternoon test that included runs with the intercooler bypassed All runs were made with a solo driver and half-tank of premium fuel. The average of many runs made in both directions on a nearly flat straight-away showed consistent improvements of 3% in 30 to 50 times (10.6 vs 10.9) and 8% in 50-70 times (8.2 vs 9.0). Each run was started with the speed stabilized, and with the higher speed runs it took about 4 seconds to achieve full boost.

Test numbers aside, the big difference is highway performance. Acceleration feels much stronger in fourth and fifth gears when running near 3000 r.p.m. It is also much improved at higher rpm, but less pronounced due to the reduced boost schedule of the APC unit. Before increasing the boost, I'd advise adding an enrichment device to keep exhaust gas temperatures reasonable. Also, turbo lag appears to be reduced. Boost initiation is the same; but once it begins, the climb to maximum boost is much more rapid. My test results put engine peaks at 147 hp and 194 ft-lbs, vs stock values of 132 and 172 respectively. However, loss of the preheat system may restrict this modification from cold-climate areas.

1983 Saab Turbo, 25,000 miles, Saab Intercooler Test
Test date: 5-5-85, Noon, 75 degrees F, lite breeze, 160 lb. driver, 1/2 tank premium fuel, 30 psi/tire
 

30-50 m.p.h (1300-2150 rpm) *

50-70 m.p.h (2150 - 3000 r.p.m)**

Induction
standard.
intercooled
standard.
intercooled
Uphill run
11.2
11.0
9.6
8.8
11.4
11.0
9.6
8.6
11.35
11.5
9.4
8.65
11.8
   
8.7
Uphill typical
11.35
11.00
9.60
8.65
% improve
3%
10% ***
 
Downhill run
10.2
10.5
8.3
7.7
10.4
10.3
8.5
7.7
10.45
10.0
8.3
7.4
10.0
10.0
   
Downhill typical
10.40
10.10
8.30
7.70
% improve
3%
7%
 
Average typical
10.90
10.55
8.95
8.20
Average %
3%
8%

Notes:

* Acceleration from stabilized initial speed in 5th gear
  ** 50-70 times include 4sec climb to full boost
  *** Estimated torque: (172(stock) X 1.11) = 191 ft-lbs.