1980 Pontiac Trans Am Turbo Tech Article

[cpu]

I was somewhat intrigued by the forums latest members, jase, 1980 Turbo Trans Am.

I hadn't seen a turbo layout like that before so I went digging.  I came across a neat article on that model car.  Thought I would share it with you



Before we get started with the 1980 Pontiac Firebird Trans Am, a bit of history is in order,  and, it concerns a sister division, Buick. In 1975, the Buick Regal was chosen to pace the Indianapolis 500, stuffed full of modified 455 cubic inch motivation, tradition continued utilizing brute force to create speed. But when the 1976 Indy rolled around and the Buick Regal was once again called upon for pace car duties, the 455 was replaced with the reborn 231 cubic inch V6, now fitted with a turbocharger. Buick engineers managed to wrestle about 306 hp out of this mini motor and the turbocharger race was on. To showcase their newly downsized 1978 mid-sized models, Buick introduced a turbocharged 175 horsepower version of the 231 V6 in the Century/Regal lineup. The engines were strengthened, compression ratios lowered to handle the 7 pounds of boost, fitted with electronic controls, and blew up at an alarming rate. But the turbo revolution had begun.

The Century/Regal pair were comprised half the lineup of all the turbocharged cars available in America in 1978, the other two being a Saab 900 Turbo and the Porsche 930. A new turbo competitor turned up in 1979, the Ford Mustang/Mercury Capri twins. Both were newly redesigned giving up their Pinto based hardware for a new, state of the art, "Fox" chassis. The "Fox" chassis had earned accolades from the motoring press in the form of the Ford Fairmont and Mercury Zephyr on its it debut in 1978. Here was a lightweight chassis (under 3000 pounds) to be powered by a turbocharged 2300 cc four-cylinder engine that produced nearly 50% more power (around 120, because Ford was secretive (embarrassed?) about horsepower numbers back then) than the naturally aspirated version of the same engine. Like the Buick turbo V6, it too blew up on a regular basis.

Now it was Pontiac's turn to enter the turbo fray. Bean counters and fuel economy worry warts killed off the big Trans Am engines, and for 1980 you could order a 301 cid naturally aspirated Pontiac V8, a 305 cid (oh-no!) Chevrolet V8, or the new Turbocharged 301 Pontiac engine. While the Mustang had long ago lost the image of a performance car, the Trans Am was regarded as the last holdout, the Royal guard so to speak. Finding a suitable replacement for the big motors was a tall order, and Pontiac engineers tried their best with the technology available to live up to the reputation so established.

For an engine that began life as an economy motor, numerous modifications were in order if the engine which was designed to operate in a vacuum to live under the pressure of nine pounds of boost. The webbing around the main bearing caps on the block was made thicker. Head gasket  materials were upgraded to keep the pressure within the cylinder bores. Main bearing cap bolts were up a size from 7/16 of an inch to an honest one-half inch. Pistons were made stronger and the wrist pins tougher to survive the stresses forced induction imposed.

The turbocharger chosen to "boost" the power of the 301 was the same Garrett TB305 unit which was in service in the Buick and Ford turbo engines. The turbocharger plumbing utilized a "draw through" design, where the boost took place behind the carburetor. Although, at best, this was a compromised because the turbocharger did not get to work to the full potential. But these were the days before fuel injection, and GM could not risk the possibility if a forced induction fuel leak. Compared to the other turbos on the market, the T/A motor lacked most of the whine associated with turbocharged engines. Pontiac asked Garrett to provide better balanced turbo impellers to reduce the noise. The idea was to make the turbo as transparent as possible, to use the feel of the acceleration rather than the noise of the turbo to let the customers experience the power at hand.

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The net output of the turbocharged 301 (Engine Code "YL") varied but was generally cited as being 210 horsepower at 4000 rpm, down 10 horsepower from the mighty T/A 6.6 engine laid to rest after the '79 model year. Bolting on the turbocharger bumped the torque up to 345 lb/ft @ 2000 rpm, a 25 ft/lb increase over the T/A 6.6L engine. The compression ratio of the engine was lowered to 7.5:1 and was fitted with a derivitave of GM's Buick electronic control unit to monitor boost and timing settings. Maximum boost was achieved at around 3500 rpm, a little below the shift point.

The turbocharger was a grand idea, but the technology to make it work properly was nonexistent at the end of the 70's. As the newer high octance fuels were ave today were not yet availiable, the engine had to operate on substandard fuels (Sunoco 94 was and the like nowhere to be found) of 87 to 90 octane, and this would have led to severe detonation under  boost if it were not for the ECU. By placing a vibration sensor in the valley between the cylinders which would detect detonation, the ECU interrupted this chain reaction by retarding the ignition timing and reducing boost pressure until the detonation was gone. By utilizing these computer controls, this process was repeatedly continued during the operation of the engine, attempting to keep the engine running at optimum performance all the time. By eliminating so much timing, the result was a none to powerful feeling from the turbo engine. With today's fuels, many owners claim quite reasonable performance and many of these engines have lived well beyond the 150,000 mile mark with little other than routine mainenance.

The effects of the timing adjustments were so severe that the required automatic transmission was programmed to upshift at 4400 rpm for the 1-2 shift and at 3800 for the 2-3 shift, 200 rpm short of the engines power peak. This was also the point at which the car was the quickest because manually shifting the transmission at higher rpms gained no speed or quickness, just noise.

The turbo 301 introduced the "turbo hood", making these the first Trans Ams since the '69's to not have a shaker hood. The hood had about a 22 inch bulge that extended upwards 1 and 1/4  inches that was off set to the left of the hood centerline. Clearance for the relocated carburetor and plumbing from the turbocharger necessitated this bulge (much as the planned 2-4bbl's on the '70 T/A resultant shaker). Underneath, a hood blanket (the first such application on the Trans Am) had a aluminized shield over the turbocharger area in an attempt to keep the hood paint from blistering. To make things interesting, a "Turbo Boost Gauge" (RPO UR4) could be ordered for $40 and consisted of a series of three orange lamps which showed the rate of boost the engine was operating under and was located at the rear of the bulge facing the driver. No real (one that showed the actual amount of boost) boost gauge was offered on the Turbo Trans Ams.

The other two available engines were normally aspirated V8's, one from Chevrolet and one from Pontiac. For the fisrt time in history, all three available engines, regardless of emission requirements, were available only with an automatic transmission. Such were the turbulent times of the late 70's-early 80's when it was so difficult and expensive to certify engines to EPA spec's, hard to certify or low production combinations were shelved by the manufacturers.

The Chevrolet sourced engine was the 305 (Engine Code CEL or CEM") cubic inch V8, which was a small bore derivative of the venerable 350 V8. The engine had a bore of 3.74 inches (350's have a 4.00" bore) and a stroke of 3.48 inches. This engine was required and only available in California and credited the price of the car by $180. The 305 or (5.0 litre) produced 145 hp @3600 rpm and carried a net torque rating of 240 lb/ft @ 2000 rpm. Certainly not a high powered screamer for a 3700 pound car. When ordered with the Chevrolet engine, the now familiar "splitter" exhaust was deleted for a pair of standard tailpipes.

The Pontiac 301 (Engine Code YN or XN) was the standard engine for all Trans Am's outside of California and was equipped with a 4-bbl carburetor. Referred to as a 4.9 litre V8 to distinguish itself from the Chevrolet (5.0L/305 CID), this was the engine Pontiac's had developed purely for economy. The engine had a bore of 4.00" and a stroke of 3.00" (ironicly the same as Ford's 302 and Chevrolet's mighty 67-69 302 cid Z28 engine) and produced 150 hp at 4400 rpm and 235 lb/ft of torque at only 1800 rpm, up five horsepower from 1979 benefitting from a slightly hotter cam and a revised exahust system.

As the new engine package was the highlight to the 1980 model year, there were only minor color, trim, accessory, and feature changes. Chassis wise, there were low friction ball joints, helping to make the ride smoother. To aid in overall durability, the power steering pressure hoses had new "O" rings at the connections to reduce the opportunity for leaks. In a move that in the 80' was the "wave of the future, the steering linkage studs and nuts converted from "standard" to "metric".

Trans Ams could now be ordered with a widening array of luxury items in attempt to broaden its appeal to those who were interested in the performance image of the car, but did not want to sacrifce the creature comforts of other cars in the same price class. These included new digitally tuned stereo radios, additional acoustical insulation packages, and a new seat covering style.

Inside, there were few detail changes. The base seats were still finished in Oxen vinyl, but the headrests were no longer pleated to match the remaining seating surface. Custom interior was still available, either in Doeskin vinyl or in Hobnail cloth. The speedometer was changed, abiding by new federal laws which limited the speedometer to 85 mph.

The big change to the outside of the Trans Am was the earlier mentioned "Turbo Hood", offered only with the 4.9L Turbo engine. Trans Am's equipped with the 4.9L or the 5.0L V8's still featured the shaker scoops. Two styles of optional hood decals (RPO D84) were offered; the conventional appearing bird when ordered in combination with the 4.9L or 5.0L engines or the "Turbo Bird" when equipped with the 4.9L turbo. The "Turbo Bird" turned the Firebird's head to the left and spit out a larger flame than the "regular" Firebird.

Last year's 10th Anniversary Edition "Turbo" cast aluminum wheels (RPO N89) were initially showcased on only those Trans Am's ordered with the 4.9L Turbo (RPO LU8) engine (which also required  the WS6 or WS7 suspension packages). This idea was short lived because Californians, who were not allowed the tutbo in their smog encumbered state, wanted the turbo wheel. Pontiac abided by their wishes lifted some of the restrictions, and allowed 305's and even some non-turbo 4.9L engined cars to be produced with the "Turbo" wheels. The wheels could be ordered in either the natural polished finish or in a gold painted version, with the edges on the gold painted versions being machined away. All wheels were fitted with a bright plastic center cap with the Firebird logo mounted in the centre.

To prove the Turbo Trans Am's viability as a big engine replacement, the 1980 Indianapolis 500 would be paced by the first time in history by a Firebird. Eager to showcase the little turbo's  ability, the engine and drivetrain would be stock, (but most likely blueprinted). The changes were limited to a rear axle ratio swap, utilizing a 2.56:1 versus the standard 3.08:1 gearing, and a larger P245/60R15 Goodyear Eagle GT tire. The taller gearing allowed the engine to operate in the 3500-4000 rpm range rather than 45-5000 rpm, exhibiting much less stress at the continual high speeds the pace car would be operated at. Pontiac built five cars for the track and the actual Pace Cars were built without air conditioning.

In what has become a popular move, Pontiac produced 5700 Turbo Trans Am Indy 500 Pace car replicas, complete with stickers and decals to make it look just like the rear thing. Outside, the car was painted in a similar style to the 10th Anniversary Trans Am, with white replacing the silver complemented with gray accents. The "Turbo" cast aluminum wheels were painted white to match the exterior and had many areas machined away exposing the natural aluminum as had been commom practice on the "Snowflakes". The exterior mirrors were painted gray and were given a dual black/red pinstripe which also followed many of the detail lines on the car. The hood bird was an exaggeration for the optional new for 1980 Turbo hood bird with the wing tips stretching to nearly the front fenders.

Inside a the seats were finised in a combination of Doeskin vinyl and Hobnail cloth in the hue of oyster with black accents. In the center of the rear seatback, a Firebird logo was stitched into the vinyl trim, with the logo also being stitched into each door panel. The red-lit gage cluster from the 10th made its way into the Pace Car.

The Indy 500 Pace Car replicas, because ot the standard 4.9L turbocharged engine, were excluded from sales in California due to the emission requirements. Pontiac laid claim upon announcing the Pace Car Replica that this car was the first and only production car with a Turbocharged V8 as standard equipment.

Additional cars saw pace car duty. Daytona Motor Speedway used Turbo Trans Ams to pace the Firecracker 400. These cars were all single color and used the natuaral finish turbo cast aluminum wheels.

Prices for the Trans Ams jumped sharply from 1979 prices to the 1980 model year, due to the difficult inflationary times in America and the popularity of past models. The Firebird Tran Am base price increased by $880 to $7179 despite losing the 403 cid engine as standard equipment. To step up to the RPO LU8 Turbocharged 4.9L engine added $350 to the price and the RPO Y84 Special Edition package commanded a $1443 premium with T-Tops and $748 without. The Indy 500 Pace Car replica with the 4.9L turbo standard carried a list price of $11,194.

Without a doubt, 1980 was a turning point for the Trans Am as well as the entire Firebird line. What we call classic styling today was referred to as a "dinosaur" in its day. What a shame. 1981 was just around the corner and many were joyously awaiting the demise of the proud automobile so they could get their hands on the replacement. The 1981 Trans Am would be the last of the line.

1980 Turbo Pace Car Specifics 4.9L Turbocharged V8 Engine, 3-Speed Automatic Transmission, Positraction rear axle with 3.08:1 axle ratio, WS6 Performance Handling Package with 4-wheel disc brakes, Hatch roof, Specific Oyster interior with Hobnail Cloth inserts in Doeskin Vinyl with Firebird logo embridered into rear seat back, special oyster luxury weight carpet, Air conditioning, Red lit gages, power windows, power door locks, power antenna, white exterior color with gray accents, unique hood decal, turbo boost gauge, white painted turbo cast aluminum wheels, leather stitched formula steering wheel with unique horn button, pin striping, custom interior door trim panels with Firebird logo embroidered into each upper panel, tilt steering wheel, delay wipers, and cruise control.


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1980 Turbo Pace Car Specifics
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4.9L Turbocharged V8 Engine, 3-Speed Automatic Transmission, Positraction rear axle with 3.08:1 axle ratio, WS6 Performance Handling Package with 4-wheel disc brakes, Hatch roof, Specific Oyster interior with Hobnail Cloth inserts in Doeskin Vinyl with Firebird logo embridered into rear seat back, special oyster luxury weight carpet, Air conditioning, Red lit gages, power windows, power door locks, power antenna, white exterior color with gray accents, unique hood decal, turbo boost gauge, white painted turbo cast aluminum wheels, leather stitched formula steering wheel with unique horn button, pin striping, custom interior door trim panels with Firebird logo embroidered into each upper panel, tilt steering wheel, delay wipers, and cruise control.



1980 Trans Am KwikSpecs Production Figures    


Engine Decor  # Built
4.9L Base  14,886
4.9L Turbo Base  5,753
5.0L Base  1,635
4.9L Base w/CC1 (T-Top)  8,692
4.9L Turbo Base w/CC1 (T-Top)Base TA  7,176
5.0L Base w/CC1 (T-Top)  896
4.9L Spcl Ed  72
4.9L Turbo Spcl Ed  103
5.0L Specl Ed  12
4.9L Spcl Ed  2,084
4.9L Turbo Spcl Ed  3,444
5.0L Specl Ed  463
4.9L Turbo Indy Pace Car  5,700
   
   
Dimensions    
Wheelbase   108.1"
Curb Weight   3717 lbs
Length   199.1"
Height   49.3"
Track Front  61.3"
 Rear  60.0"
Width   73.0"
Trunk Space   6.6 cu. ft.
   
   
Legroom - F   43.9"
Legroom - R   28.4"
Headroom - F   37.2"
Headroom - R   35.9"
Shoulder Room - F   57.4"
Shoulder Room - R   54.4"
Hip Room   52.4"
Hip Room   46.3"
Trunk Cap'y   6.6 cu. ft.
Fuel Capacity   21.0 gal
Tires Size   P225/70R-15
Wheels Size  Std Rally II 15"x7"
 Snowflake Opt Cast Alum 15"x7"
 Snowflake Opt Cast Alum 15"x8"
 Turbo Opt Cast Alum 15"x8"
   
   
   
Transmissions    
 Speeds  Usage  
 3-Auto  Std
Engines  
CID-Version Code Trans HP@RPM
4.9L YN, XN 3A 150@4400
4.9L Turbo YL 3A 210@4000
5.0L (Chev) CEL, CEM 3A 145@3600
   
Performance    
0-60 MPH 8.2 sec  
1/4 Mile - Time 16.7 sec  
1/4 Mile - Speed 86 mph  
Braking 60-0    
Braking 70-0 186 ft.  
Roadholding    
Top Speed 116 mph  
EPA Mileage City Hwy Comb
301 T/A 16 24 19
301 Turbo 14 20 16
   

[joe74ta]

WOW CPU what a marathon read the highlight for me was the fact that Mu$tangs with turbos just blew up whilst the Trans am went on to be the only turbo charged V8 in production.

[bonnevista]

Or was it just Mustangs in general.

[LU8]

 The Ford 2.3 Turbo made 132 hp on debut (1979) with a 2 barrel carb. On fuel injection it got to 200 hp during the '80s in SVO applications.