Hello, i am ready to get a C4 and i have been researching them but i cannot find where they switched from Tuned Port Injection to a Multi-port injection system.. What Year?? Thanks Russ

1985 was the last year for Tuned Port Injection.

On the front fenders of my 87 Vette is a piece of trim which says, "Tuned Port Injection". Did someone add this trim to the car before I got it ??????

mypetu39

I believe 1990 was the last year for TPI. When the LT1 engine became available, GM used sequential injection, that is each injector fired on the compression stroke.

well the reason i am making this post is that a friend of mine and i were having an argument that TPI "tuned port injection" was a throttle body injection and he said he had it on an 82 Z-28.
I dont think TPI came out until 84 or 85 on the IROC
I say that Tuned port is NOT a throttle body and has 8 injectors..
At any rate i would like to get my car with a more modern injection system hoping it will be more trouble free.. I am looking to buy a 90 to a 94.. C4 . Russ

1982 Z28 was cross fire injection which was two throttle bodies not tuned port.

Here is where I got my info:

www.corvetteactioncenter.com/specs/c4/1985/85specs.html

1985 Corvette Specifications


Dimensions
Wheelbase (in.) 96.2
Track Frt/Rear (in) 59.6 / 60.4
Length (in.) 176.5
Width (in.) 71.0
Height (in.) 46.7
Ground Clearance (in.) (minimum) 5.0
Curb Weight (lbs) 3,224 - Automatic Transmission
3,216 - Manual Transmission
Weight-to-power ratio (lbs:hp) NA
Coefficient of Drag 0.34
Weight Dist. F/R (%) NA
Coolant Capacity (qt.) NA
Fuel Capacity (gal.) 20.0
Oil Capacity (qt.) (without filter) 4.0

Engine Specifications
L98
Type Overhead valve, pushrod V8, 2 valves/cylinder, cast iron block/heads
Bore 4.00 in.
Stroke 3.48 in.
Displacement 350 ci.
Compression Ratio 9.0:1
Horsepower 230 hp @ 4,000 rpm
Torque 330 lb-ft @ 3,200 rpm
Redline (RPM) NA
Induction System Bosch Tuned Port Fuel Injection
Cylinder Block Material cast iron alloy
Cylinder Block Deck Height 9.025"
Cylinder Head Material cast iron alloy
Head Gasket Thickness (compressed) .021"
Total Dressed Engine Weight (dry) 585.7 lb
Note: These weights do not include radiator hoses, coolant, accelerator controls and engine mounting hardware.

Miscellaneous
Brakes
Type NA
Front Rotors (diam) 11.5 in. vacuum assist. vented disk
Rear Rotors (diam) 11.5 in. vacuum assist. vented disk
Wheels and Tires
Wheel Size (Front) 16 x 8.5 in. (RPO Z51: 16 x 9.5 in.)
Wheel Size (Rear) 16 x 8.5 in. (RPO Z51: 16 x 9.5 in.)
Wheel Type 5-bolt, cast alloy
Tire Make/Size Goodyear Eagle VR50, P255/50VR-16

Transmission
Automatic Manual
Type 4-Speed Automatic 4-Spd. Man. Doug Nash
Gear Ratios
1st 3.06 2.88 (1.93 OD)
2nd 1.63 1.91 (1.28 OD)
3rd 1.00 1.33 (0.89 OD)
4th 0.70 1.00 (0.67 OD)
Reverse NA NA
Axle Ratio 2.73 (RPO G92: 3.07) 3.07



www.corvetteactioncenter.com/specs/c4/1986/86specs.html

1986 Corvette Specifications

Dimensions
Coupe Convert.
Wheelbase (in.) 96.2
Track Frt/Rear (in) 59.6 / 60.4
Length (in.) 176.5
Width (in.) 71.0
Height (in.) 46.7 46.6
Ground Clearance (in.) (minimum) 4.7
Curb Weight (lbs) 3280 3266
Weight/Power (lbs/bhp) 15.1 14.4
Coefficient of Drag 0.33 NA
Weight Dist. F/R (%) 51/49 50.2/49.8
Coolant Capacity (qt.) 14.6
Fuel Capacity (gal.) 20.0
Oil Capacity (qt.) 4.5

Engine Specifications
L98
Type Overhead valve, pushrod V8, 2 valves/cylinder, cast iron block, aluminum heads
Bore 4.00 in
Stroke 3.48 in
Displacement 5.7L / 350 ci.
Compression Ratio 9.5:1
Horsepower 230 hp @ 4000 rpm (235 hp w/ alum. cyl. heads)
Torque 330 lb-ft @ 3200 rpm
Redline (RPM) 5,500
Induction System Bosch Multi-Point Fuel Injection

Miscellaneous
Brakes
Type ABS Power-assist vented discs
Front Rotors (diam) 11.5 in.
Rear Rotors (diam) 11.5 in.
Wheels and Tires
Wheel Size (Front) 16 x 8.5 in. (RPO Z51: 16 x 9.5 in.)
Wheel Size (Rear) 16 x 8.5 in. (RPO Z51: 16 x 9.5 in.)
Wheel Type 5-bolt, cast alloy
Tire Make/Size Goodyear Eagle VR50, P255/50VR-16

Transmission
Automatic Manual
Type 4-Speed 4-Spd. Doug Nash w/ OD
Gear Ratios
1st 3.06 2.88 (1.93 OD)
2nd 1.63 1.91 (1.28 OD)
3rd 1.00 1.33 (0.89 OD)
4th 0.70 1.00 (0.67 OD)
Reverse NA NA
Axle Ratio 2.73 (RPO G92: 3.07) 3.07

ORIGINAL: jrc316

well the reason i am making this post is that a friend of mine and i were having an argument that TPI "tuned port injection" was a throttle body injection and he said he had it on an 82 Z-28.
I dont think TPI came out until 84 or 85 on the IROC
I say that Tuned port is NOT a throttle body and has 8 injectors..
At any rate i would like to get my car with a more modern injection system hoping it will be more trouble free.. I am looking to buy a 90 to a 94.. C4 . Russ


You are right. TPI came out in 1985 and is not a throttle body injection. THrottle body started with cross fire, which was 2 throttle bodies and then GM saw the error of their ways, so to speak, and then started to put 2 injectors in one throttle body, a setup which they used on pickups until early 90's.

Thanks for that link, i will check it out.. Russ