1989-90 Corvette's L98 TPI HP-CR doubts - Hot Rod Forum : Hotrodders Bulletin Board
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Old 02-22-2008, 08:36 AM
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1989-90 Corvette's L98 TPI HP-CR doubts

Let's see this 89 v/s 90 Corvette specs both TPI :

1989 :

Compression Ratio 9.5:1
Horsepower 245 hp @ 4,300 rpm (coupe w/ 3.07:1 axle)
240 hp (convert.)
Torque 340 lb-ft @ 3,200 rpm

1990 :

Compression Ratio 10.25:1
Horsepower 250 hp @ 4,400 rpm (coupe)
245 hp @ 4,000 rpm (convert.)
Torque 350 lb-ft @ 3,200 rpm (coupe)
345 lb-ft @ 3,200 rpm (convert.)

On 1990 the L98 got flat top pistons and the compression ratio increased from 9.5 :1 to 10.25:1

How come the extra compression added only 5 HP ??????
i read that they "pussified" the cam to give the engines
not too much power ....and that's why the 5 HP increase only....

Is this true ?
i cant believe that !! Did GM follow certain standards ?

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Old 02-22-2008, 11:25 AM
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From the specs I gather the earlier L98s had 9.5:1 compression and the 1991 recieved 10:1. only a half point in compression is worth very little in means of power, a half point raise would give it about five more horses.
You can look at the year specs here:
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Old 02-22-2008, 01:23 PM
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A full point of compression is only worth about 3-4% power, so I think 5 hp is actually a nice gain from such a little increase in compression
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