Compression
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Technically, ALL (C4 era) cars were required to be able to operate on 87 octane, including the ZR-1. However, one of the beauties of the modern injectors/computers and attendant sensors is the ability to adjust the engine management (timing, mostly) to the "knock" level: It isn't the increased octane level that improves performance (read: POWER), but the fact that timing and even fuel mapping can be adjusted according to the chip calibration in conjunction with (knock) sensor input.
So, All things considered, the answer is YES your Corvette should perform better with 91+octane (within limits) than it will on 87- octane.
Dynamic Compression Ratio varies with host of atmospheric and mechanical conditions. So, what that value is will change...well...DYNAMICALLY with conditions present at that time. DCR is more of an engineering "dipstick" than a practical tool. It is more commonly used when designing cam profiles and phasing calculations for example:
Dynamic Compression Ratio Calculator:
(Use seat to seat specs for Intake spec for best results)
Number of Cylinders :
Bore in Inches :
Stroke in Inches :
Rod Length in Inches :
Static Compression Ratio : (:1)
Inlet Valve Closes ABDC : º
Boost Pressure in PSI :
Target Altitude : (Feet)
Density Air (DA) calculations are more akin to common correction factors for calculating adjusted HP or trap speeds, etc.
Oh, and actually the 90 L98 data shows a 9.5 CR; not 10.5. Except for the LT5 (CR of 11.0:1). It wasn't until the intro of the LT1 in '92 that the GEN II SBC CR saw 10.5:1 and 10.8 for the LT4 in '96, FWIW.
So, All things considered, the answer is YES your Corvette should perform better with 91+octane (within limits) than it will on 87- octane.
Dynamic Compression Ratio varies with host of atmospheric and mechanical conditions. So, what that value is will change...well...DYNAMICALLY with conditions present at that time. DCR is more of an engineering "dipstick" than a practical tool. It is more commonly used when designing cam profiles and phasing calculations for example:
Dynamic Compression Ratio Calculator:
(Use seat to seat specs for Intake spec for best results)
Number of Cylinders :
Bore in Inches :
Stroke in Inches :
Rod Length in Inches :
Static Compression Ratio : (:1)
Inlet Valve Closes ABDC : º
Boost Pressure in PSI :
Target Altitude : (Feet)
Density Air (DA) calculations are more akin to common correction factors for calculating adjusted HP or trap speeds, etc.
Oh, and actually the 90 L98 data shows a 9.5 CR; not 10.5. Except for the LT5 (CR of 11.0:1). It wasn't until the intro of the LT1 in '92 that the GEN II SBC CR saw 10.5:1 and 10.8 for the LT4 in '96, FWIW.
