compression help
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
I think there is some misinformation on the vac adv can, check Lars' tech papers for the low down on getting the proper set up for your eng combo.
https://www.corvetteforum.com/techti...=115&TopicID=3
https://www.corvetteforum.com/techti...=109&TopicID=3
https://www.corvetteforum.com/techti...=115&TopicID=3
https://www.corvetteforum.com/techti...=109&TopicID=3
Drifting
Joined: Nov 2001
Posts: 1,469
Likes: 6
From: 68 427 4.11s Roadster
A very large engine pushing a very heavy load through limited gear (torque multiplication) compared to light load, small engine, many many gears.
BUT the biggest is your comparing an engine that was designed for high octane gasoline.
If a modern engine they are close to this if not at 11:1.
A similar question comes up why a bike 2-cycle can spin so much faster than a merc 2.5 and produce more HP for weight. Smaller engine with gears VS large engine with no gears at all. These engines also are limited by octane.
With high comp heads my 200lb engine dynoed at 340 hp.
Pump gas heads guessed at 280-290. ( on a 1250 lb boat beats my Vette for power to weight
)
BUT the biggest is your comparing an engine that was designed for high octane gasoline.
If a modern engine they are close to this if not at 11:1.
A similar question comes up why a bike 2-cycle can spin so much faster than a merc 2.5 and produce more HP for weight. Smaller engine with gears VS large engine with no gears at all. These engines also are limited by octane.
With high comp heads my 200lb engine dynoed at 340 hp.
Pump gas heads guessed at 280-290. ( on a 1250 lb boat beats my Vette for power to weight
)
Pro
Joined: Jan 2004
Posts: 535
Likes: 1
From: Darwin, Australia NT
Pull the manifold and block the heat riser, this will make a difference.
Fit a carb insulator, insulate fuel lines.
Get your motor to run cooler, ie race waterpump, overdrive pulleys, high flow thermostat, better radiator, better fans.
Get a vacume advance canister that is adjustable in rate and amount.
Check fuel mixture.
Cooler plugs.
Lastly change cam timing.
Fit a carb insulator, insulate fuel lines.
Get your motor to run cooler, ie race waterpump, overdrive pulleys, high flow thermostat, better radiator, better fans.
Get a vacume advance canister that is adjustable in rate and amount.
Check fuel mixture.
Cooler plugs.
Lastly change cam timing.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
IMHO, current generation vettes with 10.5 and up compression can use 93 octane because of careful fuel and timing management. Current combustion chamber designs and flat top pistons work to prevent detonation. It will be tough to do with pop-up domes and old head technology without giving up too much performance.
Race Director
Joined: Oct 2000
Posts: 14,997
Likes: 79
From: central FL, near the beach.
Originally Posted by Matt Gruber
i wrote this hoping it would help
http://community.webtv.net/MATTGRU/pv
so far no takers, just my 2 VETTES
http://community.webtv.net/MATTGRU/pv
so far no takers, just my 2 VETTES
