Improved Combustion
Thread Starter
5th Gear
Joined: Aug 2008
Posts: 5
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Improved Combustion
For those of you with factory straight plug heads, here is a little engine trick to improve combustion efficiency. Right now, stocker and super stock guys are using these for added performance on the track. These also work really well for street rod applications where header clearance is tight.
http://www.kaizen-ms.com/SparkPlugAdaptors.html
http://www.kaizen-ms.com/SparkPlugAdaptors.html
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 39
From: Fremont CA
Interesting, lets QUALIFY this useage. Anyone with old style Factory straight plug cylinder heads MIGHT benefit IF, they have domes on thier pistons. The old cylinder heads plug location is lower in the combustion chamber than modern cylinder heads so when testing was done in the late 1960's (by Smokey Yunick) it was found that angling (to clear tall piston domes) then raising the plugs helped in combustion efficency. Most modern aftermarket heads have raised spark plug locations and will not show a great benefit from this modification. Also these inserts take 10mm thread spark plugs that are easy to find in a mototrcyle shop BUT! hard to find in a auto parts store. This is a good method of getting around NHRA rules in Stock Eliminator or Super Stock but, the best trick I like is the allowing of GM Performance Parts cylinder heads for L-88 replacement when they are in fact Edelbrock BB Chevy heads with RASIED exhaust ports and FAR BETTER flow than ANY Chevy OEM BB aluminum head that was ever made. If I raced in NHRA, I would be running a L88! People with L46 350HP and LT-1 Vettes along with 340, 360, 365, 375HP 327 Vettes might see some HP improvements.
Thread Starter
5th Gear
Joined: Aug 2008
Posts: 5
Likes: 0
Raising the plug in the chamber gives you the benefit of moving the plug closer to the center of the chamber. This is where the gain is made. A centrally located spark plug optimizes flame propagation by shorten the distance that the flame has to travel.
Angling the plug yields two benefits. First, with a straight plug head, the air/fuel mixture enters the chamber directly inline with the plug, thus wetting the plug. Angling the plug helps prevent fuel from puddling up in the plug. Secondly, by angling the plug toward the exhaust valve, the plug is closer to the Hot exhaust valve and thus puts the tip of the plug in a region that is more likely to have better atomized fuel and thus makes it easier to ionize the gap especially if you are not running a high powered ignition system.
One thing that is common with these adaptors is that they typically like less ignition lead due to the above explainations.
Also, 10mm plugs are readily available and one day away via many different sources on the net.
Take care.
Angling the plug yields two benefits. First, with a straight plug head, the air/fuel mixture enters the chamber directly inline with the plug, thus wetting the plug. Angling the plug helps prevent fuel from puddling up in the plug. Secondly, by angling the plug toward the exhaust valve, the plug is closer to the Hot exhaust valve and thus puts the tip of the plug in a region that is more likely to have better atomized fuel and thus makes it easier to ionize the gap especially if you are not running a high powered ignition system.
One thing that is common with these adaptors is that they typically like less ignition lead due to the above explainations.
Also, 10mm plugs are readily available and one day away via many different sources on the net.
Take care.
Last edited by Chris Cogan; Feb 7, 2009 at 02:37 PM.
