Teach me about Fast Burn Combustion Chambers
02-01-2006, 10:06 AM
#1
Staging Lane
Thread Starter
iTrader: (1)
Join Date: Sep 2003
Location: Long Island, New York
Posts: 99
Likes: 0
Received 0 Likes
on
0 Posts
Teach me about Fast Burn Combustion Chambers I was wondering if someone could explain to me what the difference between a Fast Burn Combustion Chamber and a non Fast burn Chamber is?
Any specifics on how they work, what makes them different, characteristics required, also can it be applied to a 2 valve engine (ie is the LS1 chamber a "fastburn" chamber) or is it strictly a 4 valve design? Also will they have the same volume as a non-fast burn chamber etc...
if you guys have any good articles or links to this information I would greatly appreciate. Ive read all the other threads and learned a tremendous amount about combustion phenomenon but I would still like to learn more and I figure this is a good place to start.
I remember reading something on this forum a while ago about the Northstar engine that from one year to the next changed to a fastburn chamber. When they did this they had a similar compression ratio but were able to use lower octane fuel. How is this possible, what specifically did they change and and pictures or diagrams would be great.
Thanks
Rob K
Any specifics on how they work, what makes them different, characteristics required, also can it be applied to a 2 valve engine (ie is the LS1 chamber a "fastburn" chamber) or is it strictly a 4 valve design? Also will they have the same volume as a non-fast burn chamber etc...
if you guys have any good articles or links to this information I would greatly appreciate. Ive read all the other threads and learned a tremendous amount about combustion phenomenon but I would still like to learn more and I figure this is a good place to start.
I remember reading something on this forum a while ago about the Northstar engine that from one year to the next changed to a fastburn chamber. When they did this they had a similar compression ratio but were able to use lower octane fuel. How is this possible, what specifically did they change and and pictures or diagrams would be great.
Thanks
Rob K
02-01-2006, 09:14 PM
#2
TECH Regular
Join Date: Oct 2005
Posts: 430
Likes: 0
Received 0 Likes
on
0 Posts
In general, a fast burn chamber is one where a lot of design effort has gone into reducing the spark advance requirements. This might include port-induced 'swirl' (which evolves into turbulence later in the compression stroke), shortening the flame path across the cylinder via good spark plug placement, well-positioned squish pads to increase turbulence and flame speed and shallow/compact combustion chambers with small, zero or negative flame-obstructing piston domes.
The net effect is a reduction in spark advance, e.g. from over 40 degrees for early small blocks to low twenties for Gen III/LS engines. This gives more consistent combustion, greater detonation resistance (= higher CR capability), better emissions and a reduction of the 'negative power' generated from the ignition point until TDC on the compression stroke.
The net effect is a reduction in spark advance, e.g. from over 40 degrees for early small blocks to low twenties for Gen III/LS engines. This gives more consistent combustion, greater detonation resistance (= higher CR capability), better emissions and a reduction of the 'negative power' generated from the ignition point until TDC on the compression stroke.
02-02-2006, 08:00 PM
#3
TECH Resident
Join Date: Dec 2004
Location: K-W, Ontario
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
That's a great summary Madbill
Along with that, the engine should be setup to make use of the fast burn design.
Quench heights kept to minimums, compression ratios to match fuel, piston
crown design, etc.
Along with that, the engine should be setup to make use of the fast burn design.
Quench heights kept to minimums, compression ratios to match fuel, piston
crown design, etc.
