Correct A/F Ratio...
09-13-2006, 11:57 AM
#41
12 Second Club
Join Date: Jun 2005
Location: Chitown
Posts: 1,119
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by allgood57
Check out Innovate's website on tuning tips. On our Mustang dyno we do almost all of our tuning by our LM-1. We go for 12.8:1 (it is hooked into the dyno, so we can see it on power pulls over the RPM range). We have talked a lot with Hans over at Innovate and he is very active in their forums as far as answering tuning questions. Going off of their recomendations, there should be no difference between a N/A motor and a boosted motor, be it turbo or blower. Once we get our AFRs set, we move onto timing. The reason most of the boosted motors run richer is to put less heat into the heads. If everyone was reverse cooled, power and torque would be easier, and using pump gas. Being able to run the head cooler is like added compression (and torque) for free.
09-15-2006, 02:29 PM
#43
6600 rpm clutch dump of death Administrator
The combustion process occurs much more quickly in a supercharged motor than for a naturally aspirated engine with the same ignition point. Adjusting the timing to maximize power can generate other issues such as detonation and "false detonation".
Simply put false detonation is when the engine suffers catastrophic failure and the tuner assumes it blew up from detonation when in fact combustion was smooth and detonation did not occur. Supercharged engines can develop extremely high peak combustion pressures when properly adjusted and unless the engine is capable of supporting these pressures engine failure may occur without detonation occurring.
If it is known that a particular engine can withstand say 3000 psi in the cylinder for peak pressure for instance (typically learned the hard way), then the boost can be increased substantially and the timing retarded appropriately using a data logger to ensure that the piston never sees more than 3000 psi over the range of engine speeds and boost levels. At very high boost levels additional cooling such as water injection may be required to lower combustion and exhaust temperatures.
Although combustion will be extremely inefficient power will increase (disproportionately to boost) and engine stresses will be minimized. An extreme case of this type of tuning can be found in Super Stock pull-tractors operating at extreme boost levels on diesel fuel with water injection.
Most folks in the LS World don't have access to the complex dataloggers that can log things like cylinder pressure, exhaust port pressure, etc... So, we use conventional thinking, and creep up on safe tunes. It keeps the motor alive, but it often leaves a lot of power on the table.
One of the things folks use is fuel. This is used in motors with power adders all the time. Folks use fuel to "put out the fire". Or, they use the fuel to cool the cylinder and prevent the motor from melting down.
Folks use fuel and timing with various logical reasons. The result is often the same, but understand what it does and why is something alot of folks fail to grasp.
I think with the advent of better data collection and sensors more "tuning" skill is going to end up in the hands of the end user.
Simply put false detonation is when the engine suffers catastrophic failure and the tuner assumes it blew up from detonation when in fact combustion was smooth and detonation did not occur. Supercharged engines can develop extremely high peak combustion pressures when properly adjusted and unless the engine is capable of supporting these pressures engine failure may occur without detonation occurring.
If it is known that a particular engine can withstand say 3000 psi in the cylinder for peak pressure for instance (typically learned the hard way), then the boost can be increased substantially and the timing retarded appropriately using a data logger to ensure that the piston never sees more than 3000 psi over the range of engine speeds and boost levels. At very high boost levels additional cooling such as water injection may be required to lower combustion and exhaust temperatures.
Although combustion will be extremely inefficient power will increase (disproportionately to boost) and engine stresses will be minimized. An extreme case of this type of tuning can be found in Super Stock pull-tractors operating at extreme boost levels on diesel fuel with water injection.
Most folks in the LS World don't have access to the complex dataloggers that can log things like cylinder pressure, exhaust port pressure, etc... So, we use conventional thinking, and creep up on safe tunes. It keeps the motor alive, but it often leaves a lot of power on the table.
One of the things folks use is fuel. This is used in motors with power adders all the time. Folks use fuel to "put out the fire". Or, they use the fuel to cool the cylinder and prevent the motor from melting down.
Folks use fuel and timing with various logical reasons. The result is often the same, but understand what it does and why is something alot of folks fail to grasp.
I think with the advent of better data collection and sensors more "tuning" skill is going to end up in the hands of the end user.
09-15-2006, 03:06 PM
#44
12 Second Club
iTrader: (1)
Join Date: Apr 2004
Location: Clarksville, TN
Posts: 1,369
Likes: 0
Received 0 Likes
on
0 Posts
I love reading posts like this 
Continue, please! Spill your experience!
Back in Thermo we did a lab with a logger that logged cylinder pressures, would have been nice to see exhaust port pressures as well. I think a logger that shows that would be very beneficial to other things as well, such as valve events
Continue, please! Spill your experience!
Back in Thermo we did a lab with a logger that logged cylinder pressures, would have been nice to see exhaust port pressures as well. I think a logger that shows that would be very beneficial to other things as well, such as valve events
