FI and heads?
Originally Posted by Country Boy
I was thinking.... what affect does a set of ported heads have and are they really worth it on a FI motor. I thinking this because your already forcing air into the cylinder. N/A motors are dependent on the lift and flow of the heads because the cylinder has to draw its own air and the smoother larger runner helps. Is this the same concept on a FI car?
Let me see if I can shed some light on this question being that I am there anyway. On a N/A motor, Velocity is everything and actually makes more of a difference than volume, because if you open up a set of heads and slow the air coming in you will lose power every time.
On my setup, and I think my power speaks for itself. I am guessing that my heads are worth 100Hp on my setup. They are a stage III setup from More Performance. The same setup on a N/A car would probably cost you 20 hp or more. With a forced induction car, you are forcing air, into the cylinder. However, a bigger port is still important, because it is still about how much air can you get into the cylinder. Port shape becomes much more important, because you do not want the air to slow down as it makes its trip to the cylinder. Every inch of air is power.
Someone on this thread made mention about octane and the heads. That is much more related to Compression Ratio than head and port design. My car has completely dispatched the therory about high hp and octane. I make 822 RWHP and I run all day on 93 octane and I do it with the stock GM PCM and high imp injectors. There is no black magic or black art. I make this power before 6000rpm, and I do it with only 17 degrees of timing.
The bottom line is this, More air makes more power. On a N/A car it is about velocity, on a blown car it is about volume. Because you are pushing more air in, it allows you to have a bigger port, and you can take advantage of it.
My heads are the LS6 Z06 head. They come with a bigger exhaust port which is much more inportant on a blown engine. They have the Jesel Mohawk 1.7 Shaftrocker.
I am prepared to discuss this with anyone that would like to have the conversation.
lunapark@perigee.net
Staging Lane
Joined: Nov 2004
Posts: 76
Likes: 0
From: Apopka, FL
Originally Posted by Bryan Wilkinson
Let me see if I can shed some light on this question being that I am there anyway. On a N/A motor, Velocity is everything and actually makes more of a difference than volume, because if you open up a set of heads and slow the air coming in you will lose power every time.
On my setup, and I think my power speaks for itself. I am guessing that my heads are worth 100Hp on my setup. They are a stage III setup from More Performance. The same setup on a N/A car would probably cost you 20 hp or more. With a forced induction car, you are forcing air, into the cylinder. However, a bigger port is still important, because it is still about how much air can you get into the cylinder. Port shape becomes much more important, because you do not want the air to slow down as it makes its trip to the cylinder. Every inch of air is power.
Someone on this thread made mention about octane and the heads. That is much more related to Compression Ratio than head and port design. My car has completely dispatched the therory about high hp and octane. I make 822 RWHP and I run all day on 93 octane and I do it with the stock GM PCM and high imp injectors. There is no black magic or black art. I make this power before 6000rpm, and I do it with only 17 degrees of timing.
The bottom line is this, More air makes more power. On a N/A car it is about velocity, on a blown car it is about volume. Because you are pushing more air in, it allows you to have a bigger port, and you can take advantage of it.
My heads are the LS6 Z06 head. They come with a bigger exhaust port which is much more inportant on a blown engine. They have the Jesel Mohawk 1.7 Shaftrocker.
I am prepared to discuss this with anyone that would like to have the conversation.
lunapark@perigee.net
On my setup, and I think my power speaks for itself. I am guessing that my heads are worth 100Hp on my setup. They are a stage III setup from More Performance. The same setup on a N/A car would probably cost you 20 hp or more. With a forced induction car, you are forcing air, into the cylinder. However, a bigger port is still important, because it is still about how much air can you get into the cylinder. Port shape becomes much more important, because you do not want the air to slow down as it makes its trip to the cylinder. Every inch of air is power.
Someone on this thread made mention about octane and the heads. That is much more related to Compression Ratio than head and port design. My car has completely dispatched the therory about high hp and octane. I make 822 RWHP and I run all day on 93 octane and I do it with the stock GM PCM and high imp injectors. There is no black magic or black art. I make this power before 6000rpm, and I do it with only 17 degrees of timing.
The bottom line is this, More air makes more power. On a N/A car it is about velocity, on a blown car it is about volume. Because you are pushing more air in, it allows you to have a bigger port, and you can take advantage of it.
My heads are the LS6 Z06 head. They come with a bigger exhaust port which is much more inportant on a blown engine. They have the Jesel Mohawk 1.7 Shaftrocker.
I am prepared to discuss this with anyone that would like to have the conversation.
lunapark@perigee.net
AIR VOLUME IS POWER ... the power output of any engine is determined by the amount of air it moves in and out ...
N/A engines rely on port velocity to deliver the volume, whereas a FI setup forces it in, so port velocity is a moot point (almost) for a FI setup ... so for a NA setup, increase port velocity and for a FI setup, increase port volume for total flow.
