Ported head for FI and NA, differences?
12-29-2004, 11:16 AM
#1
Junior Member
Thread Starter
Join Date: Nov 2002
Location: Germany
Posts: 484
Likes: 0
Received 0 Likes
on
0 Posts
Ported head for FI and NA, differences?
I often read that a head is ported for FI or NA and i'm curious what the differences are.
What are the differences of a FI and NA head besides the cams?
What are the differences of a FI and NA head besides the cams?
12-30-2004, 03:39 PM
#4
Join Date: Sep 2004
Posts: 601
Likes: 0
Received 0 Likes
on
0 Posts
Re: (PrettyLude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrettyLude »</TD></TR><TR><TD CLASS="quote">i know for sure the ports are different, i can't tell you how it is, but i know its different</TD></TR></TABLE>
Not always, and it most definitely doesn't have to be. On a N/A motor there is considerably more emphasis put towards low lift flow and velocity, and more often than not they run a smaller intake port. Does this mean that head won't work well for a turbocharged setup? NO!
I'll use my experience with Ford's to try and bring some relevance with them, as I'm not too up-to-date with port and valve sizes on hondas yet. A stock 302 head has a port volume of around 140CC's. A mild aftermarket head is in the 165-185CC range, while the larger heads move into the 205-240CC range, and past that you start moving into canted valve and much more race orientated setups. If you take an AFR 185CC head with small chambers that was naturally designed to favour a non forced induction application, and put a turbocharger on that motor, will it make good power? Absolutely. The key to getting more power out of a turbocharged setup is to build a better naturally aspirated setup to base it on. If a head makes more power naturally aspirated, it will make more power with a turbocharger. Now, on the flipside is where you hit a predicament. If you put something like a 235CC TFS Hi-Port head onto a moderate street/strip 347" stroker motor with a T76 turbo it is going to make a **** load of power, but still with great mid range power. Take that same head and put it on a naturally aspirated 347 at 10.5:1 compression with no turbocharger and it is going to be a total dog on the street, because on a large ported head like that for a more full-out motor there is less emphasis on low end flow, which hurts a naturally aspirated motor big time. My opinion? Heads ported with a naturally aspirated application in mind, as long as they havn't been milled too severely, will make a great head for a stout turbocharged setup. A head ported with a turbocharged application in mind is not going to make the best choice for a naturally aspirated motor. It's like every square is a rectangle, but not every rectangle is a square
Not always, and it most definitely doesn't have to be. On a N/A motor there is considerably more emphasis put towards low lift flow and velocity, and more often than not they run a smaller intake port. Does this mean that head won't work well for a turbocharged setup? NO!
I'll use my experience with Ford's to try and bring some relevance with them, as I'm not too up-to-date with port and valve sizes on hondas yet. A stock 302 head has a port volume of around 140CC's. A mild aftermarket head is in the 165-185CC range, while the larger heads move into the 205-240CC range, and past that you start moving into canted valve and much more race orientated setups. If you take an AFR 185CC head with small chambers that was naturally designed to favour a non forced induction application, and put a turbocharger on that motor, will it make good power? Absolutely. The key to getting more power out of a turbocharged setup is to build a better naturally aspirated setup to base it on. If a head makes more power naturally aspirated, it will make more power with a turbocharger. Now, on the flipside is where you hit a predicament. If you put something like a 235CC TFS Hi-Port head onto a moderate street/strip 347" stroker motor with a T76 turbo it is going to make a **** load of power, but still with great mid range power. Take that same head and put it on a naturally aspirated 347 at 10.5:1 compression with no turbocharger and it is going to be a total dog on the street, because on a large ported head like that for a more full-out motor there is less emphasis on low end flow, which hurts a naturally aspirated motor big time. My opinion? Heads ported with a naturally aspirated application in mind, as long as they havn't been milled too severely, will make a great head for a stout turbocharged setup. A head ported with a turbocharged application in mind is not going to make the best choice for a naturally aspirated motor. It's like every square is a rectangle, but not every rectangle is a square
12-30-2004, 04:32 PM
#5
Honda-Tech Member
Join Date: Jun 2003
Location: PA, US
Posts: 1,567
Likes: 0
Received 0 Likes
on
0 Posts
Re: (@lbert)
FI exhaust ports look like this....
FI Intake ports look like this...
At least thats what mine look like. Not that anyone can tell much from a picture, but the head was done for turbo setup, not asked for when done but it was also built to rev to 10500 "all day no problem" from the words of the builder/porter. Inconel exhaust valves came with it too
FI Intake ports look like this...
At least thats what mine look like. Not that anyone can tell much from a picture, but the head was done for turbo setup, not asked for when done but it was also built to rev to 10500 "all day no problem" from the words of the builder/porter. Inconel exhaust valves came with it too
Thread
Thread Starter
Forum
Replies
Last Post
6SPD_EK
All Motor / Naturally Aspirated
3
11-16-2006 04:28 AM
