ported manifold
Thread Starter
Melting Slicks
Joined: Dec 2004
Posts: 2,161
Likes: 0
From: pr, frederick md.
Thread Starter
Melting Slicks
Joined: Dec 2004
Posts: 2,161
Likes: 0
From: pr, frederick md.
this one is just everyday 383 with some real good parts thrown at it. built it for some nitrous use, but have to get a taller hood to fit the plate under the carb. while i had it apart i noticed that the intake gaskets had a black ring almost all the way around them. and the air gap manifolds are not cleaned up to well, so i just made everything the same size and smooth. has got to good for something, no?
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
toddalin,
Forgive me for not reading that entire post, but it seems to me that you're not saying that port matching is a bad thing... rather you're saying that there is a better way to do it. And that would be leaving a 1/8" step on all exiting surfaces. But this would still advocate port matching or rather port widening. Most of us who are in need of port matching are much further away from 1/8" difference on mating surfaces.
Obviously there is a limit to this step that you're talking about, if a port were 1/2" smaller on all sides it would obviously call for port matching or rather port widening. No? Ok, 1" smaller on all sides... You get the point, there must he a happy median. Without having facilities for testing I would even go so far as to assume that direct port matching (although not as good as a 1/8" step, as you claim) would be better than the very large difference between mating surfaces of out of the box parts.
Forgive me for not reading that entire post, but it seems to me that you're not saying that port matching is a bad thing... rather you're saying that there is a better way to do it. And that would be leaving a 1/8" step on all exiting surfaces. But this would still advocate port matching or rather port widening. Most of us who are in need of port matching are much further away from 1/8" difference on mating surfaces.
Obviously there is a limit to this step that you're talking about, if a port were 1/2" smaller on all sides it would obviously call for port matching or rather port widening. No? Ok, 1" smaller on all sides... You get the point, there must he a happy median. Without having facilities for testing I would even go so far as to assume that direct port matching (although not as good as a 1/8" step, as you claim) would be better than the very large difference between mating surfaces of out of the box parts.
Last edited by enkeivette; Oct 26, 2007 at 04:56 PM.
Burning Brakes
Joined: Feb 2006
Posts: 1,024
Likes: 1
From: AL
This specific section is included at the following link. But if you do a search of the 'net, you'll find other articles that also back this up.
http://www.datsport.com/Chapter_Seventeen.html
http://www.datsport.com/Chapter_Seventeen.html
thanks
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
There is so much to this subject I could write forever; but here are some basics:
Not every manifold will respond favorably to port matching, it depends on the application. Done incorrectly you can definitely screw things up. Again depending on the engine combination; if you take out too much materiel you will create too much runner volume and that hurts flow velocity. There is really no way to tell if in this particular application the engine performance was improved or hurt, unless you test its performance before and after.
Intake and head porting are a science, it is not just hacking away at metal
Not every manifold will respond favorably to port matching, it depends on the application. Done incorrectly you can definitely screw things up. Again depending on the engine combination; if you take out too much materiel you will create too much runner volume and that hurts flow velocity. There is really no way to tell if in this particular application the engine performance was improved or hurt, unless you test its performance before and after.
Intake and head porting are a science, it is not just hacking away at metal
Drifting
Joined: Apr 2002
Posts: 1,747
Likes: 37
From: Stockton Ca
I Know Nothing!
I have very little pratical experience, but I read a lot. Porting can leave waves in the port, then came CNC to make things even. I haven't seen much on what happens when the entire intake "manifold, heads, ex" is done.
I did see an article where a 4 cyl I think, had the gritty mud run through the entire In/Ex. The results were not huge, but 25 rwhp across the band is no joke. JMHO
Ricisan
I did see an article where a 4 cyl I think, had the gritty mud run through the entire In/Ex. The results were not huge, but 25 rwhp across the band is no joke. JMHO
Ricisan
Le Mans Master
Joined: Oct 2000
Posts: 8,897
Likes: 1,357
From: Santa Ana CA
I have very little pratical experience, but I read a lot. Porting can leave waves in the port, then came CNC to make things even. I haven't seen much on what happens when the entire intake "manifold, heads, ex" is done.
I did see an article where a 4 cyl I think, had the gritty mud run through the entire In/Ex. The results were not huge, but 25 rwhp across the band is no joke. JMHO
Ricisan
I did see an article where a 4 cyl I think, had the gritty mud run through the entire In/Ex. The results were not huge, but 25 rwhp across the band is no joke. JMHO
Ricisan
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Race Director
Joined: Apr 2003
Posts: 19,353
Likes: 654
From: Tampa, Florida
This is going to sound stupid but I call it the shingle effect. By overlapping shingles your hand earliy slids in the proper direction but not in opposite direction.
By mismathing the ports so the downstream opening is slightly bigger you encourage flow in that direction but not in the opposite.
By mismathing the ports so the downstream opening is slightly bigger you encourage flow in that direction but not in the opposite.
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
I have very little pratical experience, but I read a lot. Porting can leave waves in the port, then came CNC to make things even. I haven't seen much on what happens when the entire intake "manifold, heads, ex" is done.
I did see an article where a 4 cyl I think, had the gritty mud run through the entire In/Ex. The results were not huge, but 25 rwhp across the band is no joke. JMHO
Ricisan
I did see an article where a 4 cyl I think, had the gritty mud run through the entire In/Ex. The results were not huge, but 25 rwhp across the band is no joke. JMHO
Ricisan
90% of the guys I race with and against (7 second cars and faster) use hand ported heads. My Brodix -3's just got back from ReherMorrison Pro-stock team. $6,000.00 + into them, but they flow 440+ cfm and will make 1500 hp on my 555. They also did my sniper intake.
