I disagree. When you extrude a manifold, there is a minimal difference in size between stock and ported. The biggest difference comes from smoothing the rough casting and eliminating the casting imperfections. As for whether or not it makes power, probably not much on an otherwise stock engine, but on a stroker, we have seen 12rwhp from a ported manifold alone. I didnt check your math(not that I could correct it), but I dont disagree with any of your comments. You are basically stating that we can not for certain determine what is beneficial and what isnt, that it is all speculation until we have enough evidence to back up said claim. Im with you 100% and here is my feedback. The amount of time the air spends in the manifold is very minimal at WOT, but how long does it spend in the manifold at idle which is where everybody starts? I would love to see someone put a temp probe in their manifold and test this properly to see what the advantages are. The only thing I disagree with you on is the polishing the outside of a manifold to help dissipate heat, maye I read it wrong, but a smooth outer surface will not help dissipate heat in the least and will actually hurt the dissipation process. Maybe I interpreted your statement wrong. This is a really good thread and very informative, lets keep it going.
The 0.03 second figure was a 4K. At WOT (let's say 6400 rpm) it would be around 0.02 seconds. At 670 rpm I think it would be somewhere around 0.18 seconds. Figuring the manifold has a volume of 6.1L (anybody know what it is?) it only takes 2 revolutions of the engine to completely change the air in there. The stock converter stalls around 2K? so at that rpm the air would take 0.16 seconds to go through the manifold. If there is any significant intake air temperature rise to begin with. Yes, we agree (you read it wrong). Any material will radiate heat at some rate for a fixed area. If there is more surface area then it radiates more heat. Less surface area and it radiates less heat. A smooth surface has less surface area than a rough one. Polishing the manifold will reduce it's surface area.
actually andy, i think dave said the same thing you just did in regards to polishing and heat dispertion. smoother surface, less surface area, equals less cooling....
Somebody has to have a manifold laying on a bench somewhere. Turn it upside down, tape the throttle body, fill it will water, measure the water in there.
Well now I've confused (as is usually the case when Dave posts up his "thoughts" like that ... nice Mr. Brain, lol!), you guys saying that Extrude Honing the intake manifold on our cars is counter-productive?? Seems the Extrude Hone process of porting is a proven benefit on all types of cars (years of modding in the Mustang field I found it to be quite popular).
No, no, lol. You're mixing 2 different things and two different sides of the manifold (inside and outside) :happy: 1) main topic here is heat. hot intake air is bad and cooler is better. 2) then there is air flow through the manifold (not temperature related). polishing and porting and extrude honing, etc. are all to achieve better air flow through the manifold. That's better. I suppose they could be loosely related since polishing the inside of the manifold could mean less heat transfered to the intake air but that benefit would probably be insignificant relative to the gains from improved air flow. The polishing being referred to earlier was on the OUTSIDE of the manifold. Done for bling. That would decrease the heat radiated from the manifold or heat transfer from the manifold to the engine bay air. Also a small difference I think... The other type of polishing and extrude honing got mentioned as well but that was sort of an aside. it's all perfectly clear now right?:stars:
Thanx Dave, that's what I thought it's just an earlier post by someone else implied extrude honing was maybe not so good. I was following your "thoughts" fairly well though ... for once, lol!! :whistle:
If you're coating a manifold I sure hope the coating on the outside is heat reflective. Not every coating is an insulator, I would think?
I want to powder coat my intake manifold bright red. A few ppl told me I should do it in black becuase the heat will dispense quicker is this true? Does the color really made a difference?
That would depend if the air on the outside of the manifold is warmer or cooler than the manifold itself right?
Somebody else is going to have to answer this one. I can tell you something I think I heard on Star Trek though. Color comes from something reflecting or absorbing different wavelengths in the visible spectrum. I don't think black reflects anything and white reflects everything? I think a lot of heat or radiated energy isn't in the visible spectrum. Something can be hot without glowing right? Maybe black conducts heat better than red? I didn't do very well in physics.
My Two Cents!! ExtrudeHone is the only "economical" and viable way to port the 6.1 intake manifold at this time. The ONLY other way is to cut the manifold open, port it, flow it and port EACH runner until you see the flow numbers you are trying to achieve......then you have to weld it back up!!! NO ONE is going to do that for less than a few thousand dollars labor only. Now the vendor has to mark it up, tax it, and then ship it. Now you have a $3,000 manifold.:help: The next thing is port it the best you can in and around the plenum and runners/ports. You might get 310cfm at each port, hardly the required flow for a set of heads that flow 350cfm. Considering that an untouched manifold flows 290cfm at best, you now have the biggest restriction right in front of those high dollar ported heads. Just keep in mind that if you ExtrudeHone make sure the company has a flow bench and can guarantee you see at least what your heads flow, that is the goal, not some monster number. Otherwise you may end up with a manifold that is either restrictive (if too small) or to big and loses the all important velocity.
Heh, Sgt, we need someone to rig a manifold or head with a temperature probe in the air flow right at the port/head (hint, hint) :yes:
oh ok well I really need to find this out before I do powder coat my manifold. I do not want to make a mistake and find out later red is the wrong color.
Star Trek?? That's where you get all your info?? Hahhahahaha, I knew you were a Trekkie, I just KNEW it, that explains everything, lol! (btw, so am I but don't tell anyone ... you wanna try on my Mr. Spock ears??)
The Extrude Hone process is referring to the inside of the manifold as Quick stated. Powder Coating is really bad about heat soak. It will not dissipate heat or so Im told by the guy that coats my manifolds.
Chad, if you're going to paint your manifold you should paint it whatever color you like. I'd strongly recommend black because it looks so much better. Whether powder coat is an insulating material or not would have orders more magnitude of an effect than the color (unless you're going with a clear plexiglass hood).
have no fear chad, i should be getting my intake manifold back from the powder coater tomorrow!!! i will let you know how brilliant black works out!!! hahahahaha
This is one of those leagues that I am way out of . Thinking on it I think I used the term 'insulator' incorrectly. I was thinking that just because a manifold (or a cheese sandwich right off the frying pan, for that matter) is coated doesn't necessarily mean the coating is holding heat in. How the hell do you get a temp probe in there other than thru the throttle body? Pull the manifold apart and fit a wired probe and reassemble? Pull the TB and run it in thru the seam that way? How to suspend the probe so its not resting on the bottom and roasting? Duck tape would be off the approved materials list. BTW thanks for the flow info earlier. Best setup and layout on the subject I have seen yet.
