So i was thinking about buying a intake manifolt for my truck and porting it and polish it. Would it be worth doing. Iv decided that tryn to port the heads will take up to much time and money for gaskets. Now the only reason why im buying another stock one is so i can take my time and do it right

 

Dutter,

I asked a similar question in a thread at TRS - a fellow enthusiast guestimated 5% maybe. I think that your approach is similar to one I've thought about over the years, back to when I had my Skyhawk. I think that without the pressure of having to get it back in to get yourself to work, your left with your interest to get the reworked intake in to do your studies.

Kevin

 

5-10% is general rule for head porting/polishing and thats on a "performance" engine you would be lucky to see 5% on a factory Ranger engine. Porting and polishing the intake should give you some ponys. I dont know a whole lot about the Ranger engine parts but porting and polishing the throttle body is never a bad idea but dont do it inless you read up really well before hand or have someone that knows what there doing do it. Doing that will increase throttle response and few hp, and matched with porting/polishing the intake will make a nice increase in hp. You can pick them up at the junkyard for dirt cheap. Theres a billion how to's on the internet for that. You can also build a custom "ram air" intake out of sheet metal, its a easy 5-15hp depending on how fast your going but once again i am not sure if you could fit something like that in the engine bay of your Ranger. The horsepower gain from that is only when your going 50 mph+ obviously the faster your going the more cold air is rammed into the intake then the engine resulting in more hp. Just some food for thought

 

You don't port/polish an intake, that is something you do on the heads. Intakes can be port matched, but you will find the general consensus is to not polish the intake side.

Porting can and does result in gains, how much depends on the engine, and how rough the castings are. Most engines will see about a 5% gain with no other mods, but some will see more.

A full port and polish job usually involved removing the rough edges and smoothing the path on both the intake and exhaust sides. The intake side is usually left with the 80 grit finish, which is fairly smooth, but not a polished finish. The exhaust side is then polished to a finer finish. Many pros will also polish the chamber part of the heads. the reasons for why the intake is not polished is because of atomization and flow. The intake, which is usually under partial vacuum, seems to flow better on a less than mirror finish, and the slightly rough surface disrupts the flow just enough to form a turbulent boundary layer, which creates less resistance to flow than airflow directly over the the metal. It also prevents the fuel, air mixture from separating (not as much of a concern as it used to be, but it can still happen).

Just though I would clarify, since many people who are not familiar with the process have false preconceptions about what porting and polishing is, and many people have false perceptions that air will flow better over a smoother surface.

 

oh yeah do tell me more about making a custom intake I did think of a way to make a custom intake manifold, But tell me ways that youv herd of. Because maken my one custom intake would be SICKNESS,

 

Well i gota do my head gaskets this weekend, and i think ill polish my intake manifold and port and polish my exhaust ports on my heads. Think this will work out good ?

 

A lot of people do not understand what a port and polish is of how to do it. You port and then finish grit on the intake side. This is known as posting. Polishing is a separate step, and polishing is only done to the combustion chamber and the exhaust side. You do NOT polish the intake. About the smoothest you want to go on the intake is about 80 grit. The reason for this has to do with how air flows over smooth surfaces. When air flows over very smooth surfaces, it separates into boundary layers. These layers slow the flow down and create wake. This is a same principle that makes aircraft fly. These boundary layers also create opportunity for the fuel and air mixture to stratify. This stratification allows a richer mixture to 'condense' or at least remain in close contact with the smooth metal surface. When this uneven mixture is drawn into the cylinders, it does not burn evenly, resulting in lost potential performance and economy. While modern engines have come a long way towards combating these issues (fuel injection, different shaped combustion chambers, etc.) the same basic problem can still occur when a pristine surface is present. This is especially true of an older engine that does not have direct injection. The uneven mixture creates two problems in particular. You have pockets of rich mixture which does not burn completely, resulting in wasted fuel, lost power, and the dreaded carbon deposits (a 1994 4.0L is particularly prone to this problem), combined with pockets of lean mixture which can detonate, burn too hot too fast, or fail to ignite at all. This creates localized hot spots which can cause head and valve damage. The 4.0L from your vintage was also particularly known for this problem.

By leaving about an 80 grit surface, which is still much smoother than stock casting, you help keep the mixture better mixed. Also by breaking up the boundary layer, you create small miniature ball bearings which act to reduce the drag against the surfaces in the intake, increasing volumetric efficiency, improving throttle response, and as a whole producing more power.

On the exhaust side, having a smoother finish is more important, as atomization is no longer needed, and the exhaust will leave the engine at a much greater velocity than on the intake side. Having a near mirror finish helps prevent carbon deposits from adhering to the surface. The same applies inside the combustion chamber.

IF I were you and pulling of the 4.0L heads, I would not put them back on. I've seen enough of the design shortcomings of original Ford heads from that vintage to know that they are probably worn out. Two major problems are very common. The origin Ford castings were not made from the best metal. The valves seat agains the head directly (common practice on cast iron heads) but the metal is weak. The valve seats wear down, resulting in valve recession. This results in poor compression, decreased volumetric efficiency, and ultimately less power and fuel economy. Every 4.0L head I have seen that had more than 100,000 miles had some degree of receding valves, particularly the exhaust valves. Also every one I have seen had problem number two, cracked heads. The pinging that often results from the poor combustion chamber design combined with vacuum leaks or heavy carbon deposits, fractures the metal. Better metal can help resolve the issue. The cracking most often occurs between the valve seats, and results in a loss of compression.

When you pull your heads off to do your porting work, if you find either problem it is better to just get new heads, as the cost to repair can be almost as much as new castings. The new casting often resolve the OE design deficiencies. You can also get new heads ported before you ever remove your old ones. This makes it an easy swap.

 

that was alot to read lol, But good info. So i think ill just port alittle on my exhaust ports then polish. And sence my head gasket wasnt blown its just leaking on the out side can i get away with not getting the heads resurfaced i have 185k miles

 

Just make sure you look at the valves. The valve should not be recessed into the head. If it is, then valve seats are shot and need to be replaced. Recently, I have had three 4.0L OHV engines apart, a '94, a '95, and a '97 and all three had severe receding heads. The '97 only had 171,000 miles and all 6 exhaust valves had receded and the valves on those corresponding cylinders were shot. It only cost me $20 more per head to have brand new castings with steel valve seats, versus having the originals repaired. Still cost me a lot more than I wanted, I had a blown head gasket issue as well, was getting exhaust into the coolant and was getting misfires when the engine warmed up.

 

alright so basically ill just have to pull off the heads befor i can really tell.. Butthe gasket didnt blow its just leaking on the out side, idk if this helps at all. But will polishing my exhust ports help with alittle more power

 

Dutter, I would suggest you read Khan's posts over a few times and let the ideas sink in. The best bang-for-your-buck in the area of flow improvement is making the ports align with the manifold. That avoids a break in the laminar flow, or words to that effect, and the resultant turbulence out in the 'middle' of the flowing gas. If I were doing this, I would get a book by one of the professionals that have made powerful Lima engines that would document a good procedure, and give ideas of the results you would get, generally in 'stages'.
tom

 

Yeah and i only have this weekend to do my gaskets so that why im just goin to lighty port my exhaust and polish it. Cus i dont have time to the intake to and get it done, right. I thought i did but i only got this weekend to get er done

 

Yup, thry to make the ports completely align through gasket matching. Matching the lower intake to the head is a little tougher if you have a V6. The alignment can actually vary a little bit between the plenum, gaskets, etc. So on that particular part, you are just better off working on the rough sports rather than port matching. But the upper intake should be port matched, and thats not that hard to do with the right tools. Don't worry about polishing it, it shouldn't be polished. The real area when porting comes in is improving airflow around the bowl in the head, particularly rough areas around the short side radius. There are some good videos on youtube if you want to see what is actually involved. You can port the exhaust side, but do NOT port match the exhuast ports to the manifold. The manifold is larger than the exhaust so that is acts like a one way valve, exhuast is willing to flow into the larger area lower pressure of the manifold, but it does not want to flow backwards. Mostly work on removing the rough areas, and blend the short side radius and improve the overall shape of the bowl the same way you would the intake side. When you are done, you can polish the exhaust. Does this improve performance over a non-polished one? Not really, but it does help prevent carbon deposits from forming in the port, and deposits could rob power. The main thing that helps is the shape of the port and that there are no sharp rough edges or sudden breaks in the flow. And polishing the combustion chamber on the head is a good idea, it helps prevent carbon deposits, produces cleaner more consistent burns, and prevents hot spots from forming which could cause pinging.

 

Alright thanks for the info, Ill see what i can do this weekend, cus i would like to do this but i only have 2 days to get the gaskets done

 

well we got the heads off today, So i cleaned them all up from the slug in the intake and the little carbon on the valves. And i had a hard time finding ways to improve the porting, its got some pretty dam big ports so im going to leave them alone, and my valves are looking ok they still bump out alittle bit, so there not all sucked in. Im thinking ill just put in new gaskets and call it good, cus when those valves are done so will the tanny and block