Polish and port, take 2

[Flash]

Even tho you have spent tons of hours on it, and it looks like there is vary little done. RESISTING FROM MORE PORTING......you will be happy with the results.
you have made a big improvement of your flow with out disturbing the characteristics of the port!

Your polishing of the combustion chamber, will go a long way in preventing detonation as well


Flash

[gradon]

I didn't think it was due to different springs, but that the exhaust valves would be a little hotter so they used a different rubber on them.

[Flash]

I didn't think it was due to different springs, but that the exhaust valves would be a little hotter so they used a different rubber on them.

that would make sence as well
just to make sure were both on the same page. the "spring" that were talking about is around the valve seal it self...........

Flash

[SilverXJ]

that would make sence as well
just to make sure were both on the same page. the "spring" that were talking about is around the valve seal it self...........

Flash

Why not use the same rubber on both (I guess that is what the viton ones do).. probably to save money

As for the spring it can be seen on the pic on page 3

[John]

Actually using the two type seals is cheaper, Viton is more expensive, but more heat and chemical resistant, good to 400* continous and with the different chemical additives in our lubes, it is more desirable. IIRC the minimum temp materials are around 300* for stem seals. Remember this area is really water and oil cooled during operation.
John

[SilverXJ]

I started on opening up the intake manifold a bit today (1999+ style). I'm not going to go all the way to the gasket though, just a bit inside it. I figure its better to have a smaller port on the manifold side than a larger port on the manifold side and a smaller port in the head.

The bosses for the fuel injectors are interesting. Cylinder's 3 & 4's project more than 2 & 5 and 1 & 6 are even less so. I figure this was done on purpose as the longer runner corresponds to a smaller boss. I don't think I am going to do much to them unless someone can say otherwise. I could take a good bit off and smooth them off, but I don't know if that would be a good idea or not.

Any suggestions on the intake manifold?

On a side note I was looking into chroming the fuel rail..I know what you are going to say.. but I would like just one little thing to be chrome in the engine bay... Local chrome company wants $150... and a 3 week to 3 month turn around... meh... I was hoping for around half that price.

[John]

Perhaps 1bolt will be able to answer that question with his flow bench. Until then, I made the same observation, the boss sizes correspond to runners, the difference was obviously engineered intentionally, I polished any roughness (give it the finger) in the casting surface and called it good in those areas.
John

[SilverXJ]

Perhaps 1bolt will be able to answer that question with his flow bench. Until then, I made the same observation, the boss sizes correspond to runners, the difference was obviously engineered intentionally, I polished any roughness (give it the finger) in the casting surface and called it good in those areas.
John

Exactly what I plan. What I figure is that the longer runners have the smalled bosses... the reason I can figure is perhaps the longer runners have more velocity to pull the fuel from the injector into the chamber than the shorter runners? Make any sense or am I completely wrong?

[John]

It could be? But then a couple of other things come to mind as possibilities, ie, direction of flow streams.
John

[gradon]

I smoothed them all out--you can check the pics in the project section. It would be nice to chat with the engineers of the manifold.

[John]

Depends on the engineers, a few can speak plain English, too many speak only oxen schizen.
John

[SilverXJ]

Got my head back from the machine shop yesterday. $340 later I have a 3 angle valve job, valves back cut 32*, MP springs installed to 100# seat, head milled .006", new freeze plug, valve seals. Now all I need is some paint and install it.

Oh.. and I finished porting the intake manifold. I am so sick of using a grinder at this point. All i can say is I better notice a gain of some sort for all the work.

Its sad that I have this nice head and it is being thrown on top of a Titan 4.FAIL block.

[Alex22]

Here is an interesting read on the design of an inline 6 intake manifold
http://www.freepatentsonline.com/6553954.html
I found this while looking for info on the 4cyl intake manifold and thought it was appropriate for this thread.
Nice work on the porting and polish work.

~Alex

[1bolt]

I agree with the consensus that they were cast in different sizes intentionally for a very good reason, to equalize air velocity among the runners, but also to effect the gasoline stream from the injectors equally.

In 1999 a whole quarter of an inch of difference in an OEM casting is HUGE. a 16th would be hard to call a casting error, let alone a quarter.

Now if I was going to try and improve that manifold I would work those bosses, but I would take exactly the same amount off each one leaving them the same proportions. Maybe take a 16th of an inch off each.

I plan to do that with the bench in the future, already have two 99+ intakes laying around ready.

[John]

See science can be interesting. Mapping the flow stream zones at the intake discharge would be quite revealing. Do keep us posted.
John