Rember the intake port texture debates?

[nickpohlaandp]

0617171327c.jpgI would like some feedback on this texture. D.V.'s E7Te heads I am finishing up. Same finish on exhaust, intake and chambers. Why do I use the same finish on all three at this point? I am able to blend my curves pretty well with this size and style, beat up burr. So, I only need to roll my chamber edge and this chamber is done unless I see something that could use more attention. I feel this surface helps atomization a bit on intake, has a slight golf ball surface which reduces airflow resistance. On the chamber can still help atomization by breaking up any liquid fuel that enters chamber, the finish is smooth enough I feel it will not have hot spots that may cause detonation or preignition and has a bit of heat reflecton ability due to the tiny scalops. Exhaust port will get same finish due to slight airflow resistance reduction due to golfball effect and intake and exhaust will get ssr polishing with sandcloth. Input welcome. Thanks, Charlie

Well guys, I don't just gather my info from forums, I like to read as much as I can about whatever it is I'm trying to learn too. That's exactly what I've been doing for the past few day. Only thing that sucks is that (the majority of the time) you can't just ask the author a question, that's where I rely on forums and guys who know more than me to help me out.

So I'm still curious about this porting job and the guides being ground flush to the wall. I understand that you said this was done for runner volume, but a few things:

1: Wouldn't having JUST the valve stem exposed cause more turbulence than the gained port volume is worth?

2: If the answer to #1 is "No", why wouldn't you flush grind ALL guides when porting?

Thanks again. I'm sure I'll have more questions later. Gotta go to church. Later!

[Carnut1]

Exhaustpocket_2.JPG

Found this pic in the web. Stock E7TE exhaust bowl. You can see the smooth transitions and free flowing mcsa of the stock bowl with emmision bulge. It is amazing to me this was considered a H.O. cylinder head. Even with the tiny amount of guide That was removed the guide is still about 2" long. Thanks, Charlie

[BOOT]

Just occurred me to dimples/burr finish is about holding fuel or wetting the walls better for the cooling effect. Increased surface area w/o the downside of smooth wetting.

idk if anyone replied or gave my post any serious consideration and I haven't had time to sit read & think about the rest of the thread(someday) but it has popped in my head a few times and I've tried to further understand it.

People have always talked about how iron heads will make more power than alum because they retain heat in the cylinder and alum dissipates more, most people compensate for it by using more compression with alum heads. In small engine EFI apps(most use alum heads) I've seen some use shielding to keep the exhaust heat header/manifold from reentering the head. Another example is David Vizard tested a coated face of an intake valve and there was a measurable gain. I've always though the heat retained in the cylinder made for a better burn or even hotter better flowing exhaust but now I realize it's because the intake charge isn't heated as much. The alum heads take more, longer or just resist cooling more, so iron heads can be leaner or use less excess fuel/smoother finish to cool the head and that would make then slightly more efficient.

So we need a fuel resistant coating that has a semi course media(like a cart roll finish)to fight puddling.


edit: Just to be clear raising the comp on alum head is to compensate for more heat in the intake charge, but if you can beat the heat you can have the best of both worlds. Iron cooler intake charge, alum tolerates more comp.

edit2: I wonder how hard it would be to cast alum around cast iron?

[KnightEngines]

I also have Reynards, but fortunately live in central Qld.. Where it is much easier to manage as temperatures above 25* seem to cause no issue.. You in SA would without doubt suffer more & for longer each year..

I may have to move to qld
It's been as cold as 2 deg in the shop in the mornings & it's still early winter. SA weather is shite, too cold in winter, too hot in summer & only a brief nice weather interlude between them. In winter I drive to work in the dark & drive home in the dark.
I got my right hand caught in a flycutter a few years ago & mashed it up pretty good, aches like a bastard on cold mornings, especially where the screws holding it together are.

[cjperformance]

I also have Reynards, but fortunately live in central Qld.. Where it is much easier to manage as temperatures above 25* seem to cause no issue.. You in SA would without doubt suffer more & for longer each year..

I may have to move to qld
It's been as cold as 2 deg in the shop in the mornings & it's still early winter. SA weather is shite, too cold in winter, too hot in summer & only a brief nice weather interlude between them. In winter I drive to work in the dark & drive home in the dark.
I got my right hand caught in a flycutter a few years ago & mashed it up pretty good, aches like a bastard on cold mornings, especially where the screws holding it together are.

Im hearing ya there mate , I live in willunga and man it is cold and dark when I leave hime and get home! And then yes, in summer its obscene heat. My Dad lives in Surfers QLD and its nice all the time once you're used to the mild humidity. Hand in the fly cutter would not be nice at all, im not surprised that aches in the cold, nothing like a hand in a fly cutter but I have bad shoulders and in winter its a constant ache, it sucks!

[Rick Finsta]

Uuugh if you guys are going to talk weather in metric at least use units.

[RevTheory]

Textured turns don't work, I played with that quite a bit & now go the other way - polished turns & rough everywhere else.

My experience indicates that there appears toy be some truth to this.

DV

How do you guys feel about a cartridge roll over the short turn where the two cutter angles meet on CNC'd heads?

[Ron E]

Textured turns don't work, I played with that quite a bit & now go the other way - polished turns & rough everywhere else.

My experience indicates that there appears toy be some truth to this.

DV

How do you guys feel about a cartridge roll over the short turn where the two cutter angles meet on CNC'd heads?

I always do that. I've seen it not matter, and I've seen it help. Never seen it hurt.

[Olefud]

As for the effects achieved by dimpling or other surface 'imperfections' I believe we still have a lot to learn. Right now where I am at is to use those course grit rolls so the ports have a roughish finish. No port polishing in my shop - but I am watching what Larry and Chad do very closely!!

DV

Roughening the inside turns and approaches thereto has some theoretical basis. The rough surface will sustain a thicker boundary layer that is the glue that attaches the main flow stream. Also, by increasing the wall drag in such circumstances the Coanda effect that attaches flow to the receding surface (usually) up to 6 degrees or so. Of course this is just one parameter (and theoretical at that) that has to be optimized and harmonized with the rest of the port flow.

[RevTheory]

My experience indicates that there appears toy be some truth to this.

DV

How do you guys feel about a cartridge roll over the short turn where the two cutter angles meet on CNC'd heads?

I always do that. I've seen it not matter, and I've seen it help. Never seen it hurt.

Thanks, Ron. In the cases that it helps, where in the lift range is the effect typically realized?

[GARY C]

I always do that. I've seen it not matter, and I've seen it help. Never seen it hurt.

I have seen several write ups and have heard people talking about sand paper rolling CNC STR and an increase in flow #'s but has anyone ever done before and after dyno test?

[Ron E]

How do you guys feel about a cartridge roll over the short turn where the two cutter angles meet on CNC'd heads?

I always do that. I've seen it not matter, and I've seen it help. Never seen it hurt.

Thanks, Ron. In the cases that it helps, where in the lift range is the effect typically realized?

last one we did was on a large (drag race) SB2. It helped calm the higher lifts. I guess it would depend on what kind, if any trouble the head is in prior to doing it.

Gary, no help on the dyno before and after.

[RevTheory]

Thanks, Ron.

[Carnut1]

Has anyone measured the difference in cfm of an intake manifold rough cuttered vs. Cast finish? If so what did you find? Thanks, Charlie

[Carnut1]

Resized_20170716_164354.jpeg

DV and I had a conversation on port textures the other day and I was doing some fooling around today. I came up with this texture on iron and I think I will do the intakes of my next iron heads like this. I would like some input. Fyi super easy. I blew up the pic to show texture. Bottom left of 289 intake bowl. Thanks,Charlie