[riceburner65]

Wow, nothing like talking to your self here. No input about runner texture not being important with fuel injection?

[JSPONT]

Originally Posted by riceburner65

So if the injectors are being fired in bank to bank mode, the injectors will fire together every engine revolution. Then this would mean that you would have some fuel pooling around the valve head before the valve opens admitting the air fuel charge. If this is happening then the runner texture may not be as important as people are calling out. You would be more dependent on cylinder turbulence to effect atomization.

Good question, I'm not qualified to answer, were are the fuel injection guru's??? What about the professional head porters, you know who you are, answer so we can all learn a little more!

[BruceWilkie]

Texture still important. Injectors use high pressure to aid atomization but its not enough especially in batch fire mode. Which injectors you fire in a batch is important as well. When a valve closes there are reflected pressure waves that help keep fuel from just pooling...Same/similar as carbureted.

[john marcella]

You did no harm by doing that to the quench side IMO.
No good either.

[john marcella]

Originally Posted by BruceWilkie

Texture still important. Injectors use high pressure to aid atomization but its not enough especially in batch fire mode. Which injectors you fire in a batch is important as well. When a valve closes there are reflected pressure waves that help keep fuel from just pooling...Same/similar as carbureted.

My data tells me way different.

[JSPONT]

Thanks John, the video produced with the clear intake and ports, where the guy put his finger in the port, seemed to me the fuel stuck to the walls (which was plexi glass of some sort and smooth as a baby's butt) and the mixture was moving past in the center. Glad to see this will work for Charlie.

[steve25]

In that video you can clearly see where the fuel falls out of suspension where the high speed air mass does not follow as the air mass takes the path of least resistance !
I would love to see that test redone with some sections of 40 grit paper glued to the walls in the low velocity areas, but leaving enough room to still video what's going on!

[john marcella]

Originally Posted by steve25

In that video you can clearly see where the fuel falls out of suspension where the high speed air mass does not follow as the air mass takes the path of least resistance !
I would love to see that test redone with some sections of 40 grit paper glued to the walls in the low velocity areas, but leaving enough room to still video what's going on!

That was positive refected pulses holding and pushing fuel on the vertical wall of the plenum. The Problem is not that fuel is held there, its that those same pulses are pissing off the carb. Need to try and manage those pulses effects on the carb!

[riceburner65]

So it sounds like proper tuning of the intake runner with the port to make the pulses work in the direction that would pull/ push the charge into the intake would have a larger effect then the texture. I could see texture being important if there was unidirectional flow which would set up a slow moving boundary layer that would require the ability to create stripping vortices near the surface to pull the fuel off the wall and back into suspension. But with the reverberation pressure pulses you are going to have fuel clinging to the walls due to the back and forth nature of the flow.

[johnta1]

I could see texture being important if there was unidirectional flow which would set up a slow moving boundary layer that would require the ability to create stripping vortices near the surface to pull the fuel off the wall and back into suspension.

That's why you need the texture (and right texture?) to get the flow going into the intake chamber. The texture helps to get that stagnant area from being such a dead zone.

[riceburner65]

So has anyone done a back to back comparison of a smooth ported head and a ported and textured head, and what were your results. I would think that once the right runner length was found/calculated then texturing in areas where the fuel is still clinging would be beneficial. The size of the texture would probably be dependent on the boundary layer thickness, ideally big enough to generate small trailing vertex that would lift the fuel with out causing drag in high velocity flow region.

[johnta1]

So has anyone done a back to back comparison of a smooth ported head and a ported and textured head, and what were your results.

Try this site and do a search on it:

Maxracesoftware BBS

He has done a lot of them.
(and dyno'd both ways)

Magazine article on it:

Max Race

[JSPONT]

Originally Posted by steve25

In that video you can clearly see where the fuel falls out of suspension where the high speed air mass does not follow as the air mass takes the path of least resistance !
I would love to see that test redone with some sections of 40 grit paper glued to the walls in the low velocity areas, but leaving enough room to still video what's going on!

There would be no difference. After your post I got curious, I went to a local guy near me who helped Joe Mondello develop the "wet flow blench". He told me about 15 guys in the country have them. He said after flowing heads on a flow bench, and thinking you did great... then putting them on a wet flow bench makes you feel dumb sometimes.
He said up to 60 thousands (from smooth) had no effect on air flow. Real world testing. I saw a video on his wet flow testing bench. Same result.
He educated me on a ton of stuff. Texture does not have a big effect. I wish I could share all he said but he does not want me too. One test he changed the squish area and valve area (added material) lost 58 cfm but the motor made 40 more horsepower. Valve and valve angles play a huge part. When you see what goes on under the valve you start to get a different picture of what you thought.

The reason Charlie took some area out of the squish was to drop compression. So as John stated it did not help or hurt, but it did help Charlie accomplish something.

THANKS TO ALL FOR POSTING!! IT MADE ME LEARN QUITE A BIT SINCE THIS STARTED!

[JSPONT]

Here is the link you some of you asked about


https://youtu.be/7Iq1B-2paCs

[john marcella]

Originally Posted by riceburner65

So it sounds like proper tuning of the intake runner with the port to make the pulses work in the direction that would pull/ push the charge into the intake would have a larger effect then the texture. I could see texture being important if there was unidirectional flow which would set up a slow moving boundary layer that would require the ability to create stripping vortices near the surface to pull the fuel off the wall and back into suspension. But with the reverberation pressure pulses you are going to have fuel clinging to the walls due to the back and forth nature of the flow.

No ! Not at all.

You are fixated on the fuel on the wall. That is of little importance. But what it is doing is telling you a story about what is happening in the plenum. The reason that that fuel is puddled their has absolutely nothing to do with surface finish. Scratches in the surface will do nothing! Everybody wants voodoo!
What is going on is you have a bunch of reflective positive pressure pulses keeping and blowing the fuel away from the runner at that location. Positive pressure pulses underneath the carburetor are bad ! But it's a part of the system that's never going to go away. My point earlier was ,you should be thinking about is managing those pulses affect on the carburetor Signal rather than the affect on the fuel that is suspended around the runner.
40 grit 20 grit frickin 10 grit don't mean jack there !

Positive pulses under the carb are like A bunch of tiny little backfires as far as the carb is concerned. And the fix has nothing to do with runner length.

[Tom Vaught]

Originally Posted by john marcella

No ! Not at all.

You are fixated on the fuel on the wall. That is of little importance. But what it is doing is telling you a story about what is happening in the plenum. The reason that that fuel is puddled their has absolutely nothing to do with surface finish. Scratches in the surface will do nothing! Everybody wants voodoo!
What is going on is you have a bunch of reflective positive pressure pulses keeping and blowing the fuel away from the runner at that location. Positive pressure pulses underneath the carburetor are bad ! But it's a part of the system that's never going to go away. My point earlier was ,you should be thinking about is managing those pulses affect on the carburetor Signal rather than the affect on the fuel that is suspended around the runner.
40 grit 20 grit frickin 10 grit don't mean jack there !

Positive pulses under the carb are like A bunch of tiny little backfires as far as the carb is concerned. And the fix has nothing to do with runner length.

Agree!

The only time the "Wall Fuel" comes into play is on a tip-in of the carb and the fuel on the walls goes into the runners. At that point the carb needs a proper accelerator pump shot to replace the fuel on the walls and still have the proper air/fuel mixture (be it rich for a fraction of a second).

All of this texture stuff and the fuel on the walls just gives the fuel a boundary layer in the plenum vs fuel puddling in the plenum and being affected by the runner pulsations.

As John found out a super wis-bang EFI system at the right air/fuel ratio will not make any more power vs a carb system at the right air/fuel ratio.

Even EFI has a "Accelerator Pump shot" in the strategy (increased duty cycle of the injectors when you have a quick throttle position sensor change).

Tom V.

[riceburner65]

Hey John Marcella, it is not that I am fixated on the fuel clinging to the side just that there are others that seem to place a lot of importance on it, I am just trying to tie this info together, JohnTA posted a link to an article that really made me realize that there are a lot of dynamics with in the cycles of an operating engine and that you do not have a unidirectional flow. You have reverberating pressure waves that affect the flow properties through out the whole intake system and there a lot of things to consider trying to tune them to an advantage rather than working against you. For instance going back to charlie4166 modification of the squish deck in the combustion area. what kind of effect will that have? if it is not there to force the gasses back to the valve and plug side at the time when both valves are open will it change the way the pressure wave will be reflected back up the port and runner? I learned quite a bit in this thread, especially the complexity in head modification. Thanks for the links to the other videos and articles.

[INJUNTOM]

I have a question for you guys regarding the original poster's reworked chamber that he posted pics of in the first post (found this thread searching for chamber mods):

I already knew that the chamber pictured isn't done the normally excepted way, but I have a need to remove compression on my engine not looking for power at all because it's a 428HO in a '37 Pontiac Coupe not to be driven hard. It was in another car with a 700R trans for a few thousand miles and had detonation issues when overdrive/lockup engaged, etc. and lower oil pressure than I liked. Found wear on upper rod bearings that looked like textbook detonation examples. Decided to put it in the coupe with a TH400, so that should help already, but since it's apart I'm looking at possible chamber mods too.

Pistons have already been dished beyond what the TRW forged units come with. To approx. 1/8" from edge.

It's a 2 bolt 428 block built to '69 HO 4spd specs, '69 #16 heads, Crane blueprint HO cam, Long Branch, and will have a Nash ram and 2 Edelbrock 500 carbs instead of the Performer and 600 Double Pump that it had in the other car.

With the dished pistons, does the quench area really matter anymore?

Can the "eyebrow" be removed on the exhaust side?

[steve25]

Your 428 will likely stop pinging if you had flat tops and just a bigger chamber, yet the same compression ratio!
The only thing you can do now to not make fixing the issue cost a lot is to install a tad bigger Cam to bleed off some running cylinder pressure.

[john marcella]

Originally Posted by INJUNTOM

I have a question for you guys regarding the original poster's reworked chamber that he posted pics of in the first post (found this thread searching for chamber mods):

I already knew that the chamber pictured isn't done the normally excepted way, but I have a need to remove compression on my engine not looking for power at all because it's a 428HO in a '37 Pontiac Coupe not to be driven hard. It was in another car with a 700R trans for a few thousand miles and had detonation issues when overdrive/lockup engaged, etc. and lower oil pressure than I liked. Found wear on upper rod bearings that looked like textbook detonation examples. Decided to put it in the coupe with a TH400, so that should help already, but since it's apart I'm looking at possible chamber mods too.

Pistons have already been dished beyond what the TRW forged units come with. To approx. 1/8" from edge.

It's a 2 bolt 428 block built to '69 HO 4spd specs, '69 #16 heads, Crane blueprint HO cam, Long Branch, and will have a Nash ram and 2 Edelbrock 500 carbs instead of the Performer and 600 Double Pump that it had in the other car.

With the dished pistons, does the quench area really matter anymore?

Can the "eyebrow" be removed on the exhaust side?

I would un shroud the valves in the chamber. That'll buy you a cc or 2 and help with cyl fill. Then run a thicker head gasket and roll.