SBM Port Molds

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Earlie A

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Here's some pictures you might find thought provoking. These are side by side intake port molds of an OOTB SBM Edelbrock RPM head and a Trick Flow 190. Also a pic of the TF intake bowl. I was a little blown away by the bowl design downstream of the guide on the TF. Looks like this design is one of 3 things, or maybe a combination.

-Fuel shear ridge
-Swirl inducing (or swirl canceling because of the direction)
-A fix (or band aid) for the flow stall that happens after the venturi convergence point of 0.500 lift

I really don't know the answer, but I hope to find out. I'd love to get the facts, but opinions would be interesting as well.

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I put up a similar post on Speed-talk. A gentleman there said this type of port is more about complete fuel burn than it is about air flow. He said the GM LS7 port is similar. Of the three options I listed, I thought the fuel shear ridge was the least likely. The ridge in these heads is not sharp, it is rounded/eased. I actually thought it was more about air flow than wet flow.
 
just my completely non-expert opinion, but I seem to remember the area in the center of the bowl to be lower velocity or flow (both mabye). IF that's the case, then it seems like this is a good way to wrap the cyl wall side flow, around the common wall side at the last minute to help increase those numbers while promoting swirl?

Again, just a WAG.
 
Earlie A said:
Here's some pictures you might find thought provoking. These are side by side intake port molds of an OOTB SBM Edelbrock RPM head and a Trick Flow 190. Also a pic of the TF intake bowl. I was a little blown away by the bowl design downstream of the guide on the TF. Looks like this design is one of 3 things, or maybe a combination.

-Fuel shear ridge
-Swirl inducing (or swirl canceling because of the direction)
-A fix (or band aid) for the flow stall that happens after the venturi convergence point of 0.500 lift

I really don't know the answer, but I hope to find out. I'd love to get the facts, but opinions would be interesting as well.

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Take a piece of string and stick it in the port while it’s on the flow bench. You can see exactly what they are doing.

They layer the air as it comes around the long side. They are trying to force the air around the valve on the chamber wall side, and the other side of the valve guide is trying to get the air to bend around and come over the short side.

I’m not a fan of doing it. I think there are better ways to get the air around the chamber side of the valve.

Try the string thing. You can see where the air is going.
 
Earlie A said:
I put up a similar post on Speed-talk. A gentleman there said this type of port is more about complete fuel burn than it is about air flow.
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Which would true but my question is really how different are the complete fuel burn between the head choices we have is there instances of a lesser flowing head dominating a high flowing head cause of this within the mopar world ?
 
I believe, as both of you do, that it is about air flow. This is a street head that was meant to be an improvement over the Edelbrock style head, so TF needed more air flow for advertising purposes. If it were a factory head, emissions would matter. If it were a race head, hp would matter.

I have to think NBT is correct that this is somewhat of a less than perfect approach to fixing a problem, but I am not suggesting that I know a better way. It seems TF has done a really good job with an OOTB head. The low port and 18 degree valve angle of the SBM present their own challenges. This may be the best, low cost solution.

I have read several places that the intake stroke of the piston gives you X amount of energy to work with to get air into the cylinder. The more energy that is wasted on turning and redirecting air, or the more energy wasted on swirl, is energy that is lost. In other words, loss of port efficiency.

However, if the band-aid produces a higher performing, low cost head then it was a good band-aid. Until a better one comes along.
 
It would depend on use, if You're stalling it at 5K, the fuel quality isn't as much of a concern. Hot regular street use/road course it could be a big plus. I'd love to see same-cam & carb back-to-back torque & bsfc curves.
 
I think it’s a copycat type of thing by TrickFlow putting that wing there like an LS head. But let me tell you something about that. When porting an LS head that’s the second thing that gets take out. The bolt bulge in the runner is usually the first thing taken out.
 
Killer6 said:
It would depend on use, if You're stalling it at 5K, the fuel quality isn't as much of a concern. Hot regular street use/road course it could be a big plus. I'd love to see same-cam & carb back-to-back torque & bsfc curves.
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I think this stuff becomes more important in highly competitive racing with strict rules, in a basic street strip car if you build a highly efficient 10’s car and I build an inefficient 10’s car in the end of the day we both only have a 10’s car. And I probably got there cheaper.
 
pittsburghracer said:
I think it’s a copycat type of thing by TrickFlow putting that wing there like an LS head. But let me tell you something about that. When porting an LS head that’s the second thing that gets take out. The bolt bulge in the runner is usually the first thing taken out.
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I can't imagine how tight my cheeks would be grinding on a TF. Think I'll work on the Chinese stuff a while longer.
 
Killer6 said:
It would depend on use, if You're stalling it at 5K, the fuel quality isn't as much of a concern. Hot regular street use/road course it could be a big plus. I'd love to see same-cam & carb back-to-back torque & bsfc curves.
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They are probably out there. I'd like to see them as well.
 
273 said:
Which would true but my question is really how different are the complete fuel burn between the head choices we have is there instances of a lesser flowing head dominating a high flowing head cause of this within the mopar world ?
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I'm sure in the hands of a good porter a highly efficient head could easily dominate a higher flowing head. CFM is not at the top of the list of good head qualities. But CFM is what sells the most heads.
 
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Earlie A said:
I'm sure in the hands of a good porter a highly efficient head would easily dominate a higher flowing head. CFM is not at the top of the list of good head qualities. But CFM is what sells the most heads.
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Just like 52-55 degree seat angles. Looks good on paper but from what I see the way it kills the lower numbers I’ll never travel that road.
 
Newbomb Turk said:
What a dick measuring contest? Keep loving your flow bench numbers.

I’m out
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I’m not comparing flow benches. I’d just like to see some ET slips to back up what you are saying. I’ve posted my proof. Post up. Engine combo, track ran at, weight, tire size, etc.
 
pittsburghracer said:
I’m not comparing flow benches. I’d just like to see some ET slips to back up what you are saying. I’ve posted my proof. Post up. Engine combo, track ran at, weight, tire size, etc.
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Why? Your mind is made up. Go learn for yourself. Or not.

Your time slips don’t mean **** to me. By all means, keep doing what you do.
 
pittsburghracer said:
I guess so. When you hide under a hidden identity you may get called out on something.
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LOL. What’s funny is you have zero experience, yet you think you are the expert.

That’s a joke right there. Go do your own testing and prove it doesn’t work.

Wait, don’t do that. You’ll learn your flow bench is lying to you.
 
Newbomb Turk said:
LOL. What’s funny is you have zero experience, yet you think you are the expert.

That’s a joke right there. Go do your own testing and prove it doesn’t work.

Wait, don’t do that. You’ll learn your flow bench is lying to you.
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Wow I thought I missed you. I guess I was wrong about that too.
 
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