Cylinder Head Porting and Power Production
- Thread starter RAMM
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PRH
Well-Known Member
Even if was making 550hp, at that fuel flow...... the bsfc wouldn’t be anything great(.505 for 278lbs/hr@ 550hp).
I just get the sense that if the motor was actually being “tuned”, or maybe tested with a “known good” carb on it, the numbers(whether it’s hp, or bsfc and fuel flow) could look better.
It’s not just that the power seems on the low side...... it’s that the power is low and it’s using a ton of fuel.
If the power was the same as it is, but the fuel flow and bsfc were both “good”, then it would be easier to just pin it on a “bad combo”.
And, to put it into perspective for this thread....... if the heads are really 293cfm, then the current combo is showing 1.70hp/cfm.
I just get the sense that if the motor was actually being “tuned”, or maybe tested with a “known good” carb on it, the numbers(whether it’s hp, or bsfc and fuel flow) could look better.
It’s not just that the power seems on the low side...... it’s that the power is low and it’s using a ton of fuel.
If the power was the same as it is, but the fuel flow and bsfc were both “good”, then it would be easier to just pin it on a “bad combo”.
And, to put it into perspective for this thread....... if the heads are really 293cfm, then the current combo is showing 1.70hp/cfm.
rmchrgr
Skate And Destroy
Which if I'm reading you right really isn't all that terrible. What it does have is a broad torque curve and hits 500 lbs./ft at almost 5,000 rpm, should be good for something.
Looking at the 2 HP/C.I. target efficiency number posted originally, I'm not sure where to find a 15-20% increase in power but I don't think there's much to find in the cylinder heads? Perhaps a "better" intake might net 20-25 hp? Larger headers would help for sure and a roller cam. The heads are not race heads by any stretch, more like super-prepped factory replacements.
At the time, the heads were chosen based on budget constraints and ease of install because they worked with what I had on hand. The flat tappet cam was chosen for the same reasons and was spec'd by they shop that did the heads based on intended use. But just because the parts didn't cost a fortune didn't make the results any less disappointing.
Maybe I will look into re-testing after it's been checked. They dyno shop that I originally wanted to use was flooded out during Hurricane Sandy and was still not in operation at the time I tested the motor in 2016. Heard they are back up and running it again, might be worth a call.
Going by the 2.06 hp per cfm my 470 stroker has standard port stage 6 heads that flow 320 intake. 260 ex. Motor dynoed at 655 hp 627 TQ. 108 Volumetric efficiency. Cam is a Comp solid roller. .625 lift, 275 @.050 108cl. M 1 intake and a 1050 dominator carb. Can this be improved with a bigger cam. Thanks. Kim
PRH
Well-Known Member
Without sugar coating it......
That combo only making 500hp STP would be a bit of a let down to me.
But, my confidence in the dyno numbers isn’t that high.
Or, if they’re accurate, then I feel like the tune up was(hopefully) pretty far off.
Without a do-over....... it’s just a big question mark.
I’m saying, that in my mind, I would expect the sum of that combo of parts to add up to more than 500/500.
And that if that’s all they are really worth....... then no, that’s not a real effective combo.
Should easily be able to make 500/500 from a 416 with noticeably less cam and flow.
This one is a 410, cleaned up RPM heads(270-ish), 251/259 cam, Victor, qft-850, 1-5/8>1-3/4x 3 headers.
I didn’t run this one, and it also suffers from quite poor bsfc numbers....... and I think there could have been 15-20hp left on the table with that carb, as it was.
As it is, it’s just shy of 2hp/cfm.
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Because an engine is not an air pump. Oxygen is just a small part of what happens in a cylinder to make power
You burn the fuel not the air and the fuel has to be conditioned properly to achieve that aim. If you really want to make power you need to study combustion and the chemistry involved because that is what really happens. Gasses burn in a cylinder liquids do not.
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PRH
Well-Known Member
From my perspective........ there’s only one way to know for sure.
RAMM
Well-Known Member
What do you mean would it get better or worse? Would it show more on the dyno or would it perform better in the car? I can answer better if you define the metrics by "better or worse". J.Rob
RAMM
Well-Known Member
Yes of course I agree with this but that is not really what this thread is about. It is about "What makes certain head designs (within the SBM world) better than others? and how that correlates with CFM or how it doesn't" J.Rob
RAMM
Well-Known Member
Now this kind of thinking I can get behind. I think it absolutely has everything to do with the quality of the airflow/speed and it is the port shape and size that has everything to do with creating that quality airflow/speed. J.Rob
How about narrowing down he parameters for a moment to what most wallets around here will use?
Suggested heads for the topic;
OE iron
Edelbrock
Trick Flows
W2’s
Suggested heads for the topic;
OE iron
Edelbrock
Trick Flows
W2’s
rmchrgr
Skate And Destroy
Thanks for the honest answer Dwayne. I'm not ashamed of it falling short, was my first 'real' engine build, can't expect perfection first time around. Could be there's more to this engine building stuff than meet the eye. Seems like part one of the challenge is to make it run but part 2 is to make it run good.
David Vizard says if you can net 1.35 ft/lbs. per cube the combo is efficient. In the case of my 416", that would be 561 ft./lbs. so based on that somewhat arbitrary (though based on lots of experience) number, I'm way off.
Not to make this all about my under-performing combo but it seems my main question here is not about how much head flow will produce X amount of power but instead how to best utilize the given flow of a set of heads to achieve maximum potential. It's the age-old question I guess. Obviously the set of heads I have hold the potential to make more power but for whatever reason(s) they're not.
RAMM
Well-Known Member
I don't know about a bigger cam but maybe a better cam-maybe. Your engine is a pretty good example and your 1.33+ tq/ci is an indicator of how good your combo and those heads are--at least it stands out to me. If you came to me looking for more power but said you wanted to keep everything the same except cam I would tell you that I doubt I could really help you out much if at all. I'd probably tell you not to mess with it unless you had other issues to address. J.Rob
Greg; I certainly do think there is more to engine building than what meets the eye. What cam was used?
The camshaft play a critical part in this as I’m sure we all know. If there is a way to think about the cam, it would be all about pressure control into the cylinder.
What happens from he air filter above the carb (if used) to the A & F into the cylinder is dictated by the cams timing events. The easier it is to get in......
This is the concert between the intake manifold and the cylinder head. The quality of the mix down an excellent path is the goal to be timed with the cams events at the best possible time.
And now the science begins...
And why I asked what cam was used. Just curious. Nothing more.
The camshaft play a critical part in this as I’m sure we all know. If there is a way to think about the cam, it would be all about pressure control into the cylinder.
What happens from he air filter above the carb (if used) to the A & F into the cylinder is dictated by the cams timing events. The easier it is to get in......
This is the concert between the intake manifold and the cylinder head. The quality of the mix down an excellent path is the goal to be timed with the cams events at the best possible time.
And now the science begins...
And why I asked what cam was used. Just curious. Nothing more.
yellow rose
Overnight Sensation
Ahhhhh...ok I see what’re you are going. My bad. Let me think for a bit and I’ll try to get back on track.
yellow rose
Overnight Sensation
How about narrowing down he parameters for a moment to what most wallets around here will use?
Suggested heads for the topic;
OE iron
Edelbrock
Trick Flows
W2’s
Let’s throw W5’s in there, because that head should have been fixed and then continued.
RAMM
Well-Known Member
Taking your statement a little further I would add this and I've said it more than once and it still amazes me how many "engine builders" really don't understand.
The combustion process is pretty simple, it is not an explosion it is a burn. We've all heard that a million times I'm sure.
Power production comes from the rapidly expanding Nitrogen in the air which generates cylinder pressure.
Nitrogen is an inert gas that doesn't burn--it only expands with heat for anyone wondering.
It is our job to fill the cylinders with as much air/fuel mixture (in the right ratio) that will burn with as much BTU's released in the shortest amount of time. J.Rob
RAMM
Well-Known Member
1.35 ft/lbs/cube is a pretty stout number that few achieve in your average run of the mill street build. It's a great barometer to strive for but its easier said than done IMO. That being said your post is a great segway for a 407 cube SBC that I reworked in the spring that made 588hp/564 tq with Dart heads that flowed 285cfm when I was done with them. This is right @ 2.06hp/cfm and the customer reports that it is ridiculously fast and responsive--engine previously dyno'd @ 530 hp/525tq same heads that flowed the same peak--My work pumped up the .300-.500" curve quite a bit. I know I strayed from the SBM platform-broke my own rules--lol. J.Rob
ChargedDart75
Well-Known Member
I enjoy reading threads like this and learning. I'll add something: there's a reason most at home people cannot produce a ported head that will produce much more horsepower than the ootb head. The lack of experience/knowledge as well as lacking the proper equipment to tell if your changes are going in the right direction is the hindrance. It seems like most people's thought is to "hog it out" because they think the engine will benefit from this. It's simply not true, how many of you guys (RAMM, PRH, YR, etc.) have seen this and tried to explain it doesn't work like that? I think that the average car guy can do some things to the head to help it, but I don't think it will be leaps and bounds better. I'll say this also, I've read many of you all on this thread as well as several others that offer your advice and expertise free of charge, and that is one of the many things that makes this forum so great.
I think it is obvious it’s the Trick Flows being referenced without referencing them specifically, just going by the hypotheticals presented in the original post, the others have been around for some time and there’s ample examples (or data) Just my takeHow about narrowing down he parameters for a moment to what most wallets around here will use?
Suggested heads for the topic;
OE iron
Edelbrock
Trick Flows
W2’s
I would have thrown in the W5’s since I have a pair of them, 1 well ported and the other pair as cast in there boxes.
It’s just not a head everyone is running to and there not exactly out there to be had. All the other heads I listed are available AFAIK.
K.O. SWINGER
Meeting in the alley since 1976
picking up a lot of nuggets here 
Well, maybe so, but sometimes I just like to name names to zero in rather than go on assumptions just incase.
While the head has been out for awhile, it haven’t seen much tech reported by the end user.
RAMM
Well-Known Member
You are not wrong and your ability to read between the lines is impressive. I do have the TF's in mind because I have never worked with them and I have never worked with W5's either--only pressure tested one once. Like I said the jury is out on the TF's for me as I have only seen one build that I feel did those heads justice and it was built by a pro (Mike @B3RE ). Anything else I have seen online kinda leaves me wanting for more. As soon as they are back in stock @ Motorstate I plan to order some to experiment with. Best looking SBM chamber I have seen yet. J.Rob
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