Is More Flow Better, Is The Smallest Intake Port That Flows The Most The Best

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lead69 said:
You better be careful or @Rat Bastid will die of elation that someone else get's it lol. Seriously, it's nice to see some smart, articulate people who understand what the hell is going on. I'm guessing some of these guys are getting bad drinking water or something because the stuff they come up with is mind boggling.
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LOL.
Whenever people make big or outrageous claims, I like to try and dig through them to understand or debunk them. It helps me make better decisions building my own junk.
There's a lot of rules of thumb or general wisdom that can be explained by physics, but those always break down at some point.
The older wisdom tends to dominate what most know, simply because it's been around longer. But lots of that is also based on a state of the art that's been advanced quite a lot since it was developed. Lots of it simply bad takes published again and again in magazines..

But then there's folks whose claims I almost always find are supported by analyzing the engineering behind it. @Rat Bastid tends to be one of them. The only issue people seem to have is that they willfully misinterpret his words, are claiming to want a fast car but are proposing to build a dump truck, or they're thinned skinned LOL. There's also too many people who try to convince themselves they can have racecar power and speed with street car shift points and tires and he'll hear none of it. Too many take that personally.

The notion that SBMs have small port cross sections is easy to see even without the maths. Other OEM efforts which produce more output from similar bore and stroke sizes all have bigger valves and larger and better flowing ports. Even the factory efforts to support race teams focused mostly on trying to cram more through the heads (look at every W head for the sb). It's not an accident.

I do have to laugh sometimes because things like rod ratio, port velocity, spring loads, retainer weight and other notions matter a lot - but it takes a very substantial amount of development to figure out how to address each of those in a useful and meaningful way. But no one ever asks how to develop them (except maybe when this thread was started!), they use them as arguments to rationalize their choices to align with a favorite magazine or TV show. Not to mention, there's not much a hobbyist is going to be able to do to change those attributes of a build anyway. Yet they're all convinced they can have a 1/2 priced 700hp small block if they could just choose better from the catalog than their buddy did - "but no custom cams or converters, thank you"

Sorry for the rant.
 
fishmens67 said:
Torque gets the car moving, HP accelerates and maintains speed.
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Phreakish said:
The only reason fuel vaporizes without heating it in a carb is the pressure drop which results from the increase in velocity. Local pressure drops under vapor pressure and poof, gas vapors.
Vapors turn corners better, but sharp corners have stagnation points which can push the local pressure over the vapor pressure and then fuel condenses out.
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Did you ever read the paper where they figured out what size fuel droplet best follows the intake path and remains entrained in the intake charge?

Heating the carb just increases causes expansion of the fuel but doesn't vaporize the fuel that takes place after it leaves the booster and vacuum plays the biggest part in that as well as the compression stroke and where you close the intake valve. Obviously the fuels distillation temp will play a big part in how much and where.
 
Rat Bastid said:
That head is too small for 340 inches turning 8500.
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Dan might disagree with you considering he's managed 7800 with just a ported 587 head @ 410 cubes. Do you think the CSA of his heads would be bigger than a ported W2?

8000 rpm not a problem at all either, especially with a small block. try to get the intake valve 110 grams or less, Use a hollow lifter, [not the solid chunk of iron lifters], Mopar perf. lifters are hollow. 5/16" .08 wall pushrods. 150#/160# seat and 380#/410# over the nose held in place with 10* tit. retainers. If it is in your budget, put titanium intake valves and lighten the exh valves to less than 90 grams and you can reduce the springs to 130# seat and 350# open. My demon is set up with tit. intakes. With 4.88 gear I went through at 7800rpm. Have 4.56 gear now and only sees 7400rpm but slowed aprox. .05
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Hysteric said:
Dan might disagree with you considering he's managed 7800 with just a ported 587 head @ 410 cubes. Do you think the CSA of his heads would be bigger than a ported W2?


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What was the lbs-ft per cid ? A 410 with 1:1 at 7800 rpm is about 548 hp and with 1.5:1 at 7800 rpm is about 822 hp the lbs-ft per cid makes a big difference.
 
What online calculator say about 600 hp, that would be 405 tq @ 7800 rpm to make 600 hp and tq at peak hp is about 90% of peak tq so that's 450 tq peak tq, 1.09:1 tq per cid. That's fairly low.
 
lead69 said:
You better be careful or @Rat Bastid will die of elation that someone else get's it lol. Seriously, it's nice to see some smart, articulate people who understand what the hell is going on. I'm guessing some of these guys are getting bad drinking water or something because the stuff they come up with is mind boggling.
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That's the funniest **** I've read in a long time. Maybe you should head over to SpeedTalk and see what caliber of smart and articulate people you find there.

Engine Tech - Don Terrill’s Speed-Talk

Maybe you guys could head over there and try and pretend you know everything there too?

Here's an interesting thread:

Raising the port roof on a head worth it or not - Don Terrill’s Speed-Talk

I Buick friend of mine two weekends ago in his 3500 lb boat with a NA 450 or so cid Nail head motor broke into the high 10s, while only spinning to 6500 rpm.
I ported these heads near 20 years ago now so I know exactly what they flow.

Where taking on average @28" 215 cfm on the Intake and between 150 and 162 cfm on the Exh side, the difference being 2 ports on each head having to deal with a head bolt boss.

If you should ever get a chance to look at one of these heads and the ports they have you would be pulling your Chin hairs in wonderment that they could even power a car into the 11s!

So it's not just about air flow, in these heads from the burn pattern and lack of any signs of fuel wash these darn Nail heads chambers combined with there strange Intake valve bowl shape are very good at making power with the air and fuel amounts that they do receive.
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Its impressive what some people can do with so little.....
 
dirty white boy said:
rocket engines produce thrust by the expulsion of an exhaust fluid that has been accelerated to high speed through a propelling nozzle.... ant got nothing to do with a 4 stroke internal combustion engine....DWB!
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Thrust is a force the same as torque is force. Thrust is not "one rotation", just as torque is not "one rotation". That was the point of my analogy. But we're all good now.

Phreakish said:
P=fv
V is analogous to rpm.

More revs will always produce more power, all things equal.
Combustion engines produce a range of torque over the rpm range.
A "torque" engine tends to produce more down low and less up high.
A high revving engine tends to produce less torque down low, but makes the same or more torque at higher revs.
Power=torque*revs. Half the revs takes twice the torque to come out equal. Show me a "torque build" that ever doubles a race combo. Yet race combos often run twice the rpm of so called "torque" builds.
All the equations always support the higher revving system making more power, accomplishing more work, or reaching a faster speed within a set time or distance.
The high revver wins the drag race every time because of this.

This t'aint hard. No need for rockets or any other tortured analogies.

Torque is great, but without rpm you have a dumptruck. Sure, it'll get to 25mph in a hurry, or from 25 to 50, but then it's out of steam (power).
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rpm = v because torque has a rotational vector. But again, torque is the force that moves, and rotation is simply the vector (direction) in which it is applied.

It's a bit disigenuous to suggest that a high-revving engine is not also a "torque" engine, because the more torque you make at those revs, the more power the engine produces. Hi-revving engines that have little torque down low have lag, are pigs to drive on the street, and the narrower the power band (torque curve) the more gear changes are required to keep the engine on the boil.

I honestly don't see what is so controversial about reiterating the fact that torque is the force that moves the car and that higher torque at any given rpm = more power. A flat torque curve is very much an asset on the street.

Because not everyone wants "more power" at the sacrifice of driveability. Maybe you guys do, I don't know?

Rat Bastid said:
I hope they all build junk with a TQ curve that’s higher than the HP curve and then be disappointed in what they have.
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I built exactly that. A 408 with more TQ than HP, a flat TQ curve from 3500-5300rpm, changes gears at 6500rpm, has posted 11.6 at 121mph in a 3400lb car and is fun to drive. You can drive my car anywhere. I drive it to the track and drive home and touch nothing except the tyre pressures.

I'm not at all disappointed in what I have – I've got exactly what I wanted. Not everyone wants to drive a peaky pig with all its power above 6500rpm just so they can have bragging rights.

But I get that some people do.
 
Aussie Charger said:
Thrust is a force the same as torque is force. Thrust is not "one rotation", just as torque is not "one rotation". That was the point of my analogy. But we're all good now.


rpm = v because torque has a rotational vector. But again, torque is the force that moves, and rotation is simply the vector (direction) in which it is applied.

It's a bit disigenuous to suggest that a high-revving engine is not also a "torque" engine, because the more torque you make at those revs, the more power the engine produces. Hi-revving engines that have little torque down low have lag, are pigs to drive on the street, and the narrower the power band (torque curve) the more gear changes are required to keep the engine on the boil.

I honestly don't see what is so controversial about reiterating the fact that torque is the force that moves the car and that higher torque at any given rpm = more power. A flat torque curve is very much an asset on the street.

Because not everyone wants "more power" at the sacrifice of driveability. Maybe you guys do, I don't know?


I built exactly that. A 408 with more TQ than HP, a flat TQ curve from 3500-5300rpm, changes gears at 6500rpm, has posted 11.6 at 121mph in a 3400lb car and is fun to drive. You can drive my car anywhere. I drive it to the track and drive home and touch nothing except the tyre pressures.

I'm not at all disappointed in what I have – I've got exactly what I wanted. Not everyone wants to drive a peaky pig with all its power above 6500rpm just so they can have bragging rights.

But I get that some people do.
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The vector of a torque is meaningless in this context, it's always parallel to the crank. Torque is a couple which is used as a motive force. It's force at a distance, without velocity or rpm it doesn't do us any good.
Torque is meaningless though because it doesn't tell us anything other than whether something can overcome a static resistance. Without rpm, there's no power and power is what it takes to accelerate.

No one calls a high revving engine a "torque" build. The entire point is that an increase of torque is an increase in power, but there's a practical limit to max torque. Making max torque at 2k rpm won't win any races or even be "fun" to drive. Max rpm is a function of good engineering, and increasing the rpm capability does not typically lower the torque produced, and so a higher revving engine always wins the drag race.

Whether that higher revving engine is good on the street is a moot point. Different people tolerate different levels of racy on the street, and what's streetable is too subjective to define. Not everyone wants to thump around smoking the tires and losing races, but I get that some people do.
 
Torque is the power needed to get the car moving.
Torque is also responsible for the 1.20 60 ft times we so enjoy.
Horsepower is responsible for top speed and maintaining speed
Torque x RPM = HP, without torque there is no HP.
Engine basics 101.
 
Phreakish said:
The vector of a torque is meaningless in this context, it's always parallel to the crank. Torque is a couple which is used as a motive force. It's force at a distance, without velocity or rpm it doesn't do us any good.
Torque is meaningless though because it doesn't tell us anything other than whether something can overcome a static resistance. Without rpm, there's no power and power is what it takes to accelerate.

No one calls a high revving engine a "torque" build. The entire point is that an increase of torque is an increase in power, but there's a practical limit to max torque. Making max torque at 2k rpm won't win any races or even be "fun" to drive. Max rpm is a function of good engineering, and increasing the rpm capability does not typically lower the torque produced, and so a higher revving engine always wins the drag race.

Whether that higher revving engine is good on the street is a moot point. Different people tolerate different levels of racy on the street, and what's streetable is too subjective to define. Not everyone wants to thump around smoking the tires and losing races, but I get that some people do.
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The math to understanding this (part of it anyway) is…

P
L
A
N

It makes it pretty simple to figure out.
 
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fishmens67 said:
Torque is the power needed to get the car moving.
Torque is also responsible for the 1.20 60 ft times we so enjoy.
Horsepower is responsible for top speed and maintaining speed
Torque x RPM = HP, without torque there is no HP.
Engine basics 101.
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LOL, no RPM and GEARING is what moves anything.

I say again, put your torque monster into 1:1 gearing and see how hard it moves out.

Thats why God gave man the common sense to build gearboxes.

Look at it this way. If you have to remove a Chrysler crank bolt do you grab a 1/4 drive ratchet and use all your muscle to get it loose (and probably shitting your pants if you do get it loose) or do you grab a 1/2 drive ratchet and a 2 foot bar?

Thats simple gearing.

I can’t believe in 2023 this is so misunderstood.
 
fishmens67 said:
Torque is the power needed to get the car moving.
Torque is also responsible for the 1.20 60 ft times we so enjoy.
Horsepower is responsible for top speed and maintaining speed
Torque x RPM = HP, without torque there is no HP.
Engine basics 101.
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I get what you're saying, but torque isn't power. Power is literally horsepower, it's in the name. Torque and power are two entirely different entities.
Gearing will affect the 60' more than the actual torque number. POWER is what accelerates things. Power is work times time. Torque is a force times a distance, it has no unit of time involved.
HP is responsible for everything that happens as soon as the crank starts turning. HP drives the water pump, the alternator, the torque converter.

Understanding the time element in equations and systems is a major stumbling block for many people as they transition from static physics into dynamic physics. The per-unit-time part comes from RPM, displacement, movement, speed(velocity). Without the per-unit-time part, the static torque value is meaningless. Torque will only tell you if something will move, not how fast, not how far. Work is required to figure out how far something can go, power determines how quickly it can reach a velocity or a distance(displacement).

Physics 202 ;)
 
Phreakish said:
I get what you're saying, but torque isn't power. Power is literally horsepower, it's in the name. Torque and power are two entirely different entities.
Gearing will affect the 60' more than the actual torque number. POWER is what accelerates things. Power is work times time. Torque is a force times a distance, it has no unit of time involved.
HP is responsible for everything that happens as soon as the crank starts turning. HP drives the water pump, the alternator, the torque converter.

Understanding the time element in equations and systems is a major stumbling block for many people as they transition from static physics into dynamic physics. The per-unit-time part comes from RPM, displacement, movement, speed(velocity). Without the per-unit-time part, the static torque value is meaningless. Torque will only tell you if something will move, not how fast, not how far. Work is required to figure out how far something can go, power determines how quickly it can reach a velocity or a distance(displacement).

Physics 202 ;)
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Cudos to you. It’s really unbelievable how eloquently and easy to understand you make your statements. Most people have a hard time putting thoughts to words as well as you do.
 
Rat Bastid said:
LOL, no RPM and GEARING is what moves anything.

I say again, put your torque monster into 1:1 gearing and see how hard it moves out.

Thats why God gave man the common sense to build gearboxes.

Look at it this way. If you have to remove a Chrysler crank bolt do you grab a 1/4 drive ratchet and use all your muscle to get it loose (and probably shitting your pants if you do get it loose) or do you grab a 1/2 drive ratchet and a 2 foot bar?

Thats simple gearing.

I can’t believe in 2023 this is so misunderstood.
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I'm not misunderstanding at all. I agree with you.
But without engine torque the car ain't moving, period. just like the bolt.
HP determines the rate of acceleration, as in power to move. work.
I have a round about way. lol
 
fishmens67 said:
I'm not misunderstanding at all. I agree with you.
But without engine torque the car ain't moving, period. just like the bolt.
HP is determines the rate of acceleration, as in power to move. work.
I have a round about way. lol
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LOL…you can only get some much stroke. Then what?

The math is:

P.
L.
A.
N.
 
Rat Bastid said:
LOL…you can only get some much stroke. Then what?

The math is:

P.
L.
A.
N.
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Exactly.
Instantaneous torque would be defined by the crank throw along with rod angularity, bore, and pressure within the cylinder. There's only so much pressure which can be generated, only so much bore a block allows (controlled by bore spacing), and only so much throw a crank can have. Short rods make long strokes a diminishing return as well.
But RPM, that's only limited by momentum. A good cam lobe and proper springs with stiff pushrods and as little weight possible at the valve can up the RPM potential (if the head can keep up) pretty quickly. High rocker ratios help too, but between the piss-poor lifter angle and an unwillingness with most to mill-off the rocker stands, there's only so high a ratio we can fit. Plus, as ratio goes up, so does the force at the pushrod which makes the attachment hardware even more critical. During overlap, two rockers with springs compressed at 600+ lbs starts to stress things and send them on a walk.

3.58 to a 4" stroke is an 11.7% increase in stroke/torque (not really, but for argument's sake).
This is equivalent to an increase from 6k to 6704 rpm, or from 7500 to 8380 rpm.

This tells us a few things: as rpms increase, it takes bigger increases to net the same gain. Going from 9k to 10k (11% increase in revs) won't net the same as going from 5k to 6k (20% increase in revs). The same is true for an increase in stroke without an increase in rod length. But long rods tend to push decks higher, make intake tracts longer, and push carbs higher - which all have limits as to what's reasonable as well. People are afraid of RPM because they don't like to pay for balancing (pre-balanced is good enough, right?) and don't want to pay for rockers or custom cam lobes that match the motion ratios of their valvetrain.

It's all a game of trade-offs. Define what the car needs to do, and the PLAN becomes fairly obvious. It's the 'budget' aspect that starts to make the 'streetable' argument a constant validation for reigning back from what's intended.
 
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