What would it take to make 1.44 lbs-ft per cid ?

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Calculated recommended head flow cfm for a given cid and rpm.


RPM. 4,500.....5,000....5,500....6,000....6,500....7,000

273. 150.........167......184.......200........217......234 cfm

318. 175.........194.......214......233........253......272 cfm

340. 187.........208.......229.......250........270......291 cfm

360. 198.........220.......242.......264........286......308 cfm

408. 225.........250.......274.......299.........324.....349 cfm


Roughly the cc needed to get 260 fps for a given cfm.

150 cfms = 110 cc, 175 cfms = 130 cc, 200 cfms = 150 cc, 225 cfms = 170 cc, 250 cfms = 190 cc, 275 cfms = 205 cc, 300 cfms = 225 cc, 325 cfms = 245 cc, 350 cfms = 260 cc.
 
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Dale Davies said:
When you get the port too big, lower RPM torque suffers. Look at the Ford Boss 302 and Clevelland 4V heads. Huge ports and low RPMtorque suffered. They came alive at 4000RPM. CHI developed Clevelland/Boss heads they call 3V that are 4 barrel quench combustion chambers and 2 barrel ports. Realise Ford Australia used the Clevelland engine for a while after Ford North America dropped it. They also built piles of 302 Cleveland engines.
Airflow in a port stalls at some point, limiting velocity and flow. Working to get high flow velocity builds pressure in the bowl and aids cylinder filling as the piston rises before the intake closes on the "compression" stroke. This greatly aids cylinder filling and density.
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Yes but what exactly is too big ?

Everyone is afraid of too big but no one seems to know what exactly is too big or just right.




And yes boss heads are an example of excessive but many have made good power with them, here's a boss 302 vs a chevy 302 both make very similar down low torque numbers.

 
273 said:
Yes but what exactly is too big ?

And yes boss heads are an example of excessive but many have made good power with them, here's a boss 302 vs a chevy 302 both make very similar down low torque numbers.

Click to expand...

From a very good source I can say the number 1 reason those engines were pigs is because they take a very specific timing curve and it ain't all in by 3K or sooner.

Ford, like Chrysler published all this data but the super tuners even back then thought they knew more than the factory did.

Is a 302 short on torque? Yeah, if compared to a 632 it is.

I'm so sick of the whining, bitching and sniveling about low speed torque I could loose my mind.

And it all stems from the "torque wins races" crowd.

I've never heard a racer or builder say "this engine is down on torque so I'm going to go make more torque to go faster".

That's not how it is.
 
273 said:
Yes but what exactly is too big ?

Everyone is afraid of too big but no one seems to know what exactly is too big or just right.




And yes boss heads are an example of excessive but many have made good power with them, here's a boss 302 vs a chevy 302 both make very similar down low torque numbers.

Click to expand...

Yes, many factors to look at. Compression ratio will compensate. Good swirl or mixture motion from getting bias in the port and quench will also be aids to building torque.
Too big is subjective with the rest of the engine combination. You put those Boss or Cleveland 4V heads on a 408 stroked 351W and that will be a brute. The combination needs to match.
You want to build for 1.4 lb ft of torque per cube, watch DV's videos and get copies of How to Build Horsepower and his BBC Power on a Budget.
 
Newbomb Turk said:
I've never heard a racer or builder say "this engine is down on torque so I'm going to go make more torque to go faster".
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Until you hear Bruce complain a track is **** and he can't get traction because he's making too much torque.

"In the case of our drag car we use VP fuels C14+ We have tried others with different distillation and oxygenation etc but they create other tuning issues. I have never maxed out the capabilities of the C14+ and changing to other fuel characteristics just mucks up my knowledge base.
I don't get the testing necessary to fully optimize the power of the engine and when I do increase it the car just spins the wheels more all the way down the track so there is no point. The track at Sydney is rubbish its got slippery blocks of concrete, no rubber laydown, no stick, the car runs 8mph faster at Willowbank"
 
Newbomb Turk said:
From a very good source I can say the number 1 reason those engines were pigs is because they take a very specific timing curve and it ain't all in by 3K or sooner.

Ford, like Chrysler published all this data but the super tuners even back then thought they knew more than the factory did.

Is a 302 short on torque? Yeah, if compared to a 632 it is.

I'm so sick of the whining, bitching and sniveling about low speed torque I could loose my mind.

And it all stems from the "torque wins races" crowd.

I've never heard a racer or builder say "this engine is down on torque so I'm going to go make more torque to go faster".

That's not how it is.
Click to expand...
Quit your clueless yapping and read what the original post asked. You want power at 7500 or 8000RPM, go bust your left nut doing it. In the mean time, quit being such a negative person, bitching at people.
 
Hysteric said:
Robinson Analytical overcomes an impossibly small budget to build a 435hp pump-gas Olds 307 for the Engine Masters Challenge.

Ooops.....they filled in the ports and only got 1.34 lbs-ft per cid and with only 195 peak cfm.

Its also making 2.23 HP per cfm of airflow with a port cc of 145 cc........Its very EFFICIENT
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Like said before it's an impressive engine, it's not an engine most would be able to build.

But yes fits in with the discussion, Say the olds has similar port length as a sbm that's about 260 fps, if look at the chart I made post# 126 that 200 cfm needs about 150 cc to have about 260 fps which is a fairly large cfm to cc ratio.
 
Dale Davies said:
Quit your clueless yapping and read what the original post asked. You want power at 7500 or 8000RPM, go bust your left nut doing it. In the mean time, quit being such a negative person, bitching at people.
Click to expand...


No, I just don't like guys like you pumping out **** you know nothing about.

As much as you leg hump DV I understand why you don't know jack **** or his sister.

I'm not negative at all. I'm a realist. So stop posting senseless bullshit and go learn the facts. You won't find those in a Vizard book.

And, please tell us exactly how many BOSS 302's YOU HAVE TUNED. I have a whopping ONE under my belt and that was 1984. I made it better but I didn't make it right.

My mentor has done many, many of them. He knows. You don't.

Now piss off.
 
fishmens67 said:
You ain't gonna do it on a budget.
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You ain't going to do it following DV either. It won't have enough compression and the cam will be too big.

Then you will be scrambling to get enough idle timing.

Sound familiar? It should. The dude has sold a million books. And the sheep headed to the slaughter read and believe that **** like its etched in stone.
 
273 said:
Like said before it's an impressive engine, it's not an engine most would be able to build.

But yes fits in with the discussion, Say the olds has similar port length as a sbm that's about 260 fps, if look at the chart I made post# 126 that 200 cfm needs about 150 cc to have about 260 fps which is a fairly large cfm to cc ratio.
Click to expand...


And who can say it can't be better with different porting?
 
The point of building more torque per cid is to make more hp at any given rpm, the torque # in itself ain't overly important it's what it does to the power curve.
 
Hysteric said:
Robinson Analytical overcomes an impossibly small budget to build a 435hp pump-gas Olds 307 for the Engine Masters Challenge.

Ooops.....they filled in the ports and only got 1.34 lbs-ft per cid and with only 195 peak cfm.

Its also making 2.23 HP per cfm of airflow with a port cc of 145 cc........Its very EFFICIENT
Click to expand...
It is a pretty cool little engine but if you look at the power curve every 500 rpms there's a solid hp gain from 2500 to 5000 rpms and then it basically flatlines to 6500 rpms the engine could obviously use more head flow in the real world. (outside the contest)
 
Don't conflate cylinder fill and efficient combustion with airflow. Here it is again because you seem to equate more airflow with usage:

Hysteric said:
Its also making 2.23 HP per cfm of airflow with a port cc of 145 cc........Its very EFFICIENT
Click to expand...
 
fat-360 said:
G’day. I’m building a 273 over here with this sort of thing in mind. 360 crank, 253 Holden pistons, 300ci. 400ft/lbs-430 should be doable. Airspeed/compression/V/E and a small cam is how we’re going to do it.Getting the engine stroke/bore “square” is another thing. Very confident in getting 350hp/420ftlbs atm. 273’s are a “torque” engine ( ask Richard Ehrenberg), valves are too shrouded by the bore, gotta make the little thing efficient.
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fat-360 said:
I’m not here to argue with you, I’ll just do it. I’m lucky to have a mate who has written tech articles ( not R.E, an Aussie) who says it’s very achievable, not only that, he’s done it with our local 308 holdens.
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Funny how the local guys can make power with a 308 and an early HQ style head very similar to a 318 head.

Any chance we can get some details on your build?

Would your engine builder be Tony Knight by any chance?
 
Hysteric said:
Don't conflate cylinder fill and efficient combustion with airflow. Here it is again because you seem to equate more airflow with usage:
Click to expand...
No, I’m saying it’s got most of what it can get out of these heads by 5000 rpm’s. If your building a 6500 rpm engine like this one it should be making a lot more hp at 6000 rpm’s.
 
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Hysteric said:
Funny how the local guys can make power with a 308 and an early HQ style head very similar to a 318 head.

Any chance we can get some details on your build?

Would your engine builder be Tony Knight by any chance?
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64/65 273 heads(yea those ones),360 crank,253 pistons 300ci,I’m the builder,and the guy who is advising me is the marvellous Bob Kotmel.
I’ve got a W2 410 combo that makes an easy 600ish atm, this 273 will go in when I give the car to the missus, I’d like a Ve/f/g to put the 410 in
 
fat-360 said:
64/65 273 heads(yea those ones),360 crank,253 pistons 300ci,I’m the builder,and the guy who is advising me is the marvellous Bob Kotmel.
I’ve got a W2 410 combo that makes an easy 600ish atm, this 273 will go in when I give the car to the missus, I’d like a Ve/f/g to put the 410 in
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Old Bob Kotmel aye, Isn't he a legend in Australia motorsport!

Looks like you're in good hands!
 
273 said:
No, I’m saying it’s got most of what it can get out of these heads by 5000 rpm’s. If your building a 6500 rpm engine like this one it should be a lot more hp at 6000 rpm’s.
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Just so you can understand the context from a Chrysler equivalent perspective its making 2.23 HP per Cube with a 318 head on a 318 engine. You can get far more flow from a 318 head than 195 cfm.

I'm sure if the Robinson Crew wanted more air they could quite easily get it. Its USING ALL THE AIR ITS GETTING. Like I keep saying you can give an engine more air it doesn't mean it will USE it.
 
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