Slightly strange head flow question.

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You need to fix your quote.

2. By mentioning the car doesn't look for anything but you do is retarded slight at me and you should be ashamed at a poor poke. To say I ment the car, the actual car is looking for something like a live animal is dumb. Your statment is dumb. Splitting hairs on terminolgy of the cars description is also dumb. Perhaps people in Nashville, via your description build crap and lame street strip cars.

Theres my view, only by your description. Thankfully, I know this not to be the truth and impossible. Just wondering how the shoe fit on you.
 
Since you clarified that you were looking for a simple "calculation, here's some calcs you can run to determine your engines requirement and potential.

Of course, you could always fall back on 2 times the intake flow to determine potential HP. For example, running a 250 cfm intake port (head) will get you to ~ 500 HP.

On the 360 heads on a 318, without trying to start an argument or sounding disrespectful to other members, I can tell you that the absolute, all around, best street cylinder head upgrade was the 360 heads on a 318 - and everyone I've ever built made much MORE torque on the bottom end than any of the 318 heads and it revved like a 340. Why? Because the stock 360 head has excellent velocity and will work well with cams up to .508 lift with either a Torker or an LD-340 dual plane. In fact, these engines were more fun (sometimes) than my big blocks, and those little 318's were nearly indestructible. No one ever believed I was running a 318 with such a combo !

Anyway, here's some calcs that should get you started:

Solving For Air Flow Rate

CFM = CID X RPM X VE / 3456

VE = 3456 X CFM / CID X RPM

CID = NOS X SV

CID = NOC X 0.7854 X Bore (squared) X Stroke (To calc displacemet on strokers etc.)

HGV = HGCV X 0.7854 X Bore (squared)

PDV = (0.7854 X Bore [squared] X DPD) + (VPD - VPB)

CR = 1 + 0.7854 X Bore (squared) X Stroke / CCV + HGV + PDV

Injector Sizing Calc if needed:

ISH = HP / 16

Key below:

Where

VE = volumetric efficiency
CFM = engine air flow rate - cubic feet per minute
CID = engine displacement, size or volume - cubic inches
RPM = engine speed - revolutions per minute
NOC = number of cylinders
BORE = length
STROKE = length
HGV = head gasket volume
HGCT = head gasket compressed thickness
PDV = piston deck volume
DPD = deck to piston distance
VPD = volume of piston depressions
VPB = volume of piston bumps
SV = swept volume
CR = compression ratio
CCV = combustion chamber volume
ISH = injector size per horsepower
HP = horsepower

Again, I hope this helps.

Southernman
 
CFM = CID X RPM X VE / 3456

VE = 3456 X CFM / CID X RPM

CID = NOS X SV - What is this one supposed to be? Because SV is the same as the CID formula below. Displacement is Swept Volume x Number Of Cylinders.

CID = NOC X 0.7854 X Bore (squared) X Stroke (To calc displacemet on strokers etc.)

HGV = HGCV X 0.7854 X Bore (squared)

PDV = (0.7854 X Bore [squared] X DPD) + (VPD - VPB)

CR = 1 + 0.7854 X Bore (squared) X Stroke / CCV + HGV + PDV

Injector Sizing Calc if needed:

ISH = HP / 16

Key below:

Where

VE = volumetric efficiency
CFM = engine air flow rate - cubic feet per minute
CID = engine displacement, size or volume - cubic inches
RPM = engine speed - revolutions per minute
NOC = number of cylinders
BORE = length
STROKE = length
HGV = head gasket volume
HGCT = head gasket compressed thickness
PDV = piston deck volume
DPD = deck to piston distance
VPD = volume of piston depressions
VPB = volume of piston bumps
SV = swept volume
CR = compression ratio
CCV = combustion chamber volume
ISH = injector size per horsepower
HP = horsepower
 
OK guys, that was a typo, but it was late last night when typing it.

The CID should have been CC's, which corresponds to the total swept volume of all cylinders, and the NOS should have been NOC (number of cylinders including gasket area)... Come on - you guys knew this...

Also, when someone asks for a "formula", or formulas, there are hundreds out there that can be used to get you where you want to be. These are just a few of the more common "formulas".

I do think that many rodders confuse a "recipe" with a formula, as there are many recipes to going fast, each having it's own little nuances that builders bring to the table.

If you're asking for a formula, then that means working from a good calculator but, if you're really after a rodding recipe, then most of the magazines out there do a good job of providing recipes for the rodding crowd. Popular Hotrodding's Engine Build Off is a prime example. Additionally, many of the posters here have excellent recipes that reconcile to most any budget.

However, as noted above, my personal experience with 360 heads on a street/strip 318 are based on "my" history with the application and not everyone here will agree with my assessment. Therefore, I recommend you network with friends that have built their engines, or rely on magazines that do a great job of flushing out performance on their dime, which can save you considerable money when building yours.

One other thing: there is a magazine called Engine Masters, and it's editor is a hard core Mopar guy named Steve Dulcich. Every issue has a Mopar based engine build - with dyno results, and usually a good run down on costs.

If you're a Mopar engine builder, I'd recommend subscribing to Engine Masters or picking it up at your local news stand.

Sorry for the confusion with the formula, but hopefully there were a few that others could use if needed.

Southernman
 
Depending on the engine being built and the targeted performance level, the head choice will be ethier or. I don't see the 360 head fitting the bill for all sizes. Been there done that several times.
 
I want to bring this thread up again! its a interesting question!
-Where is that edge where the engine not answering to more cfm?

usually for me(read backyard tuner) I used to stick to known combos, or hack together something and test:cheers:, but now,

I have this program called PIPEMAX, it cost a few bucks but is worth every cent. just type in some basic numbers about the engine and this program calculate cfm needs to make the power the camshaft is capable of!

If you look at the pic, you see the one row (3. from left) that is piston CFM. This is the cfm value the piston is capable to "suck" ... so I guess there is no need to go beyond this number. (sure you have to use correct area and length on intake runner! this is the hard part:D make alot of cfm out of a small and not optimised port)
 
Norway-dart said:
I want to bring this thread up again! its a interesting question!
-Where is that edge where the engine not answering to more cfm?

usually for me(read backyard tuner) I used to stick to known combos, or hack together something and test:cheers:, but now,

I have this program called PIPEMAX, it cost a few bucks but is worth every cent. just type in some basic numbers about the engine and this program calculate cfm needs to make the power the camshaft is capable of!

If you look at the pic, you see the one row (3. from left) that is piston CFM. This is the cfm value the piston is capable to "suck" ... so I guess there is no need to go beyond this number. (sure you have to use correct area and length on intake runner! this is the hard part:D make alot of cfm out of a small and not optimised port)
Click to expand...

Pipemax shows you just how you can add more cfm/port but not make anymore power...because the engine can't access it. You have to build the engine so that it will access the airflow provided by the heads ports. If you don't do this, it's just like not degreeing the cam and then blaming the cam/company for a poor camshaft.

It can be relatively easy to build a performance engine, but engines are complicated even if guys want to dumb them down to make themselves feel better about it.
 
But in this case you already have an assembled engine, and Every engine has a maximum cfm it would be capable to make use of?

I agree,the engine is a complicated thing, but thanx to pros sharing ideas and mathematic, we need fewer tries today to make maximum power of a spesific camshaft than before...

To make maximum power, the combo has to be perfect. Pipemax show you the ideal line, and if you put in your engine , you may compare and find out if it will make more power with more cfm.
 
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