cubic inches vs. head flow vs. rpm

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abdywgn

abdywgn

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with a given desired result in mind, how do you determine the combination of the above? if the cubic inches are too small for the head flow or the head flow is too much for the cubic inches, then the rpm goes up. so how do you find the sweet spot where the planets align and the car never gasps for air or has it's tail twisted so tight that the oil pan becomes a scrap metal bucket.
no particular combination in mind just a brain teaser to sit and figure out. my guess is that experience has a lot to do with it and I hope those that have will answer without giving away hard earned secrets. just point grasshopper to the path of enlightenment. thinking that's enough kombucha for tonite.
 
Im sure Yellow Rose has a 12 variable formula for this....where $ is how much power you want to make....

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c'mon guys! high school trig class was wwwaaayyyy to long ago to remember how to do stuff like that. but I do think some of that formula comes to mind: hp = $$, more hp equals $$$, and if you hafta ask how much $$$$ is, you can't afford it.
 
yes, the question was more about picking the parts based on desired results so it doesn't end up wheezing or coming apart.
 
Do you have idea ,for a combination..and do we get compensate, for our articulate brilliance:) ..:):):)
 
performance goals: as quick as possible, NA, no laughing gas, looking as plain jane as can be. please do compensate in anyway you wish. oh,this oughta be good!
 
that is the secondary question. the first one, if answered, would provide the basis for the second. this did start out as a serious question and still is. but since we are having fun with it, like a pendulum, it can go both ways. somewhere in there should be morsels to gnaw on and develop a plan that could be used regardless of the outcome desired. "A universal formula" to aid gearheadkind the world over.
 
abdywgn said:
that is the secondary question. the first one, if answered, would provide the basis for the second. this did start out as a serious question and still is. but since we are having fun with it, like a pendulum, it can go both ways. somewhere in there should be morsels to gnaw on and develop a plan that could be used regardless of the outcome desired. "A universal formula" to aid gearheadkind the world over.
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If you have a unlimited pocketbook, we can help you ....:)
 
aw c'mon! I jest bought me the ole farm truck to haul this thing if ever I get started on it.:)
 
Best bang for the buck( talking strictly the motor) is a freshened up R5P7 deal. Easily found under 10k and usually will put out 750-800 horse if it utilizes a roller cam.
Buddy stuck one( flat tappet restrictor plate motor with dinky 248/258 cam) in a 68 Dart and went 9.40’s with it using a 904 behind it. Modified a set of 2 inch W2 headers and built his own front end
 
The first thing to do is figure out what heads are available. Once you have your choices, then you pick the head that requires the least amount of work to get where you want to be.

IMO, there is no such thing a an OOTB head. They all need work to make power.
 
The way I see it is first you need to decide hp goal. With that in mind pick heads that can accomplish this. The rule of thumb is 2 hp per cfm but you rarely see output like that in non race engines with cams in the 265 to 285 range along with CR in the 9:1 to 10.5:1 range is gonna be more like 1.7 to 1.9 hp per cfm. Next you want to figure where your powerband will be idle to 5000 rpm or 2000 to 6000 rpm etc.. and thats where displacement comes in. Basically a 1 hp per cid engine is gonna peak around 5000 rpm and 1.25 peak around 6000 rpm. Obviously theres a lot of factors that come in to play that a very lose guesstimation.
 
that's a much louder bang than I am anticipating. were you ever to Oswego IL to race? my education and thoughts of how a car should be built is stuck in that era. along with the amount of money I have to spend on the car. your reply is certainly valid but 10K would be the very upper end if not over the limit of this budget. unless you know somebody who wants a hydrocarbon gas analyzer for $$$. my hope was to gain understanding in how to decide/pick parts.
 
fishmens67 said:
some of us have know how, need a little less cash. Success isn't always achieved with cash.
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Thanks! that's part of the answer that I'm looking for. ( I really should give you all thanks for answering ). now I need to ponder what has been written, some in fun and some to edify. when engine builds and combos are talked about, I'll glean info that will put me steps closer to answering this question. so, thanks to you all! it's high time I went.
 
@273 Gyes to a degree depending on who your dealing with or more importantly the thickness of there wallet in answering the question, “How fast can I go?”

I’d rather point to speed talk and review a few topics there as I’m not so exacting on the needs of specific “Race engine” needs. While I can spec and build a small block on lapsed to 750 hp, doing it in person yourself is another tale to be told.
(AKA Lie about! LMAO!)

There is a formula for needed cross section as well as cylinder head flow, valve sizes etc for a given C.I.D. Any of the parameters are bendable of another is flexible enough that cover the others short coming.

This can be a fun topic to discover. While I have read about it, I’ll keep my nose out of it and lips sealed on it. For most people, the aftermarket has a good general selection with head porters to modify them for the “more.”

I would freely give away any information on what I know. I stand in a spot where I won’t loose any money or sleep over it. It’s just the higher race end particulars I’m not familiar enough to share with confidence on be right for a particular application. I’d rather clam up than make a mistake.

So far, there are good books on the matter. A few videos that show differences and a few members to ask in THERE combo changes to start getting ideas.

A good example of good head vs better head to s the engine master video on the sbm stroker w/ported Edelbrock heads. You can see how it benefited really well with the ported heads.

Id like to see a set of “bigger heads” on top 408.
 
abdywgn said:
with a given desired result in mind, how do you determine the combination of the above? if the cubic inches are too small for the head flow or the head flow is too much for the cubic inches, then the rpm goes up. so how do you find the sweet spot where the planets align and the car never gasps for air or has it's tail twisted so tight that the oil pan becomes a scrap metal bucket.
no particular combination in mind just a brain teaser to sit and figure out. my guess is that experience has a lot to do with it and I hope those that have will answer without giving away hard earned secrets. just point grasshopper to the path of enlightenment. thinking that's enough kombucha for tonite.
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Read the yellow highlighted areas.

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Here's how I see it, there is basically 3 different categories.
First would be what I call basic. Production block, production heads and I'd even throw eddys in there or any head where the ports resemble a stock port. I beam rods, factory cranks and 4" cranks are the norm it seams. The combinations seem to top out around the 500hp mark.
Next would be moderate. W2's and other aftermarket heads come in to play here. Usually still production blocks with the addition of H beam rods and stroker 4" cranks are used. These builds seem to target a 600 hp mark.
Last would be aggressive. After market blocks, high end cylinder heads, H beam or aluminum rods, 4+" cranks and even some exotic parts. I would consider this category a max effort with a 600+ hp goal.
Now the disclaimer, this is a very basic break down of how I look at it. I'm sure someone on here has or knows of someone that made 1000hp with a stock block, crank and heads. There is overlap from one category to the next with any combination of parts used.
Also, I've been told camshaft lift and compression is your friend for making power so I would look at maximizing those to the combination of parts you chose.
 
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