How does cid make power?

[Rat Bastid]

$900 going to $4k doesn't sound reasonable just for being Canadian.
Your previous post is the one which turned it into "does it make sense to build a stroker" when you brought cost into it.

CID by definition makes power. The volume of air expanded is exactly what creates HP. If you start with less air, you have less expansion. Look at it this way: expanding air is work. Work is HP. More air requires more work in order to expand it - which equates to more HP. HP is work, work is HP. It's physics 101.

But you discount or ignore RPM. You get more firing cycles with more RPM. RPM IS horsepower. That is the central theme of engine building. Torque does NOT make a car quicker or faster. That takes RPM.

If you have more RPM (and can feed it) you can use more gear. More gear is a longer lever to move a car. Gear ratio is a far more effective lever than an increase in stroke is.

 

[Phreakish]

But you discount or ignore RPM. You get more firing cycles with more RPM. RPM IS horsepower. That is the central theme of engine building. Torque does NOT make a car quicker or faster. That takes RPM.

If you have more RPM (and can feed it) you can use more gear. More gear is a longer lever to move a car. Gear ratio is a far more effective lever than an increase in stroke is.

Totally agree - that's the 'work' part. Work is 'per unit time', which means RPM has to be part of it - should have made that more clear.
You get torque from the force exerted by the expansion event - but add them up and you get HP.

Adding CID without adding flow pulls the RPMs down where peak occurs because heads get saturated/choked. But CID, backed up by adequate flow, will always increase HP at all points. Kinda like you keep saying: it has to be apples:apples. A 408 with stock 273 heads is a pineapple.

 

[273]

HP is work. A 512 is 22% larger than a 400. So the 400 needs to turn 22% more revs to match the HP potential. But like @33IMP says: why not turn the 512 22% faster again? This gets completely circular in a hurry. The 512 will do more at a lower rpm - which is a good thing because reality sucks compared to thought experiments.

To turn the 512 22% higher you would need to upgrade the whole top end, the 400 can spin 22% higher with similar top end as the 512.

 

[Phreakish]

If you have more RPM (and can feed it) you can use more gear. More gear is a longer lever to move a car. Gear ratio is a far more effective lever than an increase in stroke is.

Agreed.

There are constraints though: not everyone is willing to dump the cash needed for a 9k capable valvetrain and oil system into a street car, or willing to run the highway at 4500rpm. To me, that's where the benefit of a stroker is: make the power at lower revs as a crutch for street driving. It's a trade-off. But that's a slightly different topic, albeit related, than 'does CID make HP?' - because CID definitely does IF one assumes it's properly supplied. Otherwise all our shitbox econowagons would have 14hp lawnmower mills in them, right?

For a racecar, there are other options.

 

[Phreakish]

To turn the 512 22% higher you would need to upgrade the whole top end

So?

the 400 can spin 22% higher with similar top end as the 512.

Wrong. Top end is top end, doesn't matter what's under it!

 

[273]

So?

Wrong. Top end is top end, doesn't matter what's under it!

The thought on this site is generally a similarly built engine of different displacements the larger one will make more hp, so you have to at least build similar equipt engines to compare. Obviously if you build the larger engine with way better parts it's gonna make more power.

 

[Hot Metal]

example of size, our dyno'd 589ci (4.565x4.500) mild 10:1cr wedge, strange combo but its how we got it, originally built as a 605 with a 4.625 crank.... -13 365cnc heads, .625" 260/[email protected] s/roller, 440-2, puny old 950HP carb, 2.1/8"x4" TTI's a mere 695hp@5500-5900, 720ftlbs@4400

 

[Phreakish]

The thought on this site is generally a similarly built engine of different displacements the larger one will make more hp, so you have to at least build similar equipt engines to compare.

Your logic in this endeavor has been wildly inconsistent.

The question was does CID make horsepower. The answer is absolutely.
The secondary question is whether a comparable engine with more CID will make more HP, and the answer is still absolutely.
The tertiary questions is whether the larger engine will make more PEAK HP, and that's a lot more complex because flow will dictate the rpm range for both, and the answer would depend on WHAT RPM you want the power compared at.
The quaternary question is whether it makes financial sense to increase the CID for more power, and the answer is again complex. If you have a bad-*** top end, then yes - make more CID. If your 273 peaks at 4500 rpm, you probably need to open your wallet for a better set of heads first.

There is no blanket answer for whether CID makes HP in ALL cases because that game is too easy to rig. At what RPM? What is the goal? Where is the torque needed?

A bigger bore wins in every case, but that's physically constrained by the engine design (bore centers). Stroke is the only other way to increase CID once bore is maxed out - but the question isn't about stroking vs boring, it's CID vs CID - and in general more is better unless there's other factors crippling the performance already. If the CID of a PERFORMANCE engine is increased and power doesn't increase, then something else (tight wallet) is holding the engine back - not the CID.

 

[67autocross]

I'm Canadian everything cost more up here.

Even in the great white north adding a stroker crank will likely add about $600 to the average forged piston street small block....

 

[33IMP]

But you discount or ignore RPM. You get more firing cycles with more RPM. RPM IS horsepower. That is the central theme of engine building. Torque does NOT make a car quicker or faster. That takes RPM.

If you have more RPM (and can feed it) you can use more gear. More gear is a longer lever to move a car. Gear ratio is a far more effective lever than an increase in stroke is.

....but what if you don't want 3800 rpm on the freeway (like my a12 was) or a soft, soft lower end , just to get some rpm?
I'd rather have 550 lb/ ft, and 550hp, than 350lb ft, and 650 hp.
Agreed, the 650 hp will be quicker/faster. But it might take 5.38s to get past my 3.91s.
I don't want 5.38s in my street car.....

 

[Rat Bastid]

....but what if you don't want 3800 rpm on the freeway (like my a12 was) or a soft, soft lower end , just to get some rpm?
I'd rather have 550 lb/ ft, and 550hp, than 350lb ft, and 650 hp.
Agreed, the 650 hp will be quicker/faster. But it might take 5.38s to get past my 3.91s.
I don't want 5.38s in my street car.....

I’d have to know car weight and tire diameter but I doubt you’d need a 5.38 gear.

Then my answer is you have to build what YOU want to drive. Just don’t presuppose that everyone can’t handle a gear lower than 3.91 on the street.

4.56 is my go to strip/street gear. If you are a street guy then build according. But that doesn’t mean you won’t get outrun by a smaller CID engine.

 

[33IMP]

I’d have to know car weight and tire diameter but I doubt you’d need a 5.38 gear.

Then my answer is you have to build what YOU want to drive. Just don’t presuppose that everyone can’t handle a gear lower than 3.91 on the street.

4.56 is my go to strip/street gear. If you are a street guy then build according. But that doesn’t mean you won’t get outrun by a smaller CID engine.

I have had 4.56s and 4.11s in my 62, along with the 3.91s in it now. It runs (essentially) the same times, no matter what gear.
I had 5.43s in my Tina for a while, but it is faster (and quicker) with the 4.57s. Both cars are cylinder head limited, probably why gearing doesn't matter.
I'm gonna try the 3.50s in my Opel first, then we'll see if it needs more.... or if 600 lb ft can pull it.

 

[rumblefish360]

Thats a 3% different by equal or even I mean practically,

Please restate. English rules not exactly observed.

there a less than 2% peak hp difference in the curve

Correct, as dictated by bore size.

it's a wash

Only as far as peak HP is concerned.

and with gearing torque is basically wash too,

Dream on. When you have been there and done that will you actually relent on this.

for a 50 cid $3000-4000 I wouldn't call these wins and be upset if I was convinced this was the way to go.

I’m not understanding this. Please restate

2% got to be in the margin of error between to identical engines. I picked those gears with 26" tires in mind that difference is equalled if the 410 had a 27" instead of a 26" 410=3904 vs 360=3912, If you want to see these as wins that's up to you.

Before we get into the gearing and wheel size, let’s stick with your question on engines.

A side note yes more torque is a gain but less powerband rpm is a negative when it comes to power not always cancelling each other out but when I laid the two power curves over one another it practically did.

How is making more power in a shorter power band a loss and how much of the power band is less in the two examples.
If I took it to a wild extreme of 2K rpm’s, you would achieve the max power sooner and change into the next gear quicker. On the street it equals more fun feel acceleration. Turning less rpm’s consistently will equal longer engine life.

Losing rpm in the powerband might be a bonus in driveablity but negative in power production.

What?!?!?! Are you even looking at what your typing?
First you show the increased power but then call it a negative after you say more torque is good?
Are you in drugs or something?
This makes zero sense!

 

[rumblefish360]

Lot's on here don't seem to fully understand the relationship between tq and hp but endlessly go on about half truths like torque is king, no replacement for displacement etc... Which can occasionally lead to bad choices $$$$$

Well your certainly one of them that’s for freak sure.
While I never heard of a hot rodder or drag racer say torque is king, in some other areas it might be.

Also, there is no replacement for displacement except supercharging or turbo. But what if we take said (properly sized) turbo and put it on the larger engine that didn’t have it?
Moooooooooo power!

Many ways to increase power, the call is yours, the engine owner.

 

[rumblefish360]

I’m lost over the $3000 to $4000… why would it cost that much more to build a stroker?

Especially since he never includes the proper top end but just stunned s the engines ability with what ever it came with on top to begin with because it was fine for the smaller engine.

This is his comparo factor. Stock engine kicked *** but now I put a 4 inch arm in and the engine blows chunks.

 

[273]

Well your certainly one of them that’s for freak sure.
While I never heard of a hot rodder or drag racer say torque is king, in some other areas it might be.

Also, there is no replacement for displacement except supercharging or turbo. But what if we take said (properly sized) turbo and put it on the larger engine that didn’t have it?
Moooooooooo power!

Many ways to increase power, the call is yours, the engine owner.

 

[rumblefish360]

I'm Canadian everything cost more up here.

Your problem, move south for better prices and car selection, don’t dump on us and make misleading statements.

Here the under the curve if you lined up the peaks like you would if gearing properly.

Misleading since your working only with one rpm snapshot and not the entire curve. This is bullshit.

This thread not about which ways better to build power cid vs rpm or that you shouldn't build strokers or whats more streetable

First off, your twisting words again, gotcha red handed since you started the thread and titled it ;
How does cid make power?

but does cid make hp?
Which to me it doesn't.

But you proved yourself wrong above! You typed all over the place the proof of proving yourself wrong!!!!

Your one smoked puppy!!!!!

Do you even know what your writing?
Do you read what you wrote?!?!?!

 

[rumblefish360]

View attachment 1715976259

But you prove yourself wrong!!!!
It’s not opinion when I’m pointing out the obvious and then showing it by the writer himself, YOU 273!!!!

 

[273]

Your problem, move south for better prices and car selection, don’t dump on us and make misleading statements.



Misleading since your working only with one rpm snapshot and not the entire curve. This is bullshit.



First off, your twisting words again, gotcha red handed since you started the thread and titled it ;
How does cid make power?



But you proved yourself wrong above! You typed all over the place the proof of proving yourself wrong!!!!

Your one smoked puppy!!!!!

Do you even know what your writing?
Do you read what you wrote?!?!?!

 

[273]

But you prove yourself wrong!!!!
It’s not opinion when I’m pointing out the obvious and then showing it by the writer himself, YOU 273!!!!

 

[rumblefish360]

Yup

 

[273]

Yup

All joking aside, feels like we're talking two different languages don't see no point continuing

 

[rumblefish360]

All joking aside, feels like we're talking two different languages don't see no point continuing

A shame…. You were getting really funny with the pictures.

What your looking at is the HP @ peak and calling it the final factor in the decision. This is short selling the stroker. Ultimately, the bore size is the limitation on HP being able to be made. The stroke increase is for torque. Since your increasing the cubic inches, the possibility of more HP is possible even with the same bore size but yet still limited because of it.

Being that stroke is increase to make more torque, the HP will increase in all areas as long as the torque is superior against the stock or lesser stroke engine. This is where your he win is.

Unless the engine size becomes vastly different, the change in rpm peak to peak is small. You listed this yourself and claimed it was huge until you seen different but still called the 300 rpm change large, which then called for a gear ratio and/or tire size change. This would inky be needed in the maximizing of the vehicle in a drag race.

 

[Cheapsunglasses]

A lot of people only care about peaks, not everyone looks at the entire graph

 

[33IMP]

A lot of people only care about peaks, not everyone looks at the entire graph

That's true, but then they should look at the e.m. episode with the 383 Chevy vs the 383 Mopar. Peak hp and torque, virtually identical. The mopars torque bulge in the midrange was HUGE.