367 vs 410 Engines Masters
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I disagree with your conclusion based on the video you posted. I'm not the only one who disagreed with you.
No, but the application matters.
As I've stated many times there was no application, your the one talking about his car that you brought into the convo like on page 10. As I've stated like a million times I'm only talking about there 367 vs 410 and even the 323 performance potential nothing else.
The application was on page one in the 1st post. Either you didn’t see or you chose to ignore it.
Yes, and I have said the way they compare each engines hp has only a limited usefulness.
In a car the stall speed, gears, tranny and it's gears, weight, tire size etc.. can be vastly different and so can the rpm at any given mph so what matters more what hp is being made at any given mph (hp @ mph) or on the dyno graph what they each make at 3000 rpm, 4000 rpm, 5000 rpm etc.. ? I care more about hp @ mph.
As long as you don't care what rpm your turning cruising down the interstate then have at it.
This is my post I get to set what I'm talking about I don't care what he built the 367 for and you didn't until like page 10, and since then I keep on telling you that's not what I'm talking about and keep restating what the subject is, my thread, you want to have a debate about what's a better engine for his car start your own.
Subject on hand does only reading the dyno graph vertically leave out some usefully comparisons especially comparing engine with two separate powerbands that start stop at different rpms. To me horizontally is better for engines with different powerbands and generaliy when viewed that way the potential ain't as bad as they make it out with their vertical readings.
Here's post 1# Where did I say lets debate what's the best engine for his car.
I stated off with the differences
My 1st statement says their not factoring driveline
stated I'm not arguing the 367 is better
Like I said a million times similar performance if the drivelines was setup to take advantage of each.
I know a lot of people think this thread is a dumpster fire, but I did learn or at least became more aware of that even though you can gain/lose peak power, Power in the rest of the curve ain't gained or lost but moves to a different rpm. Eg.. say you make 220 hp @ 2,500 rpm and you put a bigger cam in now and at 2,500 rpms you now make 200 hp yes at 2,500 rpms your engines loss 20 hp, but really your engine still makes 220 hp it just moved to a new rpm (say 2750 rpm). So you still have 220 hp just now at 2,750 rpm and a few mph higher, now if you want back at the same mph you could change to higher stall and or deeper rear gear and or smaller tires and or lower 1st etc.. gears.
The power hasn't gone away how you have to use it has changed.
The power hasn't gone away how you have to use it has changed.
340six
King Of Bling
340six
King Of Bling
You sound like you need a short stroke 340 main 2.96" stroke crankshaft like MP used to offer. Make ya a Trans Am 340.
Big bore, Short stroke, solid roller.
Many years ago (early 90s) when I built a X Block they had one a guy was getting polished at the machine shop. Was also getting TA heads.
I'd love a 2.96" especially in short deck block and a big bore.
PRH
Well-Known Member
I’ll ask that you show an example…….
That a certain weight of fuel and air = hp potential in a somewhat narrow range (efficiency) ?
And that fuel and air take up a physical space (depending on temp, altitude etc.) size Cubic Feet and an engines needs to displace that size of air over time CFM, depending on cid per revolution x rpm x ve% = cid per minute or CFM. Engines of similar efficiency is gonna have to move similar amount of air per minute or CFM.
Do I have a bunch of data (dyno cfm results) to back this up nope, cfm is not often shown but when it has been it doesn't seem to contradict so far.
And unless I'm missing something seems pretty logical that there would be a correlation between what an engine displaces CFM wise and it's hp (same with fuel), especially more so than what the measurement of a non running engine is Cubic inch Displacement.
These 3 engines make similar peak hp 423-431 hp.
323 x 6200 / 3456 = 580 cfm
367 x 5800 / 3456 = 616 cfm
410 x 5500 / 3456 = 652 cfm
We don't know each's VE% but even without that seem in fairly similar range already and bet the VE's would narrow it even further, not saying they would be identical since there's other efficiencies at play.
PRH
Well-Known Member
I can pull up dyno sheets where that formula doesn’t pan out, which is why I asked.
One that’s close power wise to your example………
365”@6200 - 420.5hp …… 563cfm
Formula shows 654cfm.
I guess some of it comes down to point of view…..
I don’t consider 580, 616, and 652 as “similar” cfm.
One that’s close power wise to your example………
365”@6200 - 420.5hp …… 563cfm
Formula shows 654cfm.
I guess some of it comes down to point of view…..
I don’t consider 580, 616, and 652 as “similar” cfm.
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That formula is just the measurable space of a running at any given rpm, cid x rpm = cubic inches per minute / 3456 = cubic feet per minute, never said it was gonna be actual air being displaced, isn't that how you calculate VE% the actual cfm measured on the dyno divided by the theoretical maximum at a 100%, that formula ?
I think the rule of thumb is like 1.4 cfm per hp for an average decent engine, your engine is making 1.34 cfm per hp, say the those 3 engines did the same, so 323 would be using 570 cfm and 98% VE, 367 = 567 cfm = 92% VE, 410 = 578 cfm = 88% VE, based on if it took similar cfm per hp to make those peaks 563-578 cfm to make 421-431 hp, if so looks very similar.
And yes we don't know for sure, but would you think any of those engines would be consuming a vastly different cfm especially way outside the 80-110% VE ? And the 1.3-1.5 cfm per hp ?
Wouldn't that be 86% VE ?
Like I said this hasn't factored in the VE% so it's not really telling us much, especially cause we can tell by there peak hp rpms they not making the same VE% at peak hp.
Cid spread is a lot larger than there rpm spread.
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PRH
Well-Known Member
All of those figures are 100% VE(along with the 654 for my 365 example), so I guess that’s all it’s telling us.
Basically, piston pumping area displaced for a given rpm.
Yes, cause we don't have the VE%, 90% of the time I included VE% in that formula, I didn't there cause is was a basic simplified version of what I'm talking about wasn't meant to encapsulate every possible variation of mass of fuel and air, physical size of fuel and air and efficiency level, It was just half a sentence. I'm pretty sure at similar altitude and temp and cr etc.. the cfm per hp is gonna be similar.
The amount of fuel and air going through your engine over a period of time (displace) is gonna have a strong correlation with it's hp ?
Not really, the point was the cfm measured is the actual displacement of an engine at that time and place, not 410 or 367 etc.. that's what a non running engine is and matters a lot less.
PRH
Well-Known Member
I guess I’m going to stick with analyzing my actual results from real builds, and worry less about internet “rules of thumb”.
I would to if I had a dyno but since I don't got to do with the best I got.
But does your results shows most of your engines not being in the 1.3-1.5 cfm per hp range (measured cfm on the dyno), you find there vastly different then the so called average range ?
PRH
Well-Known Member
Some are within that range, but many are better(lower) than that.
Even combos where the hp/ci isn’t all that good.
Fundamentally, I like to look at hp/ci, with some mental adjustments made for deficiencies in the combo(small heads, low cr, lift rule cam, etc).
Maybe it’s as much as comparing to similarly handicapped combos as the hp/ci.
Even combos where the hp/ci isn’t all that good.
Fundamentally, I like to look at hp/ci, with some mental adjustments made for deficiencies in the combo(small heads, low cr, lift rule cam, etc).
Maybe it’s as much as comparing to similarly handicapped combos as the hp/ci.
I generally I include @ rpm to hp/ci, cause like the 365, 367, 410 are all turning quite of bit more rpm relative to the 323 peak rpm for similar hp, showing the 323 is being pretty efficient near peak hp. And since it has 2nd highest lbs-ft per cid next to the 367 to me shows it has a decent under the curve. Hence this whole discussion about these engines having similar potential
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