F1 Cosworth and the Hemi fuel engine would rev at a rate of 50,000 revolutions per minute per second
my hydraulic roller cammed 540 cid engine revs from 6000 to 7000 rpm in 0.3 sec ... makes it really important, and almost impossible, to time that shift at 6300 rpm correctly
"rocket scientists" are specialists in V8 combustion engine dynamics
stop! stop! I'm laughing so hard I can't breath!
with those last three posts let's wrap this baby up and send it to SNL for immediate airing
That is the rate that those engines gain revolutions when free reved. The point is they can reach maximum rpm in about .16 seconds from idle speed in the case of the 500 inch hemi fuel engine and about .28 seconds in the case of a rather small 183 cid F1 engine. They free rev at the same rate to maximum rpm which is truly phenomenal especially when you hear either one.
It just shows that there is a lot more to it than component mass.
That is the rate that those engines gain revolutions when free reved. The point is they can reach maximum rpm in about .16 seconds from idle speed in the case of the 500 inch hemi fuel engine and about .28 seconds in the case of a rather small 183 cid F1 engine. They free rev at the same rate to maximum rpm which is truly phenomenal especially when you hear either one.
It just shows that there is a lot more to it than component mass.
Fair enough, I see your point so my post edited accordingly
But I think you'll agree it's still apples and oranges to the point of this hijacked discussion - the engine architectures are nowhere near the same.
The premise on this sidebar has been - generally, when you have a SB and BB making near same power, the parasitic drain from the rotating assembly and reciprocating mass on a BB has a greater impact on acceleration vs SB.
Granted, when you're making 8000 HP on a nitro fed hemi, the rotating & reciprocal parasitic loss difference to a race fueled 800 HP cosworth is obviously overcome by the shear power of the hemi.
Btw, if you do the math with those motors, the cosworth with max RPM at 18000 and hemi at 9500, then the cosworth gets to 9500 RPM .01 faster than that godzilla hemi and David beats Goliath once again - but by the slimmest of margins lol. (just funn'in with ya)
The use of the word "generally" should have been used from square one, instead of it being an open and shut case that all small blocks will accelerate faster than all big blocks, which is really the original premise, and then it all snowballed from there.
*My* original premise is that you shouldn't assume such, due to the fact that a lot of big blocks have lighter rotating assemblies than small blocks, and due to the fact that there is certainly more to it than just rotational inertia and momentum. The rotating assembly may be super-light, but if you have the highest tension piston rings out there, or there is considerable reversion in the system, low compression ratios, poor exhaust, heavy flywheel weight, etc., then it's not going to help you.
I've always maintained my part of this debate in the context of a general rule of thumb. I also understand your premise Brent, but would ask when you say a lot of big blocks have lighter rotating assemblies than small blocks are you talking unmodified OEM to OEM motors? If not, are those BBs built with exotic light-weight components + whatever tricks you have up your sleeve to lighten the rotating assembly that beat the OEM SB? Seems to me if you use the same exotic light-weight components + tricks your SB build will have a rotating assembly correspondingly lighter which puts us back to square one.
I've always maintained my part of this debate in the context of a general rule of thumb. I also understand your premise Brent, but would ask when you say a lot of big blocks have lighter rotating assemblies than small blocks are you talking unmodified OEM to OEM motors? If not, are those BBs built with exotic light-weight components + whatever tricks you have up your sleeve to lighten the rotating assembly that beat the OEM SB? Seems to me if you use the same exotic light-weight components + tricks your SB build will have a rotating assembly correspondingly lighter which puts us back to square one.
When Max first posted that post, he mentioned a "stroked small block", so no, I didn't really think about the OEM side of things.
With the OEM, the difference in acceleration could be chalked up to the design of the engine and the parts used. For instance, a 427 S/O out of a Galaxie or Fairlane back in the 60's would be much more zippy than a smog-controlled 351W from the 70's. If you compared those two, you'd probably find the the FE would have really tall, heavy cast pistons, long 6.490" rods, heavy ring pack, etc, and the 351W would have heavy cast pistons (but much smaller when you look at a 4.000" bore and a 4.230" bore, plus the short deck block), shorter 5.956" rods, etc, etc. The SBF would easily have the lighter rotating assembly, but there are other variables.
When I do rebuild an OEM-style engine, I will use more modern parts: forged pistons, modern ring pack designs, modern connecting rods when available, etc. It makes a difference.
On a stroked FE or stroked SBF, I'll use high quality, modern parts, but nothing exotic. If you look back to the two pictures I posted of a stroked SBF piston and a stroked FE piston, you'll notice that they are both within 2g of each other, and those are not custom, exotic pieces.
The bottom line is that even though the rotating assembly is lighter, it doesn't necessarily mean that the engine will accelerate quicker. That's been my point all along.
Can you make a small block accelerate quicker than a big block? Yep. Can you make a big block accelerate quicker than a small block? Yep. But there can't be a blanket statement made that says the smaller engine is always going to be zippier.
... The bottom line is that even though the rotating assembly is lighter, it doesn't necessarily mean that the engine will accelerate quicker. That's been my point all along.
Can you make a small block accelerate quicker than a big block? Yep. Can you make a big block accelerate quicker than a small block? Yep. But there can't be a blanket statement made that says the smaller engine is always going to be zippier.
All true until you get to that last sentence Brent, no one has made a blanket statement that says the smaller engine is always going to be zippier, show me where?
Take 1000 BBs and 1000 SBs of comparable build, more SBs will be zippier than BBs in that population of 2000, ergo a general rule of thumb.
"As far as FE and stroked small block, the small block will rev much much quicker, probably require less maintenance and be a more durable engine assuming a Dart block."
That is a general statement, with no qualifiers. It's not correct.
There was no mention of which small block. Which big block? What flywheel? What compression ratio? What cam?
Too many variables to make a blanket statement like that.
So based on your own experience of driving 1000's of each, that's the conclusion you've come to? Because I will admit that I haven't driven, built, or probably even looked at 1000's of each, but from my own experience, that is not the "general rule of thumb" that I've seen.
Well, does this conclude CC's 1,000,003rd chapter of "Big Block versus Small Block, Which is Zippier"?
Now, can we get someone to start a nice mellow "Is a CSX Continuation Series a 'Real' Shelby Cobra"?
Or how about a "My Roush Engine is Losing Oil Pressure, is it Covered Under Warranty?"
And there's the always interesting "My MSD Crapped Out, Why Can't MSD Build a Better Box?"
And my favorite, "I Was Jogging Through My Local Park (in Australia) and I Found a Rare Dual Quad FE Intake Manifold Stashed in the Bushes, am I full of BS?"
Several years ago, when a local hotrod shop was installing the engine in my new Superformance, there were 2 other Superformance cobras also being fitted with motors in the same shop. I remember seeing all 3 engines sitting in the same bay, all with dyno sheets hanging down. My KC 408 had very similar hp & tq as the Roush, but not nearly the same on the price tag. Surprisingly, the KC 408 had way more hp than the third engine -- a BB 427 (another builder - not a KC, nor Roush). I'm very satisfied w/ my KC motor.
then lets start one about gyroscopic inertia during a turn---start off comparing 6 cylinder straight six (longer crank) against a ready mix concrete truck---(saw one on way home a few minutes ago)
Well, does this conclude CC's 1,000,003rd chapter of "Big Block versus Small Block, Which is Zippier"?
Now, can we get someone to start a nice mellow "Is a CSX Continuation Series a 'Real' Shelby Cobra"?
Or how about a "My Roush Engine is Losing Oil Pressure, is it Covered Under Warranty?"
And there's the always interesting "My MSD Crapped Out, Why Can't MSD Build a Better Box?"
And my favorite, "I Was Jogging Through My Local Park (in Australia) and I Found a Rare Dual Quad FE Intake Manifold Stashed in the Bushes, am I full of BS?"
Cobra Make, Engine: Some polish thing... With some old engine
Posts: 2,286
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Quote:
Originally Posted by RodKnock
...
And my favorite, "I Was Jogging Through My Local Park (in Australia) and I Found a Rare Dual Quad FE Intake Manifold Stashed in the Bushes, am I full of BS?"
Hey, I'm glad that story left an impression on you too...
In the words of one of our esteemed moderator "bite me!"
Quote:
Originally Posted by blykins
Here, I already have the answers:
No.
No.
No.
Maybe.
Maybe? I thought you new that guy better...
Definitely full of BS!
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