Bench Racing

Sweet5ltr

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Here is my bench racing question;
What engine makes more average power?

Before looking at results, choose what you'll go with;
(a) 500ci with 600 ft/lbs @ 3,500-5,000
(b) 400ci with 500 ft/lbs @ 4,500-6,000
(c) 300ci with 400 ft/lbs @ 5,500-7,000


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performance being the only goal for given range

Torque x RPM / 5252 = HP (we see the relative advantage of displacement here)

500ci, 600 ft/lbs @ 3,500-4,250-5,000 (399HP-485HP-571HP) 485 average HP
400 ci, 500 ft/lbs @ 4,500-5,250-6,000 (428HP-499HP-571HP) 499 average HP
300 ci, 400 ft/lbs @ 5,500-6,250-7,000 (418HP-476HP-533HP) 476 average HP

Formula 1 engine, lets say 250 ft/lbs @ 18,000
(833HP, that's why they have brutal acceleration when in the power band)


All things equal, that's why there is 'no replacement for displacement' when building a street engine in typical street friendly power bands, but at the same time, acceleration of a larger displacement engine is favored at low speeds vs a smaller displacement engine (making less torque/higher RPM) at high engine speeds.


Using strictly static measurements, what engine would produce more -inertia/power- at the tire (during launch) giving its initial torque peak ;
(torque x rear gear x 1st gear ratio of 727 transmission x stall converter matched @ torque peak) *final numbers indicate acceleration value*
500ci- 600 x 3.55 x 2.42 x 3500 (18,041)
400ci- 500 x 3.55 x 2.42 x 4500 (19,330)
300ci- 400 x 3.55 x 2.42 x 5500 (18,900)
'wildcard' 450ci- 550 x 3.55 x 2.42 x 4000 (18,900)

How street gearing and a typical 3,500 converter affects the outcome;
600 ft/lbs x 3.55 x 2.42 x 3500 (18,041) <--- no replacement for displacement!
500 ft/lbs x 4.30 x 2.42 x 3500 (18,201)
400 ft/lbs x 4.56 x 2.42 x 3500 (15,449) Even with 4.56 gears, this car will not launch very hard. Install a 4,500 converter and it will hit substantially harder (19,863)..


Results are surprising right? It would take a stock 440 wedge making 500 ft/lbs @ 3,500 RPM, 4.30 gears to run with a larger engine making 600 ft/lbs with 3.55 gears (HUGE difference). This is why choosing the correct torque converter and gearing is SO IMPORTANT! Proving why a car with lots of torque requires less gearing to have identical acceleration as a car with less overall torque.

Real world through average limited power bands, a slightly smaller engine favoring HP (torque at higher RPM) will out accelerate a larger engine favoring torque (torque at lower RPM) if setup properly, this was some of the math behind my decision to go with a smaller displacement engine and turn higher RPM:

Looking at these two numbers, peak torque, what made more peak horsepower;
512ci making 650 ft/lbs @ 3,500 (RPM range 3,500-5,500)
470ci making 600 ft/lbs @ 4,500 (RPM range 4,500-6,500)




470 making 600 @ 4,500 x 3.55 x 2.42 x 4500-600 ft/lbs (23,196) 5500-575ft/lbs (27,169) 6000-550 ft/lbs (28,350) 6500-525 ft/lbs (29,317) -wildcard- 7000-500 ft/lbs (30,068)
512 making 650 @ 3,500 x 3.55 x 2.42 x 3500-650 ft/lbs (19,544) 4500-625 ft/lbs (24,162) 5000-600 ft/lbs (25,773) 5500-575 ft/lbs (27,169) -wildcard- 6000-550 ft/lbs (28,350)

**************************
470ci 525 x 6500 / 5252 = 649 HP (7000 RPM = 666HP) +17 HP
512ci 575 x 5500 / 5252 = 600 HP (6000 RPM = 628HP) +28 HP




That is why it's VERY important to think about all these aspects during a build, a 512ci stroker making peak torque @ 3,500 RPM (650 ft/lbs) will get beat by a 470 engine making peak torque @ 4,500 RPM (600 ft/lbs) in acceleration (if correct torque converter is used WITH IDENTICAL GEARING). Most engines make peak HP 1,250-1,500 RPM away from Peak TQ. What all this pretty much says is, pick the largest displacement engine possible that can run the highest reliable engine speed, if a large engine is bottlenecked by small camshafts and poor-flowing heads; it will not perform optimally.

Look at the graph of this 440 Six Pack, 441 ft/lbs @ 4800 RPM and 403HP. (441x4800/5252=403HP)

http://www.hotrod.com/articles/rest...f/#032-440-mopar-six-pack-dyno-test-chart-jpg

Move the peak torque up 1,000 RPM with a larger duration camshaft, properly matched intake manifold, carb, and longtube headers, and if it makes 441 ft/lbs @ 5800 RPM; it will make a 487 HP peak.

Brute acceleration, what converter would be 'overall' better in this application, going off the dynograph?
2.5k rpm (12,650 w/ 4.10 gear)
3k rpm (15,150 w/ 4.10 gear) ?? what, engine makes more torque here right!? but it does not have optimum acceleration at this RPM.
4k rpm (19,208 w/ 4.10 gear)
5k rpm (20,538 w/ 4.10 gear)
5.3k rpm (20,561 w/ 4.10 gear)
5.5k rpm (20,190 w/ 4.10 gear) *lower acceleration while dropping off power band, makes sense now right?*

Now lets say the engine drops 500 RPM per gear change (2nd gear - 1.45)... It looks like 5.3k is around the perfect shift point (all things being equal)

5k - 4.5k (12,546)
5.3k - 4.8k (12,584)
5.5k - 5k (12,306)

That is why sometimes slightly smaller displacement engines 'run better than they should'. Build for slightly less torque at a higher RPM, with an engine that allows higher engine speeds (N/A engines).

100% bench racing, 100% gearhead discussion, yalls thoughts? Kind of interesting right?
 
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Mike67

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Wouldnt that formula be over 1500 rpm span of each motor not the range???
Torque x RPM / 5252 = HP
 

dieseldazzle

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Bench race all day long. Talk rod to stroke ratios, swept this swept that, compression this, roller that blah blah blah.. then go for a ride in a PROVEN perfectly matched combo. Don't care if it's a 300 incher or a 500 incher it's always about the right como and when that right combo is to be had using very little brains and very little cash, both of which is me lol, then I'll take the cubes for my street car anyday of the week. Takes less money and less brains, almost can't go wrong. Works for me
 

Sweet5ltr

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Bench race all day long. Talk rod to stroke ratios, swept this swept that, compression this, roller that blah blah blah.. then go for a ride in a PROVEN perfectly matched combo. Don't care if it's a 300 incher or a 500 incher it's always about the right como and when that right combo is to be had using very little brains and very little cash, both of which is me lol, then I'll take the cubes for my street car anyday of the week. Takes less money and less brains, almost can't go wrong. Works for me

What this bench racing proves, is that it certainly is ALL IN THE COMBO. Just because a car has an elephant under the hood, does not determine how quickly it will accelerate in a given distance. Just because the engine has a peak mechanical range of 6,500 RPM, does not mean peak acceleration will be from shifting @ 6,500 RPM. This bench racing goes over some of those variables.
 

dieseldazzle

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What this bench racing proves, is that it certainly is ALL IN THE COMBO. Just because a car has an elephant under the hood, does not determine how quickly it will accelerate in a given distance. Just because the engine has a peak mechanical range of 6,500 RPM, does not mean peak acceleration will be from shifting @ 6,500 RPM. This bench racing goes over some of those variables.

Right so you are saying you'd rather have the smaller cubed perfectly matched combo and I'm (bench racing here) saying no way man I'm going with the larger cubed perfectly matched combo.
 

Budnicks

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http://www.dragzine.com/engine-blocks/pro-stock-engines-whats-the-secret-to-those-big-power-numbers/

not sure why the damn link doesn't work but go to www.Dragzine.com &
read the article "May 6th 2016" about
"Pro Stock Engines: What's the big secret to those big power numbers ?"
Pro-Stock engines & the relationship to
bore diameter & rod length etc. vs big power gains,
it's not the length of the stoke as much as, rod ratios & bore
1500+ hp out of a 500ci or less

I've had really good luck with 383/431ci-484ci engine combos
shorter rod combo's out of 383/400 blocks,
hp vs ci, best bang for the buck
more of the 383 combos than the 400 block combos...
383 4.25"-4.31" blocks were are a dime a dozen & with a girdle, fully studded
good main-caps, good hardware & quality H-beam rods they can be strong...
Albeit it's claimed the 400 blocks are "allegedly" stronger, in the webbings &
have a bigger bore 4.34" std, both are a win, win...
I've never actually broke a well & properly built/assembled 383 "block",
even @ 720hp & +300 N20 shot added

IMO especially N/A
the cylinder-heads & camshaft working in sequence together
is a really big deal too, especially in these BB wedges...

I'm usually in the camp for "never a replacement for displacement"
but it doesn't always hold true for all aspects...

I know it's apples & oranges but it actually applies here...

Any way just thought I'd add that link,
for some reason, that doesn't work...LOL
 
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Sweet5ltr

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Right so you are saying you'd rather have the smaller cubed perfectly matched combo and I'm (bench racing here) saying no way man I'm going with the larger cubed perfectly matched combo.

As my example placed it, this is a build for most street engines, very little voodoo involved. This is why there is no replacement for displacement, other than a slightly smaller displacement engine willing to run a higher mechanical RPM.

512ci-Dual Plane-240* Duration Cam-Stock Port Window Heads (650 ft/lbs @ 3,500 [peak tq] -575 ft/lbs @ 5,000 [peak hp]) (547 PEAK HP)
3.55 gears. 727 (2.45, 1.45, 1:1)

470ci-Single Plane-270* Duration Cam-Stock Port Window-Heads (600 ft/lbs @ 4,500 [peak tq] - 525 ft/lbs @ 6,000 [peak hp]) (600 PEAK HP)
3.55 gears. 727 (2.45, 1.45, 1:1)

6.2 Hellcat (650 ft/lbs @ 4,800 [peak tq] -6,000 [peak hp]) (707 PEAK HP)
2.62 gears. 8HP90 (4.71, 3.14, 2.10, 1.67, 1.29, 1.00, .084, .067)

Building PROPER combinations, 440/470/512 are in a 3,800# b-body, time adjusted by average power available;
512ci (estimate real world powerband at dragstrip)
(490 average HP 3,500-5,000 RPM / 547 PEAK HP) (11.53 @ 115 MPH)
470ci (estimate real world powerband at dragstrip)
(556 average HP 4,500-6,000 RPM / 600 PEAK HP) (11.05 @ 121 MPH)
6.2 Hellcat (Hellcat by calculations still makes 620 ft/lbs @ 6,000 RPM - BLOWERS RULE)
(650 average HP 4,800-6,000 RPM / 707 PEAK HP) (11.0 @ 121 MPH) <-- Pretty close estimate for advertised ET right?
440ci six pack (estimate real world powerband at dragstrip)
(345 average HP 3,200-4,700 RPM / 390 PEAK HP) (12.96 @ 103 MPH)

Force at launch;
2,500 converter in the 470ci w/ 3.55 gear (500 ft/lbs @ 2,500) (238HP - 10.9* baseline representation)
2,500 converter in the 440-6 w/ 4.10 gear (440 ft/lbs @ 2,500) (209HP - 11*)
2,500 converter in the 512ci w/ 4.88 gear (600 ft/lbs @ 2,500) (285HP - 17.7*)
4,000 converter in the 470ci w/ 3.23 gear (575 ft/lbs @ 4,000) (437HP - 18.2*)
3,500 converter in the 512ci w/ 3.73 gear (650 ft/lbs @ 3,500) (433HP - 19.8*)
3,000 converter in the 6.2 HC w/ 2.62 gear (575 ft/lbs @ 3,000) (328HP - 21.1*)
5,000 converter in the 512ci w/ 5.13 gear (575 ft/lbs @ 5,000) (547HP - 36.1*)
5,500 converter in the 470ci w/ 5.13 gear (550 ft/lbs @ 5,500) (575HP - 38*)

What this shows, is how substantial a proper torque converter and gearing are to acceleration. 470 & 512 strokers make 100+ more HP @ 3,000 RPM but will not launch as hard as the Hellcat due to it's torque multiplication.

Remember when Direct Connection tested a low-compression 8:1 Duster with every purple cam'? What camshaft accelerated the car the fastest?
.590 w/ 270* duration, moving the 400's torque peak up to a higher RPM; making more horsepower (which is a calculation of torque for given time) at the engines desired operating range at the strip.

This shows the relationship between adequate torque and reasonable horsepower. Slightly smaller displacement engines built for horsepower will out accelerate a slightly larger displacement engine built for low-speed torque in a given distance (if all things are equal). If both a smaller/larger displacement engine make torque peaks at identical RPM, the larger displacement engine will make much more horsepower over its given range.
 

mopar 3 B

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As my example placed it, this is a build for most street engines, very little voodoo involved. This is why there is no replacement for displacement, other than a slightly smaller displacement engine willing to run a higher mechanical RPM.

512ci-Dual Plane-240* Duration Cam-Stock Port Window Heads (650 ft/lbs @ 3,500 [peak tq] -575 ft/lbs @ 5,000 [peak hp]) (547 PEAK HP)
3.55 gears. 727 (2.45, 1.45, 1:1)

470ci-Single Plane-270* Duration Cam-Stock Port Window-Heads (600 ft/lbs @ 4,500 [peak tq] - 525 ft/lbs @ 6,000 [peak hp]) (600 PEAK HP)
3.55 gears. 727 (2.45, 1.45, 1:1)

6.2 Hellcat (650 ft/lbs @ 4,800 [peak tq] -6,000 [peak hp]) (707 PEAK HP)
2.62 gears. 8HP90 (4.71, 3.14, 2.10, 1.67, 1.29, 1.00, .084, .067)

Building PROPER combinations, 440/470/512 are in a 3,800# b-body, time adjusted by average power available;
512ci (estimate real world powerband at dragstrip)
(490 average HP 3,500-5,000 RPM / 547 PEAK HP) (11.53 @ 115 MPH)
470ci (estimate real world powerband at dragstrip)
(556 average HP 4,500-6,000 RPM / 600 PEAK HP) (11.05 @ 121 MPH)
6.2 Hellcat (Hellcat by calculations still makes 620 ft/lbs @ 6,000 RPM - BLOWERS RULE)
(650 average HP 4,800-6,000 RPM / 707 PEAK HP) (11.0 @ 121 MPH) <-- Pretty close estimate for advertised ET right?
440ci six pack (estimate real world powerband at dragstrip)
(345 average HP 3,200-4,700 RPM / 390 PEAK HP) (12.96 @ 103 MPH)

Force at launch;
2,500 converter in the 470ci w/ 3.55 gear (500 ft/lbs @ 2,500) (238HP - 10.9* baseline representation)
2,500 converter in the 440-6 w/ 4.10 gear (440 ft/lbs @ 2,500) (209HP - 11*)
2,500 converter in the 512ci w/ 4.88 gear (600 ft/lbs @ 2,500) (285HP - 17.7*)
4,000 converter in the 470ci w/ 3.23 gear (575 ft/lbs @ 4,000) (437HP - 18.2*)
3,500 converter in the 512ci w/ 3.73 gear (650 ft/lbs @ 3,500) (433HP - 19.8*)
3,000 converter in the 6.2 HC w/ 2.62 gear (575 ft/lbs @ 3,000) (328HP - 21.1*)
5,000 converter in the 512ci w/ 5.13 gear (575 ft/lbs @ 5,000) (547HP - 36.1*)
5,500 converter in the 470ci w/ 5.13 gear (550 ft/lbs @ 5,500) (575HP - 38*)

What this shows, is how substantial a proper torque converter and gearing are to acceleration. 470 & 512 strokers make 100+ more HP @ 3,000 RPM but will not launch as hard as the Hellcat due to it's torque multiplication.

Remember when Direct Connection tested a low-compression 8:1 Duster with every purple cam'? What camshaft accelerated the car the fastest?
.590 w/ 270* duration, moving the 400's torque peak up to a higher RPM; making more horsepower (which is a calculation of torque for given time) at the engines desired operating range at the strip.

This shows the relationship between adequate torque and reasonable horsepower. Slightly smaller displacement engines built for horsepower will out accelerate a slightly larger displacement engine built for low-speed torque in a given distance (if all things are equal). If both a smaller/larger displacement engine make torque peaks at identical RPM, the larger displacement engine will make much more horsepower over its given range.
Unfortunately you will never convince the big cubes builders of this. Those of us that build of more than 1320 ft its a no-brainer as high torque and low rpms with low gears go not get you down the road very fast or vary far between fuel stops.
 

68 HEMI GTS

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my standard port window 511 with a six pack in a 4000# race weight combo runs like a raped ape, shift at 62-6300 and trap a bit over 6500. That's running through mufflers the way I drive it to the track. It's all about the right combo, the small high hp motors really work well in light cars. The big heavy cars really need the torque to get em motivated. I'm sure there is more in my combo if I wanted to start throwing torque converors, intakes, open exhaust, and even suspension (mine is all stock) at it. I think an engine than can turn a 10 sec quarter in a heavy car and not be killing itself with rpm is a plus. I'm pretty confident if I switched all my parts over to a 470 short block with the same compression, the road chickens et would suffer a small amount (even if I did turn it harder) After all, I had all the same parts on a 446 and the best et I seen was 11.58.

IMG_2221.JPG

IMG_2532.JPG
 
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Sweet5ltr

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Way too much info for me

It's a lot of information but quality information. Results are surprising.

512ci (650 ft/lbs @ 3500 & 547HP @ 5000)
11.53 @ 115
470ci (600 ft/lbs @ 4500 & 600HP @ 6000)
11.05 @ 121
my standard port window 511 with a six pack in a 4000# race weight combo runs like a raped ape, shift at 62-6300 and trap a bit over 6500. That's running through mufflers the way I drive it to the track. It's all about the right combo, the small high hp motors really work well in light cars. The big heavy cars really need the torque to get em motivated. I'm sure there is more in my combo if I wanted to start throwing torque converors, intakes, open exhaust, and even suspension (mine is all stock) at it. I think an engine than can turn a 10 sec quarter in a heavy car and not be killing itself with rpm is a plus. I'm pretty confident if I switched all my parts over to a 470 short block with the same compression, the road chickens et would suffer a small amount (even if I did turn it harder) After all, I had all the same parts on a 446 and the best et I seen was 11.58.

View attachment 399346
View attachment 399348

Mike, you're forgetting that in the bench session the 512ci motor is built identical to most 'big cube' street engines that utilize stock port window cylinder heads, 230-240* camshafts, and dual plane intakes; peak HP will be near 5,000-5,200 RPM given the 3,500 RPM torque peak. It's hard to say this is not an accurate representation.

The 470ci engine is built slightly more aggressive, identical cylinder heads, 250-260* duration camshaft, and single plane intake manifold; peak HP will be near 6,000-6,200 RPM given the 4,500 RPM torque peak.

Of course if the 512ci is built to have an identical torque peak (all components proportionally increased), it will make a dramatic amount more power. Saying it's all in the combination is simplistic. The point being, building a low-speed maximal torque engine (peak acceleration at lower engine speeds) does not create maximal acceleration, building a maximal torque engine at higher engine speed does (peak acceleration at higher engine speeds).

Rear and transmission gear ratios (torque multiplication) will compensate for any losses of acceleration, at the impact of reduced top speed.

Average acceleration through 1/4 mile *number is average representation of acceleration due to torque multiplication*
6.2HC with 727 w/ 4.10: 26*
6.2HC with 8HP90 w/ 2.62: 26.4*

That is how important torque multiplication and gearing are, identical acceleration through quarter yet one car can run 200 MPH and the other around 125 MPH at their mechanical limit. So it is safe to say, most people would choose the 4.10 geared 3-speed to accelerate faster than the 2.62 geared 8-speed in identical vehicles, torque multiplication says it doesn't. Once again, it all comes back to the combo! If a big engine has an identical torque peak as a small engine, in most cases, it will make dramatically more HP (acceleration) through that given range. In your case Mike, a 470ci engine would need to spin to 6,800-7,000 RPM to make similar power with identical components (everything being proportionally equal).
 
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68 HEMI GTS

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Ok I see what your getting at. I didn't realize we were capped with stock 906's and a baby camshaft. But if your theory was accurate my 511 wouldn't breath through the stock port window. While I agree a m/w port would make more power and turn a bit more rpm it doesn't appear to be wheezing through the standard port window and the dual plane six pack. It still makes plenty of power over 6g. Granted I'm using a bigger camshaft than your given example, but it's not huge by any means.
 

Sweet5ltr

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Ok I see what your getting at. I didn't realize we were capped with stock 906's and a baby camshaft. But if your theory was accurate my 511 wouldn't breath through the stock port window. While I agree a m/w port would make more power and turn a bit more rpm it doesn't appear to be wheezing through the standard port window and the dual plane six pack. It still makes plenty of power over 6g. Granted I'm using a bigger camshaft than your given example, but it's not huge by any means.

It's funny you said your 446ci ran 11.5's and your current 511ci engine runs 10.9's. It's really proportional to my initial bench test theory, you probably make 50-70 ft/lbs more torque from peak-to-peak in comparison to your 446 (5000-6500 RPM) right?
 

dieseldazzle

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I understand what my man is trying to say but its just bench racing and I was just poking at him. 470s rule I'll stop my 512 build and do it all over lol
 

68 HEMI GTS

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It's funny you said your 446ci ran 11.5's and your current 511ci engine runs 10.9's. It's really proportional to my initial bench test theory, you probably make 50-70 ft/lbs more torque from peak-to-peak in comparison to your 446 (5000-6500 RPM) right?

What are you saying?? Lol. whats funny? It does exactly what I expected it to do, i didn't just guess at parts. I've been at this for a bit.. it's a big torque monster for the street. I built a combination for an intended application. According to what I'm getting out of your theory the motor should be all done by 5500 rpm with standard port window. Is that the case? Using the McFarland formula?
 
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Sweet5ltr

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What are you saying?? Lol. whats funny? It does exactly what I expected it to do, i didn't just guess at parts. I've been at this for a bit.. it's a big torque monster for the street. I built a combination for an intended application. According to what I'm getting out of your theory the motor should be all done by 5500 rpm with standard port window. Is that the case? Using the McFarland formula?

My post was not negative but to prove a rational point, we've all been doing this for awhile and it's interesting to see what we're gaining or losing by running a certain engine combination. There is no replacement for displacement other than an engine of slightly less displacement making slightly less torque at a higher RPM; all being equal. If torque wins races, diesels would be king, but we know that isn't the case as HP (acceleration) is only a figure based from the amount of torque applied over a period of time (which torque needs to be positioned to peak during the engines desired performance range).

You make 50-75 more ft/lbs at an identical operating range from increased displacement alone, that's why you ran 6/10's faster than your 446 (if everything was equal). Unless you could have spun your 446 to 7,000 it would have not matched your 511. My bench racing engines are purely static/representative and had nothing to do with anyone's combo, we could easily say both engines could run at a theoretically higher RPM, the limit and values were just for this bench racing purpose. In reality, there are far more factors involved and I only chose a smaller displacement (in my build) due to the increased compression height, decreased piston speed due to shorter stroke (theoretically allowing the engine to spin to higher RPM's), and improved rod-ratio. That's what I'm trying to get at, don't take it personal and only at face value. Every combo is unique, and there are multitudes of ways to obtain the desired end result.
 
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dieseldazzle

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My only concern here is you may sway folks to not build what they should build. Going with a 500 inch off the shelf cost effective kit in an RB block with pretty much any off the shelf quality head and a mild cam makes for an awesome power plant that you really can't go wrong with for a good strong street or even part time strip car. Choke it with manifolds and it still makes decent power very forgiving.

They see this post and they are on the quest for a 470 and only a 470 cuz that's what they read about.
 

Sweet5ltr

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My only concern here is you may sway folks to not build what they should build. Going with a 500 inch off the shelf cost effective kit in an RB block with pretty much any off the shelf quality head and a mild cam makes for an awesome power plant that you really can't go wrong with for a good strong street or even part time strip car. Choke it with manifolds and it still makes decent power very forgiving.

They see this post and they are on the quest for a 470 and only a 470 cuz that's what they read about.

I'm under the impression anyone building a stroker B/RB engine is building it after ample research for their desired result. In a low-deck, the 512ci (4.25" stroke/6.535" rod) has a less than optimal rod-ratio for sustained high RPM use/power, but is far better for low-speed mountain pulling torque (that's why it's often called a stump puller). The 500ci stroker is better with its 4.15" stroke/6.76" rod but it has a very short piston (excellent strip engine). The 470ci engine has a shorter stroke, 3.915" stroke/ 6.535" rod allows the use of a taller piston at 1.485" (increased piston stability). Rod ratio is improved over its bigger brothers, it's a better suited candidate for sustained high RPM. The 451 is the best candidate, with a 3.750" stroke / 6.76" rod length. This engine would be more suited for a 7,000-8,000 RPM full-out race build in a light a/e-body. Rod-ratio is a bit more important in big block, as well as stroke, due to the increased rotating mass. Most street engines are setup for low-rpm (sub-6,500). That is where it's better to have big cubes, which will make more power in this range. If bigger worked for every application, there would be no need to offer anything under 543/512, and not care about the details, but as we've said it's all in the combo. Every kit offers pros/cons. Take it all with a grain of salt.
 

not so famous bob

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I'm under the impression anyone building a stroker B/RB engine is building it after ample research for their desired result. In a low-deck, the 512ci (4.25" stroke/6.535" rod) has a less than optimal rod-ratio for sustained high RPM use/power, but is far better for low-speed mountain pulling torque (that's why it's often called a stump puller). The 500ci stroker is better with its 4.15" stroke/6.76" rod but it has a very short piston (excellent strip engine). The 470ci engine has a shorter stroke, 3.915" stroke/ 6.535" rod allows the use of a taller piston at 1.485" (increased piston stability). Rod ratio is improved over its bigger brothers, it's a better suited candidate for sustained high RPM. The 451 is the best candidate, with a 3.750" stroke / 6.76" rod length. This engine would be more suited for a 7,000-8,000 RPM full-out race build in a light a/e-body. Rod-ratio is a bit more important in big block, as well as stroke, due to the increased rotating mass. Most street engines are setup for low-rpm (sub-6,500). That is where it's better to have big cubes, which will make more power in this range. If bigger worked for every application, there would be no need to offer anything under 543/512, and not care about the details, but as we've said it's all in the combo. Every kit offers pros/cons. Take it all with a grain of salt.
I didn`t rea all this b.s., but 5500 rpm for a 440/500-512, and 6500 400/500 ?
 

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