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Re: SCAT superlight crank
[Re: AndyF]
#2578567
11/14/18 11:05 PM
11/14/18 11:05 PM
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Joined: Jan 2003
Posts: 7,477
Minnesota
Hemi_Joel
master
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master
Joined: Jan 2003
Posts: 7,477
Minnesota
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That's light. Does it have a horsepower limit?
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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Re: SCAT superlight crank
[Re: AndyF]
#2578655
11/15/18 08:59 AM
11/15/18 08:59 AM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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I see they're still not sure whether American V8 engines turn CW or CCW...
Boffin Emeritus
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Re: SCAT superlight crank
[Re: AndyF]
#2578675
11/15/18 11:49 AM
11/15/18 11:49 AM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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Catering to the boat market. :-)
Getting old just means you were smarter than some and luckier than others.
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Re: SCAT superlight crank
[Re: AndyF]
#2578680
11/15/18 12:07 PM
11/15/18 12:07 PM
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Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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Got a new big block superlight crank from SCAT. This one is 4.250 stroke with the 8 bolt flange. The crank weighs 64 lbs which is 7 or 8 lbs lighter than the standard weight crank. It looks nice. I'm going to pair it up with some Molnar 7.100 connecting rods. Andy would you be willing to give up the weight savings and have center counter weights?
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: SCAT superlight crank
[Re: AndyF]
#2578699
11/15/18 01:04 PM
11/15/18 01:04 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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AndyF,
I went with the 440Source ultra light crank and their 7.1 rods. My Ross pistons came in around 524G's. I was hoping the light weight would be easier on the stock block. So far, I am unable to detect any signs of walking. Which main caps are you going to use?
Do you think the lighter reciprocating weight reduces the stock blocks susceptibility to cap walk?
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: SCAT superlight crank
[Re: AndyF]
#2578700
11/15/18 01:04 PM
11/15/18 01:04 PM
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Joined: Feb 2003
Posts: 6,849
fullmetaljacket
master
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master
Joined: Feb 2003
Posts: 6,849
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Re: SCAT superlight crank
[Re: AndyF]
#2578790
11/15/18 03:57 PM
11/15/18 03:57 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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Do you think the lighter reciprocating weight reduces the stock blocks susceptibility to cap walk?
I'm pretty sure it's "yes", but is it significant? IDK.
What I don't understand: we KNOW the crank manufacturers understand windage, pumping loss, and aero shapes at that speed in f/s. If they don't, the volume of information available is huge.
Assume they don't want to change the shape of their basic product on the shelf.
Why not offer directional profiling as a post-manufacture operation with a high markup? Even 2 hours of shop time with a grinding wheel (not a head porter or master machinist, just an adult) contoured to do only the nose is an improvement. Position it, feed in until the improved shape appears, back up, dil over to the next.
Remember, the bow wave and trailing wake are resistance (uses power to heat up the oil and crankcase vapor) regardless of power output - it's there with the spark off.
Boffin Emeritus
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Re: SCAT superlight crank
[Re: polyspheric]
#2578799
11/15/18 04:00 PM
11/15/18 04:00 PM
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Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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Do you think the lighter reciprocating weight reduces the stock blocks susceptibility to cap walk?
I'm pretty sure it's "yes", but is it significant? IDK.
What I don't understand: we KNOW the crank manufacturers understand windage, pumping loss, and aero shapes at that speed in f/s. If they don't, the volume of information available is huge.
Assume they don't want to change the shape of their basic product on the shelf.
Why not offer directional profiling as a post-manufacture operation with a high markup? Even 2 hours of shop time with a grinding wheel (not a head porter or master machinist, just an adult) contoured to do only the nose is an improvement. Position it, feed in until the improved shape appears, back up, dil over to the next.
Remember, the bow wave and trailing wake are resistance (uses power to heat up the oil and crankcase vapor) regardless of power output - it's there with the spark off. The question is how many people will pay for that extra work for what's on the shelf? I agree at some point you'd think these guys would change the shape to a better form. But if what you have is selling, and 99.99999% of the buyers don't say a word, is it worth it?
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: SCAT superlight crank
[Re: als499]
#2578838
11/15/18 05:43 PM
11/15/18 05:43 PM
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Joined: Jan 2003
Posts: 30,992
Oregon
AndyF
OP
I Win
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OP
I Win
Joined: Jan 2003
Posts: 30,992
Oregon
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Looks good! Is it for a B or RB , is there a part # available for it ? Thanks The one in the picture is for an RB engine. Summit carries these or you can order them direct from SCAT. Here is a link to Summit: https://www.summitracing.com/parts/sca-4426015-3/overview/model/3They also have low deck cranks. I have a fully machined superlight 3.90 stroke crank in my 470 engine.
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Re: SCAT superlight crank
[Re: AndyF]
#2578845
11/15/18 05:57 PM
11/15/18 05:57 PM
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Joined: Jan 2003
Posts: 30,992
Oregon
AndyF
OP
I Win
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OP
I Win
Joined: Jan 2003
Posts: 30,992
Oregon
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Here is a couple shots of the SCAT superlight in my low deck 470 engine. The 470 crank was the first Mopar superlight and they fully machined it including gun drilling and profiling the rear flange. It looks like when they put the superlight into production they deleted some of those features. I worked with SCAT back in 2015 to develop the first Mopar superlight. Or maybe it was the first low deck superlight, I don't really know for sure. The engineer I worked with had some dimensions but not others so I had to round up some info for him.
Last edited by AndyF; 11/15/18 05:58 PM.
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Re: SCAT superlight crank
[Re: AndyF]
#2578847
11/15/18 05:59 PM
11/15/18 05:59 PM
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Joined: Jan 2003
Posts: 17,840
S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,840
S.E. Michigan
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Real nice looking crankshaft. The rods as well.
The picture seems dark compared to the work we've come to expect over the years. I have to wonder if the lighting wasn't adjusted from the usual, or maybe if something isn't sprayed on the journals to cut down on glare.
Rich H.
Esse Quam Videri
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Re: SCAT superlight crank
[Re: AndyF]
#2578848
11/15/18 05:59 PM
11/15/18 05:59 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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My point is that soliciting this as a feature DOES NOT EXIST. No one asks if you want it, or even mention that it exists. The effect is "our product is as good as can be made", when that's certainly not true. A question never asked has no answer. I used to offer it an a feature on the Harley-Davidson cranks I sell*, but (since it's not done by the manufacturer, but contracted out) it became $$$ long ago. I still encourage this work and give advice on where/what in the engine booklets I write**. * http://www.victorylibrary.com/stroker-flywheels.htm** http://www.victorylibrary.com/books1.htm
Boffin Emeritus
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Re: SCAT superlight crank
[Re: AndyF]
#2578853
11/15/18 06:05 PM
11/15/18 06:05 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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PS: really light weight crank also has the effect of raising its natural frequency (in Hz), and pushing every destructive harmonic order higher in the RPM range.
This is probably within the capacity of any good S.F.I. 18.1 damper, but it can be both good and bad.
Good: the harmonic order you now have at the top of your scale may no longer affect you.
Bad: you may inherit one from below your normal power range.
Boffin Emeritus
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Re: SCAT superlight crank
[Re: AndyF]
#2578957
11/15/18 10:55 PM
11/15/18 10:55 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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Back in the day, a crank's original forging (hot from the die) was flat, with the four throws opposed 180° apart. The two 3-dimensional 90° throws are obtained by twisting the crank: pulling one throw up and one throw down. The process was called "struck and twisted".
4340 is (IIRC) the frequent material of choice for cranks and other forgings that have large cross-sectional changes.
Boffin Emeritus
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