NEW 4" CRANKS $250.00 any good?

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Bill Dedman

Bill Dedman

bill dedman
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Just got my new Mancini "flyer" in the mail and they're having a sale on stroker cranks for 360 motors; a 4" Eagle cast crank for $239.00. (bottom of page 4; column 2)

There's also an M-P (360 mains) 4" crank for $249.95 at the top of column 4, on page 2.

That seems awfully cheap to me, but I wouldn't want to pass either of them up if they're a worthwhile purchase, quality-wise. I can always use 40+ more cubic inches....

Anybody have any idea of these things are any good? I have no experience with strokers, so I'm just curious, here...

Any info will be appreciated! I don't want to buy a "pig-in-a-poke" (whatever that means.) :happy10:
 
Thanks for that advice on the 500hp limit. I'm already making close to that (maybe more at the flywheel) but I'm not turning the engine over 6,000 and only running 10 pounds of boost, doing it, so I MAY not hurt anything.

I am willing to take that chance.... LOL!:cheers:
 
typical ast 4" cranks surpass 500hp. I know of two that make 560+, one runs 150hp NOS on top of that with no issues (2nd season w/it). The Eagles are decent parts. I had two when they first came out. Used one, sold the other when my plans changed. The one I unboxed was pretty good for a cheap crank. I would buy one if I needed one with no hesitation
 
Thanks, Moper; I think you have a lot of experience with this stuff and I trust your judgment.

I may order one next week, early. Then, I'll need pistons and rods. I'll have to have forged pistons custom-made, reverse-deflector, because of the boost I run. I need some standard-bore, 8:1 compression JE, Diamond, Arias, or ForgedTrue, I guess. Cast won't get it... Rods; I have NO IDEA...

Any suggestions?

Thanks for any ideas/information.

Bill
 
I have the mopar 4" in my 416 no issues with it,my stroker made 520+ h.p...thats a good price my crank was $400.00 when i bought it..
 
Bill Dedman said:
Thanks, Moper; I think you have a lot of experience with this stuff and I trust your judgment.

I may order one next week, early. Then, I'll need pistons and rods. I'll have to have forged pistons custom-made, reverse-deflector, because of the boost I run. I need some standard-bore, 8:1 compression JE, Diamond, Arias, or ForgedTrue, I guess. Cast won't get it... Rods; I have NO IDEA...

Any suggestions?

Thanks for any ideas/information.

Bill
Click to expand...

Mancini has the Eagle H beams on sale too!
 
This is just me guessing, but i think sales are down on all kinds of stuff, and the pricies are beginning to be cut to get some cash moving. The Eagles when I got them were $289 each thru a warehouse distributor.
 
rods ...scat I beam 4340...light weight...595 grams...

no clearancing needed on the bottom of the bores....

cheaper then the H rods....ebay about 280 a set...
 
Lots of good info there.

Now, if I can find a job to make the money for this stuff, my 11 second car might turn into a 10 second one... but, it won't be next week.... or even next month.

Nothing happens very quickly after you pass 70... LOL!

Guess I'm lucky not to be just holding down a rocking chair, somewhere! :cheers:

Bill, in Conway, Arkansas
 
The good thing about those 4" cranks is the engine makes the HP at 5500 to 6000 rpm so you don't have to rev super high. That should help the cast ones live. My 408 made peak HP at 5900 and held almost level to 6100 until it started to slope down. I've got the mopar cast 4" and it looked great. I don't have many miles on it though.
 
Good point about the self-imposed rev limit on these 4" cranks.

When I assembled my engine originally, I had no idea that it would ever have a supercharger fitted to it, so I went with what was cheap; hypereutectic pistons and stock-type, composition head gaskets.

Then, when I decided to add forced induction to this weak short block, I decided that if this time bomb were going to live very long at all, I was going to have to attempt to ensure its longivity by adhering to a few hard and fast rules, such as,

1. Paying a LOT of attention to the amount of spark lead employed (less is more!)

2. Cooling the charge with an alcohol/water injection system.

3. Running a minimum of 93 octane, and better, if I could find it.

4. Keeping the rpm's below 6,000.

So far (and, I don't have much experience with this combination, yet,) the MSD "BoostMaster" boost-oriented spark retard and the Snow Performance "BoostCooler" methanol/water injector, along with my assiduous efforts not to exceed 6,000 rpm have paid off in a reciprocating assembly that still reciprocates and head gaskets that apparently, still seal. This is after eight full throttle passes down a 1,000-foot drag strip which netted me some timeslips that indicared that the blower and headers together, had increased my horsepower appriximately 45 percent. Picked up a little over 13mph in 1,000 feet and reduced the e.t. from 11.00 to 9.74, with poor 60-foot times.

I have been reasonably happy living with a 6 grand redline, and I think that a 4" stroke motor won't be pushing me to increase that limit. But, oh the torque.... :cheers:
 
Well,piston speed for a 4" stroke at 5500 rpm is 3666. Well within limits for stock pistons actually. As for imposing rpm limits on a cast crank..I'd rather impose one based on rods and rod angle/piston material. Cast cranks have the ability to absorb tosional vibration better than forged. But they flex more...
 
>>>"Well, piston speed for a 4" stroke at 5,500 rpm is 3,666. Well within limits for stock pistons actually."

Stupid question here, but is the "longevity projection" at that 3,666 figure affected by factors having to do with loading; i.e. boost?

I will be running as much as 15 (maybe more) pounds of boost, and wondered if the dynamics of forced induction might play a part in the factors determining what is safe bet for cast pistons, disregarding totally, the possibility of detonation.

I get the feeling that while stock-type pistons might, indeed, live at 3,666 fpm in a normally-aspirated engine, a supercharged example might not be so lucky.

What do you think? Is it a factor (boost)???
 
For a 4" stroke engine you really need to go with a forged piston because of the excessive piston speeds. Now if your building a low RPM stroker for a towing vehicle then cast would work. Remember, you will be over reving the engine by accident occasionally in a performance application.
 
I kind of agree, but definitely with the boost I'l be runnning, a cast piston probably wouldn't be a good idea.

Anybody got any old 360 stock (4") bore TRW "Powerforged" pistons lying around gathering dust, used, or not? TRW stopped making them years ago...
 
'64 Cuda said:
For the small price difference, is the Mopar crank better than the Eagle crank? Any reason to choose one over the other?
Click to expand...

Mopar cranks were made by Scat. They used to have an exclusive marketing deal with Scat. I don't know if scat is still the supplier to mopar
 
IMO, all the cast ones are about the same quality. I've used Scat too, and they are on par, mopars as said, are Scats. Eagles are the latest intorduction to market, so that may be why they are cheaper than SCAT. Nothing by MP is cheap anymore. On average they mark up the lowest bidder by 100% on everything.
 
I was looking at the web sale { I'm not on their mailing list } and there was a footnote about the sale cranks being irregular in journal size , it says that they will have at least one main or rod journal that has been over ground which I take to mean you will need to figure out which one and by how much then have the rest ground to match so as not to have a hodge podge of bearings -am I wrong ?
 
That "irregular journal" information is not in their mailer that I got. I'll give them a call tomorrow (when they're open) and find out what the deal is on that issue.

Thanks for the heads-up!!!
 
It's possible. Some venders will sell units that have ben repaired. They won't repair all of them if it's a rod, just the one that's bad. So you'd need to buy 6 rods std, and 2 oversize. If it was mains, they turn all 5.
 
Stroker update:

My 4" crank was shipped today from Summit (Eagle--$239.00) I called them and asked about the journal size, and the tech I talked to said that it was "standard" throughout.... no undersized journals. I'll "mic" it when it gets here later in the week, and let you know if it's "as advertised." :)

Bill
 
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