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Forged, Stock, or Other...

  • 4.75lForgedAssembly,MMR

    Votes: 3 30.0%
  • 4.6lForgedAssembly from?

    Votes: 4 40.0%
  • HE Pistons/Mark Crank

    Votes: 1 10.0%
  • Do something else.

    Votes: 2 20.0%

  • Total voters
    10
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Super Moderator
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Discussion Starter #1 (Edited)
I've accumulated almost all the parts I need to finish my build.

I still need a Forged Crank, Pistons, rings, and bearings to round out the set. :)

I found a really nice Forged Rotating assembly at MMR that looks nice, but I'm not planning to run 7000 RPMs, Nitrous, or a blower, so hypereutectic pistons and my Mark crank is totally adequate.

So, my Solution: A Poll!

What should I buy?
 

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Premium Member
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1,268 Posts
Don't buy what you don't need with a fully forged rotating assembly.

All you need are some decent forged pistons (Probe or Mahle) and good rods. Manley H beam rods is what I would recommend. Rings and bearings would be needed regardless.

The stock crank will be plenty good for almost double the stock HP.

Even if your plans change, for just a few hundred more now you'll be good to go later.
 

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The Parts Guy
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7,268 Posts

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Super Moderator
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Discussion Starter #4
Why? It wants to rev to 7k. :grin2:
My biggest concern is the Torque Converter; no one wants to quote rpm numbers on their website... :grin2:

I'm hoping with the cobra cams and Mach 1 intake my peak hp rpms should be just below 6k; I should be happy with that, right? :)

I have some very nice Manley rods to use, that I bought here.



My 'other' brain wants FORGED PARTS!!! :rofl:
 

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The Parts Guy
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7,268 Posts
My biggest concern is the Torque Converter; no one wants to quote rpm numbers on their website... :grin2:

I'm hoping with the cobra cams and Mach 1 intake my peak hp rpms should be just below 6k; I should be happy with that, right? :)

I have some very nice Manley rods to use, that I bought here.
Cobra cams with a Mach 1 intake should make peak power slightly above 6k. You'll want to shift past the peak if you're hunting a decent E.T. Any good TC-builder can set you up with a TC capable of living at 7k+.

The 4V sounds real good at higher rpm.
 

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Super Moderator
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When my MarkVIII was naturally aspirated with the 5-speed and cobra intake, I would routinely rev it to 7K, and that was on a 150K+ mile bone stock long-block, so the cast crank is not necessarily a weak point. Now with the blower on it, I have the rev limiter set to 6500, and I am still running a bone stock long-block (although this one has only around 100K). With that being said, if you are building a 4.6, you should definitely upgrade the pistons and rods, which means you need to get the rotating assembly balanced, so really the only added expense is the cost of the crank itself. If you cheap out on the crank for the $500 or less that it would cost, and then down the road you decide that maybe you do want to throw some boost at it, you will be real pissed at yourself if you blow up the motor and take all those expensive parts with it.
 

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West Virginia Chapter Director /, MA Drag Race Te
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2,643 Posts
My biggest concern is the Torque Converter; no one wants to quote rpm numbers on their website... :grin2:

I'm hoping with the cobra cams and Mach 1 intake my peak hp rpms should be just below 6k; I should be happy with that, right? :)

I have some very nice Manley rods to use, that I bought here.



My 'other' brain wants FORGED PARTS!!! :rofl:
Most aftermarket Converters especially with Billet covers will easily take the 7K RPM. As others have said that set up should be no problem running to 7K RPM and peak HP should be somewhere around 6K +/- depending on set up NA. Most stock 99-01 Cobra's could do that.
 

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Super Moderator
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Discussion Starter #8
Thanks, Guys!

This is exactly the kind of advice I need. :)

I think I'll find a nice set of forged pistons, and bearings, and an oil pump, and...

This is my first mod build, so the fewer new parts to trash the better. :D


Will an 18" degree wheel fit in the car?
A better question: What size fits in the car, and is big enough to work well? I saw a pic of a 24" and know that won't fit except on a stand. :)



Next week, I'm going to look at two "93 Mark" engines in a warehouse; supposedly, one has an 8-bolt crank.

I'm hoping it has a funny-looking intake, too. :)
 

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The Parts Guy
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Why are you wanting to degree the cams with the engine in the car? Won't you have it on a stand for assembly?
 

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Discussion Starter #10
Why are you wanting to degree the cams with the engine in the car? Won't you have it on a stand for assembly?
I do; but at some point I'll want to set up a set in the car, most likely. I try to think ahead. :)

I have a small timing wheel, ~6", that I've used on bikes for years, but it's way too small for this. :)
 

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Discussion Starter #12
Aren't the rods the weak link on basically every N/A modular engine?
Only for boost or nitrous; I haven't seen a set broken without adders. :) You can break anything with enough "adder", lol.


The Coyote rods are even popular for those uses.

I have a nice set of manley rods to use.
 

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West Virginia Chapter Director /, MA Drag Race Te
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Put a set of forged manley pistons in it then and you'll have a good strong bottom shortblock.
 

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Premium Member
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With that being said, if you are building a 4.6, you should definitely upgrade the pistons and rods, which means you need to get the rotating assembly balanced, so really the only added expense is the cost of the crank itself. If you cheap out on the crank for the $500 or less that it would cost, and then down the road you decide that maybe you do want to throw some boost at it, you will be real pissed at yourself if you blow up the motor and take all those expensive parts with it.
I've seen stock cranks hold significant nitrous or boost.

I guess it really depends upon the goals of the build, but I wouldn't bet on a $500 crank holding much more than a stock cast unit. Most quality forged cranks are going for much more.
 

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Discussion Starter #16
I've seen stock cranks hold significant nitrous or boost.

I guess it really depends upon the goals of the build, but I wouldn't bet on a $500 crank holding much more than a stock cast unit. Most quality forged cranks are going for much more.
I haven't seen a quality crank for less than ~$1200, that I would actually buy.

I've seen more stories of forged cobra cranks breaking than anything else, pretty much. :)

MMR says that their forged stuff is better than others because it's American made, a claim I'd like to believe. :)

But, I've done an analysis, and ordered parts.

I'm going with a fresh set of Hypereutectic pistons, Speed Pro with a 3cc dish. Total seal rings to match.

I'm going with Clevite bearings, an FRPP oil pump, the Manley rods, and my Stock Mark crank.

The block, crank and pistons all measured as new; within original shipping specs. With stock size bearings, I should have real close to 0.001-0.0015" of clearance.

I still need to decide on a windage tray, head bolts, degree wheel, and some other small parts.

I'm going to put the crank and two rods and old pistons into the block, assemble the heads to the block with an old HG, and get the cams timed correctly, and get the adjustable gears on the cams correctly.
I can use the old bearings and lots of assembly lube while I'm getting everything assembled right and getting the cams right, then it's a straight up assembly problem from there.

I hate spinning new plain bearings against each other, with no oil pressure; I don't suppose someone makes welded needle bearing cranks for mod motors? :) That's how my GS750 hits 14k, lol.

I should be able to measure it fully assembled, verify it's correct, and put it in. :)


This is being a fun project; I've learned a Lot while doing it. :)

I've never done an engine where the 4th decimal was important; had I not used the good tools, all the measurements I took would have been the same. :)

The hard part of measuring something like that is it has to be done in one shot, at one temperature, which should be recorded. If you need to do a measurement at another temperature, you can redo your original measurements that relate, and compare the expansion/contraction to make a reasonable guess at how the new measurement fits in. :)

Or, much easier, do the new measurement at the same temp as the originals. :D

Going from ~55°F to 90° was almost 0.001" in the bore size, and over 0.0003" on the crank.
 

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I didn't realize forged 4.6 cranks were going for that much money, I just threw a number out there based on pricing them out for SBF's. I'm still running a completely stock long-block on my Mark, so I never priced it all out. Yeah, at another $1200, I would probably stick with the stock crank too. Like I said, it held up to repeated 7K rpm shifts in my car just fine, and is holding up to 10psi in the car now just fine as well.
 

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Discussion Starter #18
I can buy a newly rebuilt chevy long block locally for what I Spent at summit yesterday, lol.

Apparently only fanatics rebuild these engines, lol.

Thanks for the pieces you added to the pile, Mikey!

All the really nice parts come from here:

Manley Rods
DOHC C-heads
XR3E Cobra cams
Mach 1 intake
24lb dual pattern injectors
255lph walbro FP
Apten Mod
Good front crossover tube
COP or Coilpack Valvecovers
02 GT MAF and airbox
98 Mark inlet tube

:headbang: TCCoA Rocks! :headbang:
 

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Discussion Starter #19
Santa Claus somehow got my bank card, and all this killer stuff showed up for Christmas! :)

There's too many 8's or 16's or even 32's to do a 12 days of Christmas. Even in base 12, lol. Geeks...

I have 11 days off, and it's supposed to be 50ish.

Life is good!

Merry Christmas, Y'all!!​

:grin2:
 
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