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Scat 9000 crankshaft vs forged

 
Old 06-08-2019, 04:12 PM
  #21  
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Originally Posted by jackson View Post
OP
pin OD ~ 0.927" ---------------------------------------- 1/2 that ~ 0.464"
rod journal OD ~ 2.100" ------------------------------ 1/2 that ~ 1.050"

0.464 + 1.050 = 1.514"

6.0" - 1.514" = 4.486" between bottom of pin and top of rod shell = 6" rod
5.7" - 1.514" = 4.186" between bottom of pin and top of rod shell = 5.7" rod

saw a pic with pistons on rods with shells in bore.
reach in there with a steel rule or caliper & measure from top of shell to bottom of pin. My bet's on 6.

it'd also pay to get a cheap, small graduated cylinder and cc piston top; also measure compression height.

Seems Eagle did make a cast 3.75 internal balance crank for 5.7 rod; I recall it was for 350 mains & it cost more than their typical external.

Got into shop and did the measurements as you indicated.
Yes they are 5.7" rods.
The crank does have 400 mains. The guy at Eagle was able to confirm that this and that it is an internal balance. Make for a nice setup.
Thanks Jackson...
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Old 06-08-2019, 05:46 PM
  #22  
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I have a Scat 9000 in mine (with Scat 6" rods and probe flat tops). Has held together fine for ~50,000 street and track miles so far, and I use it hard...

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Old 06-08-2019, 11:11 PM
  #23  
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Originally Posted by Metalhead140 View Post
I have a Scat 9000 in mine (with Scat 6" rods and probe flat tops). Has held together fine for ~50,000 street and track miles so far, and I use it hard...

Thanks for realtime info.
Now you have me rethinking my forged crank plan.......

When I get to this stage, I always compare it to the Chinese restaurant menu...too many choices.
Which means ...back up and think some more.
And avoid impulse buying.

Thanks again

Nice video.....

Last edited by bmans vette; 06-08-2019 at 11:41 PM.
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Old 06-09-2019, 12:40 AM
  #24  
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Mine was secondhand when it went in too, was previously fitted to a drag race bracket car, was then rev limited to 6600 though. Cleaned up with no more than a polish and I put it in my engine. If I'd been buying then I probably would have bought forged, but I had it there and my research said that it should hold up, so I figured what the hell... So far it's been good! I have my rev limiter set at 7200rpm.
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Old 06-09-2019, 12:03 PM
  #25  
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OK...now I am thinking that if I am going to replace the crank and pistons anyway, why not go 421 with this one?
Quick compute means I will need a dished piston with 16cc in the dish to get 10.71 CR.
Perhaps 18cc & drop the CR a little less....10.5?

IF I do this, I'll go with a forged crank.

Thoughts???

Found a great deal online and waiting for an answer.

Last edited by bmans vette; 06-09-2019 at 12:04 PM.
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Old 06-09-2019, 10:30 PM
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To me the additional cost for the forged crank was just part of the cost of building a good foundation for the bottom end.
The plus side is if I ever need a little more hp, I know the bottom end is ready
and will take whatever I want to throw at it.
One more small detail is your oil pan.
What ever you do check that the crank and rods clearance the oil pan and wind age tray.

Last edited by OldCarBum; 06-09-2019 at 10:40 PM.
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Old 06-09-2019, 11:16 PM
  #27  
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Originally Posted by OldCarBum View Post
To me the additional cost for the forged crank was just part of the cost of building a good foundation for the bottom end.
The plus side is if I ever need a little more hp, I know the bottom end is ready
and will take whatever I want to throw at it.
One more small detail is your oil pan.
What ever you do check that the crank and rods clearance the oil pan and wind age tray.

Thanks.
I keep leaning towards forged just like you say.
The oil pan is driver's side and I have several from 383 stroker projects.
Extra capacity Milodon and Moroso.
In order to add a windage tray I'll have to change the studs to the ones with extra length and nuts.
Or find a pan with a built in tray but enough clearance for the crank stroke.

Thanks for your input....
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Old 06-10-2019, 09:14 AM
  #28  
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Originally Posted by bmans vette View Post
Update on my strategy....

I am using paypal 0% financing (my balance is zero right now) to buy any part over $600...it gives me 24 months to complete the project and sell it while making small payments
So....the Scat forged crank might just be the best way to go.
part # 4-400-3750-6000 400 mains, 2pc rms, 3.75 stroke, 6.0" rods, forged, internal balance.

Local shop will do balancing as opposed to buying a balanced assy from someone in CA or TN and not having any protection if not done well.

I already have a good new set of 6.0" H forged rods, clearanced for stroker and using ARP 8740 cap screws.

Best laid plans of mice and men......

Once the shop tells me the actual bore I will be using 4.155 or 4.165, I can do my hunt for the pistons....
Are your heads 76cc? my 406 with 14cc dish, 63cc heads, .041 gaskets and .005 piston in the cyl. is 10.5, I know it has a Scat crank, I think its the 9000, and forged probe pistons also.
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Old 06-10-2019, 09:47 AM
  #29  
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Originally Posted by OldCarBum View Post
To me the additional cost for the forged crank was just part of the cost of building a good foundation for the bottom end.
The plus side is if I ever need a little more hp, I know the bottom end is ready
and will take whatever I want to throw at it.
Some of the LS guys made fun of me 10 years ago because I went all forged internals on my LQ9 pushing 500 to the wheels, stating stock short blocks were doing that. 10 years later I'm still smiling with the same forged shortblock and well over 100 passes at 7,000+ rpm. I doubt a stock shortblock would have even lasted a year.
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Old 06-10-2019, 10:13 AM
  #30  
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Originally Posted by Kacyc3 View Post
Are your heads 76cc? my 406 with 14cc dish, 63cc heads, .041 gaskets and .005 piston in the cyl. is 10.5, I know it has a Scat crank, I think its the 9000, and forged probe pistons also.
My heads are Dart 200 with 64cc combustion chamber. Basically the same as yours. I used the compression computer on Summits site. But I used .035 gasket for computations for .040 quench .
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Old 06-10-2019, 12:48 PM
  #31  
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Why are you changing the bottom end for a car you're just going to sell? You have posted the crank is fine and the rods have been ground for clearance or balance but are otherwise fine.

Put new pistons in it if the bore wear dictates it needs it and then get it back together so you can get the car sold. I doubt you will fully re-coupe the cost of any better parts. No-one trusts what's inside a "built" engine.
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Old 06-10-2019, 03:56 PM
  #32  
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^as above. If this is not a keeper, I would not be getting completely invested in it. Built it with what you have so that it is reliable and get it gone.
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Old 06-10-2019, 04:01 PM
  #33  
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Originally Posted by lionelhutz View Post
Why are you changing the bottom end for a car you're just going to sell? You have posted the crank is fine and the rods have been ground for clearance or balance but are otherwise fine.

Put new pistons in it if the bore wear dictates it needs it and then get it back together so you can get the car sold. I doubt you will fully re-coupe the cost of any better parts. No-one trusts what's inside a "built" engine.
I understand your take here but the reason I am doing this is that this is complete frame off resto-mod project in the process for years.
If this was just a restoration, then I would do what you are saying.
But I am building an entire car with much stronger features than what was stock then.
The drive train will include a heavy duty refurbished 4.11 rear, a T56 trans with strengthened internals. And the suspension will be all coil-overs, offset Van Steel trailing arms, etc.
So just throwing back in a 406 built with a cast crank and lower grade rods (albeit forged pistons) just does not come up to the same level as everything else.
I understand what you say about a "built" engine acceptability
I will document everything with bills, pics, machine shop work and dyno results.

But thanks for your input.
I do appreciate it.
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Old 06-10-2019, 08:24 PM
  #34  
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Honestly, that's my take on it too. A solid well built ~406 will provide more performance than most purchasers will be able to handle, and certainly enough to scare them. If I were building it to keep for myself then the extra cubes, if not too expensive, are a no brainer, but for something you'll sell the 400 cuber will more than do the job, cost you less, and offer less potential problems. I doubt you'll get return on the investment to build it bigger - and if you build it bigger then more people will be questioning the use of a stock gm block...
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Old 06-11-2019, 12:03 AM
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Originally Posted by Metalhead140 View Post
Honestly, that's my take on it too. A solid well built ~406 will provide more performance than most purchasers will be able to handle, and certainly enough to scare them. If I were building it to keep for myself then the extra cubes, if not too expensive, are a no brainer, but for something you'll sell the 400 cuber will more than do the job, cost you less, and offer less potential problems. I doubt you'll get return on the investment to build it bigger - and if you build it bigger then more people will be questioning the use of a stock gm block...
And I appreciate your take on this also especially after watching your video.

IF....I had an existing 406 with a Scat crank and some Scat forged rods and the forged Probe pistons, this would be a no brainer. Freshen it up, blueprint it, even if it still needs a cam, etc
My problem continues to be that this is an Eagle cast crank which by reputation is just not as strong as the Scat 9000. The rods are also Eagle but are forged but only 5.7". 6.0" just a little better for the torque and strain on the engine.....right?. And the pistons may not fit if the wear is too much and I have to go up in size.

So....if I have to spend money to buy new parts, then why not go full forged?
I still have the cost of the machine shop work no matter what.

Fortunately the Scat forged crank I bought will sell for more than what I paid for it and it is free shipping. I had to ****** it up or lose out on the deal.

So I still have time to shift gears ....again....lol
Let's see what the shop says after they get the block.

Thanks again for everyone's input.
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Old 06-11-2019, 12:04 AM
  #36  
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Originally Posted by PainfullySlow View Post
^as above. If this is not a keeper, I would not be getting completely invested in it. Built it with what you have so that it is reliable and get it gone.
Thanks Michael...
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Old 06-11-2019, 12:48 PM
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There is a perception that Eagle cast cranks are weak, possibly deservedly so. However, the time on the engine has proved the crank doesn't have any manufacturing defects so it'll likely stand up.

I'd rather see you save the no-limit budget spending for your car, not for one you are selling. Every dollar saved in the right spot on that car is another dollar that can go towards your car. How nicely put together it looks and how well it runs and drives will go further towards making more money on the car than a receipt for a crank.

I hate to say it, but I do hope you make money. Buying a built project car is normally considered the cheaper way to get into a similar car yourself vs building it from scratch yourself.


Last edited by lionelhutz; 06-11-2019 at 12:53 PM.
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Old 06-11-2019, 02:18 PM
  #38  
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Originally Posted by lionelhutz View Post
There is a perception that Eagle cast cranks are weak, possibly deservedly so. However, the time on the engine has proved the crank doesn't have any manufacturing defects so it'll likely stand up.

I'd rather see you save the no-limit budget spending for your car, not for one you are selling. Every dollar saved in the right spot on that car is another dollar that can go towards your car. How nicely put together it looks and how well it runs and drives will go further towards making more money on the car than a receipt for a crank.

I hate to say it, but I do hope you make money. Buying a built project car is normally considered the cheaper way to get into a similar car yourself vs building it from scratch yourself.
Good perspective.
Thanks.
Sometimes my ego gets in the way of a good decision.
Always been somewhat of a perfectionist, which means I have to tear things down to build them back up.
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Old 06-11-2019, 09:59 PM
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Production block and cast crank - Scat or Eagle - have just about the same limits. No reason to use a crank that'll handle 800hp when the block will begin to come from together at 600hp or so. Forged factory cranks are good for 4-bolt blocks with nodular caps, etc., but IMHO an aftermarket forged crank in a production block is throwing money away. Save that coin for the next build with an aftermarket block. Then lose your everlovin' mind and build a monster!
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Old 06-11-2019, 10:13 PM
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Originally Posted by L88Plus View Post
Production block and cast crank - Scat or Eagle - have just about the same limits. No reason to use a crank that'll handle 800hp when the block will begin to come from together at 600hp or so. Forged factory cranks are good for 4-bolt blocks with nodular caps, etc., but IMHO an aftermarket forged crank in a production block is throwing money away. Save that coin for the next build with an aftermarket block. Then lose your everlovin' mind and build a monster!

Another good take on this.

See highlighted part = I may have already.........
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