The key is when he says, comparable performance. That cam in a 427 would be fairly rowdy. In a 482 it would be an RV cam.

Well then you might just ease that stroke back to 4.125".:3DSMILE: That's what I did and, remember, there are some really smart engine builders on this forum that swear shortening the stroke makes an FE "revvier." Brent ain't one of them, but they're out there....:cool:

I don't know of anyone that would pass a 4.250" to go for a 4.125" unless they were out of 4.250" cranks and Scat was backordered. Then they try to pass it off to the mass as a positive by saying, "Oh your engine will rev faster...."

Nonsense.

That connecting rod de-burred original crank has a crack.

No way.......

Now you have the perfect reason to go a big forged NEW rotating assembly!!

Jason

I can't understand the desire to spend $1100 on a forged crank for a 500-550 hp engine????

Got plenty of 700 hp/7000 rpm FEs out there with cast Scat cranks.

Doug just needs to get it fixed. That car has spent way too much time up on jack stands. Dang, I think it spent close to a year up on the lift of one of our local club members... maybe longer.:LOL:

I have a lift in my garage now so I don't need to abuse one of the lifts of our club member. I do have his engine crane and cradle though ;)

You guys have to remember Doug will be reusing his stock iron medium risers heads. I'm not an engine builder, but with 482 cubic inches and a bigger cam, those heads will be a huge constriction in this puzzle. :confused:

Typing this out on my phone since CC won't open for me on any PC or any browser....so bear with me.

It's not necesarily a "bigger" cam; think of it as proportionately bigger.

Those MR heads do quite well for what they are, prob on par with an out of the box Edelbrock head. A 482 with similar head flow will easily hit 500-525 hp with a ton of torque.

If you are getting the one line "Memory Allocation Error...." when you try and hit the forum, it can be tricky to fix. I'll skip the explanations as to why it occurs and just give you the steps that usually work:

1) Using the browser that can't get to Club Cobra, go directly to a post instead of the forums list, new post lists, etc. for example, go here: http://www.clubcobra.com/forums/all-...ml#post1428014

2) Assuming you got through to that page, immediately Log Out using the drop down menu at the top of the page.

3) Using your browser's drop down menus, clean both your cache and your cookies. Make sure you don't have "preserve for favorites" checked while doing that as it will prevent cleaning the Club Cobra cache and cookie stuff.

4) After doing that, go to www.clubcobra.com and you should be able to get through. Try logging in now. If you see an unusual alert from, say, FireFox that tells you that there is an error in the redirection, and that it "will never complete," then you must repeat this process. It will generally work on the second time if it didn't work on the first.

Anyway, that's how you fix it. And yes, it's a forum software issue.

I'm just asking, but even though the cam is proportionately bigger for the 482, isn't the whole enchilada about air and gas flow. I'd think those stock heads would be limiting with Doug's new stroker package.

It is. Obviously, a bigger/better head would make more horsepower, but the MR head isn't really an extreme bottleneck.....no more so than an Edelbrock head with no work done to it.

My bad, I was thinking 460 power, not FE power.
A cast crank will be plenty........
However....
Given the total cost of a rebuild, the personal labor and effort involved. the loss of use of the car for what may be an entire driving season depending on where you live. The added cost vs. the piece of mind the forging brings..
Because of my business I come with a different perspective. I see daily that Castings do not compete with Forgings.......ever.
For me, A few extra hundred dollar bills is money well spent if the car is driven like the race car it is.


Jason

Duplicate post
My bad...

the forged crank is a heavy mass not necessary for a street engine.
the cast crank is a better choice all around for the street,
i see all to many people thinking they are building a motor to compete at lemans.

I suspect most people think cast iron, when they hear cast. I do believe Scat cranks are cast steel, which is quite a bit stronger than cast iron and less brittle.

That said they are a step up from cast iron and the OEMs made some pretty big power with cast iron cranks.

Sure forged is better yet, but it does nothing for you to have more strength than you need.

As for stroking an engine and not changing the cam, heads, bore, or compression, at least theoretically (well there were university studies on flat head engines, so it is pretty true), the engine will have the exact same Hp, but at less rpm and more torque. To make the math simple let's use a 3" stroke verses a 4" stroke.

Here is the rpm, torque, and Hp chart for a 3" stroke.
RPM Torque Hp
2000 - 100 - 38
3000 - 150 - 86
4000 - 150 - 114
5000 - 125 - 119
6000 - 100 - 114

Here is the rpm, torque, and Hp chart for a 4"stroke in the otherwise same engine.
RPM Torque Hp
1500 - 133 - 38
2250 - 200 - 86
3000 - 200 - 114
3750 - 167 - 119
4500 - 133 - 114

The reason or theory is that the maximum air flow into the engine is limited by heads, valves and the rest of the induction side, as well as the exhaust side. So at any given CFM the Hp will be exactly the same. With a longer stroke that given CFM will occur at a RPM that corresponds to the ratio of the stroke change. Thus the torque will increase by the inverse ratio of the stroke change.

I pulled those numbers out of my ass, but chose them to make the math easy to follow.

3/4 of 2000 rpm is 1500 rpm - the same cfm of air is flowing thus the Hp is constant.
4/3 or 100 ft-lb of torque is 133.
38 Hp = 2000 * 100 / 5252
and
38 Hp = 1500 * 133 / 5252

So the engine will make more torque at lower rpm. However if you improve the air flow into the engine you can have your cake and eat it too. You will have more torque, more cfm, and thus more Hp.

I sort of feel the same way (even if it's not justified).

A steel crank is truly a waste of money in anything under 700 hp on an FE. But we make more money on steel cranks, so I'm sure your builder will be happy to sell you one though. :D

A new cast crank is $625. Steel is $1199. Big difference for no benefit.

Olddog,
"Cast crankshafts" are typically made of cast, Ductile (Nodular) iron with a Carbon content of 3.0-4.0%. (“ Cast Steel” by comparison is typically .1-.6%) These materials are characterized by a spheroidal graphite morphology as can be seen in the photomicrograph below

http://www.clubcobra.com/photopost/d...00X_ETCHED.jpg.
It is the sphereoidal shaped particles that mitigates stress concentrations and allows for the higher strength and fatigue resistance, allowing its use in this application.

Brent,
Why is the margin higher on the forging? I would think the markup would be the same
There is no question that a properly prepared cast crank is capable of supporting the majority of builds. They just lack the fatigue strength and resistance to crack propagation that is found in a forging. I always think about what happened to Eljaro back in 2011
http://www.clubcobra.com/forums/fe-t...nk-broken.html
That was enough for me. $500 isn’t going to break me on a $15-$20k motor. I’ll buy rotating parts at the top of my budget, not the bottom…..
Here is an excellent study that was done in 2007
http://www.autosteel.org/~/media/Fil...ve_summary.pdf

Pretty easy answers.

Eagle is junk. Period. You can't compare castings between two different manufacturers and call them equal just because they're both castings. I wouldn't use an Eagle product in my lawnmower. There are more than several threads about Eagle FE cranks failing. The ones that you find on Scat are very few and far between, and even then, I personally haven't seen one that wasn't caused by lack of oil.

You will not find an Eagle part of any kind in my shop.

Why is the margin higher? It's not. The profit margin is the same, but the profit is higher because it's a more expensive part.