Eagle Cranks

[Nick Micale]

Originally posted by CTX-SLPR
Howdy,

Here is my deal, I'm building a dual purpose street strip motor that I'm hoping to make about 600hp+ off of, basically whatever I can get away with without turning the motor into an improvised explosive device. .......... Can I use a machined to neutral balance stock balancer hub and flexplate and if I had to get an aftermarket one of either, which should I get?

After a couple comments about machining a stock balancer to make it neutral balance, we did some checking. First, I have replaced a few stock balancers on street GN's that have cracked, worn the keyway and ruined cranks. For someone to machine lots of material from this cast piece and use it in a performance motor is asking for trouble.

The BMS piece is a hub, NOT a harmonic balancer. It will do nothing to dampen the crank harmonics and flex.

At this point, to answer part of your question, only BHJ make a performance Buick balancer with a trigger wheel.

Many broken and cracked stock flexplates that have been mentioned on this board can attest to the lack of strength it contains. To remove material or modify it will not help it live in a high performance application. We use JW flywheels in this application

At 600+ HP, you are at 3 time the level these stock parts were designed and built to withstand. When they let go, lots more $$$$ damage is done than doing it properly in the first place.

 

[750H.P.V6]

I agree with Nick completely.

There never seems to the time (or money) to do things right the first time but there is always time to do it over. Personally I've taken my lumps and paid the price. The Stage II price that is. If I was going to build a high H.P. stock block I'd be sure to not go cheap on parts. Since there is now a vaible replacement crank why not build your combo right form the begining.

Neal

 

[86brick]

Originally posted by V8Killer
FYI, I just checked on the summit website for the Eagle crank, part # ESP-423134005967................it came up as $699.00...........WTF
Is this price right???

The $531 price might have been an introductory price, but the best way to find out is to pick up the phone and call Eagle.....

$699 is still very cheap for a forged 4340 steel crank (I thought the crank was going to be in the $900 range when the discussions of this crank started).....

 

[tminer]

I've mic'd my crank. I barely know what I am doing and I used cheap Chinese mics.

The mics and my results are very repeatable. The mics have .0001 increments. I can kind of tell when it is right between 2 increments and call that .00005.

I made about 5-6 measurements around the middle of each journal. I did initially check across the journal length at 0 and 90 degrees relative to throw and saw no taper. I also did the runout on both sides of the oil hole and saw no difference.

Mains were all 2.4990" all the way around.

Rod journals:

1. 2.2479 - 2.2487 (.0008)
2. 2.2479 - 2.2481 (.0002)
3. 2.2484 - 2.2487 (.0003)
4. 2.2485 - 2.2487 (.0002)
5. 5 2.24815 - 2.2482 (.00005)
6. 2.2479 - 2.2482 (.0003)[/list=1]
   I measured runout with a dial indicator (CC degree kit) using my 109 block with old bearings in 1 & 4 saddles. Both 2 & 3 mains had about .001" indicated, maybe just a hair more, so runout is ~ .0005".
   
   I installed the old thrust bearing (1.055 long, using calipers) and attempted to check thrust. The amount of pressure that I applied made a big difference, but I settled on a fairly high amount without the crank lifting out of the saddle (I also was holding it down) and saw about .0135". I will say that the thrust surfaces are closer than the stock crank. Same for the rod journals. I do not have inside mics and the T-bars I bought at Harbour Freight are just junk, or I haven't figured out the touch.
   
   ...
   
   I just went and took the calipers to the thrust and a couple of rod journals. The rods were .850 and interestingly, the thrust was 1.0685 in the one place I could get to it (just barely) which coresponds exactly with my prior results (1.055 + .0135).
   
   Rod journal #1 seems to have a high spot right close to the oil hole chamfer. Almost like it distorted when it was chamfered, or is that done before hand? Can that be machined off if it is just a high spot?
   
   Tom

 

[tminer]

Originally posted by Nick Micale
The BMS piece is a hub, NOT a harmonic balancer. It will do nothing to dampen the crank harmonics and flex.

Isn't that true of the stock piece? It is weighted to externally balance the rotating assembly, but it does not have a dampener.

Not that one can't make a strong case for using a dampener, just that using the BMS hub with the internal balance is no worse than using the stock hub with a stock crank. Should be better off because there is less flex with internal balance. Is there less flex with a 4340 crank than a cast one?

Tom

 

[CTX-SLPR]

Is the GMPP stage II hub internally balanced and doesn't it have the crank trigger wheel like the stock hub? Also does ATI make a hub and balancer combo?

Thanks,

 

[Nick Micale]

Originally posted by tminer
........Not that one can't make a strong case for using a dampener, just that using the BMS hub with the internal balance is no worse than using the stock hub with a stock crank. Should be better off because there is less flex with internal balance. Is there less flex with a 4340 crank than a cast one?
Tom

Am glad and appreciate that everyone has kept this discussion "civil" as we are just sharing info and experiences!

On that note, I would like to say that the use of a forged crank would indicate high HP and high RPM - at least in most cases. It is VERY difficult to do any track time and not see how the rev limiter works more than once! Point here is we are discussing performance, not street driving. All the HP engines we do [and other builders I know] have internal balance cranks.

In that scenerio, I do not want to trust a cast iron balancer or damper. Since NHRA has deemed any 10.99 and faster car must have an SFI approved balancer, they must have found out other motors besides Chevys can over rev.

We are going to be balancing an Eagle crank in a couple days and have all 3 "balancers" to check out. There is probably more than one way to go with the balance situation, so we will try to find out more.

 

[Nick Micale]

Originally posted by ILBCNU6
............... The BHJ balancers are out of time 4* or more and have other problems too. You can still get the Buick MS ones and are a lot cheaper.

Gene, like to know what "other problems" you have found with the BHJ Buick balancer?

Out of a dozen or so we have done lately, only found one [used 2 years] that was 4 degrees off.

We just sent BHJ a new GM, stock balancer to verify their jig and the 4 balancers we just ordered. All interruptor rings were correctly positioned within a fraction of a degree.

 

[tminer]

Here is some info on dampners.

I think there is still some confusion on the nhra/sfi thing. Are they requiring a dampner, or are they requiring that if one has a dampner, it must be sfi approved?

Technically, niether the stock nor BMS hubs are dampners. SFI isn't an issue for me (no rollbar), but I am planning on spinning this sucker wicked fast.

Tom

 

[tminer]

I believe that the flexplate bolt pattern is not symetrical. It can only go on one way.

Tom

 

[REDS HOT AIR]

on another note

Its not a good Idea to put a cast balancer/hub on a steel crank

I havent exactly pin pointed why but I have had and seen alot of problems with cast balancer/hubs cracking or chatter on the snout of the crank and in turn it tears up the snout of your new crank

either way theres a rule in my engine builds ...if it has steel crank I will only install steel balancer/hub

 

[CTX-SLPR]

Howdy,

Does anyone know if the GMPP Stage II hub is internally balanced and has the correct trigger wheel on it? I seem to remember it saying it has some sort of trigger on it.

Thanks,

 

[Nick Micale]

The BMS part is a "hub" like you said, NOT a balancer or damper. The link tminer has above says lots about why NOT to use the hub.

A quote from Jim Ruggles "A flywheel of undesirable weight or size can turn an expensive crankshaft into a tacky mail box post."

The BHJ steel damper is a press fit and must be installed with a special tool like for a big block Chev.

 

[QuickWrench]

Originally posted by ILBCNU6
...His shop can mill the [Eagle] counterweights too as they look like huge square weights stock. He is concerned as they look much heaver in weight than a stock cast crank?

True.

But, the lack of counterbalancing material on the stock crankshafts is one of the primary reasons that the stock crank shouldn't be used in applications over 5,400 RPM; Even the addition of heavy [and expensive] Mallory to the stock counterweights doesn't allow it to be spun over 6,000 RPM very reliably.

I take the added material as a benefit, and a way to enable talented machinists and balancing shops to customize the rotating balance without extensive Mallory or knife-edging operations. We'll see...

Originally posted by ILBCNU6
PS. He has been waiting for over a year for a "Scat" forged crank and they cost $2600 and paid up front!

I hear you. When I worked for Summit Racing, their Summit-branded crankshafts were provided by Scat and Cola, and had unbelievable lead times. I've used Scat, Cola, Lunati, and Eagle Chevy forgings. Eagle's have always been excellent, and are usually the bang-for-the-buck winner, although they do tend to require very close attention during the machining phase.

Take care,

 

[CTX-SLPR]

Thanks for the answers guys,

I guess what I'm truely asking is how much will it cost to set up the Eagle crank with machine work, balancer, damper, and flexplate verus cleaning up my turbo crank, balancing it and adding a damper to it? And one final thing, what is the max hp I can expect a that stock turbo crank to live at?

Thanks,

 

[tminer]

Originally posted by CTX-SLPR
Thanks for the answers guys,

I guess what I'm truely asking is how much will it cost to set up the Eagle crank with machine work, balancer, damper, and flexplate verus cleaning up my turbo crank, balancing it and adding a damper to it? And one final thing, what is the max hp I can expect a that stock turbo crank to live at?

Thanks,

You'd need an sfi flexplate for the stock crank too. Machining should be the same, assuming that the Eagle balance is close. So basically the cost of the crank. The internal balance dampner is actually a little cheaper because it dosen't need have the counterweight.

TSM folks are over 700 hp with stock block/crank/rods and a girdle. I don't know if they are internally balanced, but if they are then I've read that that can cost over $500 because of all of the Mallory metal that is needed.

HTH,
Tom

 

[GNVYUS 1]

I could of sworn when I was doing my rebuild 3 years ago that ATI made a high quality balancer for us under $400?

Is BHJ the only aftermarket high quality balancer?

 

[tminer]

It does look like it here. ATI 918051 is available at Summit for ~ $350. Comes up as "PUMP", but it is also the one for use with the oem oil pump as opposed to dry sump.

Tom

 

[CTX-SLPR]

Well that certainly is good news, is TA the only people that sell a neutral balance flexplate for these motors? I know there's is $230, any better deals out there? I know ATI makes a damper and balancer but I'm guessing it doesn't have the correct trigger on it, how much am I looking for a new damper/balancer for the internal setup?

Thanks,

 

[turbo buicks]

HEY CTXSLPR, YOURE AN AF PHYSICIST. THINK YOU COULD GET ME SOME STEALTH PANELS FROM A 117 TO PUT ON MY CAR SO COPS CANT TELL HOW FAST IM GOING?