scat vs pen crank in 95 block?

[J.Peart]

Just trying to figure out my budget on my rebuild, and with the economy and the bad canadian exchange rate right now im trying to see where i can trim some costs.

My question is is it worth getting a Pennisular forged steel crank (~900USD) over a SCAT cast steel crank (~400USD) if I'm putting it into a 95 block?

I'm kind of thinking that although the Penn crank is stronger than the SCAT, the block would probably crack before either the SCAT or the Penn crank would break. This would make the block the limiting factor and the Penn crank not worth it unless i got an new AMG block or something.

Thoughts? recommendations?

 

[randomid25]

i would go scat. I think you are right. Anything other than a brand new amg block would probably junk out way before the scat crank

 

[mitchedo]

If I'd had to replace either the crank or the block during my rebuild, I would very carefully have considered a new P400 long block, but that's $7000 plus the custom pan you'd need to make. If just the crank, I'd have been very tempted to go with the forged crank.

There's something to be said for a seasoned block, isn't there? If it hasn't cracked by now, it's probably a good one. 95's don't have piston sprayers, right?

My crank and block were fine, so I spent the big bucks on a Fluidampr. Those things are spendy.

Tough decision. I would lean toward the forged crank, but I'm glad I don't have to make the decision. I was dead set on studs for the mains until I found out they were gonna cost me a fortune, so I put in new factory bolts. It all depends on how much you're comfortable with for a total bill. Once things get toward $5000 or so, the P400 looks better.

If I had to choose between a SCAT with a Fluidampr vs a forged with a stock balancer, I think I'd go for the SCAT with the Fluidampr.

 

[J.Peart]

yeah the '95 blocks dont have the piston sprayers.

Yesterday i went to a good head shop i know to price my rebuild kit and i talked with the owner for a while. I ended up deciding on the SCAT crank and new stock balancer. This is because i plan on using ARP main studs as well as having the block machined- including balancing the rotating assembly, and, if needed, line honed. perhaps i should have mentioned this earlier.

If i have the money i may still fork out the extra cash for the fluidampr though...

 

[davo727]

Savin my nickels for a Peninsular, but just spent all my nickels buying and fixin up a little stepside for my daughter. Hoping to get the crank in March and get goin on this rebuild.

 

[sshewins]

Even if the block cracks (at the webs and not too bad) do the repair MGW did.

I would go with scat and fluid damper, FWIW.

 

[Missy Good Wench]

The Lock and stitch insert are a sweet deal.

If the cracks are within the length of the bolt hole its a perfect fix.

If the cracks are out into the web then I would not use the block.

The best deal is to insert the block even if its not cracked and then it won't.

I would use a scat crank and insert the block and be done with it.

The $500 saved will pay for other much needed goodies.

Best

MGW

 

[Sunshine]

Bill Heath sells Scat for $459..

This is the crank we specify for our land speed race truck engine as well as all engines we build for company trucks.
Highest quality materials and state of the art manufacturing processes result in an exceptional replacement crankshaft for the 6.5.
Why risk an expensive engine build-up by using a factory crank------especially when it has already logged a bizzillion miles?? The factory crank is of questionable quality when new.
For the money---this is the only way to go!

 

[BustedWrench]

This is something I've been arguing with myself over--I sold the engine I had in my '82 dually for a very good price and got a good used AMG block as a core, so the plan is to take my time and the dollars necessary to build it for maximum possible strength.

No shortcuts allowed, but on the other hand there's no point spending money just for the sake of doing so. Who actually manufactures the forged crank, and would it be worthwhile for 'anybody at all'? or is it just an unnecessary expenditure?

 

[J.Peart]

I talked with someone at pennisular when i was looking at my options for a crank but if he mentioned who made it i cant remember. I know its not chinese though if thats what you're wondering. i think its definately worth it if you are using a new AMG block, but for someone like me its probably not worth it.

I'm kind of in the same boat. im rebuilding my motor, trying not to cut any corners. rather spend more money now and not have to worry about it in the future.

18:1 mahle marine pistons,
scat crank
upgraded cooling system
new balancer pulley
fluid damper
ARP head studs and main studs.
rotating assembly balanced
block machined
ATT turbo
and my existing mods

expensive but it should be worth it.

 

[Ratman]

According to SCAT, the cast steel crank has a 15,000 psi higher tensile strength than the factory nodular iron piece.

So far, 10,000 miles on mine, -not a single issue with it, -and I ain't nice to it either.

I'm running a new factory-style balancer and crank pulley on my serp-drive.

For whatever it's worth.........

 

[BustedWrench]

According to SCAT, the cast steel crank has a 15,000 psi higher tensile strength than the factory nodular iron piece.

So far, 10,000 miles on mine, -not a single issue with it, -and I ain't nice to it either.

I'm running a new factory-style balancer and crank pulley on my serp-drive.

For whatever it's worth.........

Fair enough, I'm thinking I can probably save the five hunnerd bucks--but are there ANY applications where a forged crank would be better for this application?

 

[Ratman]

Fair enough, I'm thinking I can probably save the five hunnerd bucks--but are there ANY applications where a forged crank would be better for this application?

Well, yes. There is NO substitute for a forged crank, however, for the modest amount of fuel us guys are running, I'd say it's probably not necessary.

Comparing a cast steel crank to a forged crank is NO comparison, -they are completely different, -however, the cast steel is still a step up from the nodular iron.

If ya got lots of money, go forged, -if not, upgrade to the SCAT over the factory piece.

Cast cranks "time-out" -meaning fatigue is cumulative, -so re-using them is always a roll of the dice.

My .02

 

[BustedWrench]

Ok, that's exactly what I was looking for I think. I figure I might as well go all the way on this engine, because I have another truck to run around in--this one's for working hard. As the money becomes available, I'll be looking for a high output pump, an ATT, and experimenting. I believe I've read about a mechanical 4-plunger pump, or DB4, somewhere . . .

 

[Ratman]

Ok, that's exactly what I was looking for I think. I figure I might as well go all the way on this engine, because I have another truck to run around in--this one's for working hard. As the money becomes available, I'll be looking for a high output pump, an ATT, and experimenting. I believe I've read about a mechanical 4-plunger pump, or DB4, somewhere . . .

A fellow 6.5 buddy of mine and I contemplated the idea of retrofitting a DB4. It could be done pretty easily, -but the mounting pattern is exactly 180 degrees off from the DB2, -meaning the stud locations would have to be modified in the front cover. This normally wouldn't be a huge deal, especially for a guy like me who is a machinist, however, there are bosses cast into the cover for the studs. I considered modding a front cover for a DB4 until I spoke with Matt at Peninsular. He said they offer a DB4, but that their marine DB2 makes dang near just as much fuel as a DB4, -and has a much better track record for reliability.

Without a doubt, plenty of fuel can be had from Peninsular's 4974 DB2 (to the tune of 340HP).

The 4974 has .340" plungers in it, which is a step up from most DB2's and DS4's which have .310" plungers.

I'd say stick with a 4911 DB2 (.310" plungers) and just turn it up to max fuel rate.

Much more than that, and you'll seriously need to keep a close eye on EGT's to be safe.

 

[ak diesel driver]

So how come someone has put bigger plungers in the DS4?

 

[OregonHorseTug]

Fair enough, I'm thinking I can probably save the five hunnerd bucks--but are there ANY applications where a forged crank would be better for this application?

Marine or aircraft duty cycle 75-100% continuous power for most of the tank of fuel, non stop for several hours. That's the sort of thing we don't normally see in a road rig. To answer your question, what's your "mission profile"? Are you pulling 20k up the longest inclined freeway on the continent? Say I-90 east bound out of Seattle or Spokane or west bound out of Ellensburg?; I-80 out of Pendleton up Cabbage Hill or I-84 East through Utah? I don't see where you're from but this is the kind of hills I'm used to. Looonnng hard pulls with a big load will fit the bill for a forged crank if you are doing it week after week. But, these other guys and gals are right about the block. Will it handle the pressure as well? That's what I'm wondering about as I keep upping the continuous horsepower on mine.
Mike

 

[Ratman]

So how come someone has put bigger plungers in the DS4?

Well, maybe someone more in the know on the IP's could chime in on this, -but I don't think the .340" plungers will retrofit into the DS.

The local stanadyne guy told me that in order to fit the .340" plungers into a DB2, the head and rotor had to be changed out, -so I can only assume it would be the same for the DS.

Also, correct me if I'm wrong, but I believe the DS is a 4 plunger pump??

 

[BustedWrench]

Marine or aircraft duty cycle 75-100% continuous power for most of the tank of fuel, non stop for several hours. That's the sort of thing we don't normally see in a road rig. To answer your question, what's your "mission profile"? Are you pulling 20k up the longest inclined freeway on the continent? Say I-90 east bound out of Seattle or Spokane or west bound out of Ellensburg?; I-80 out of Pendleton up Cabbage Hill or I-84 East through Utah? I don't see where you're from but this is the kind of hills I'm used to. Looonnng hard pulls with a big load will fit the bill for a forged crank if you are doing it week after week. But, these other guys and gals are right about the block. Will it handle the pressure as well? That's what I'm wondering about as I keep upping the continuous horsepower on mine.
Mike

Mission profile? I'm a gauge nut and know intimately what the limits are and what it takes to reach them, so after a few years of pulling with my hopped up 6.5 I want to expand the envelope, as it were. I live near Edmonton, Alberta, and I'm in construction, so it could be anything from a load of shingles to a small excavator. Not so many long hills, but lots of steep ones--I run out to various places in B.C. fairly regularly so I'm driving through the Rockies a lot.

I didn't scale all my loads, but I regularly saw 12-14psi sustained, and that's on the intake side of a full size Cummins intercooler. Yeah, lag was an issue.

As for the block, I've been following Bill Heath's posts with great interest. Concrete in the block, fully studded bottom end, plus a new align hone and balanced rotating assembly to reduce odd stresses should help considerably. In addition to all that, my block is spending the next six months or so in a shed where it will be exposed to changing temperature and moisture conditions. Because it's used I'm not sure if it'll make a big difference, but as much stress relief as possible is always a good thing.

 

[BustedWrench]

Well, maybe someone more in the know on the IP's could chime in on this, -but I don't think the .340" plungers will retrofit into the DS.

The local stanadyne guy told me that in order to fit the .340" plungers into a DB2, the head and rotor had to be changed out, -so I can only assume it would be the same for the DS.

Also, correct me if I'm wrong, but I believe the DS is a 4 plunger pump??

The DS4 is a 4 plunger pump, and I thought the big plungers were .330", not that it matters much.

Thanks for the info on the performance DB2's, I've looked a little bit at Kennedy's pumps (300HP marine DB2 for 1200) and need to call Pen' yet as their website is somewhat lacking. I don't know much about the DB4, but if reliability is an issue then the custom work to run it isn't worthwhile as far as I'm concerned.