Don Terrill’s Speed-Talk

Have been on friends boat and have seen them turning a stock small block Chevy 5200 R.P.M. as if that is its normal speed!

We turn the scat 9000 3.48 stroke cranks 7400 rpm in 400hp imca stock car motors for at least 100 nights before we think about replacing them, i have yet to see one fail. One 408 cleveland i built made 715hp at 7,300 rpm with the pro comp rod and scat 9000 crank, never broke it. Was drag race engine though. I have a Scat 9000 3.75 stroke crank in my neighbors boat that turns 3,000-5,000 rpm all day pulling kids on the tube. Has 100 hours on it now. No problems.

This is getting interesting. The marine spec has always been a high water mark for OEM parts. And to see that sort of endurance out of the SCAT assembly is certainly noteworthy. What sort of power level does the tubing boat have?
It seems though, from the information I've come across, is that the extra stroke adds considerably more stress to the components involved. Cranks, main caps and the like get put through more than what the additional 1/4" might seem to represent. Maybe there's a story out there about circle track 383's surviving as well as their 350 counterparts.

More digging and I came across this:

viewtopic.php?t=38519#p474921

In particular this post:

I have seen the 9000 series cranks last for years running in the lower class at our local dirt track, 425 hp range.
But in the next class up, 500 hp they last about a season and destroy themselves.
On drag race engines they seem to live much longer.

The picture is from one of the upper class engines.
The crank came out in five pieces.
The customer built the engine himself.
The crank rods and pistons were originally supposed to be for a mild street build but he decided to go dirt track racing instead. We would normally use a steel crank in one of these engines.
It made it through one season and a week into the next.

I will say, I firmly believe it was not the quality of the crank that caused the problem but the fact that he used in in the wrong application.

We have used at least a hundred of the scat 9000 cranks over the years and this is the only one I have seen break.

If you are concerned enough to ask such a question about a possible sustained speed run causing a failure of a low end aftermarket crankshaft option that could kill you, you already know the answer. If you can't afford better hardware: don't do it. Maybe see ya in Nevada.

I wonder how much/if their life expectancy may improve with an LS firing order. Is there any data out there regarding that?

Out of everything on the Camaro, the crank is the only component worth worrying about for 5 minutes at WOT?
Maybe looking crankshafts in Mercruisers might help your decision. I don't see a 500HP Mercruiser small block anywhere, though.
SCAT doesn't list the alloy of the 9000 crank. If it is cast 4340, all your concerns are moot. If it's anything else, the advice already given is clear.
We've all got stories of abusing cast cranks in SBC and for me, cranks were the last thing on my mind.

Driving flat out for several minutes is an experience and makes one understand "straight" roads really aren't above 120mph.
Good luck on your endeavor.

Sparksalot wrote: ↑Wed Mar 25, 2020 2:51 am If you are concerned enough to ask such a question about a possible sustained speed run causing a failure of a low end aftermarket crankshaft option that could kill you, you already know the answer. If you can't afford better hardware: don't do it. Maybe see ya in Nevada.

True enough. But if you don't ask, you'll never know until it's too late. If the endorsements were resoundingly positive, there would no longer be a question. As it is, it seems a forging is the way to go.

RevTheory wrote: ↑Wed Mar 25, 2020 6:40 am I wonder how much/if their life expectancy may improve with an LS firing order. Is there any data out there regarding that?

I hadn't thought to ask. I'm finding the greatest source of information (besides ST) comes from the circle track forums.

Rick! wrote: ↑Wed Mar 25, 2020 7:27 am Out of everything on the Camaro, the crank is the only component worth worrying about for 5 minutes at WOT?
Maybe looking crankshafts in Mercruisers might help your decision. I don't see a 500HP Mercruiser small block anywhere, though.
SCAT doesn't list the alloy of the 9000 crank. If it is cast 4340, all your concerns are moot. If it's anything else, the advice already given is clear.
We've all got stories of abusing cast cranks in SBC and for me, cranks were the last thing on my mind.

Driving flat out for several minutes is an experience and makes one understand "straight" roads really aren't above 120mph.
Good luck on your endeavor.

Trust me, I'm well aware of what's involved. But this is about the crankshaft.
As far as marine applications go the high HP stuff is all aftermarket (at least from what I've been seeing). Any endurance builds all lean heavily on a 4340. Speaking of which, despite this type of forging being given a numerical descriptor, I've learned that all 4340's are not necessarily the same percentage of alloys. So there's that to consider as well. There might be a step function change in the quality of SCAT's entry level offering as compared to a Howard's Track Smart crank. That'll be another step in this process.
Looking forward to the highway.

I've been using them in USRA/IMCA type CT engines, 550-575hp and 7200rpm. SRP Forged or KB Hyper pistons, 12-13:1cr. Dart heads or Brodix T1 heads.
.5 percent overbalanced, 6" SCAT Pro Series Rods with 7/16ths bolts, 6 3/4 ATI dampers. The cranks live a good life. I crack check them at 100 nights, replace them at 200 nights.
My only worry is using the 8" damper on the 350 snout. That's a good amount of weight to deal with in CT engine where your on and off the throttle so much the crank is loading in both directions every lap.
SCAT recommends the their 6 3/4 dampers and 8" dampers on the BB snout.
I'd still buy forged given an option.

Lizardracing wrote: ↑Wed Mar 25, 2020 11:42 am I've been using them in USRA/IMCA type CT engines, 550-575hp and 7200rpm. SRP Forged or KB Hyper pistons, 12-13:1cr. Dart heads or Brodix T1 heads.
.5 percent overbalanced, 6" SCAT Pro Series Rods with 7/16ths bolts, 6 3/4 ATI dampers. The cranks live a good life. I crack check them at 100 nights, replace them at 200 nights.
My only worry is using the 8" damper on the 350 snout. That's a good amount of weight to deal with in CT engine where your on and off the throttle so much the crank is loading in both directions every lap.
SCAT recommends the their 6 3/4 dampers and 8" dampers on the BB snout.
I'd still buy forged given an option.

Very informative. And I see again where their durability is hedged by outright replacement as preventative maintenance.
All that said, I think your last sentence is the most telling.
I have that option although up here, in the Great White North, that option is expensive (although certainly less expensive than a failure which is a comment I'll add before I get flamed!).

Not sure what you call expensive. I am up here as well and the difference in cost for a std weight crank is not much more then a cast 9000 series when it comes down to it.
It depends on how you buy and from where you buy as to how many hands touch it before you get it.

ProPower engines wrote: ↑Wed Mar 25, 2020 3:08 pm Not sure what you call expensive. I am up here as well and the difference in cost for a std weight crank is not much more then a cast 9000 series when it comes down to it.
It depends on how you buy and from where you buy as to how many hands touch it before you get it.

I'm not well connected out in Alberta like I was back in Ontario. That said, even from Summit, so as compare vendor apples to apples the difference is almost 3 times the cost between the two. About $310 CDN for a 9000 series with 350 mains and 6 inch rod vs $870 for a 4340 forging.
What got all of this started was one of the local speed shops had a package deal on a reciprocating assembly and machined block. Included in that was the 9000 crankshaft.
Before the CDN dollar went in the tank, I was looking at a Callies Compstar and Howard's Track Smart cranks for about $1050.
When it's all said and done the price differential adds about 15% to the cost of the shortblock. Not a terrific amount but the sale priced package got the wheels turning budget-wise. As I mentioned, had this been a suitable package overall (the speed shop sale thing) it would have put enough in reserve for better cylinder heads. The the whole game changes. But the reciprocating assembly didn't have the best parts. Pro Stock rods with 3/8ths hardware and a piston profile I'd have a hard time incorporating. I spoke with the SCAT rep for this area and we modified the package with Pro Comp 7/16ths rods and different pistons but after all was said and done, I saw I'd be better off with plan A and that's selecting my own components and having a local race shop do the machining.
I've still got a lot of work to do before I get to that point though.

The boat motor I was talking about has a eq vortec head on it and hydraulic roller with a eps manifold as it has to sit under the sun deck of the boat and idle at 600 rpm to go into gear clean. It made 466ft/lbs at 3600rpm and 380hp at 5,200 rpm. Not huge horsepower but makes really good torque it made 422ft/lbs at 2500rpm and spends most of its time in the 3,500-4,000 rpm range. Sometimes for hours at a time, only taking a couple minute break here and there to switch kids on the tube or pick up the ones that flew off haha!