Should i use a forged crank for this build? Lunati lifter failure....

[Shaun]

Hi guys,

Id like a bit of advice from those in the know regarding an engine build that im about to undertake. Its an Australian delivered 6.0 L98 engine in a VE Commodore, and ive recently installed a Harrop 2300 blower, Pat G spec cam, lunati link bar lifters, dual valve springs and yella terra roller rockers, but unfortunately it developed a rattle in the top end yesterday after a power run. It turns out that a lifter failed and destroyed my cam, so im in for a rebuild. Ive had nothing but problems with these lifters, having tried various push rod lengths to quieten them down, but to no avail. I certainly wont be using them again.....

Anyway, i pulled the engine out of the car yesterday, so ill do the bottom end as well with forged pistons and rods, but im not sure if i need to add a forged crank to the parts list? Im not interested in going a stroker, but i was wondering if the supercharger would place increased load on the crank that may cause failure of the standard crank. Its putting out 440kw at the tyres at the moment, and ill probably increase the boost with the forged bottom end, but it will always be a daily driven car with reletively conservative power levels. My friend has a 1000hp twin turbo VE thats running a standard crank, so im not sure if its needed.

Any advice regarding the need of a forged crank would be appreciated.

Thanks,

Shaun.

[TooManyHobbies]

Not 100% required, but there is the always dangerous "While it is apart I might as well"

[thebeast]

I'm stock crank at 13lbs of boost and 700rwhp.
If you want to, do it. But not necessary

[G8-4-Speed]

As few as had issues with stock cranks, it is hard to make it a mandatory part. BUT a forged GM crank and flywheel is only about $450 over a new stock crank. The rotating assembly has to be balanced anyways so you have to decide if the $450 is worth the extra piece of mind.(may cost more down by you) A note on your valvetrain. Keep it lite...The Terra rockers and link-bar lifters are both big weight adders as well as solid stem intake valves. Work on spending money to remove weight, not add it and the parts should hold up better. Dual springs are extra piece of mind and needed to control heavy parts but they aren't helping hydraulic lifters if the springs pressures are high. There are guys having good luck and beat on stock junk all day long, other can't seem to throw enough money at it to keep it together. Some have all the luck, others seem to have none....

[Shaun]

Ok, thanks for the comments guys. All the research ive done suggests that a forged crank isnt a necessity at the power levels in looking at. Id love to get one, but i think the coin would be better served elsewhere.
Ive only been looking at aftermarket cranks like Eagle, Scat and Callies etc, but what about the LS7 crank? Can it be used in a 6.0 litre build? Does it produce the same stroke? Are they as expensive?

Shaun.

[Crazy Paul]

what about the LS7 crank? Can it be used in a 6.0 litre build? Does it produce the same stroke? Are they as expensive?

To stay at 6 litres with stock bore of 4.00" you use a 3.622" stroke crank.
LS7 crank has a 4.00" stroke and the front snout is longer than your current crank due to the drive on LS7 crank for dry sump (pumps).

12611649
LS7 Forged Steel Crankshaft
• Forged 4" stroke crankshaft for LS7 engine
• Includes 58X reluctor wheel
• Rebalancing required if LS7 rods and pistons are not used
• Machine .886" from snout for use in wet-sump applications
GM full retail $1100....you might get it for just under $900.

[Shaun]

Thanks for the info guys.

On second thought, ive been looking at rotating assembly packages from CNC Motorsports (somewhere in the States), and they're asking about $2100 for Eagle crank and rods, Mahle pistons, rings and bearings and its all balanced. Thats pretty good value for money i reckon, so maybe ill opt for a package like that. Im not interested in a stroker build, as the standard capacity will produce enough grunt for a daily driven wagon. Also, i can increase the boost with the new bottom end, and i like the responsive nature of the 6.0 built engines. Id really like to use Manley dished pistons and Total Seal gapless top rings if possible, so hopefully they can do a package with those specific parts.

Regarding the lifters, ill keep away from the Lunati link bar items and i think ill use the Comp short travel hydraulic roller lifters with GM Performance lifter trays. Its hard to know what to do though....

Im also interested in a Mezeire 300 series electric water pump. Anyway, im rambling too much now...

Shaun.

[Stone Cold goat]

My opinion.

LS3 crank would do you fine. Also, like Rick said, Link Bar lifters are very heavy. Im using Cadillac Racing Lifters on my stroker build.

[Shaun]

Ill have a look at the Cadillac racing lifters; ive heard them mentioned a few times on here.

I pulled my engine down today and discovered one of the lifters on number 3 had collapsed. You can see that the piston hadnt returned up to the height of the circlip, so the pushrod and rocker were flapping around in the wind and making a huge racket. I actually expected there to be much more damage, but my cam looks fine and even the roller on the lifter looks ok. I was expecting the roller to have gouged the lobe on my cam out. Anyway, im committed now, so ill order some parts tomorrow and go the whole hog with the build. Apparently if i get the 65mm pulley from Harrop it'll produce around 15psi, so that'll breath some life into the car.....

[Shaun]

Ill have a look at the Cadillac racing lifters; ive heard them mentioned a few times on here.

I pulled my engine down today and discovered one of the lifters on number 3 had collapsed. You can see that the piston hadnt returned up to the height of the circlip, so the pushrod and rocker were flapping around in the wind and making a huge racket. I actually expected there to be much more damage, but my cam looks fine and even the roller on the lifter looks ok. I was expecting the roller to have gouged the lobe on my cam out. Anyway, im committed now, so ill order some parts tomorrow and go the whole hog with the build. Apparently if i get the 65mm pulley from Harrop it'll produce around 15psi, so that'll breath some life into the car.....