chevydarrell

Hello All,

I am interested to hear from anyone that has put the 4.8L
crank in a 6.2L block. What are your experiences? Would you
do it again? I am interested to build and turbo this motor.
Should I, Or shouldn't I?

Thanks
Darrell

gnx7

iTrader: (28)

Why not just run the standard stroke crank? I spin one to 7800rpm on occasion and make well over 1000rwhp. I mainly try to shift in the low 7000rpm range on the strip.

Unless you have an intake manifold and killer cylinder heads to support a much higher RPM there is no real point in running the shorter stroke and giving up all those cubes. That also means Ti valves, solid roller cam, and a transmission that can also shift that high.

Busa_rob

iTrader: (1)

I'm building a iron block destroked 6.0 with a 4.8 crank. The destroked stuff is starting to catch on as lunati now makes the right sized rods off the shelf so you don't need to run the offset sbc rods.

There's very few things on the web about the destroked engines, but what you do see of them they're absolutly retarded in regards to HP/tq curvs.

gnx7

iTrader: (28)

This is a stock $100 cast LS1 crank at 14psi. The heads flow 380cfm (MAST LS3) and a 100% stock LS3 intake/90mm TB running a baby cam and stock LS7 lifters.

Yellow lines are without airfilter. Other ones with and slightly lower boost and you can see how badly it chokes up at the higher RPMs.]

Busa_rob or ChevyDarrell- How high are you going to spin the motor?

Busa_rob

iTrader: (1)

At least to 8k, if not higher.

Ping King

iTrader: (20)

I have a 4.8 crank and gen4 rods sitting in my basement, ready for the right block.

There are a few instances where i'd run this combo.

1. rod length to stroke ratio is nice.
2. Keep pistons more centered in block during their stroke. helps a lot if filling the block somewhat.
3. minimized displacement, along with wide bore allows for nice flow, but keeps many turbo compressor maps in a good spot.

You could also just run a std stroke.

rkreigh

the short stroke cranks are great and probably the strongest of the cast cranks and with a long rod you could really zing the engine if you have the valve train and turbos to match

it's hard to find the forged cranks in the short strokes without spending big bucks on them though

stock stroke or 4.0 seem to be more available

but if you are going to run the stock crank, this would be a good strong one

DavidBoren

It won't spin any higher than any other LSx. The stroke/piston speed is not necessarily the limiting factor with rpms, the oiling system is. The advantage of the 4.8 crank is the 1.9+ rod ratio. Makes for a really smooth revving engine, and aids reliability by decreasing the working angles/side loading.

I think the heads designed for the 4.065" bore have much too large of intake runners for the 339ci of displacement you end up with using the 3.27" stroke. And with that in mind, I think that the 4.00" bore with the 3.27" stroke, making 328ci, is a smarter combination because the cathedral port heads have smaller volume intake runners, better suited for the smaller displacement associated with short stroke.

The thought of a 260cc intake runner ls3 head on a 339ci engine just sounds like it would be a dog down low, gutless and sad in every respect under 5000rpms.

I suppose you could still use cathedral port heads on the 4.065" bore, easily enough. But I still think you would want to stay with a relatively small intake runner volume, just with bigger valves.

Either way, never use the term destroke... it gets people all worked up about decreasing displacement... always tell people you plan on overboring a 4.8L to 4.065" bore. That way you give the impression you are increasing displacement, and increasing displacement is always smiled upon.

1CAMWNDR

iTrader: (21)

In theory the engine should be able to accelerate the short stroke/long rod combo faster. But I think depending on the weight of the vehicle it may be sluggish to get moving. And if max rpm is your goal the 3.622" or 4" cranks will go near 8,000 rpm if you have the vlavetrain to take it.

I personally love the idea of a 4.03" bore 3.269" (or whatever the stock 4.8 crank is) stroke 333" engine as a replacement for a 5.3L.

dacajun

iTrader: (19)

I believe ICAM hit the nail on the head, "I think depending on the weight of the vehicle"

Why would anyone want a high revving engine when you have to get a heavy 3k plus street car going??? Torque is your friend, use it!! Plus it's way, way easier on the valvetrain!!! I'd say take that LS3 block and put a 4" stroke crank in it with some nice flowing cylinder heads and the right turbos to complement it!!!

stoverz28

iTrader: (8)

I could see it working out well in six speed cars, as far as transmission life goes anyway. I'd be curious to see how well a t56 or 6060 could stand up to a high horsepower short stroke set up.

Busa_rob

iTrader: (1)

Why would anyone want a high revving motor? Uhh because turbo maybe?

Check out this article, there's plenty of torque, and with broad HP curve like that that's a seriously quick car.

http://www.hotrod.com/how-to/4-8l-cr...pm-ls-stroker/

ls1_chevelle

iTrader: (9)

Hopefully this link works.

So far they have done 31 pulls to 9000rpm with a hydraulic lifter.

for ****, wont let me link to facebook. Look up Billy Godbold from comp cams on facebook.

IronBlocked

http://www.jegs.com/i/COMP-Cams/249/7228-16/10002/-1
With a stock cast 6L crank, imagine a 4.8 would do even better

93camaro_zzz

iTrader: (13)

Damn, 9K out of a hydraulic roller? What is more info on that setup?

ls1_chevelle

iTrader: (9)

6l cast crank (doesnt list anything else in the comments)
out of the box comp short travel lifters
9.5:1 comp
Made 587.7hp and 454tq in the video

Busa_rob

iTrader: (1)

Can you explaine the diffrence in a short travel lifter vs a standard?

ls1_chevelle

iTrader: (9)

"What you now own are .010-zero preload lifters. Depending on the cam profile, valve springs, and oil pressure per rpm, there comes a time early on in the rpm range that the hydraulic workings of the lifter are no longer applicable. At this time the lifter is a solid lifter or a regular shimmed hydraulic lifter. What little bit of actual "hydraulics" is left in the lifter is for quiet idle at zero lash and nothing more. "

Google/search is your friend, but I'll spoon feed the odd time.

Busa_rob

iTrader: (1)

Does comp know they hired a ********? I mean, **** me for asking a question about a part that I have never seen talked about on here. And double **** me for trying to learn something new from someone who appearently works in that industry.

Jimbo1367

lol. wow