maikell77

First off I am building with the short stroke on purpose. The car I have in mind for the engine is light weight and I plan to road course the car. That said I'm most wanting the engine to have a good linear power band up top. So far I have a LR4 that is in pretty good shape. I plan to go through the whole thing.

Goals: 7500 rpm capability, powerband in the 3500-6500 range,

The following I have more or less decided:

cam: XER273HR
Crank: stock 4.8l crank, polished and balanced
Block: stock 4.8l block, new bearings and at least clean up honed
Head: 853 castings with 0.030" milled off, home prot job, new springs, seals, and retainers to match cam
Rockers: stockers with trunion upgrade
Bearings: replace all
Lifters: replace with comp hydraulic roller lifters
Timing set: dual roller
Oil pump: new standard volume pump
Head bolts: ARP
Intake: Edelbrock victor Jr
Carb: 750cfm?

Then either
1.
Pistons: speed pro hyp. 99mm bore pistons ~ 11:1
Rods: stock with ARP bolts, resized to ensure roundness
Gasket: Cometic
2.
same as one except use Wiseco forged "junkyard dog" pistons ~11:1 comp ratio
GM head gasket
3.
Rods: eagle I beams 6.25
Pistons: Mahle Power pack 3.898" ~9.6:1

So the question is will the stock rods reconditioned survive trips to 7500? If not then I will have to give on compression, or deck the block.

If the upgraded stock rods will survive, are the forged pistons worth the upgrade?

Ping King

iTrader: (20)

I have an iron 4/8/5.3 block that i had planned on boring to 3.905 and running a stock 4.8 crank.

You can run a 6.300 rod and the correct piston to have proper clearance to the deck and quench. I had planned this out for a while.

I may actually sell this block and build on a 6.0 or a LS3 block, so PM me if you're interested. I'll sell it for what i paid. I also have heads i may be interested in selling.

The rod to stroke ratio with a 4.8 crank is almost 2:1 which is perfect. Everyone will jump on board and say how its stupid and you should just build the motor for more displacement..blah blah blah.

Just do it and be happy.

maikell77

Where did you find the 6.3" rods? 6.25 is as long as I have seen.

Thanks for the input!

Ping King

iTrader: (20)

I believe lunati makes 6.30 rods. You can also run sbc rods but they're offset. This was done in the early days when Ls specific rods weren't available. I would just buy a centered Ls specific rod.

maikell77

Looks like with the 4.8 stroke, I am limited to sbc rods or stock ones.

Just about to pull the trigger on 6300b3d rods and the wiseco K474M965 pistons. I just to rely on the stoke rods at the speed I want the motor to turn.

S10driver85

I'm really interested in doing this build myself, but limiting to about 400hp plus or minus, I think I would run 10.1 compression. And go for longevity.