BURNRBR

Looking to buy a pull out lq4 and put a stoker crank in. When i get around to starting i will measure the bore and see if it needs refinished. i am hoping to leave stock pistons and rods and just change to a stroker crank.

My question is how would each of these different length cranks change compression ratio?

Would there be any issures with piston to valve clearance?

I would be running factory truck intake. fuel injectors and throttle body. Cam would be somthing like whats below with the full comp cam k kit. Probaly Black Bear tune.

The cams im looking at are
Comp cam 408-11

Basic Operating RPM Range 800-5,800

Intake Duration at 050 inch Lift 206

Exhaust Duration at 050 inch Lift 212

Valve Lift with Factory Rocker Arm Ratio 0.515 int./0.522 exh

Lobe Separation (degrees) 112

From comps website- they report this cam is a good torque cam. That is what i am after.

or
Comp cam 412-11

Basic Operating RPM Range 1,200-6,000

Intake Duration at 050 inch Lift 212

Exhaust Duration at 050 inch Lift 218

Valve Lift with Factory Rocker Arm Ratio 0.522 int./0.529 exh

Lobe Separation (degrees) 114

This cam is the step up from the 408-11 cam. slightly more towards horsepower than torque.

any opinions on cam selection would be appreciated. Should i chose a bigger cam?

Estimated hp and tq numbers. (looking to break at least 450hp hopfully more with the stroker crank.)

And most interested in the Crank selection and compression ratio number.

Thanks.

tarinitup

iTrader: (11)

You cannot use stock pistons with stroker crank. Do some more reading. Also cam selection is too small.

BURNRBR

Thanks. I havnt found much info so far. but each day i find a little more.. those cam specs are from when i was looking to do my 5.3 so i thought they would be small for somthing like a 408.

If anyone can lead me to some 408 builds (preferably more budget minded) I know it is not going to be cheap. I am not looking to do a head swap or port and polish. would like to keep them stock to save $ and just install new springs and maybe new valves.

I have been looking on texas speed and im surprised at the price of their stroker rotating assemblys. I honestly thought they would be higher.

What about the stock pistons make them not work for the stroker setup? do they hit the heads and valves?

Thanks for any help. sorry if im asking questions that have been answered on another post. I just havnt found them yet.

Whitecrewcab

iTrader: (2)

When you make the crank throw longer, you have to move the pin up in the piston so it won't stick up out of the block.

oakley6575

iTrader: (5)

Last summer I built a stroker LQ4 with a 4" stroke and wiseco pistons. Also LS3 heads/intake. Cam is a 231/239.

Your cam selections are way to small. More cubes can handle a bigger cam with decent drivability.

Atomic

iTrader: (42)

I would not go over a 4" stroke on a lq4/lq9 block because of the shorter piston skirts. You can solve this by sleeving it...but then you are pretty deep into it and would be better off going with a gen4 block from the get go.

Compression ratio depends mainly on piston dish size and head chamber size. You can get whatever compression ratio you want by choosing the right pistons and rods.

custm2500

iTrader: (10)

To make 450-500 hp at the crank isn't hard. It obviously depends strongly on your cam, and compression. But I don't think I have seen a 408 make less then 450 at the crank. Mine is fairly radical with almost 13:1 compresion it made 525 at the tires.

oakley6575

iTrader: (5)

Will you post up a dyno graph of your tq and hp curve with some motor specs. Not to thread jack, but so we can get an idea of what it takes to make 500+ out of a stroker.