speedfreak2685

iTrader: (12)

Im going to start buying parts next week to start putting my motor together. I was all about the forged 347 with hand ported 317's on it and putting the small pulley on my D1 until i saw the flow numbers on ls3/l92 heads. Good lord those things can flow some air! Here is my thought process:

forged 347/317 head combo:
Can reuse my block/crank ext
probably make 750 easy
lighter than iron block (not positive how much though or if it really matters)
Can keep my FAST 90 intake combo
slightly cheaper overall since i don't have to look for a block

Forged 370/ls3/l92 head combo
Make more power with less boost/cylinder pressure i would assume
could sell my FAST intake combo and buy ls3 intake and recoup a little money
Have to source a block so overall build would cost a little more
slightly heavier due to iron block
slightly stronger block possibly??
better power potential if I ever went to a F series blower.

Both sets of heads would cost roughly the same*

Thoughts?

SKULL

iTrader: (7)

just the blocks alone an iron over an aluminum is 100 lbs heavier fyi

speedfreak2685

iTrader: (12)

Wow! How much more power does it typically take to make up that weight difference at the track?

SKULL

iTrader: (7)

100 lbs usually turns into .1-1mph from what i heard which then comes down to how fast are you going. so i would have no idea on giving you a great answer. its just something to take into consideration when trying to reach a specific weight for your car. itll be 100 extra lbs on the nose.

my opinion if you are shooting for anything over 750 in the future. the iron block is worth it because when you get over the 750 mark the walls of the cylinders in a ls1 start moving and just bad stuff happens lol

gnx7

iTrader: (28)

Run the largest bore you can so that you open up your valve selection and potential airflow.

I've read a few times the same thing about LS1 blocks losing ring seal on high HP street driven cars. LS2/6.0 iron or LS3/L92 is the way to go.

SKULL

iTrader: (7)

if you have the coin. ls3 is the best answer

speedfreak2685

iTrader: (12)

I wish I did haha

speedfreak2685

iTrader: (12)

Id love to go with a ls2 block but im sure i will just go with a iron block if i decide on that route.

sheikss

iTrader: (11)

I thought the weight difference between iron and aluminum blocks was alot less than 100 pounds.

speedfreak2685

iTrader: (12)

Anywhere I read it looks like the consensus is between 89 and 93 pounds heavier.

sheikss

iTrader: (11)

There is a thread on here where a guy weights the blocks and it looks like they are about 110 pounds heavier.

SMOKNSS

iTrader: (3)

I would just go with the 6.0 block. Like was posted above 100 lbs. is pretty close to a .1 off of your ET. With a boosted motor .1 is not that bad. You could always take weight out of the car to make up for it and the turn the boost up a tad.

speedfreak2685

iTrader: (12)

The boost will be turned up either way haha. I just noticed how well those ls3 heads flow and got intrigued.

speedfreak2685

iTrader: (12)

Anymore thoughts before I pull the trigger on these parts?