SSkeet

Trying to decide between going for 383 or 408. Which do most of your prefer? I hate the idea of adding 60-70# over what I have RIGHT IN THE FRONT of the car, but I am looking for low end torque. But which will give most power throughout? Is the 383 going to give better top end? Since this is a daily driver, I do not want ALL MY POWER DOWN LOW.

1. 383
2. 408

Thanks

necrocannibal

iTrader: (5)

Well I have a 408 and the added weight isnt a big deal, believe me. People blow that way out of proportion!!!

Samba242

If you are really concerned about the weight, hold on for a 6.0 LS2 block. Aluminum with the same displacement...... Just my $.02

mnc2886

Cast iron will take a mother of a beating as compared to aluminum. It depends on your setup. I wont put down aluminum because it is more efficient and disappates heat better. For blown, or big spray, I wouldn't trust an aluminum over time, even if it did have a forged bottom end. Just my $.02.

Sam 04 GTO

You can see the route I chose.

With a car that weighs 3,700lbs to begin with, what's another 85lbs? I need the torque in a big way. I've lightened the car a bit, so the net gain should only be around 50lbs or so.

SSkeet

Well I like the idea of the added strength of the iron, but dont like the weight and heat.

SSkeet

I know, I am leaning toward the 408, oh but I really fear for my poor little baby 4L60 even though its fully built.

My budget puts me right at getting the motor. Already have built 4l60, full suspension, TQARM, Relocation brackets, panhard, SFC, In tank Walbro, 42# bosche. What I dont have is TH400 and something better than stock rear.

I will just take it ez for a while. But now the question is: What provides better power throughout? Or is that more dependent on cam selection? I appreciate the feedback.

11 Bravo

iTrader: (3)

383. 70-85lbs, whatever it is, is a buttload of extra weight on the front end weather you "feel" it or not. The aluminum block is strong enough for 95% of us.

CHRISPY

I have a 385 and love it but I wouldnt mind a 408 either. The extra ~25RWTQ will be nice and noticeable especially for a street car.

You can offset the weight easily (K-Member, A-Arms, Hals etc) and the durability of the ironblock is great.

cant go wrong either way imo

11 Bravo

iTrader: (3)

But think of how light you would be with those mods and an alu block

VINCE

iTrader: (1)

I would run my 408ci against a 383ci car similar to mine any day..

maximumrebel1

Definitley 408. No replacement for displacement. 70 pounds is less than .1 in the 1/4 and you will make up for that with the extra power. Either way should be good for ya.

HairStraightBack

Put a post in the RR section. The experienced guys should be able to tell you how much of a difference that weight should make.

11 Bravo

iTrader: (3)

Yours don't count. It's a freak

SSkeet

I cant wait

kumar75150

Some people also want to take corners and brake. For that reason, I decided not to go with a 408 in my Vette.

slow trap

iTrader: (22)

the 408 should make more power all across the board.the bigger bore will unshroud your valves and in return pick up flow some.copy vinces mill and you'll have a monster.

PREDATOR-Z

LS1=91lbs
LS1 heads=20lbs each
iron block=183lbs

This according to the GM service manual. (Bare block and head castings)

Actually it is around ~92 pounds of extra weight.
All depends on your set up. Light car with 383 would be my choice, also I'm not too crazy about the difference in expension between Alum heads and Iron block, especially on nitrous.
with a forged bottom like a Callies crank and rods + ARP mains etc.... it would match 408 output if properly built.

Ben R

Going with the 408 just gives you free torque and horsepower.

The only reason not to do it is because you don't want the weight, but most people don't even notice the extra weight.

cyphur

iTrader: (10)

Iron blocks are durable, great for power adders(boost/bottle). Weight is an issue if you're always staring at your timeslip, wanting a better time. So if you're that person, be prepared to do offsetting mods to counter that extra weight(tubular K-member, shocks, et cetera). Talking about a TH400 you're pretty much a drag racer, so its not like you're gonna need to do a lot of cornering with this pig. A full suspension can always be tuned anyhows, presuming you got the good stuff The extra horses from the 408 over the 383, combined with the weight loss mods, should make up for the extra weight.