87silverbullet

iTrader: (11)

I had 1 3/4 on my ls1 and now I am going 416 and thinking about just skipping over 1 7/8 and just going to 2". Has anybody here done it and do you feel any bottom end loss? I am thinking about going true duals with it or a Mufflex system with a 4" in/out Magnaflo muffler. I just don't want to go with this set-up and end up with some sorry *** 60 ft times.

fuel

iTrader: (13)

whats your hp on motor and are you running ant nitrous.

litle88

iTrader: (20)

Going 416 as well, so I'm subscribing

Jimmy P

iTrader: (177)

I had 2" primary headers on my 402..but that was with a F1C procharger setup making good power.

vette0009

yeah I'd run the 2" primary as well

v8pwr

iTrader: (19)

If you're spinning the motor high enough they'll work well . If you're not low end torque will suffer somewhat . I'm building a 402 and have ARH 1-7/8" stepped to 2" w/ HVMC that opens up to 3.5" .

87silverbullet

iTrader: (11)

The motor is not done yet just getting prepared with all my parts. The shortblock is being put together as we speak. I have PRC L92 heads going on the motor, the cam was spec'd by Geoff@EPS for the bottle. I will be hitting it with a 250-300 shot direct port.

So will 2" hurt any or should I go stepped 1 7/8 to 2"?

ChucksZ06

iTrader: (9)

I think you will be fine...gives you room to grow.

87silverbullet

iTrader: (11)

I think so too. I just don't want it to be a dog off the line on motor and it just be a nitrous junky.

Austin Auflick

iTrader: (1)

I have 2" primaries on my 370 LS3 build. To tell you the truth the low end suprises the hell out of me. Not the slightest bit doggish.

hivoltagedriver

iTrader: (1)

An LS3 is a 6.2L (376ci). How did you build a 370 out of it, or is it just an LS3 top end (looks like maybe that from your sig)?

My vote would be for stepped headers, but it depends on the rest of the combination.

Austin Auflick

iTrader: (1)

hivoltage: yeah it's the motor in the sig. Iron block, LS3 top end. I'm sure the 2" primaries really help on n2o. But honestly there's no sluggishness NA. I can break the tires loose, go side ways and all that hotrod ****.

fuel

iTrader: (13)

what size is the stall. if you have a high stall will put you closer to the power band and 250 shot of n2o it will breath better.

87silverbullet

iTrader: (11)

When I more done with the motor and get the intake and get it plumbed for the direct port I will call up and gnet a converter spec'd for my combo.