91Z28

I am thinking about going this route because I believe the stock intake is holding me back. Otherwise, I can't really understand my low hp numbers.

However, I see it is a big risk for possible no reward. I see this intake gets very, very mixed reviews. No gains, minimal gains, big gains, etc. So, before I spend 1500+ and roll the dice I would like to see how much of a PITA it is to put into a truck anyway. I know they have idler pulley relocation kits but I want to know if the stock fuel rails work and how you route air from the box to the TB and if there are any WP issues. Anyone done this?

v8hunter

iTrader: (2)

I'd like to see you give it a shot. I'm pretty suprised at your low hp numbers with all of your mods as well....not sure where i read this but I heard something about the 6.2 intakes being restrictive above 5800 rpm. If you have a cam I'm sure you want to rev well past that.

I did install a ported fast 78 intake on my 99 ls1 t/a about 5 years ago with the stock fuel rail and it was reasonably easy. All of the lsx engines look the same to me so I'm not sure why your truck would be any different/harder.

I'd venture to guess that you would have to rig something up for the air intake.

91Z28

Putting a car intake on a truck is a bit of a PITA. I know about the idler pulley relocation kits, but I am interested in knowing if there are issues with the water pump and the fuel rails.

I know the trucks dyno horrible for many many reasons like the big tires, 14-Bolt rear (also a transfer case for me too) and the 6L80E having no 1:1 gear, etc and have seen that they only put down 312-315rwhp stock (compare that to other 400hp LS engines that come in cars). I just hope an intake upgrade could net me another 10 to the wheels, but have doubts about the FAST.

NemesisC5

Your factory truck intake will flow more than a FAST 102 LS3 intake. The taller truck intakes have more plenum volume and a straighter shot from the long runners into the heads intake ports.

zero2sixT

iTrader: (4)

I would like to see some numbers on that. The truck 102 does outflow the car 102. I doubt the factory truck intake could touch the flow numbers of the car 102.

Op,

There is a ton of variable that contribute to dyno readings. That dyno might read low. You do lose a considerable amount of power through a 4x4 drivetrain. Taller tires, d/a, etc...

I have read a few threads about VVT cams. Seems some people couldn't make high numbers with them. That was over a year ago, though.

You would definately benefit from a fast intake. People see gains with a fast on a stock 5.3.

My advice is to find yourself a benchmark, or make a few passes down a 1/4. If you can run with a 12 sec car, or click off a decent time or mph, you know you have a good combo.

SeTxCC

iTrader: (4)

I thought I read on another forum that fast should have a truck intake out for rectangular heads soon. Maybe someone on here can chime in on that

Wouldn't you sacrifice some low end torque by swapping to a car intake? For me that wouldn't be worth gaining a few ponies on the top end in a heavy crew cab

91Z28

Yes, that is another fear I have which is why I am hesitant to "roll the dice" so to speak.

I have heard nothing about them releasing a truck intake for the rectangular port heads.

NemesisC5

Some good info on the FAST LSXRT 102

FAST 102 "Truck" Intake (**NEW** Chassis dyno results added!) - LS1TECH

Fast LSXRT Intake Manifold Upgrade - GM High-Tech Performance Magazine

91Z28

That intake will not work with rectangular port heads.

NemesisC5

I know, merely posted to illustrate that truck intakes (even oem) have less design limitations than car intakes. The additional plenum volume and straighter runners are more suited to supply an engines air/fuel needs.

Before I would purchase a car intake for your truck I would PM Tony Mamo @ AFR to get the lowdown. He is R&D Manager for AFR and a FAST intake guru with countless hours porting intakes with the use of a flowbench.

Best of luck with your combo