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Discussion Starter #1
Anyone done the Gwatney or Crawford rod mod yet? Seems there is pretty solid gains to be had. Even more so than a ported TB and manifold.

 

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please elaborate.....
 
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Discussion Starter #3
Radius rods are installed at the internal opening of the runners. They smooth out the airflow similar to velocity stacks. People have shown up to 15hp gains on the dyno and 2-3 mph at the track.
 

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never heard of them but i'm intrigued...
 

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Very interesting!
 

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A refreshing move away from critiquing exhaust pipes, just as important to the performance equation is induction on a naturally aspirated motor, and there's quite a bit to learn to get it signing sweet*
Yeah I was the first LS3 manifold and throttle body Rick Crawford did back in April 2013, only one in Australia. Helps straighten the air out before it enters the intake tract, dyno results have shown an increase and definitely the best bang for buck mod after tune.

It seems to work on the same principle as a velocity stack.. it gives the air a streamline flow effect meaning the air flow is all going in one direction vs if there wasn't a radius the air entering would be turbulent as it enters the inlet of the port so causes a choke point at the throat which hurts flow.

Whether it provides better laminar flow or promotes tumble in the runners, it definitely improves velocity and flow.
Rhino79 aka Ryan Stevens at GPI has also been modding the intakes for Camaro dudes, got the idea from Rick.
Here's some lovely pics of my setup with RCR RamAir mod (Camaro guys and GPI calls Rod Mod):

Gutted plenum (front)


Plenum rear


Rods installed


Ported Throttle Body


Holeshot


MAF Tube sized to match VE and Harmonics


Air Straightener

Primary Air Box
 

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Just a FYI, futral motorsports does these also. That's who I went through
 

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Very cool! A couple things to consider. The pillars inside the intake were placed there for structural rigidity to preven the floor of the intake manifold from resonating and angering the knock sensors on the old LS1 engine. Our knock sensors are not in the valley cover so it should not cause problems with KR.

The pipe from the PCV system that comes out of the left side, has a 90° turn then ends also serves a purpose. As oil is sucked into the intake via the PCV system (it still does even if you have a catch can, just less makes it into the intake) the oil droplets are able to more evenly distribute through the intake manifold and into the cylinders. By removing this pipe the oil will leave the pcv system on the left wall of the intake manifold just behind the throttle body. More oil will be able to get into the positive bank of cylinders vs. the negative bank with the #2 cylinder having the potential to get the most oil.

There are trade-offs with almost every mod, it is good to know what they are to make an educated decision. That said, this looks like it makes good power!
 
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Bit the bullet and got an intake coming from GPI.


Would love to do a before and after dyno, but I don't have the time or money for that.... my butt dyno is going to have to suffice.
Haha, my butt dyno isn't that finely tuned, so I doubt it'd be able to tell a difference!
 

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So does any of the forum sellers sell these manifolds ready to go ?
 

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I would like to know difference between GPI and Crawford power gains wise?how does the GPI intake cost??
 

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GPI runs $275 after exchange. I remember reading Rick suggesting there was minimal gain, if any, from the porting and post removal, ~1hp, or something like that. The rod mod is where the power comes from.
 

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Are the GPI intakes also ported or just have the rod mod done? The site says nothing about them being ported is why i ask.
 
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