Hey guys I was looking around for some LS3 intake manifold mods but I wasn't thrilled with the performance gains but they were there. Katech posted some 7 horsepower gains from one of the primary people that do them, but the price had increased notably with them.

I looked around on some other forums that utilize the LS3 engine and they were doing some pretty different mods on some of those other forums; they were adding these metal Runners that run all the way back into the intake and are anchored in to redirect the air flow. The guys at Gwatney told me they experimented with many LS3 manifolds but could never pick up more than just three or four horsepower with all the other mods and time and it just wasn't worth the time. Said they only do this now, the metal rods, as it made all the power. There's no other porting that is included. And there's only a couple people that do this mod, one of the companies is called Gwatney performance and they do this one for $250 + $25 shipping, and they say it's a pretty consistent 14 rear wheel horsepower gain all the way across the powerband on a cammed car like mine. Forum results back these claims up.

Of course I would have loved to have combined this modification with standard intake manifold porting that other modifiers do, but then it would have been a very expensive stock manifold. And maybe the 2 mods combined wouldn't be compatible?

These are the photos. My photography skills suck. I'll get some new Dyno numbers up here in the next couple of months.

Stock




Modified by Gwatney:




I also bought this insulating material that I planned to install on the bottom of the intake manifold as well.




Wish me luck!

 

Im interested to read your future update on this. I am forced induction right now but thinking about going back to n/a and this mod has my attention. Good luck with the mod and please keep us posted. Thx

 

My friend has a cam/bolt on Grand Sport and he ran 11.0s @ 123 pretty consistent then all he did was install an intake with the radius rods in it and went 5 10.80s @124/125 in a row. He said he could tell it pulled a little better even before he went to the track.
I dont remember who did his intake but it was a copy of the Rick Crawford design.

 

Rick Crawford (I think Futral was doing some intakes for him before the flood) intakes use the radius rods and pull the posts out and have very similar gains for about the same money. The rods do all the work.

 

There are only 2 people doing the radius rods from what I can tell.

Rick Crawford and Gwatney. Rick will suggest Gwatney when he is too busy.

Gwatney told me point blank that they do nothing else to the LS3 intake manifolds as they tried many different things and the other porting mods made little to no difference. Where-as the radius rods give good torque and all over power gains, every time. They also only charged $250 and had 1-2 day turn around.

Rick Crawford is the guy that came up with the radius rods and his description was this (copied from his message: "The intake is cleaned up in the ports and the plenum pillars and casting are removed in the inside. Radius rods are added to clean up the airflow going in to runners...essentially acting like velocity stack without adding restriction. It's the only LS3 intake that picks up a reasonable amount of cfm after being modified/ ported. All other ported intakes we have tested only picked up 1-2 cfm over stock. whereas ours picks up 11 cfm thru the center runners and 22 in the corner runners."

Essentially I feel like maybe a pit of attention payed to the ports would have been a good thing because obviously BER is documented to gain about 7 flywheel hp with just porting. So obviously something can be had there. But Rick Crawford was another $90 but the big issue is that he has a 2 month waiting list! So I went with Gwatney and am very pleased with the service although the intake was sent back to me quite dirty, and I was told it would be ready to install.

I'll get it all on over the weekend.

 

Rick was outsourcing to Futral for a while, not sure if that's still the case since the flood.

 

Some of the Camaro guys are claiming 3-4 MPH in the quarter with this mod. Any chance you'll get yours to the track to see if that holds true? If so, this is a great mod for the money.

 

I mostly go to the curvy tracks, and even that has been pretty scarce as of late. I also don't have a previous 1/4 mile time to compare against.

The good thing is is that it is a proven mod, and it's very reasonably priced.

And I of course added the questionable, but also rather cheap heat insulation mod. I think I'll be happy if that would just quiet my valve train noise a little.

 

Ah, well I'm very interested in your thoughts after installing this. It still bothers me a bit that everybody I talked to when doing my cam said to leave the intake alone. I feel like there has to be something more there and hopefully this is it!

 

Cleaned the intake up real well and insulated the bottom while it was off.





I'll get it installed over the weekend.

 

I went ahead and insulated the bottom of my air intake too because I noticed it gets scorching hot during the summer.




But you can't see it from the top once installed.




I'll let you know if it drives any different in another day or so.

 

I know the ls3 intake have some power in store to be had i too went inside mine and cut off the 3 support towers and seal the floor with epoxy also found the problem with the lower runner entry straight divider to be knife sharp used sand paper to round it up smooth and match ports to head there was a lot of miss match when pair to the trick flow 255 heads.

I'm happy with my results headed to the track 11/13 to see wasap.

 

I took the car out today, and it's notably stronger, particularly above 6000 RPM. Very pleased with the results. Even though I have a small cam, for the first time my car really zings right past red line and still pulling hard. Previously anything after about 6200 or 6300 RPM was pretty much wasted because it flattened out so much. Not anymore!

Also I have a gauge that tells me my intake air temps, and they were within one or two degrees of ambient the entire time. Which is much better than it is usually. That's because the insulation I put on the air intake tube sitting above the radiator. Also at idle, intake Air temps rose much slower than before and then cooled off much quicker. Very pleased for the money spent.

 

Thanks for for all the info! I've been debating on sending my intake to get this mod done as well by GPI. I'm subscribing for dyno numbers!

 

I am very pleased with the Gwatney mod.

However the picture of the work that Rick Crawford does (above from another poster) looks much cleaner and clearly more work was done. Now Gwatney claims the extra work isn't worth anything at all. But when BER can get 7 hp not even adding the radius rods that suggests to me there is more to be had.

My advise, if you can wait 2 months for the intake to get back to you, and you don't mind all of your communications being exclusively thru FB, then I'd use Crawford.

For me, Gwatney was the correct choice.

Good luck!

 

I absolutely have less valve train noise with insulation on the bottom of the intake manifold.

The car also pulls noticeably harder up top. I think this particular mod really complemented the other mods I had already and I'm pretty confident I have over 20 horsepower gain total. It's very noticeable.

 

Thanks for the input. Pretty sure I'm going to pull the trigger on this mod here soon.

 

I would like to know how the small airflow rods are attached to the manifold...with all the +|minus heat cycles a manifold has to indure I would hate for one of them to let go so to speak.

 

They are secured with a nut and bolt.