I made a few changes and the car picked up about 4 psi of boost. I'm giving it everything the little D1x can do now. Removed the crappy more than 180 degree turn intake pipe that comes with the GTO kit and fabricated this little brace to take the flex out of the procharger bracket. I'm hitting 19 psi now at 7000 rpm. It got me thinking what is the boost level you guys would start feeling uncomfortable with the Ls6 intake? Also if you were to switch intakes with fitting under the stock hood being mandatory which one would you go with?

 

i would not worry about it. Back in the day folks have put 30+ PSI into them.

 

Im hitting 22psi for yrs with my turbo setup and never worry about it.Im sure others are above that

 

30+ isn't uncommon. Hopefully a true ls6 and not a Dorman.

 

2004 GTO came with the true ls6 intake as far as I know. It's the factory intake that came on the car.

 

boost away lol.

 

I'm giving her all she's got captain.

 

All of it.

 

Wow guys my intuition was telling me it was time to switch intakes. Nothing to do with boost levels but...

I had been tuning some trucks recently. All naturally aspirated tunes from bolt ons to complete rebuild with heads and cam. We had some warmer weather today finally so I thought I'd go collect some data with better traction. First time I get on it off a stop light car is running great look over at the log and it levels off at 100 kpa. So I think that is weird and get on it again while watching the boost gauge and AFR everything looks real good and car is running strong. Pull over at a state park and shut down to look at my scanner since I must have changed something doing the last truck tune. Immediately get chewed out by the DNR for parking where I did. Ok no problem start up the car and move. Looking over the scanner and take off again. Something was still up with the map sensor logging. So I go home and sit down to fix the issue. Got it fixed I'm going out for a test hit. Pull out of the drive and the car starts stumbling and I get a weird smell. Now wtf car was running great. Drive around block. It's a small town so now issues and I'm back in my drive way. Car is stumbling to run and AFR is whack. Can't remember honestly if I shut it off or it died it all happened fast. Popped the hood fuel every where. Front passenger side rail mount of intake had broken and the rail raised enough that the cylinder #2 injector oring was out of the rail spraying fuel every where.

Lucky I wasn't making a wot pull when that happened. Even though I do carry a 5 lbs fire extinguisher in the car I'm very lucky there was no fire.

So it looks like I'm shopping for a low cast intake now. Want something that fits under the hood, but no more plastic intake for this guy.

 

That is a freak failure. I wouldn't chalk that up to the intake being plastic. That said, glad it didn't cause a fire!

 

Definitely freak failure, but since I have to buy an intake now I'm not going plastic again. Thankfully my scanner was jacked because I was heading to mexico for wot logging if everything looked good. Motor was up to full temp and shut off for maybe 15 minutes to sort out the scanner before starting it back up and as soon as I pulled out of the drive it stumbled.

Now I'm open for recommendations on a cast cathedral port intake that fits under a stock hood with minimal other modifications needed.

Here is o ring popped out of rail. At first I didn't know how that happened, but the rail looked crooked. The little plastic pillar with the brass insert for the rail bolt was broken right at the base and let the rail lift enough for the front injector o ring to pop out. I carry a 5 lbs extinguisher, but it still would have been bad if it caught fire. At least I wasn't wot or something far from home.

 

Ive actually had something similar happen from crap aftermarket fuel rails. Sprayed fuel all over the top of the motor, thankfully no fire either. I am assuming you don't want to spend $$$$ on a machined billet piece. Most of the sheet metal stuff is close to the same style/size which pushes the powerband to the right quite a bit over factory style intakes. Other option is the BTR. Price is reasonable for what it comes with, but I havent seen data that shows significant gains:
https://www.michiganmotorsports.com/...RoCxC4QAvD_BwE

 

Im looking at this one.
https://www.holley.com/products/ls_p.../parts/300-621

looks pretty much plug and play except the 4 bolt throttle body will force me to buy a throttle body as well adding to the cost. Not sure if I have room or want to run an adapter.

 

I have to wonder how much that differs from the cheap Chinesium sheet metal intakes that are half the price. I'd go BTR over that Holley intake for the same $, but thats just me.

 

The Holley price includes rails while the BTR is extra with rails.

Are you aware of any intakes that are 3 bolt throttle body?

 

There is this old guy.
https://www.holley.com/products/ls_p.../parts/300-111

 

EDIT!!!! I was mistaken!

 

Really glad you were able to avoid a fire, no need to mention how bad that would have been.
My vote would be the BTR intake, if you wanna spend a bit more, the Shearer Fab LSx Surge intake is badass.
https://shearerfabrications.com/coll...30874841579579

 

The LS6 plastic intakes are pressure tested to over 80psi from the factory. They are fine. Going to a small runner like that is going to destroy the cars performance below 6k. With a RPM dependent boost setup that's naturally weak in those areas to start, I wouldn't slap a tiny runner intake on it. Likely lose 20-30ftlbs or more below 6k across the board. The BBK or LS1/LS6 style cast intakes would be better IMO if you are dead set on a change. They are crazy heavy compared to the LS6 as well.

 

I would think something like the BTR or Surge intakes would be the best for fitment and power throughout the range?
I've got a Vic Jr. with an elbow and have been contemplating making a change as well.