They said it couldn't be done
 

Being a H/C/I car I'm trying to milk out every bit of power I can and the only place to go from where I'm at currently was a new intake setup. So I started doing some research and it looked like the FAST 92 was roughly the same dimensions as the LS6 manifold and looked like it would be a fairly straight forward swap. So I ordered up a ported 92, ported LS2 TB, and a LS7 MAF and dived into the swap.

Upon pulling off my LS6 manifold I noticed that even with a catch can, I get a lot of blow-by oil getting into my manifold. Not much you can do about it if you already have a catch can installed.

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Next up I wanted to keep the 92 intact as much as possible unlike the LS6 where you have to cut off the brake booster. So I simply rerouted my PS reservoir onto my CAI box.

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Now you still have to do some cutting to the 92 to make it slide under your PS pump. The HVAC nipple that our cars don't use had to be cut off and JB Welded.

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You also have to flip your PS Pump nipple so it can clear the 92 along with filing a decent indent into the 92 where it hits the PS Pump nipple.

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Lastly the steam vent coolant line needs to be bent to allow the 92 to slide all the way back. It bends fairly easily, just leave it connected to the heads and use a screw driver to bend it into shape.

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After all that was done it bolted up just fine and looked beautiful. There's no need for a TB adapter to clear the headers because it shoots up at an angle already. Gotta say the swap went a lot better than I was expecting, however if you still have a DoD valley cover you might have more issues.

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As for Dyno numbers I was a little disappointed with the outcome. Turns out the LS6 manifold along with our TB and MAF flows plenty for a H/C 5.3. I however did still gain some everywhere.

Old numbers:
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New numbers:
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And here's some dyno porn for you guys:

Thats bad ass looking how much did the whole swap cost approx?

Something isn't right you should be eclipsing 400whp. I would say however the 102 would've been a better choice. Its already been done as well. Also how close is your heatshield to throttle body clearance. I had to cut mine off to clear the throttle body.and also you should consider dumping the cai the huge bend and having the maf right there is not optimal.

I was hoping for 400whp but as my tuner said I just have too small of a cam to move all the available air. Even with a huge cam in our cars I'd find it hard to make 400whp with our amount of drivetrain loss.

This truck is making a bit more than me with the same setup except he has 1.8rrs and a LSXrt manifold: http://www.performancetrucks.net/for...esults-494763/

And this 5.3 is similar only difference is LS2 manifold and TFS' next step up cam: http://www.pro-touring.com/threads/5...nd-445-tq-woot!

And I'd say a good 1/4" where the rivets are and closer to 1/2" clearance from the heatshield itself.

Ported FAST 92: $1100
Ported LS2 TB: $400
LS7 MAF + Housing: $260
4" 60 degree elbow and 4" cone: $60
All the extra tubing for PS relocate, coolant line, and brake booster: $20
Tune: $300

So roughly $2140 for the entire swap. I can say it doesn't show on the dyno that it makes much more power but you can definitely feel it. It pulls harder and with the ported TB it has much more throttle response. Would I switch from an LS2 or LS6 to a 92? Personally no, I don't feel like it was worth it, however if you're coming from a LS4 manifold it's something to consider.

did you have some knock in the 3k range?

I'm not sure where, but I did have knock on 91 octane before he pulled some timing. He said by switching to e85 I could probably pick up another 15whp lol... and I'm running about 11.3:1 SCR / 8.4 DCR

I think it will be pretty tough to break 400 whp with the 4T65 auto. It has roughly 20% driveline loss, so you would need about 500 fwhp to get 400 to the wheels and 500 fwhp is about the highest I have seen for a N/A 5.3L on an engine dyno.

Still some good #'s and it does look nice!

I havnt had good success with intake swaps on my ls4 so dont feel bad. But as fieroguru mentioned its looks good and those are still decent numbers...

My local tuner just got a new dyno and was offering 6 pulls for $100 last month. That didnt include them tuning just the pulls, but since they wont tune a Microsquirt and I do my own tuning so it was a great deal for me.

I picked up a new LS6 intake off a crate motor for $200 and thought I would throw it on and wake up my ls4 some. I did 3 pulls before the intake swap, then changed the intake at their shop and ended up doing another 10 pulls trying changing the tune to get some kind of positive results...

Good thing the shop owners didnt charge me for the extra pulls cause I couldnt get any noticable gains from the truck intake I had on first. In the end I lost 6hp under 3500rpm and gained 8hp above 4800rpm with the ls6 intake.

Now Im sure if I had my new cam installed I sure the results would have been different..

Nice work man!!!

so you went from a truck intake to the ls6 and didnt get much of a gain. did you ever run it with the ls4 intake?

No never ran it with the ls4 intake, just looking at it before I swapped the ls4 drivetrain in I could see that it flowed badly. But the main reason I didnt use it is because I use Microsquirt for engine managment and cant use DBW.

But no real improvement with the ls6 intake over the truck intake. I still have the stock ls4 DoD cam in so Im sure that was why there was so little difference. I have since put the truck intake back on and sold the ls6 intake....

My GXP with 243 heads, Pat G cam, Ls6 intake, DT headers w/3" exhaust dyno'd 350hp/330 lb/ft tq which was good for 110mph in the 1/4. Once I swapped over to the TFS heads my MPH jumped to a little over 113, so I picked up another 30 whp during July. Lots of heat soak (105 IAT)

I was planning on going with the TPiS 90mm intake and LS2 MAF/TB, but was concerned with the dollar per HP gain. I would have spent a little over 1K for 10hp or so..

Very interesting build, and I am glad that there are a few of you left who continue to challenge the LS4 naysayers. 400whp has got to be possible! Make sure your exhaust is up to the task. 3" is a bit too small. I wanted to use a 3.5" collector that merged into my 3" converter with a electronic cutout before the cat.

Data log some VE at WOT for us. I was around 96-98% @ WOT around redline/6200 rpm

I have read that the FAST 92mm is a poor design, and that the LS6 is still superior. A FAST 102mm Truck manifold would be a excellent mod if your willing to do more fabrication. I would recommend going with a electric PS pump, extending your ECU harness and doing a little hood modification. This work can be done!

whats holding these engines back , im shocked with doing heads cam and headers and intake and not making over 400 . 5.7s with cams and ls6 intake can do 370 easily .

is it the headers or what . I know its a 5.3 but ive seen many with heads cam do over 385 easily .

Im not into the ls4 so i dont know a ton about it just trying to get my head around it .

FWD platform is holding the LS4 back. Crap transmission, big brakes, heavy duty axles, and heavy wheels. 18-22% power loss easy. Not to mention that I'm sure the accessory drive is pretty power robbing too. The serpentine belt is 114 inches long:eek2:

Also, these engines run hot since everything is up front. Trans/engine/exhaust and lack of engine bay air flow. Water meth would be killer on these engines since IAT's go through the roof. My tuner had to open the hood after each run, and had to let my engine cool down with a huge fan for 30mins at a time. Not good for dyno numbers.

Its all about air flow and relative displacement. To get the same airflow as a 5.7L engine at 6200 rpm (assuming you use the exact same parts), the 5.3L needs to spin to 6667 rpm. Most guys don't target their build to increase the RPM range that much, or are not willing to give up the tq down low to get there.

My LS4 peaks at about 6800 RPM, using a mostly bone stock collection of LS(x) parts with the exception of the camshaft. My setup has a lower driveline loss (about 12%) so if I built a 500 fwhp engine, I should see 440 rwhp (or a 60 whp gain). But that would mean dropping another $2500 - $4500 into it when I could just build a turbo setup for it and have twice or triple the hp gain.

I have a turbo sitting in the garage I'm on the fence about going turbo or nitrous but either way I can't see the point in n/a if no one breaks 400whp

David I thought the 243 heads flowed very well?

I am swapping a 406 sbc with a 4 speed out of a 62 vette for a 2012 4.8 ls with an automatic. the problem I have is the truck intake is to high for hood clearance. I am looking at and bidding on a ls2 on e-bay but I think that the price has already exceeded the true value. Can some on point me in the right direction cost wise. A couple of years ago I did an ls1 into a elcamino and didn't have anywhere near this problem.