@snrusnak I don't think long tubes will give you much joy with this motor. It's already weakest on the bottom of the tach. Looking tubes will forget rob from the bottom of your powerband. By the time you get the motor set up to make use of long tubes, you could drop in a 392 crate, and make the same numbers, plus get dd mileage out of it.

 

Well keeping the primary tubes to a smaller diameter should not lose any low end. It's a fairly small v8, so 1 7/8" primaries aren't needed. I disagree and think there's a lot to be gained if you look at how restrictive the stock manifolds are.

 

the stock manifolds do fine, unless you start to run boost.

 

Yeah they do fine but there is more to be gained just like any other engine where you're looking to increase performance. There's a reason that just about everybody who is serious about performance swaps their log manifolds for headers.

If all I was looking for out of my truck was for it to run fine then I wouldn't change anything from the factory, because it already ran just fine.

 

I read the stock manifolds were awesome for boost.


My boost controller isn't installed yet and I have no problem finding boost..this is with stock headers.

 

^I'd agree with that. Boost makes it easier to overcome poor flowing intakes, heads, and exhausts, so those three things become less important than on a NA vehicle.

 

in some cases yes.

the reason headers make more power is because of the way they RUN off the block and they dont just hug the engine, my stock manifolds used to PING so bad, when i got headers now it sounds like a 1970 hemi.

stock headers or manifolds?!?! jw not trying to be a smart ***....

 

ur right, stock manifolds

 

I don't come on this forum very often but did want to come back and update this. I put my torque converter in finally this weekend, and my quad cab 4.7L really moves out pretty good now. Next time I go to the track I'll update how much it improves my time. I'm thinking it'll be a couple tenths faster. Unfortunately the heavy wheels and tires kill my acceleration. I probably won't go for a while though, I don't make it out there very often, I'm really just building the truck so I can have some fun on the street. Maybe I'll use the flashpaq to get a comparison of the before and after. That should at least be close.

Oh and I know a guy on another forum with a 2010 4.7L single cab, running 17" wheels with 26" slicks, flashpaq, airaid CAI, and muffler delete and he ran a 14.9. He now has mech fan delete, 180 tstat, ATI 25% underdrive pulley, and I think an aftermarket y pipe. He has 3.55 gearing and open diff, I think he is going to swap to 4.10 and LSD. He ought to have one heck of a runner there. He's hinted at either turbo or juice as well.

 

Running the stock cats and Y-pipe the stock manifolds on the 4.7 do OK, however when you ditch the cats and build a custom exhaust they hold you back considerably. Between the JBA headers and custom catless 2.5" exhaust with Magnaflow dual in/dual out internal X muffler, I gained over 35 ft/lbs at the wheels with HO cams and 25 HP. With hand ported/milled heads and 218/224 cams the truck is making 290 RWHP/308 RWTQ with Superchips 91 tune and a PSC-1 for fuel adjustment. Runs low 9s in the 1/8 despite stock torque converter, 3.55s and 31.5" tall AT tires. Truck crosses the traps at ~76 mph in 2nd gear at around 4,500 rpm. I did some before and after dyno'ing on the truck.

06 Flexfuel 4.7, HO cams, 2008 intake, JBA shorty headers, stock exhaust and intake, 180*F thermostat, and IAT resistor

vs

06 Flexfuel 4.7, hand ported heads, milled .015", 218/224 regrinds, solid lash adjusters, 2008 intake, 4" custom CAI with custom heat shield, JBA shorty, 2.5" catless duals with x-pipe, Superchips 91 octane tune with a Split Second PSC-1, running with 09+ 5.7 injectors

Air/Fuel mixture was not recorded but in the high 11s, low 12s on both, seems to run best there.