Hello everyone! I have 2014 XJ 5.0 SC and I plan to do intake, exhaust, both pulleys and a tune. I have not seen many people upgrade their exhaust, is there a reason why? I would like to do a 3” cat back exhaust with an H pipe. H pipe because I read (past tense) its not as pitched tone as the X pipe. I dont want a really loud car, Im going more for performance than sound. Does anyone have any experience with a 3” exhaust? Can you comment on that?

Here is my intake pipe in the making, I do plan to enclose the filters and keep the OEM fresh intake horns. Its going to be 3” as well.

Thanks guys.

 

Unless you're going ***** deep into a build to include an R2300 swap and making the Ardent headers fit, leave it. No power will be found in the intake or exhaust and if anything, you'll lose a bit because you're eliminating the helmholtz resonators on the intake pipes. And while this is subjective, I think these things sound like absolute *** when you uncork the intake.

 

Really??? No I will not be doing a swap nor headers. What do the helmholtz resonators do that make it lose power if removed?

Thanks!

 

The resonators works by natural resonation of air in cavity. If removed you get less optimum airflow. On forced induction this is not so notable, but in naturally aspired the effect is huge. There are engines where Helmholz effect are used as supercharging.
Your OEM air intake are well over the capacity your engine can take in max rpm. You need to improve if you: Increase displacement or you increase max rpm what both make your engine to breath more. Of course if you are do look more sound instead of power, then go on and mod it. (there are plenty of power on 5.0 SC)

 

Gotta agree with Mandrake. But try it and see? I think there will always be a small benefit at least.
I have been under my car a good bit and that 3" exhaust job will be tough?

Post up some more pictures of what your doing!
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Dang! I always thought those things on the OEM intake pipe were to muffle the sound to make it quieter and was a bit restrictive due to the folds the pipe has. Well, the intake pipe is made, dont have pics of the entire thing yet but was sanding the inside of it I guess for less turbulence, if any. Here are some pics…

Cant believe, or understand why a 3” exhaust does not add any performance over stock. I guess I have to read a lot more on that. Not that I doubt what ya’ll are saying.

I will post more pics..

 

Any engine tuner know that intake should not be smooth. You actually increase the drag. (an golf ball have these tiny holes in purpose)
The Ford (or any engine manufacturer) have been spend decades to learn secrets of engine intakes to take most out of the drop of gasoline. The best lab have been F1, WRC, LMS, .. where ever factory teams compete. These solutions are taken to the standard vehicles too, specially after when economy and pollution were really taken in to the counter.
Think this: Your SC will have any moment more air to offer to your engine what it can take in by any rpm. (Positive pressure, even in max rpm) Naturally when pulleys are changed the pressure increases, but only little more air is pushed in to the cylinders, its more about combustion pressure. If you want to improve an flow what matters you need to focus areas between SC and cylinders. SC will get all the air and huge much more needed thru std intake system. (as long as your filters are not blocked)
OEM intake is capable well over what 5.0L can take on max 6000rpm. Increase it to +6.0L or move max rpm to +8000 and then you need to remake the intake.
Of course there are other gains with custom intake like sound.or just visual. If you are after that, then go on.You have plenty of power anyway. and probably just by sound it will feel quicker

 

Thanks much Mandrake for the mention of Ardent Performance as I have not seen their stuff before.
I don't plan on headers but they do make a very nicely fabricated set for about $2900. Note that even the header guys keep the rest of the exhaust system stock.
XFRS 5.0L Headers

I think the XF and XJ would use the same headers but not sure?
I like that they don't advertise HP or TQ numbers too. So many claim big increases where there are none?

If you do want intake noise and blower scream you can get that. Install cone filters and open up the stock air boxes.
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Thank you! Thats good to know, I appreciate your time. I guess the SC scream is gonna have to do. I had read about the golf ***** a while back but If remember correctly the dimples helped due to the distance the golf ball traveled (some 400 yards?) I could
be wrong, it was a while that I read on that. But again thanks a lot!

 

Correct. With dimples the ball is more slippery when moving thru the air.
When i tuned an engines for racing in past of the days, i used acid gel after modifying the intakes for finishing the channel surfaces. (if the rules allowed modifications and if the intake needed to be worked by example increase of max rpm)

 

I'm grossly oversimplifying this, but the helmholtz resonators act kind of a like the tuned pipe on a two stroke engine. They reflect the sound waves back into the intake. Sound waves are pressure waves, and if you're hearing a sound coming from the intake, particularly SC whine, then you know that pressure waves are escaping opposite of the desired airflow direction. Since pressure waves have the ability to influence the movement of a mass of air, if they're going in the opposite direction of the air you're trying to move, they're slowing that movement down. In even shorter terms, noisy intake = reversion = less flow going the way you want it to go.

No difference in exhaust manifolds across the entire AJ133 line, all the way from an NA version up to Project 8. Go look at a set of them on eBay. Them and the cats are where the true restrictions to pumping losses come from on these cars. Unless you're talking a single 3" exhaust, a dual 3" exhaust is going to take all your low end away and given their gross oversize compared to the power output of the engine, they're probably taking top end away as well. What happens with a gigantic exhaust is that you lose exhaust gas velocity and as a result, the scavenging effect it creates. A dual 3" exhaust is going to be so overly huge that the engine will never be able to produce enough exhaust gas to regain the scavenging effects. This isn't the 1970s... the intakes and exhausts on modern cars are far less restrictive than what the old farts and those too stupid to engage in critical thinking want to tell you... right after they lecture you on how "an engine needs back pressure for low end torque." 🙄

If you really want to take a deep dive into engine and exhaust theory, just about every automotive white paper can be found here: https://saemediagroup.com/ Knowledge is power, power is movement, movement is progress.

 

OK,

Severe thread drift here...

I'll put my Test Pilot and aeronautical engineer head on here.

1. Dimples only work on small bodies, but they do work. A golf ball with dimples will travel about 50% further than a plain sphere. The dimples create a tiny boundary layer that reduces friction drag, if we combine that with the spin of we also create lift.. However, a secondary effect of lift is drag (see how it gets complicated really quickly). Think about this, do you see aircraft with dimpled surfaces?

2. So, as we aren't interested in lift within an intake (think of the inverse, where the air is the sphere and the ball is now a tube), we want to create the smoothest path for our precious air to follow....Well yes, and sadly, no. If we create a very smooth surface for the flow across we will end up with something called 'Laminar Flow' ( the P-51 had /has such a wing). So, 'Great, what's the problem', well a laminar flow can only stay attached to the tube/wing in ideal conditions, after that it goes nuts and turns into a turbulent mess. What I'm saying is that if you attain laminar flow, and the ask it to turn a swift 90, you'll have problems.

3. All of this is quite stupid as you can do what you like to airflow, but it's a waste of time if you then shove it into a supercharger than, by design is going to mash it into a tumbled mess.

4. I'll admit that I have never studied gas flows in small diameter tubes but, I can't see how anything over the OEM set-up would result in extra hp.

wombat

 

I gather it's been a while but if you're a test pilot & aeronautic engineer, you must've been through fluid dynamics - an elemental must for any jet pilot I believe.
Many prefer to forget those classes along with discrete structures (one I could I think I could have done without myself anyway), diffy-q's & what not though, and with computer tools & calculators we have now, some say we don't need those classes any more anyway...
But then since you've moved through that phase of your life, the college classes that got you there have long since served their purpose & yielded to the real-world practical arts & sciences that apply after getting those credentials..

 

I'm sorry, I don't understand your reply.

I'm a current TP, and I work with the a/c designers on a daily basis. The construct of Pitot /Static systems has evolved beyond all recognition in just the last 5 years. Without going into classified details, the need for tubes and ports is no-longer required.

wombat

 

12jagmark.

If you would like to challenge me over my knowledge of aerodynamics, and fluid flows, perhaps you could enlighten the forum why pitot probes on modern airliners are angled below LFD?. And, why they won't be in future?

wombat

 

Oh, this is going to be fun.