So if you put a spacer anywhere it should be between the upper and lower. But..... would it surprise you to find out the runners on the 5.0 truck intake are actually larger than those on the 5.8 truck intake? It surprised me the first time I saw it, and knowing that the 5.0HO motor makes more TQ and HP with a bigger cam than the truck motor, you have wonder why Ford used this intake on the trucks. Here are uppers from both truck intakes flipped upside down so you can see the runners, 5.0 on the left, 5.8 on the right.



The pic is not on the same scale but here's the 5.0HO intake. BTW.. the difference in total runner length between the HO and truck intakes is only about 1/2".




So...... On a budget your options for added low end power are..

1)swap on a used 5.0HO intake and add a spacer between the upper and lower
2)install longtube headers
3)upgrade the cam

Right now the 33" tires are killing you. Gearing should really be the first thing you do.

 

Thanks, the 33's are killing me. I would like to re-gear, but as I understand it, its not that easy. And also expensive. I figure, if I have to take them down that far, I may as well put some type of locker. I was thinking about lower than 410's and higher than 488's. A 456?
Also, with the different intake, would I need computer modifications?

 

Ok, let's see how slammed I get for this:

The Edelbrock EFI Truck Intake has the long, skinny tubes, sitting up high, just as the bone stock Intake Manifold. Ford did that for a reason I believe...if not, then why didn't they just put the 'stang intakes on all trucks? Would have saved them $$. (I personally would like to see my set-up in a stang w/ cowl hood to see how that truck intake etc. would make it go). I understand and appreciate the analysis of why TB specers are useless, but what about the fact that it is well known that certain cylinders (#1 vs. #8) consume more of the available incoming air than others---naturally aspirited of course which equals less efficiency. Would not the spacer help break up the air flow path of dominant cylinders somewhat for better equalization of available air to all cylinders? The search for perfect efficiency seems to never end does it? Give me a blower.......

Now, if you are on a real budget and have some skill, you can port your own upper and lower intakes larger and smoother. Alternately, you can port the lower intake only to allow the upper to "dump" in easier.
While you are in there, pull your heads and take them to the cylinder head shop and have them worked over real well, you may be surprised how economical it may be, and some of the folks, at least here around Charlotte, are real good at it. You can get flows very respectable to the high $$ heads for a fraction of the cost. If you do not want to touch yer motor, then I agree that a gear swap is probably the most under appreciated, but real sleeper upgrade. Dollar for dollar, about one of the best upgrades you can do. Finally, if $$ is really, really limited, consider a chip, which will bump things up a bit and make that 5.8 feel more like getting up and going.

 

Thanks for all the info. People on this site are very helpful. This is not my daily driver, so I may be able to do some of these mods. I am prefering to leave the motor alone until I have to rebuild it. Then I can do it allat once. You make an interesting case about equal cylinder air use. I have heard before that anything for the intake should do better when the walls are rough and the exact opposite on exhaust. For example, getting valves re-done on ur head, the motor would perform better from the intake valves being left rough(in the chambers, not the edge) and then the exhaust would be polished to allow air out better.
By the way, I bought this truck less than a month ago and now I have a huge list of things I want to do to it. Thanks alot, HAHA

 

I won't slam ya... your info is a little incomplete that's all.

The Edelbrock Truck intake actually has longer runners than the stock intakes, about 4" longer, and they are smaller than the 5.0 runners, but a little bigger than the 5.8. This follows the general guidelines for Tuned Runner Intakes and tries to better match runner length to the desired powerband and airflow, and people report it does improve power on stock motors. As for the Ford 5.0 truck intake, I really believe they messed up and got it wrong and then didn't bother fixing it. This was the first truck motor that got EFI, so if it was a good design why did they make a totally different version for the 5.8? Wouldn't it be more cost effective to use the same intake with different lower sections? Who knows why this happened.

The imbalance in airflow to different cylinders you speak of has more to do with the curve and shape of the ports in the lower section, the truck uppers flow quite well and are very symetrical. In the lower the center ports have a straight shot at the valve but the 4 corners have to go around an S bend. Most of the aftermarket intakes including the Eddy Performer make an effort to correct this, the lower section is much taller and all runers are relatively straight, so cylinder balance is much better. Compare the shape of the front runners in particular on the intakes below, that's Eddy Performer and Victor on top and the stock intakes below.

 

If you are going to stay with 33's I would go 410 on the gears. That will be a little lower than stock. I had 35's with 456's and it was great and now I have 488's with 38's and I like it. I think if you go any lower, you wont like it on the highway. I agree if you go inside the diffs, get lockers.

 

That's good info for sure......and we all know the pro's and con's of what Ford puts out on the market....Maybe the wider deck width on the 5.8 has something to do with the height in terms of engineering and costs?.....who knows......I think a lot of us, at the time, with the $$ to spend, were/are willing to try and do about anything to gain as much (peceived) out of a motor as we think we can.....good customers for Summit I guess.....

I can't comprehend 4:88's unless for off road only......

 

hey guys i know this thread is a little old so sorry to repost...

but on the subject of gears. i have a 2006 ford xlt f250 5.4l triton v8. motor is completely stock, i want to get going a little quicker but i dont want to be screaming at high RPMs going down the highway considering its my daily driver and im on the highway alot, what size gears would u recommend for me?

 

I would suggest checking with the guys in the forum for your model year truck. While the guys here in the Bronco forum are likely to have good answers for you, the question may have a good answer in that forum already. I could only offer an educated guess and suggest "one step" (meaning the next most common gear ratio taller that is commercially available) taller than whatever is in the truck right now. You MIGHT be able to go taller than that but I don't know transmission gearings or even what the factory axle gearings are for your truck.

 

Conanski - "The imbalance in airflow to different cylinders you speak of has more to do with the curve and shape of the ports in the lower section, the truck uppers flow quite well and are very symetrical. In the lower the center ports have a straight shot at the valve but the 4 corners have to go around an S bend."

So why do think they stagger the gt40 ports; for a shorter path or for better velocity??

Compare the photos, does the gt40 351w lower look any better/worse in terms of the s bends than an eddy performer lower (looks about as straight to me)?

Do you think the round transitioning to square (gt40) in the lower or square straight through the lower (edelbrock truck/stang performer) would have better flow?

Also, I haven't measured yet, but the eddy truck performer (5.8) lower is considerably taller than a stock truck 5.8 (very short), any idea where a 351w gt40 lower (lighning, cobra R) stands in terms of height in comparison to those two??

These intake discussions always interest me. I cant wait until I have a solid understanding of fluidynamics....(someday)

Oh and as for the throttle body spacer thing, my uncle bought me one(street & performance products brand), I put it on and I think I made myself believe it did something when it didn't (stupid unreliable butt-dyno). It may have done something at WOT (maybe) but another buddy of mine took his off (poweraid) and said his torque band felt better, but his truck runs pretty strange regardless. Anyways if somebody wants a shiny red anodized piece of metal between upper and TB that's supposed to swirl intake air more than a foot away from where it ever enters the combustion chamber you can send me your money ($50) and its all yours.

 

im bringing this thread to life for a second time to talk about the fuel atomization a little more...has anyone ever heard of adding fine stainless steel screen in between the intake and head covering the port holes? the theory is that when the mixture hits the screen it gets busted up more thus helping eliminate droplets of fuel. i thought about it for awhile and came to the conclusion that the added benefit of atomizing the fuel more would be negated by the fact that you are essentually reducing your port size by using the screen. not to mention the possibility of sucking a peice of that screen through your engine should it deteriorate or come apart somehow. anyone tried it though?

 

The design intent of the GT40 intake is unknown but I suspect it's all about packaging, putting 8 round tubes in a row would have made the intake too long front to back. There's no real downside to transitioning from round to square or any other shape as long as it's done smoothly and overall port cross-section remains constant. But surprisingly the stock lower intake sections all fail to some extent in this regard, they all narrow down to dimensions less than the port opening on the heads and this hurts airflow capacity. The number of bends also has an effect on airflow and measurements consistently show the runners on the front and rear of the stock lower intakes flow less than those in the middle. A guy that goes by the handle Tmoss over on the Corral forum has done extensive testing on the stock 5.0 intakes and has a very good reputation porting them to balance airflow between runners and increasing overall airflow.

Here's an end shot of the stock 5.8 truck lower and the Typhoon/Performer lower in my shop. The GT40 lower may be a little taller than the truck lower but I don't think it's as tall as the Performer. According to Tmoss the GT40/Explorer intakes can perform as well as the Performer with some porting work, I suspect overall port volume is similar so that's not surprising.

 

Performer's tallest, gt40 next, and of course the uber low 5.8 truck lower.

The gt40 lower ports going into the head seem to be a slightly larger area (easily fixed with some gasket matching).

But here's where I think the performer outdoes the gt40 lower, runner curvature. It seems like the performer has considerably straighter shots on runners 1, 5, and 6.


I calculated that the eddy performer has slightly more more port area at the top where air enters the lower (2.226 sq. in. ports) vs the round gt40 style ports (2.074 sq. in. ports)

 

do you have to buy the lower and upper do they come in a set when you buy the performer? will the stock upper fit on the performer lower or do you have to match the set to get any benefit out of it? also do you need to get a bigger T.B. to go with the intakes?

 

You can order just a lower if you want, however the 5.0/5.8 truck intakes have very different port shapes and wouldn't work with the preformer/typhoon lower. The edelbrock 5.0/5.8 performer efi truck intakes do not require an aftermarket TB.