cgolden87

Ok guys so I’m a bit of a newbie at this so bear with me. I have been thinking about upgrading my whole intake system, filter to lower plenum. But I don’t want to make the mistake of having to buy the same part twice, I want it all to work the first time. From my understanding, and based on what I have learned from others, the idea is to get more air in there faster and with as little turbulence as possible to help the engine breath better. So go bigger throttle body, intake, etc. But at the same time bigger is not always better if the parts don’t match properly.

If I put a 75mm throttle body on and don’t match the rest then I’m going to create a bottle neck point where the openings don’t match and that choke point will create less clean flow going into my intake. I planned on using the Cobra intake from Ford Racing but I don’t know the opening size. I assume that it must be the stock 65mm, but if anyone knows for sure that would help. Another question I have is if I buy that intake can I have a shop polish it and possibly bore the opening open another 5mm to bring it up to 70mm and increase the airflow. After that I could get a larger throttle body, mass airflow, and cold air intake. Also, I noticed several companies sell throttle body spacers, has anyone used those and found that they make a real difference? I think I would do all of the work this summer and do it all in one shot so I want to get a parts list together. Any suggestions on those parts and what you all would recommend based on previous experiences would be greatly appreciated.

Also any insights into airflow in general are welcome here since I am trying to learn a bit about the subject. This is an opportunity for the gear-heads to educate a newbie, thanks guys.

varam03

You are on the right track with what your saying.,...but take this advice as it comes from personal experience and lots of reading...anew mass air, throttle body, and intake tube/filter setup is worth at most 10hp and thats coming from stone stock parts to new aftermarket parts..thats at least 500-600 dollars in parts for 10hp..an intake manifold is worth about 10hp more, when your using stock heads, and there is another 500$...then the stock heads become the bottleneck,but this time, plan on 300for heads at a junkyardand then another 200 to rework(basic porting andmilling)a pairof gt40 iron heads from an explorer, then 100 in bolts/gaskets, but they are probly worth 40hp with the preceeding mods... see my point? all these mods cost similar, specially if you go with iron heads...if you cant afford to do it all at once, do the heads first, then the manifold upper and lower later...then move out to the tb and then mass air and then air tubing...why this order? because if you do it any other way youll be removing parts twice...I did mine this way and bought mostly used stuff off ebay and just ran a high 12 on a 168k mile stock shortblock, stock cam motorwith iron gt40's and an edelbrock performer 5.0 intake manifold..3.73 gears and basic drag springs/shocks on MT et streets.. no nitrous..etc..

cgolden87

So I gather from your post that the best approach is to start from the bottom and work up as a matter of convenience and when power is the prime consideration. My issue is that I am also just a beginner and the idea of getting in there and swapping the heads is a bit more intimidating than simply changing the intake, but I appreciate the insight. Those HP figures seem a lot lower than I would expect, but I’m guessing they will make more of a difference later on when more modifications have been done internally.

varam03

Don't be scared, have a little faith in your hands, go to sears, buy a set of craftsmans metric/standard tools for around 200$ and a good extension/swivel set for your new ratchets, and go to work, might need a torque wrench too, sears for around 30-40$...until last november I had never driven a 5.0..now ive rebuilt the upper end, there are about 25 step by step bits here with pictures...on exactly what to loosen/tighten..etc..I did my heads in feb..and it was laughably easy when I look back on it..its the wiring thats a little challenging..the heads themselves are only head on with easy to access bolts....theres not much to screw up unless you cant follow instructions...and as for the horsepower numbers looking low..thats because the stock heads are the main bottleneck on the 5.0 with the intake manifold being the next in line.....once you change those out, even with some junkyard ford explorer gt40heads, especially if you port them...you awaken the motor for a mild street build...until those heads get changed though, your best bet for any real horsepower is nitrous or a charger...or you could get gears and suspension and get down into the low 13's at the dragstrip...with a decent tire out back......point im trying to make is...set aside a couple days and have your parts layed out, do some reading...and have a spare vehicle for parts store runs for stuff you forget..and go to town under the hood...best part is, youll understand how an engine works when your done...and that makes it 50000% easier to fix it if it breaks years later

nitrous_bob

ok, first off no matter what ne1 says, you do not need more volume in an uncompressed form. your fine where you are, you'll spend $1000 to upgrade all of that and gain about 5 hp

now see where you said "more air at a faster rate " ???

simply opening up the area creates more volume but slows down velocity. and you don't want that. the stock induction will support about 300 hp, the biggest bottleneck is the heads. thats where you need to start in the induction, unfortunately when you do the heads you will then benefit by the intake as well. so that whole thing is a bit pricey.

not sure how stock you are... but what you need to do on a budget is make what you have work better. my '89 ran 13.20's and the valve covers had never been removed...just 4.10's, long tubes, smog delete, cai, et streets and some other minor crap. 5.0's are torquey and have a nice hp curve, good gears ( 4.10 is the only choice imo) and cheater slicks will do the same for you as adding 100 more hp if you are currently stock geared. and after that, you can increase traction even more w/ lca's and some more minor suspension work (air bag, drag shocks and struts) if you can improve your 60 foot time by 1 tenth... it knocks off 2 tenths on your ET.

i know this isn't where you wanted to go here... but since your asking , and willing to listen , do it right the first time.

anyways... do that stuff first, then maybe spray a little to satisfy you til you get enuff for the whole HCI swap. or even just heads, intake swap and maybe 1.7 rr's, a little less involved and very streetable. also will be capable of running 12's on motor and 11's on the juice.

mjr46

IMO....messing with anything factory produced= waste ...ie cobra intakes, gt-40 heads ect ect........I'd buy a crate motor if I were you but I know budget often dictates the choice of lesser components but honestly I feel an INTAKE AND THROTTLE body bolted on is a waste....when I do mods to the engine I go more for the seat of the pants feel and in this case AN H/C/I should be considered as 1 complete mod for best results

cgolden87

Well I guess more background is always a plus. From what i'm getting out of all of this there is little to be gained from spending all of this money on the top end. The engine is a 91 5.0 and the car is a 67 Fastback. If your curious hit the link.

As far as my current setup goes it is relatively stock. The cam is an E303, the exhaust is good except for the stock manifolds that need to be replaced with a new set of headers. I recently switched the whole igniton to MSD, threw on a 6AL box, new wires, coil, distributer. And I just installed a set of underdrive pulleys. The idea here is just as much about show as it is about more power. I wanted to make my engine bay as presentable as the restof thecar so I am not looking for tenths on the track. That being said a Mustang being all show and no "GO" is pretty lame, i'm looking for a balence between the two. I am going to stay away from the bottle since I don't fell i really need it, but I might supercharge it later once the engine is built to handle it.

My long term plans for the car are probably somewhere along the lines of making a little bit more power and polish for now and then eventually building a completely new lower end. Bored to a 347, forged pistons, etc etc. That seems to be a very popular route for making a lot of power.

For now I'm just trying to find ways to keep myself busy and learn a little more about it with simple mods. Also I noticed you guys throw H/C/I around as well. Hate to sound like an idiot here, but what are those abbrevations? (Headers, Cam, and Intake maybe)

Either way it sounds like my money would be better spent at this point on an electric fan or saving up for a good set of heads and worrying about airflow later on. By the way thanks for the help guys

67mustang302

Velocity in the induction system is definately very important, and often very overlooked. There's no need to go bigger than a setup that can feed the rest of the combo, otherwise you sacrafice velocity, and often, power. As far as turbulence, that's a double edged sword. Some turbelence is bad, as it disrupts airflow and may have negative impacts on velocity and atomisation of fuel as it enters the cylinder. Some turbelence is good if it helps with atomisation and allows for a faster rate of combustion. Induction systems are far more complex than simply how much they flow, which is why there is a lot of research that goes into something like a good set of cylinder heads for instance. Some heads that have smaller ports and may not seem to flow as much as other heads, make more power by eliminating bad tubulence, taking advantage of good turbulence, and keeping velocity high, as well as having a design that allows for more rapid combustion. There's a lot of wierd stuff that goes on in an induction system, especially once the air/fuel starts making it's way through the intake ports on a head and past the valve. Experience has shown that in most cases(particularly on street engines) the best power is made with a "smaller" setup than most would think appropriate, provided it's of good design.