alright so, im not looking to buy anything just yet, but i am looking to learn more.

so, SOHC vs DOHC whats the difference? i mean one cam vs two, but is two better? and how or why?

and these PI head swaps... Replacing the heads on your engine.. is a good thing. so are replacing your cams, or in my case cam. which ties back into my first question.

and then if DOHC is better, is it possible to switch to DOHC withou replacing the entire engine?

and since were on the subject how much longer should i expect my engine to last, especially since im now thinking of putting some money into it.

lots of questions .... thanks for everyones time.

 

The SOHC heads are going to give you a bit more grunt in the lower rpms but when you start gaining rpms, the 4V heads really take off. Personally, a ported set of PI (or the FRPP 2V head) is a perfect match for the 4.6 on the street. However, in all out racing, the better upper rpm power of the 4V can't be beat. The easiest, and cheaper route for you is definately the PI, FRPP, or ported PI route. Just remember, the PI heads will bump your compression up. The 4V swap is possible but too many little details are involved.

 

ok so theres another question i have, what is compression exactly? in reference to this anyway.... more compression equals.... something that gives you more power when its properly done? ive heard people talk about more compresion being bad, but also ive heard its good.

 

Compression ratio is the ratio of cylinder volume over combustion chamber volume. Basically, how much is the volume reduced. Higher compression allows for the air/fuel mixture to burn better giving you more power. However, too much is bad. Around 11:1 is about as high as you can go on pump gas. For super/turbo chargers though, a lower compression ratio is desired so that you can run more boost (around 8.5:1).

 

don't forget... you have 2 cams in a SOHC V8. One on the right head and one of the left. In a 4v motor there are 2 on each side. The 3v engines have kinda the best of both worlds. Nice tall flow numbers and only 1 cam per side. Fewer moving parts, less valvetrain mass, and more potential. I still like the 2v heads. There's a lot left in the aftermarket, we just have to give it time.

 

Also, the 3V heads are smaller than the 2V heads which is a bonus when a 5.4 is involved.

 

alright so.... going back to the heads, what are the main differences between PI, FRPP, or ported PI. im guessing ported is good from what little i know, but what does that mean, besides the obvious. and i have know clue what frpp is, an abbreviation for something? well i look that up but still, what are the differences? im trying to ask questions that i cant just easily search and find, sorry if some of them are basic though.

 

ive been looking through the site and found this



so what does "more aggressive" mean? who makes these more aggressive heads and cams? and if i was going to replace my heads and cams with PI or the more aggressive ones, i would need to reaplce the intake manifold also? what else would i need to go along with that?

 

frpp is ford racing performance products

I think the frpp heads are the PI heads. For your model car (sn95) you will want to pick up a 11 bolt head (Romeo mfg.) so you can use your current valve covers.

I would assume port and polished heads and higher lift cams will allow more air into the engine allowing you to get more HP
to go PI you will want to use a PI intake to line up with the ports, as also as the older intakes choke airflow and make the new heads almost worthless.

Used pi heads can be found for about 300 or so w/PI cams. new your looking at 400 or so per head, possibly with or without cams.

you can Buy a set of used heads get them checked and have them resurfaced ( for the head gasket to sit flush) and replace the valve seats if you have the $$. I was a 4.6L newbie and assumed my stang didnt have the mod done, purchased a set of used heads, only to find out that IT had a full PI head/cam/intake swap and already installed.
a mistake kickin my butt till i sell them LOL

 

ported heads have had material ground out of the intake and or exhaust runners to increase flow. More air in and out = more power. The PI intake is plastic and I hate it for that but it's otherwise well matched to a street driven 4.6.

Properly chosen cams from comp, vt, crower, AFM and others will really wake up the motor.

PI heads are stock 99+ stang heads. If you're going to spend the money try and find yourself a nice set of ported heads and some good cams...vt stage 1 or 2 are popular, as are comp's xe2xx line.

 

The FRPP heads are not PI. They basically are PI heads but they use the NPI ports. The FRPP just bolts in while PI you need a matching intake manifold, alternator bracket, and probably other little things. Plus, w/ the FRPP, you have room for more power since ported versions flow better than the PI version. Also, if you plan to supercharge, the FRPP heads don't increase your compression like the PI heads. Basically, your call but ported PI would be the best route since the aftermarket won't support the old NPI style heads.

 

Yep 3v's will give you the best of both worlds low end power on par with the 2v and great top also. 3v heads are about 20 pounds lighter aside than the 2vs. I went with the 3v and dont regret it a bit, only thing is that it is not an easy swap.

 

what are some good site or companies that i can look at that make good high quality performance "aggressive" heads and cams and all that? ive tried searching some, but its not like looking for exhaust, seems its a little harder to find...

 

eventually down the road when i get enough cash i do want to get a supercharger i think... kenne bell im thinking right now, but thats so far away. right now i want to beef it up and get it ready for the supercharger. so thats my long term plan if that changes anything.

thanks for all the help so far btw

 

for heads check out fox lake racing, VT Engines, Steen Racing, DSS Racing, Modular Mustang Racing (MMR), and many other fine retailers. Shipping to Alaska may be a tad rediculous. Never know. For cams, wait till you have a blower inbound. The cams you'll want for a blower car are different than what you'll usually want on a NA car.

If you're going to go all the way with the blower and heads you may as well pop the extra couple grand for a built short block. It'll save you money down the line.

 

so with short built shortblock do you mean a brand new engine which means new heads and cams that comes with a blower? and that would cost what 6-8 grand?

 

a short block is the bottom half of the motor without any of the heads, cams, timing cover, intake or oil pan. Heads and cams will cost you about 2K, a built short block will cost 2k-999999999million. Nothing comes with a blower.

Heads, 2k w/ cams
Shortblock, 2500
Blower kit 3500
misc parts 1200
tune & chip 500

Spend some time searching around the interweb... we can't educate you from scratch.. you need to know some basic terminology before you're even remotely qualified to pick your own parts.