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which head for the 4.6L?
which head is the best? barring money, whats my best bet. i want to make at least 300hp n/a when im "finished" but i also want to stay emissions legal. i have heard that AFR makes great heads and that the 185 is a good head, but i was reading a little and it seems like its for the 302-351 engine? or can you use it on the 4.6L engine. so which head is the "best" and what kind of horsepower increase can i expect from it. (or should i do intake first, i cant afford to do both at once unfortunately).
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While I don't know very much about aftermarket heads for the 4.6L (almost nil :D). I do know that the AFR heads are not going to fit on your 4.6. Nor will any 302 or 351 head. You need an OHC head. I believe ford has one, but there must be a few more choices out there by now. Pick up a MM&FF and check the ads, there has to be someone in there that is selling them.
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I think the Bullit heads are a popular choice. Don't know for sure but I am quite sure I have seen them mentioned before. Do a search and check them out.
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The best flow numbers (stock) for an aftermarket OHC head are the ford motorsport pieces... very nice and very expensive...
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Los - so are you sayin i cant spend $1200+ and get aftermarket heads?
Hammer - yeah i read on some websites about the FMS heads... i noticed they have good numbers and are $$, but i guess i have it stuck in my head that if its still ford, its not "aftermarket" and couldnt be as good as other brands, stupid thinking but thats just what registers when i hear it. when you said that they have the best flow numbers (stock) you meant without being ported etc. right? can you buy aftermarket heads that are already ported or anything? i mean, why would you buy aftermarket heads then have to have them ported again, you would think it would already be the best that it could be. sorry if that is a stupid question but i dont know much about this. thanks for your help.. anyone have any experience with different heads on their 4.6L or are you all using stock and ported or 99+ and ported? |
just buy th head swap kit it makes decent power increase and the engines will be rated at about 275 if your still stock. well worth the 1200.00 kit
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which kit are you talking about, exactly Badass_yellowGT? so that kit adds about 60hp? 215 stock to 275? thats a pretty good increase, more than i would have guessed. would you suggest this kit over some FMS heads?
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The 99 PI heads\intake swap gives a good power increase for a decent amount of miney. It is also not a direct "bolt-on" and minor changes to your setup have to be made. Bad news is that compression is increased and its not to friendly if planning on going forced induction.
The Ford Motorsport Cylinder heads flow better (more horsepower) and compression ratios are much more favorable if you go to forced induction (blower). Bad news is they're quite expensive... Quote:
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In my opinion, if money is no object, the route to go is the FMS heads\intake combo. It's almost a straight "bolt-on" affair, gives great power numbers, and is ready for a blower when you are. My old 98 with that setup made 385 hp at the rear wheels with about 6.5 lbs. of boost present at the intake (8 lb. pulley)from the blower. This was with a conservative tune keeping the timing down. Over 400 rwhp would have easily been attainable with a more aggressive tune and a 10 lb. pulley. |
thanks, you're response is just what i wanted to hear. i do plan on going for a blower eventually *if* i ever get the money. i might have a new car by then, but i do want to set it up right in case i ever want to. the FMS intake/heads sound good. like i said i can only get one or the other then save and get the other, i wanted to get heads first but should i get intake first? what kind of hp numbers can i expect to add with just heads? with just intake? with both?
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The best bet for the 97 gt's is the FMS heads, the FMS intake or the FMS screw type blower wich replaces the intake. These are costly but will work best with the engine and other components. No real aftermaket heads are available, only ported 99 PI heads. FRPP has a set of heads for the 96-98's for about 750.00 bucks that I saw on the GEF racing site. Don't quote me on that price!
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Actually there are more than just the FMS heads out there. Sean Hyland Motorsports makes one. I am about to get my PI heads ported/polished/valved with comp cams and springs. I will post back with dyno #s after the work, but I was told I should see no less than 300 at the wheels.
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Yes but they're not like "AFRs" or Trickflows. They're the same mill PI heads found in any 99+ GT, ported and whatever else and sold at a high price. You'd be better off sending them to a place to get it done yourself.
But SHM and most of the other aftermarket support groups sell great heads. |
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I don't know about anybody else, but I think AC97's question had to do with a performance increase, not what the term "after-market" meant....
I couldn't care less who makes it. Ford, Trick-Flow, SHM, or God himself... The determination of what goes into my car is based on two factors: price and performance. |
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thanks for your replies. i was just curious what is out there. im actually surprised to hear there really arent many options, i thought there would be alot. it sounds like the FMS heads are my best bet.. do they make more than one model, if so which is the one that i would want? what kind of numbers can i expect on an otherwise stock engine?
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Just going from your factory NON PI (power improved) heads to a set of PI heads like the SHM with a port and valve job you can expect to see atleast 40-50 rear wheel HP over stock.
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As stang00 said, port and polished PI heads can expect around a 40 rwhp increase.
From the factory FMS heads alone will get you around 35 rwhp, add the FMS intake, and you're looking around 45-50 rwhp. These are all stock numbers from the factory, so any additional work done SHOULD give you an even better increase.... The worked over PI heads give you an extra 5-10 rwhp at peak, but the FMS heads give a better power output along the curve, lower compression ratios, and room to grow if need be. Part #s: M-6049-D46 : heads M-6067-D46 : Head changing kit M-9444-D46 : Intake install kit M-9424-E46 : Intake Manifold Possibly a new Engine Management Computer (M-12650-A461 Auto trans. or M-12650-B461 Manual trans.) or custom\dyno tuned chip with the stock computer. I would contact Ford Racing (586-468-1356) or another knowledgable company such as Dallas Mustang (800-MUSTANG) for specifics on your application and help with purchasing the exact parts you may need.. |
awesome. thanks.
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The FRPP heads outflow ported PIs straight out of the box, throw port work on top of that and they are ther best bet for performance, BUT at a much higher premium. FRPPs will cost near double the PIs new for new, unless they've come down recently. Another good question for you would be what are your overall plans for the car? If you ever decide to go with a power adder you need to know that the PI heads will increase compression on your motor and create a very N2O happy environment, whereas if you decide to go with forced induction the FRPP heads will leave compression unchanged, a better environment for boost. |
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I also don't like to estimate high and then see someone disappointed when they get it on the dyno... |
I am surprised nobody has brought up the fact of porting a set of 96-98 non-PI heads. The PI swap gained a ton of popularity because out of the box it adds decent power, but 30% of the gain comes from the PI cams. When you start talking about porting, you can get the 96-98 heads to flow better then a set of ported PI's. Then throw in a set of PI cams and you have at least as much or more power for less money.
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Because when ported, the PI's don't flow better.
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Bill |
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Renegade Racing has been doing this for a little bit now, and they get better intake flow numbers from the ported NPI heads then they do the ported PI heads, but on the same note they get better exhaust flow from the ported PI heads then from the ported NPI heads.
Also, you will probally make a little more power with the ported PI head then with a ported NPI head because you are getting some power from the higher compression that comes with the PI head swap. There are ups and downs really. If you use PI heads you up your compression so it would be harder to use a supercharger with that much compression. But with NPI heads it will stay the same the compression and you can boost your 4.6 with less fear of detonation. IMO, the renegade NPI's offer a better bang for the buck then converting to PI heads and the other parts required. |
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Also just a heads up but the intake side of these heads isn't restrictive it's the exhaust side so by opening up the intake side even more it isn't going to help as much as opening up the exhaust side more. Bill |
Here's what a set of Renegade's heads flowed for a friends street car, and Jim could have gone a bit more, but he wanted to keep the port ratio at around 70% for a good split.
intake: .100"-68 .200"-120 .300"-166 .400"-190 .500"-208 .600"-220 exhaust: .100"-95 .200"-142 .300"-161 .400"-170 .500"-172 .600"-178 Something to remember..absolute peak is nothing for comparing flow numbers.. Add up the values from .100-.600,and them add up the same values from the head that is being compared-and see who has more total "area under the curve". Also remember..you spend alot more time at .300-.400 lift than you do at .600 from just the physical aspects of camshaft lobes. I am not trying to start a war here or anything. I guess I expressed myself wrong in the first couple of posts. I just don't think that the PI's are the all high and mighty for street cars when you get into porting. From what I have seen is the NPI's can be made to work very well, and for less total cost. Sure, out of the box, there's no comparison, PI hands down. |
91LX2Bfast - what kind of a price would i be looking at to port my NPI heads? or are you saying that you buy these heads from renegade?
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Well, just like any good porting, its not cheap. Your looking at $1500-1800 for the whole meal deal w/ bigger valves, Modmax spings, etc, etc, etc. But you get what you pay for.
I have seen some pics of some of these so called "ported" head kits and the porting is no better then what anybody can do with a dremel in his own garage. If you are going with a ported head setup, no matter what head you are using, choose a porter very carefully. |
i found a set of ported stock cobra heads for 1100 bux
if you aren't in a hurry, you might be able to find a deal somewhere... |
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