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Old 11-17-2006, 14:32   #1 (permalink)
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4.6 build up

I'm building a 4.6L 2v in a 98 nascar f150. It is a vin (6) winsor built engine. It does not have PI heads, and for financial reasons i do not plan on doing a pi swap. Does anyone know if aftermarket cams built for 96-98 4.6 engines fit non pi heads? or is there machining that has to be done. also, will pi cams fit non pi heads. I am planning on going with higher compression pistons, will flat tops work in a non pi head engine since the stock compression lower without pi heads. worring about piston to valve clearance. Is 10:1 compression about the highest i can go on pump 91octane? Is it a better idea to go with stock compression and run more radical cams? The engine is out right now and block machining is done. now i just need to know the best combination of parts to go back together with. this is a budget builder. I am a GM tech so i'm not really familiar with the tricks of building a SOHC ford. It is a 5 spd truck so stall is not an issue, 3.73 limited slip in the rear also. ANY INPUT OR OPINION WOULD BE GREATLY APPRECIATED
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Old 11-29-2006, 07:09   #2 (permalink)
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Re: 4.6 build up

Quote:
Originally Posted by NASCARF150
I'm building a 4.6L 2v in a 98 nascar f150. It is a vin (6) winsor built engine. It does not have PI heads, and for financial reasons i do not plan on doing a pi swap. Does anyone know if aftermarket cams built for 96-98 4.6 engines fit non pi heads? or is there machining that has to be done. also, will pi cams fit non pi heads. I am planning on going with higher compression pistons, will flat tops work in a non pi head engine since the stock compression lower without pi heads. worring about piston to valve clearance. Is 10:1 compression about the highest i can go on pump 91octane? Is it a better idea to go with stock compression and run more radical cams? The engine is out right now and block machining is done. now i just need to know the best combination of parts to go back together with. this is a budget builder. I am a GM tech so i'm not really familiar with the tricks of building a SOHC ford. It is a 5 spd truck so stall is not an issue, 3.73 limited slip in the rear also. ANY INPUT OR OPINION WOULD BE GREATLY APPRECIATED
Your biggest problem with that engine is the intake manifold. It's terribly restrictive,and even portwork or cams will not see much gain unless you can let them breathe properly.
Non-PI heads are honestly equivalent to PI heads as far as flow is concerned,and the gains that are seen when swapping them out for PI heads is from the camshafts and the intake manifold,plus the bump in compression. You can use OEM PI cams in the older Non-PI heads('96-up) for a nice powergain for very little investment.
I've swapped in a set of PI cams in my '98 F150,and there's a nice TQ increase,but not much in the HP dept....again,that restrictive intake hurts you there.
The aftermarket cams out there for '96-'98's are good and will work perfectly in those heads,and the .500" lift is much less abusive to valvesprings than the higher lift cams.If you want to-you can get away with right at .550" lift on the non-PI head if you use a set of Crower's offset retainers.I'm running the Comp 270AH cam in my Tbird right now,and it's got ported non-PI heads.
There was a huge discussion/debate and alot of data to be read in this thread on modulardepot.com:
PI vs NPI-data - Modular Depot Forums
And the followup to it on what we found with the intake manifold:
Results - modified PI intake on NPI heads - Modular Depot Forums

After you're done reading that..lemme know if you have any more questions.
JL
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Old 11-30-2006, 18:59   #3 (permalink)
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Re: 4.6 build up

those threads are exactly why i ditched 2v anything.

my car was bone stock when i bought it. i lost to a couple of 4 cyl cars, and i added an SLP "X" pipe and high pressure regulator...

i lost to a couple of v6's, and i added a PI intake and port matched, as close as possible, my npi heads to a PI intake.

i still barely beat V6 HO pontiacs, so swapped to ported PI heads, stepped longtubes, stock PI cams, filter, and i lost to a 4v N/A cobra, and enough was enough.

i spent a load of money to get this in here and experiment with intake, exhaust, sensor combos, but it's worth the torque and HP. this swap can be done in a stang much cheaper than i did it.

forget 2v, and spend you money putting a 3v or 4v into your car.

filter, 'x'pipe, pullies. ~408fwtq SAE ain't bad for no real mods.

no arrogance. i can't wait to install those stepped torque headers i used on the 4.6. they have 2 torque peaks at 3200 and 4200 rpm with no HP loss, and the tapered runner intake i'm working on with 85mm TB. add 270 cfm/208cfm foxlake heads, stage 4 CC's and i will quit.

here is the end cap installed
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340.1 rwtq SAE 249.9RWHP SAE
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