Having a hard time deciding.
 

Alright guys. Two combinations. I need to go after a different car soon, and I'm not about to get slower, LOL.

1994-1995 5.0
Steeda #19
GT40P Heads
Cobra Intake

vs

1996-1998 4.6
Cams?
99GT Heads
Bullitt Intake

Those are the basics. Can the 4.6L make 320hp N/A reliably? I'm leaning towards a Saleen S281 (the older N/A version) but the car has to be able to back up the looks a little. I've settled on a 320hp N/A combo or so. I want it to retain a lot of the stock drivability characteristics, not kill me at the gas pump, and most of all, last.

I know the 4.6L can make the hp, but the combo I listed for the 5.0 will make it, take it, and come back for more 100,000 miles down the road.

What's the scoop?

320 HP at the flywheel or at the wheels?

If it's at the flywheel, I would say you could get pretty close...

Other than the crappy 96-98 intake, there's really not a weak link in the engine.... (We won't talk about the deceased T-45 as I'm currently waiting for my Tremec TKO...)

Change out the cylinder heads and and intake with some ported PI heads and Bullit intake, you're looking at around 270 hp for the 96-98. Cams might be good for another 15hp (285)

Between some cold air, MAF, full exhaust... you'd get pretty close to 320.

The problem is the expense of the parts... they're not cheap...

The Saleen 281 would probably get to 320 N/A a bit cheaper.

But to be honest, if you're going with a modular.... a blower is a way to go. The engines (with good heads) just respond INSANELY well with relatively low boost.

For you, I would recommend a roots style blower on a 96-98 with a good set of ported heads. Runs just fine as a daily driver...

If you're really looking at cash flow, (I hate to say this), the 94-95 with the 5.0 will be the better choice as the parts are just SO much cheaper...

I'm talking 320hp at the flywheel. A GT40P setup N/A isn't going to do any more than that either.

I was thinking I could get some 99GT heads/cams, Bullitt intake, and whatever else I needed to do the swap for under a grand if I looked around. The parts might be used, but that's not a big deal. The rest of the setup would probably put me close to 2 grand. Not a whole lot more than the GT40P setup.

I don't think there was much special about the S281. As I recall it was pretty much a GT engine.

With the 5.0, I'd get new GT40P heads, $500 + Steeda Cam + Cobra Intake $400, + exhaust and all that other stuff, I'd be sitting at around 1800 I think.

The difference is I KNOW the 5.0 GT40P setup will make a true 320hp with 9.5:1 CR and last a long time. I don't trust the reliability of the 4.6L at 11:1 CR

In my opinion I'd go the 5.0 route. Just the 99-up heads/intake will run around $1000 if you're very lucky. Then the cams and whatever else will be pretty high as well. You'd be better off getting a roots blower put on. The 4.6 lacks the torque of the 5.0. Parts for the 4.6 are alot more expensive than the 5.0 parts. Plus they are much more difficult to work on.

Any particular reason you want to use the GT40P heads? Why not the regular GT40 cast irons and you won't need the odd ball headers and you'll have a little more exhaust valve openning on the heads? You can easily get into a set of the regular cast irons (used) for about $350. There's usually a set for sale from someone's GEN 1 on the classified parts section of the National Lightning Owner's Club website. I don't know anything about the Steeda cam but a custom ground cam would be the best way to go. Anyways, good luck getting your combo together.

Also the S281 is basically cosmetics with some small suspension mods. The motor is the reg GT motor but the 99-up has a bump up in hp to I think around 285 hp from their Saleen Powerflash chip.

Getting into the technicalities of the GT40P vs GT40 Iron heads is probably best left to the Windsor Power Forum. Trust me though, the GT40P heads are superior, not to mention the fact that I'll be buying headers for either heads so it really doesn't matter.

Like I said earlier, the price of modifying the cars will basically be the same. While people seem to think the 5.0L is dirt cheap to modify, it's not when you consider the PI head swap on the 4.6L. Either combination will wind up running $1800-2000 when all is said and done. If I was trying to get more than 320hp, I would not be going N/A. There are just too many sacrifices. Poor fuel economy, loss of drivability, and reliability issues begin to surface, even on the 5.0.

The custom cam route is way overrated IMHO. Unless I was going with forced induction/N20, there is no reason to take the chance with drivability on the 94-95GT computers. The Steeda #19 is .480/.480 220/226 with an LSA of 115. It works very well with the 94-95GT computer systems (which are junk anyway), and I'm going with a mild cam. I don't put a lot of faith in the current ideas about camshafts. The XE Series cams from Comp Cams are a joke, and the fact people are buying into it disturbs me. Large cams are not warranted for anything but the most aggressive N/A EFI combinations.

While the 5.0 is certainly king of the street yet, the 4.6L has come into it's own, even with a limited aftermarket catering to it. In my opinion, it's not always best to have a huge aftermarket with lots of bad players in it. The first gen 4.6L has really stumbled upon a gold mine with the PI heads. The only question I have is about it's reliability with the stock pistons, because it still can't match the 5.0 with mild modifications without the compression. I just don't know what the compression is yet, or how reliable the engines are under that level of compression (I know it's high).

Thanks for the responses thus far, I've been running around moving stuff back out of a house I've been sitting for the past 3 1/2mo, and working my tail off at the office and I haven't really had a chance to check back in. I know the 5.0 back and forth, but when it comes to the 4.6L, my knowledge is a little lacking. :)

Here's the information I eventually came up with.

99PI heads, 44.75cc +/-1.5cc combustion chambers.
96-98GT pistons have a 9cc dish and/or relief.
99GT pistons have a 17cc dish and/or relief.

All told it makes for 10.65:1 CR on the stock Gen I pistons with the PI heads. There is so much tolerance in the heads, and I don't like the compression ratio being close to 10.7:1. If I go the 4.6L route, I'll have the heads cc'd to 47cc. That will bring the ratio down to 10.25:1; perfectly acceptable as far as I'm concerned.

I think those tolerances are VERY poor considering how small the combustion chambers already are. If I didn't do the work I could wind up with one cylinder over 10.9:1, and another as low as 10.3:1. That's a huge difference.

Kinda wish I could find a nice 94-95GT in blue though. So far, it's nearly impossible to find one in blue, with a stick, in good shape, with low mileage, and for less than 10k.