Puzzling Out a 2v Street Engine

[Stanley]

I've started trying to work my way through the world of 2v 4.6L upgrades for my 97 Bird, and thought I'd make a new thread for my user case (and general understanding). There's a lot of threads on building out these motors, but they're all over the place--in terms of price ranges, intended vehicles, and intended general use--and often discuss parts or companies that no longer exist. I'll try to be detailed about my specific plans so I can get more relevant, modern info.

I know very little (hence this thread), so try to bear that in mind. If something I've said seems completely loopy, it probably is, because I only know enough to be dangerous, so don't worry if you feel like you're explaining something to an idiot (you are). I'll be having a mechanic assemble everything I get, rather than trying to do anything myself.

I'm looking for:

1. Reliability. I plan on taking the car on multi-day-long road trips with the missus: I absolutely don't want a princess that only works with lots of downtime in between. I'm happily willing to spend more money to get seemingly redundant levels of toughness, like a part rated for horsepower I'm unlikely to reach (as long as there's not negative effects otherwise). I want quality.
2. Street Use. It's a daily driver, and I'll never take this to the track.
3. Compatibility with a Rev I AED supercharger. I will find one of these things one day (if you have one for sale, let me know ), and whatever I'm doing needs to work with it.
4. A setup that works on pump gas.
5. Fitment under the stock 97 Bird hood (no alternate hoods, no hood cutouts). In terms of general room I'll be going with an AJE subframe, and can relocate the battery to the trunk if need be, but I can't grow the thing upwards.

I know some items fight against other items (e.g. a supercharger and reliability concerns). There's always going to be give and take, but as far as I understand an AED doesn't compromise day to day use if you build right and there's tons of daily driver vehicles out there with supers and turbos. I'll figure all that out as I go along here.

I'm happy to lose power to meet other criteria (especially the pump gas part): I'm not after the most HP/torque ever.

Price is generally not a factor, at least in terms of typical aftermarket stuff. I'm not looking to cheap out if the better solution exists, within reason.

What do you suggest in terms of what's available today for my particular criteria? Individual parts, or better yet, whole kits. Thanks.

 

[XR7-4.6]

My thing with the AED is being M90 based it’s actually a little undersized for the 4.6 displacement, it’s big enough to provide boost and the accompanying extra horsepower of course but it’s really only good for ~300RWHP ,which for me is A-ok )as a fan of NA builds), but it’s kind of weak for the cost of the unit unless you get a killer deal. That’s why the SVO is generally considered more desirable, as it’s a similar footprint that fits under the hood but it uses the bigger displacement M112 supercharger designed for smallblock V8 displacements. They don’t have an intercooler like the AED but they also run cooler as you aren’t overdriving them for the same amount of boost and have much more potential to grow, and spray meth injection is an easy substitute for cooling the charge, and less complex and probably more reliable than the air/water intercooler setup of the AED. I would favor either of these blowers in terms of long term reliability over centrifugals like Vortechs that require external oil feeds and periodically need rebuilding, and fitment is kind of a pain in our engine compartments.

As for the build aspect, with a roots on pump gas you want to keep stock compression or maybe even go a point lower so you’d want to factor head chamber volume and piston dome into the engine build itself if you intend to go that far. Better flowing heads will always make more power and don’t pose any reliability compromises so if money is no object TFS heads, 9:1 compression, SVO blower and mild blower cams(ones with more lift/duration but not much overlap) would be a potent and reliable combo IMO

 

[Stanley]

I had looked into the SVO, but my concern was that it was never designed for our cars specifically and there seemed to be more general knowledge required to add one on properly, knowledge that I don't want to presume I'll find here up in the wilds of Canada. Reading some of the threads on SVO installs over at TCCOA, there seemed to be a fair bit more of "oh, you need to do this, and you'll want to adjust that, and make sure you fabricate that part". Perhaps I misread the situation there and am making it more complex than it really is.

Trick Flow heads come up again and again, so I've dug into that a fair amount. In the interests of just getting everything in one go I looked at their top-end kits, but there's four different ones for our engine:

FORD 4.6L/281 Ford modular V8 Top End Kits - Trick Flow Makes Serious Horsepower

Find FORD 4.6L/281 Ford modular V8 Top End Kits and get Trick Flow Makes Serious Horsepower!

www.trickflow.com

Besides that, my main issue is that their kits are just giant lists of numbers, with no real human feedback/rundown/analysis. I have no idea how any particular one would run. Will it idle roughly? Can I use pump gas with it? At what range does it make its power? What even is the head gasket size?

 

[XR7-4.6]

I had looked into the SVO, but my concern was that it was never designed for our cars specifically and there seemed to be more general knowledge required to add one on properly, knowledge that I don't want to presume I'll find here up in the wilds of Canada. Reading some of the threads on SVO installs over at TCCOA, there seemed to be a fair bit more of "oh, you need to do this, and you'll want to adjust that, and make sure you fabricate that part". Perhaps I misread the situation there and am making it more complex than it really is.

Trick Flow heads come up again and again, so I've dug into that a fair amount. In the interests of just getting everything in one go I looked at their top-end kits, but there's four different ones for our engine:

FORD 4.6L/281 Ford modular V8 Top End Kits - Trick Flow Makes Serious Horsepower

Find FORD 4.6L/281 Ford modular V8 Top End Kits and get Trick Flow Makes Serious Horsepower!

www.trickflow.com

Besides that, my main issue is that their kits are just giant lists of numbers, with no real human feedback/rundown/analysis. I have no idea how any particular one would run. Will it idle roughly? Can I use pump gas with it? At what range does it make its power? What even is the head gasket size?

The SVO was designed to drop in place of a 96-04 type SOHC manifold assembly specifically, that’s what really matters for us as 4.6 MN12 manifolds are effectively identical to the 96-04 Mustangs. And actually there’s some rumor the SVO was designed for the MN12 to begin with as a SC successor.


I can’t speak to the variety of TFS heads by part number but ideally with boost you’d want the largest chamber volume, likewise with head gaskets you want a thicker gasket as both will reduce compression for safe boost. As far as idle quality the heads make no difference, the cams are what will dictate that which is why I recommended a mild blower cam(with boost regardless you don’t want much overlap which is what hurts idle quality). One way or another though a competent tuner should be able to make it happy, and you’ll need a good tune one way or another.

 

[theterminator93]

I tend to agree with Matt. I never considered the AED to be worth the hassle, especially since the advent of TFS head castings. Even without a supercharger, using those, a moderate set of cams, and a decent exhaust alone (even without a 'real' intake) you will be flirting with the same numbers you'd get with the AED. I grant you the curves will look different, but that's where gears and stall come in. If you build up the bottom end to support 7000+ RPM and add a decent intake, you'll be soilidy over 300 WHP. It will still be streetable with the right combo of converter and gears (a 10" converter is a nice compromise, and 3.73s aren't too tall for higway use), and plenty of fun.

I built my combo just as the TFS heads were coming to market, and I stuck with ported PI heads instead of changing my plans to get the TFS heads. If I had to re-do the build, I'd go TFS heads all the way. I remember a guy picked up a set of their heads not long after I finished my build, and just used the PI intake and cams with them. He made only 10 WHP less than I did, but I had stage 2 PI heads and cams and an exhaust!

 

[KevinVarnes]

If you are willing to budge on the hood thing, the Tork Tech kit is an option. You can run a stock Cobra M112 blower (durability) or any other aftermarket blower designed for the Cobra. They basically sell you the intake, intercooler, belt mechanism and you source the rest of the parts yourself.

There are several here with SVO superchargers on their cars, so I think you should be able to find the help you need if you go that route.

 

[Stanley]

As far as idle quality the heads make no difference, the cams are what will dictate that which is why I recommended a mild blower cam (with boost regardless you don’t want much overlap which is what hurts idle quality).

I was asking about cams because the kit comes with them as well as heads. But while something like, say, this MHS camshaft has a nice write-up saying it's designed for boost but also fine for daily driving, the TF kit's camshaft listing just has a pile of numbers. But thanks for letting me know that it's overlap I should be focused on in my particular case: that helps me sort through the noise and home in on what I care about.

If you are willing to budge on the hood thing, the Tork Tech kit is an option. You can run a stock Cobra M112 blower (durability) or any other aftermarket blower designed for the Cobra. They basically sell you the intake, intercooler, belt mechanism and you source the rest of the parts yourself.

No, I hate the look of every aftermarket performance Bird hood I've seen for our generation: I feel it just makes the car look like it has indigestion. The old Turbo Coupe hood is wonderful, but we never got anything like that that I'm aware of (and it wouldn't help in any case, I gather, since that sort of design isn't any higher).

---

Correct me if I'm wrong, but it seems like I could build a decent engine on the stock block, with the ultimate goal being to add boost, eventually (when I find one of these unicorns), but in the meantime still enjoy a decent bit of performance enhancement despite a low compression ratio and no boost. Say, one of the 44 cc TF top kits, a decent intake, and the Kooks headers.

How does one calculate compression ratios, anyways? Assuming a stock engine first, I tried:

Compression Calculator

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www.summitracing.com

with numbers from:

Ford 4.6L 2V Engine Specs · Help Center

And I got a 1.37:1 ratio, which my keen spider sense tells me is a bit off. But I don't know what I did wrong.

 

[XR7-4.6]

Oh I should have mentioned I’d buy the MHS cams(or similar) and buy the Trick Flow heads by themselves, they come in a few flavors with one with a larger combustion chamber than the other which for a roots blower would definitely be the one I’d go with. I wouldn’t buy a bundled kit.

For the compression ratio use this calculator.

Compression Calculator

Get fast, Free Standard Shipping on orders over Summit Racing Equipment from $109 -- no shipping, handling, or rural fees! Exclusions apply.

www.summitracing.com

I’m not sure the deck clearance or factory compressed gasket thickness but since they effectively feed the same calculation just set deck clearance to 0 and compressed gasket to 0.044” as that amounts to about 9:1 stock SOHCs are with the corresponding piston dish and chamber volumes factored in

 

[Stanley]

Oh I should have mentioned I’d buy the MHS cams (or similar) and buy the Trick Flow heads by themselves, they come in a few flavors with one with a larger combustion chamber than the other which for a roots blower would definitely be the one I’d go with. I wouldn’t buy a bundled kit.

Any particular reason? Both the 38cc and 44cc heads are available in those kits, and I figured with them I'd get guaranteed compatibility as well as savings as a bundle. Why pass those things up?

 

[XR7-4.6]

I don’t really tally much if any savings, the heads are about $2,800 for the pair, the Ford Racing 2V head changing kit is $175(which has all of the consumables of the TF kit) and the MHS cams linked are $800, and I’ve seen Comp SOHC cams for less last I looked. That all tally’s for a lot less than the kit with a lot of unnecessary items

 

[Stanley]

Looking at intakes (since there's no supercharger to be seen at the moment), the TF Streetburner looks to be the best mix of non-race performance and not requiring a pile of unique parts (like the Bullitt does). Assuming I could find one, is that an accurate assessment?