SOHC or DOHC

[Veinot]

Hi,
I want to take a Grand Marquis and make it a grand tourer with mild to mid street performance. I am thinking for the suspension to use suspension parts out of an Interceptor, but I don't know what to do about the engine really.

If I want between 300-400 hp and tourque can I get that out of a SOHC or will I need to go to the 4.6L DOHC?
What might I want to concider doing to the SOCH to make that power?
If I have to swap what would I look for in a junk yard? Mustang? Mark VIII? Maybe...
What should I keep in mind to take from the donar besides the engine?

Thanks for the advice, and I appoligize for my general ignorance on the subject

PS is there any reliability difference between SOHC and DOHC? just an after thought

[1990LTD]

I don't know about reliability but I know there's more aftermarket for SOHC goodies than DOHC

[hemihotrod402]

I'm not very knowledgable about the 4.6, but I think if you want to make good power, the best bang for the buck is a supercharger, along with the other required neccesary upgrades.

[1980c10]

what year is the car in question

[87CrownVic]

SOHC engines are more plentiful and subsiquently more affordable. 4.6L SOHC engines are also severly easy to make 300+ horsepower with. OE 3-valve heads and cams from the mustangs with headers & properly sized exhaust would make 300 horsepower and well over 300 lb/ft of torque.

1980c10 makes a good point though, what year are we talking here? there are some considerable differences between early 4.6's and mid 2000's stuff.

[79lincolnlover]

If you want the DOHC V8, swap one from a Lincoln Mark VIII. Grab the computer and wiring harness as well. Member "SVT98t" seems to know a thing or two about mod motors. You should contact him

[jayh]

what year is your car, that has an effect on the answers

[Pirate]

I suggest staying away from either engine, as both the SOHC and DOHC are money pits when you want to modify them....especially the DOHCl the cams alone for the DOHC motor, should you want to change them start out at $1200+....

[BGoins12]

I would stick with a Windsor V8 personally and turn it into a FI'ed 347 stroker or better, and have fun with it. Not only that, but Windsor parts are far cheaper than Modular parts would ever be.

But, if you are hardcore stuck on doing a 4.6....do a 2-valve SOHC, there is a decent aftermarket for them since they were used in the Mustangs for years. The DOHC Mods are very expensive to mod and rebuild.

[SVT98t]

OK. First, the Interceptors aren't always as awesome as people say they are.
Yes, they look sweet, but there's only 40hp difference between my (once) stock 93 Mercury Grand Marquis (MGM) and a 01+ Crown Vic Police Interceptor (CVPI).
The susspension is a nice upgrade for anyone wanting better handling and ride.
If you want a decent set of sway bars, go with the Marauder's.
I know when i upgrade the sway bars on mine, they are going to the Tank.
You will not break 300 rwhp on a 4.6 without significant mods. (minus nitrous)
I'm talking:
-bore and stroke
-forged everything
-steel crankshaft
-cams
-bigger injectors
-ported PI heads
-full exhaust
-bigger MAF and tune (MZT mod)
-PI intake
-Throttle body, CAI

The list can become very long, as well as the price for doing all of this.

And with most builds, it doesn't happen overnight. Take your time and decide what you really want to do. You really can build anything you want. As long as you have enough cash to pay for everything.

You could try a 4.6 DOHC swap. I'm not saying it's impossible. It has been done.

http://www.mercurymarauder.net/forum...is+pics&page=2

Check out the vids.
Vortec supercharged 4.6L DOHC in a 97 MGM.

Your best bet is to save up and get a supercharger. Nothing crazy. But 8-10 psi is definately in the safe range on a stock motor. And you can still rock out to about 375hp or so with a balls-load of torque.

Now don't forget, that if you upgrade the engine, you WILL have to up grade the transmission and drivetrain.
A built-up torque converter (TC) is one of the best way to go. I put a 3500 stall TC on my Marauder and it put almost 50 hp to the wheels. They're just more efficient. A great TC will help you launch much better.
And the J-mod to the separator plate is a great mod to do. Regardless of what you have done to your car, I highly recommend that.
And an aluminum driveshaft to the mix.
You'll need a trac-loc (posi) rear end. With an open differential, you won't go forward very well with all the power.
And 3.55s, 3.73s or 4.10s would be great for the get up and go.

It'll definately be an ongoing project.

But, if you have the money, you can do it.

I'd beef up the 4.6 SOHC.

www.adtr.net
www.reinhartautomotive.com
www.innovativeinterceptors.com

ADTR has a stroker kit for the 4.6. Nothing beats a 5.1L! There is no replacement for displacement!


and www.seanhylandmotorsport.com
the have a bunch of everything available for the 4.6

Ok, there's alot of info here. Take a look, and then ask us some questions!!

-ryan s.

[Veinot]

Sorry for the lag, I really wasn't expecting so many posts so quickly...

to answer the year of the car question, I don't have one yet, there are alot around from 1995 and up starting at 1300 and up. Police CV's here can be bought for 2k and up. I looked at what was available and started trying to get some answers, I want to know what I am getting into before I make a purchase. From what I have read I am looking for a 98 to 06 CV Marquis, I'm skitish about jumping into something.

Since I have posted I found a huge Ford GM debate reguarding the SOHC/DOHC and the LSx series. What I gathered from that was a 4.6L is ok untill you spend to build it up, there was also talk about it being heavy for its size due to the OHC setup, and they said the same thing about the blower/supercharger pretty much need one to make big power. Due correct me if I'm wrong and missinterpreted what I have read.

Personally I would rather a push rod 302 or 351 for the reasons mentioned above, and because I know where there afew around, but I didn't think one could be stuffed into a 98 and up CV without some serious sergery, nore could I find an example of one that has been done. I really hope I am wrong with this... apparently a 4.6L SOHC is actually physicaly bigger than a 302, I got this off the GM Ford debate, but I don't know if this is true or not.

From what I have just read and from the GM vs Ford debate I figured that I would go with, unless I could find away to swap a 302, a SOHC because I never had a DOHC that made it past 100 000 kilo's (these were doges though), but still the DOHC is still burned in my head meaning DOOM!!! and the SOHC seems to be widely concidered more easily and cheaply moded and worked on.

I have heard that the big issue with the 4.6 is air flow, hence the supercharger comment, wouldn't porting out the intake/exaust values and a more aggressive cam allowing the valves to stay open longer fix this issue?
Thats about as far as I got with my searching and thoughts, I have no clue as too how much this will cost for the stuff. I'm sure port and polish will run me more than 500$.

[Veinot]

then cam, custom valves, springs, ect... it will be a project over time.

[87CrownVic]

You will not break 300 rwhp on a 4.6 without significant mods. (minus nitrous)
I'm talking:
-bore and stroke
-forged everything
-steel crankshaft
-cams
-bigger injectors
-ported PI heads
-full exhaust
-bigger MAF and tune (MZT mod)
-PI intake
-Throttle body, CAI

The list can become very long, as well as the price for doing all of this.

I'm not trying to get into a flaming argument here, but I think I'm going to end up doing so, because this is serious bullshit.

#1 Bore and stroke can stay just as they are.
#2 No need for forged everything with a modular 6-bolt engine (we're talking 300hp here, these engines make 260hp in 2000's 2V mustangs.)
#3 Would a forged crankshaft be made out of anything BUT steel for this application?
#4 As I pointed out earlier, aftermarket cams are most likely not even needed to produce 300hp if you used OE 3V SOHC heads with their respective cams. The 3V heads perform virtually identical to 4v (cobra) heads in blown as well as N/A configurations and aren't NEARLY as hard on the wallet.
#5 There's no need for a new fancy TB. Just run a throttle cable on the TB from the 3V donor.

However, I would agree with your points on full exhaust and MAF/injectors (which wouldn't even require tune if matched when purchased)

I have no doubt you have intimate knowledge of these cars, mainly by looking at what you have accomplished with your own. I also have no doubt a minimum of 300hp and well over 300 lb/ft of torque could be achieved for well under $2,500 though.

[jayh]

300rwhp used to be tough with a 2v but with tfs heads, its easy to surpass that now
the kenne bell is probably the way to go, along with tfs heads if you can afford it
no need to build the bottom end, thats more for strength than power
steer clear of Sean Hyland
the 302/351 swap could work, it depends on where you live
converter, valve body, gears, and exhaust should be considered mandatory on any high performance application

[Veinot]

If you change the heads from 2v to 3v will there be any tuning required on the ECM?
Is there an advantage to a DOHC setup as oppose to a SOHC setup? I'm sure there wouldn't be in my case where I am not asking for very much power out of my car.