Stangbass

So I'm getting to the point where I'd like a little more power from my ride. So I've been making plans to build 4.0l to safely support around 300hp as a DD/weekend fun car.

Problem is, I start calculating what it takes to accomplish my goals. Forced induction will be necessary which will run around $6000. The rear end will be $1000 - $1500 depending on if I can find a decent takeoff. Replacing the T5/clutch/driveshaft will likely run me another $2000- $2500. So I'd be looking at $9K to $10K for a car that would probably run close to a bolt on 3.7.

So I've been thinking about just cutting my losses with the 4.0 selling or trading it and using the 9 grand to find a nice used 2011+. I'm seeing some good prices on used 3.7's and it will likely be better next spring when I plan on doing one or the other.

So what say ye? Keep my car and drop some cash/sweat in it, or swap it up? Direct experience between the two engines greatly appreciated.

Tanner05

Take this from a 4.0 owner who decided to build, it is a pain in the ***. Not just a little bit of a headache, but quite a bit of one. First, you're going to have to try and track down the parts (Which is a little harder than you'd expect, especially the pain of messing with shipping and stuff.) Then you'll have to take the time of your car being off the road while you install. A few of the parts (My husband and I have replaced all of the drivetrain so far) my car was out of commission for over a month with working on the car only weekends. If you've got another car at your disposal to drive, then not a problem. Don't get me wrong, I love this car. I love knowing that all of this extra work is put into it and that she's a pretty bad *** little 4.0 right now, but it was still a pain.

Unless you're really invested in that car, cut your losses and get a 3.7. You aren't losing much if you trade, maybe a little money, but you're getting a lot better platform to build from.

I would've done the same, but couldn't see giving up the '05-'09 body style.

VistaBlueFrank68

What...Little Miss sexy glasses! (My husband and I have replaced all of the drivetrain so far).

Get the 3.7 Dude! For instance the 4.0 Cam Chains - Driver side front of the engine, Psg to the rear? WTF, it's a euro-design.

4.0 High compression - you'll blow-it up with FI.

4.0 7.5" rear sucks, with 4.0 no problem but to get 300 you'd need FI and blamo your engine or your rear. Forget slicks.

You'd have to build the internals, Long Tubes, T/B, CAI, every trick they even have a guy who makes cams and heads for 4.0 called Super-Six. Bottom-line you'll spend a fortune and find all the negatives for the 4.0 are positives with the 3.7.

Doing a 4.0 is a sign of anti-social, I dare you world to knock this chip off my shoulder-ism.
Don't do it man, or I'll have to do a Psych-thesis on self-destructive Modders.

Andy13186

trade for gt500, 5.0, or 03 cobra then build that

JimC

Really - tell that to all of us who have successfully done it. Put the Xcharger on mine at 90,000 miles and sold it with 203,000 still running mid 12's. New owner says it is still running strong with 212,000. That car was putting 290 to the rear wheels; another Xcharger on here is running a little over 300 to the rear wheels. Before the Xcharger the car had a 75 shot of nitrous that I used for 2 race seasons.

Again - lots of 4.0's that are boosted with no issues and running stock internals. It seems that everyone who says it can't be done is someone who hasn't done it - and you who say it can't be done always come out with the "have to build the internals" stuff. Yet, there are all of these cars that have done it, on stock top and bottom end, and continue to run fine, without all the stuff that you say has to be done to get there.

The only thing you are correct about is the rear end. Have to replace the 7.5.

Nuke

Where's the "Neither" option in the poll? If your going to do anything it's upgrade but why to a 3.7 if you need more power? The jump is still less than that of a 4.6L (yeah, yeah, a few measly crank HP but less torque and less to build on). Go for a 5.0 and don't look back.

VistaBlueFrank68

Nuke - Fuel milage for a 3.7, my 4.0 got 24 mpg even with a 3.73.
F/I is fine but would you trust it out in the desert at 120 on a long drive? Dependability?
I was going to get a centrifuge and only boost my V6 by 2-4 lbs, but with the cost it was eventually better to get a 5.0 and spend my money making it perform to it's best, with an N/A engine modded to 400-450 at the ground. How many have replaced their hydraulic clutch-lines with steel braided? Same effect as steel on your brakes. It shifts better/faster.
It's a way, the DoJo of N/A. It's a slower steady path, but it's not for everyone.

So no I have no personal knowledge of F/I so I'll refrain from bad mouthing it in the future but I don't trust something that keeps warning me about Detonation, Belt Slipping, Heat Soak, Unsightly Ring Burn, Spun this and that and most Mustangs are stock 11:1 compression if you get a factory S/C they run 9.5:1.

I'm sure it can be done safely and effectively by experienced modders but a teen with a 2005 4.0 who wants to put a 28 lb. pulley on their car?

aaquib1992

What desert are you doing 120 on in Washington! (just messing with ya lol)

I've seen plenty of cars with much higher compression ratios get boosted, just because you have a high compression engine does not mean it is unfit for FI. Just like any boosted car, a good tune will make or break you (no pun intended).

As for those timing chains, I have not seen a thread here on the forums the entire time I've been a member where a 4.0 owner has had to replace their timing chains (any, front or back). If you are quoting the problem the old rangers and exploders had with the weak chain rattle and such, those issues were long ago fixed with better design and stronger tensioners.

As far as building the internals, I don't know of any 4.0 guys (to my knowledge) that have had to do that, just a lot of people replacing valve springs to prevent float, but again, I'm not well versed in that topic.

That said, OP I would do what the majority are suggesting and switch to a different platform if you want the easiest route, less wrench time, and a new platform with that new car smell. The 4.6Ls can be had now for quite a good price and take to bolt-ons well, and the 3.7s are also good starting platforms as mentioned.

I would wait until you are ready to start work, then take a look at market prices for the cars you want. Then calculate exactly how much you'll be spending for a new car vs. going FI with your current one.

Good luck man.

VistaBlueFrank68

aaquib the timing chains need to be moved to change the cams, you can only pull the driver side cam straight-out the passenger side chain is against the firewall. If you drop one during the swop, it's pull the engine time.

It's really an exercise in futility to build a 4.0. The factory can always do it 10x better for a 1/4 the cost. The future is the Variably Timed Independent 4 x cams. 5.0's will rule the world [slap], sorry did I temporarily become a 5.0 Fascist?

aaquib1992

I am aware of the poor placement of the chains and the difficulty of access, but how is that relevant to building up a 4.0? I have never heard of a 4.0 on this site needing one of those chains to be replaced (FI or not).

And as for the second part, you know what they say about opinions... Why is it that every time a 4.0 or 3.7 owner makes a thread about boosting their cars at least one 5.0 guy has to steer the conversation towards the almighty 5.0?

We get it. Satan drives V6s. But we are getting off topic, OP does not want a 5.0, and he already stated that his power goals were well below what the 5.0 offers. Viable options for these goals are 4.6s, boosted 4.0s, and 3.7s.