Making my 3.8 in to a 4.2

[oaktonarcher]

Well first off I wanted to know is it worth the time and money for .4 extra liters? second i read an artical here about this and it was for a 98 i think. and i have a 03 I have heard its easyer to change my engine over to a 4.2 is this true? and would it just be easyer to drop in 4.2 liter from a f 150? thanks for any input

[plstktnkr2]

yes for your years its easy,just change the crank, and if you want get the 4.2 valves. the 4.2 as it exists in the truck will be too tall for the stock stang hood, so you just swap intakes. on my motor, whole bunch of stuff to change but it's an 87 non roller motor so its not as strong but will work.
According to RGR the mill with right camshaft will make ~300 HP

[Rick0636]

Yep, I think the easiest way for you to go is to get a complete 4.2L from an F 150 and swap the intakes off your 3.8L. Of course while you had the engine out would be the perfect time to have the heads ported and polished, p&p the intakes, change the cam, all sorts of fun things.....

[oaktonarcher]

ok could i just go to jy and pick up a good condition 4.2 take it home put on the heads and cam and other stuff and then take it to a local shop and have them drop it in for like 300 bucks? or do i take the crank and the other stuff and put in a bunch of work and just tune my existing engine in to a 4.2. and is it worth it for a 4.2?

[Dom]

The way i see it, you could probally strip both engines down to the blocks, and then just take the 3.8 upper assembly and bolt it down on the 4.2. Basically, they are the same engine. [Someone correct me if I'm wrong. :-? ]

But, your going to want a tune to take full advantage of the stroker.

[Monkey]

yes, the 3.8 and 4.2 blocks are identical. to get best results though, add the split port heads and intakes on a 4.2L though and not single port

[tire]

i hear a v6 f150 "rental special" is a great deal for an almost new 4.2l

i won't say, but i know someone who's done it. dang gutsy, and not my style, but those rental trucks and cars would never know the difference anyways.

[ASSEMbler]

The computer changeover sounds like a nightmare.

[Monkey]

its not... all you need is a chip. its the same block, and the computer knows this. you just increase the stroke a bit, but the bore is the same. you can actually run a 4.2L engine in your car w/o adding the chip. the stock ECU will be sufficient (you will need to be dynotuned though)

[Monkey]

Quote: Originally Posted by V6PowerStang i hear a v6 f150 "rental special" is a great deal for an almost new 4.2l i won't say, but i know someone who's done it. dang gutsy, and not my style, but those rental trucks and cars would never know the difference anyways.

im down if youre down... you want a 4.2L blown mustang austin? just take out the extra insurance against it, and they cant do anything

[ASSEMbler]

insurance?

[dark]

so, f 150 4.2L + EE 99 plus venom pack + chip/dynotune = ~300hp?

and that will work with a ram air hood? (oni a 97?)

*whistles*

[Monkey]

ram air hood wont work with anything unless you get a specially designed upper intake. the ones that feed into the MAF box suck because of all the bends which slows down velocity of the air.

you can however get a ram air hood for looks and keep the screens open for engine cooling.

[oaktonarcher]

Well thanks everyone it think ill try the rental special. j/k to risky. but thanks for the help.

[dark]

Quote: Originally Posted by Monkey ram air hood wont work with anything unless you get a specially designed upper intake. the ones that feed into the MAF box suck because of all the bends which slows down velocity of the air. you can however get a ram air hood for looks and keep the screens open for engine cooling.

^that's what i meant. i don't care about having ram air, i just like the look of the hook

[Tin Kicker]

What do you guys figure a jy 4.2 is worth? Here's what I'm looking at...

I sell auto parts, and I've just sold (yesterday) a 4.2 to a guy with a '97 F150. The core value is $375. His has blown a head gasket, but no other damage, so no big deal. Think it's worth it to buy the core?

Opinions please...

[plstktnkr2]

Yes buy the core do the gaskets and stuff and you will have an engine you could sell or keep for your stang. my conversion in a non roller block is so far 3,ooo bucks

[ASSEMbler]

Someone please make a faq about the 4.2 swap.

I'm still confused how you would deal with the change in compression ratio.

[Ponycarman]

Quote: Originally Posted by Monkey its not... all you need is a chip. its the same block, and the computer knows this. you just increase the stroke a bit, but the bore is the same.

The computer doesn't know anything except for what it is told. You slip a 4.2 in there and the computer will think it has a 3.8 regardless, unless you tell it otherwise, like with a chip.

The 3.8 computer may be able to handled the extra requirements of a 4.2 by looking at it's O2 sensor inputs but I suspect it'll be finicky about it. I suppose you could up the fuel pressure a few psi to compensate and keep the computer closer to what it think it should see.

Steve

[ASSEMbler]

Exactly what I thought. It's cheaper to get a V8 though, the 4.2 blocks cost about the same as the V8 here and on ebay..

Know what?

Drop in a TRITON hehehe

:shock:

[dark]

^yea, but what's the fun in that?

nothing like hearing this exchange...

*grinning* "yo, that's a fast mustang, what is it a cobra?"

*shrug* "nah, it's a v6"

*suprised as fuck* "whaaaat!?!?!"

[Dom]

Quote: ^yea, but what's the fun in that? nothing like hearing this exchange... *grinning* "yo, that's a fast mustang, what is it a cobra?" *shrug* "nah, it's a v6" *suprised as F**** "whaaaat!?!?!"

That's what it's all about.

Quote: I'm still confused how you would deal with the change in compression ratio.

There's nothing to worry about. :-?