in kinda dissatisfied with the 4 valve 4.6. it makes killer top end but zero low end. thinking about putting the 5.4 3v back in and porting the heads. 9:1 compression.


im mulling buying h beams and pistons and turbo charging it. if i do i will boost it about 12 -15 psi. ill get back in here and detail the job if i do it.

 

Maybe you need for gear in the rearend to let it get in the powerband. Take advantage of the 4.6s high rpm potential. Throw in some 4.10s

 

teh 3 valve willkill the 4 valve on the low end but the top end (6,000 rpm +) the 4 valve is the only way to go

 

I agree the low end blows, mine wont spin the tires on dry pavement even with all the help I have given it, however, it pulls pretty nice in the higher rpms. I have been itching to put gears in but am scared about how much its going to cost.

 

It would be cheaper than building up your 5.4 and porting the heads. But I'd go with 4.30s or 4.56s with that 4v engine.

 

4v's do not outpower 3v at top end like you might think. not as large a margin as is popularly represented.

there are a bazillion 350-370rwhp non ported 4.6 3v's out there, and a handful of 370rwhp 4v's. it has to do with available intakes really.

3v port dynamics and the total volume of air that gets in the cylinder is superior with 3v.

4v has to flow 340 to make the power a 3v does at 300cfm.

my ported 4v's out flow any 3v. BUT.... a ported 5.4 3v with amodded C&L intake will make as much power as non ported gt500/gt supercar engines.


thats the point. i want massive torque mild gears and 700rwhp. its easy to make with 5.4 3v. trust me. with that intake these engines will mkae as much power as any LS series motor.

im suprise none of you have done that. cut it in two and reweld it back. simple and makes massive hp.

 

cost isnt an issue. it never has been. leave cost out of the equation.

 

Have you thought about putting a KB or Whipple on it or are you trying to stay N/A?

 

I'd throw your old 5.4 back in there.

where you been? haven't seen hide nor hair from you since you last discussed yanking the 5.4 some time back.

now that I'm back in a Mustang again I'm actually quite interested in what you've done.



have you considered your old 5.4 3v with the Roush Non-Intercooled Blower (+112 HP)? it runs about $2,300 shipped from Roush.


with your skills, I think you'd be able to fabricate a Intercooled intake extremely easily using the non-intercooled intake and get that extra +35 HP. The only real difference between the 2 is that the intercooled has a heat exhanger cast into it. same shape otherwise. Then some tuning and you'd have a very reliable 500 CRANK HP motor with very conservative tuning @ about 8-10 psi

 

ill take the 4v off your hands if you pull it out

 

Did you ever get to make that custom manifold for the 3v 5.4?

 

What year Cobra did the 4 valve 281 come out of?

 

01-02 NA
03-04 SC
or a Mark VIII

 

They didn't have an '02 Cobra here in the USA.

It would either be 96-98 using the Teksid block. 99 or 01. Then, like you said, 03-04 or the Mark VIII.

 

i thought they had 02 cobras, but only like 500 of them?