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4v swap vs 2v PI swap

3K views 4 replies 2 participants last post by  XR7-4.6 
#1 ·
Hello, I'm new to the forum but I've been researching and reading a ton on here since I got my 95 Cougar. Great info on this site!

So I picked up a fairly clean 95 xr7 v8 for cheap 112k on car. So far, I've rebuilt the front suspension, Sct tune from Lasota, gt intake tube and air box with afe filter, pbr calipers on front, cobra rear disc conversion (was a drum car) stainless lines, poly bushings in rear knuckles, diff mount and rear spring insulators, lowered on 1.6 vogtlands with new shocks, bca transmission valve body/accumulator upgrade, trucool trans cooler and an addco 1 1/4 rear bar will be here soon.

I'm impressed with the way the car drives with these upgrades.

Next is engine/power upgrades. I have found a 03 marauder 4v for a good price and was considering the 4v swap.
For about the same money as a 4v swap, I could get everything to pi swap with rebuilt/ported heads.

I'm torn between the 2 options. There is something inherently cool about a 4v swap, but it seems a 2v with good heads has similar performance. I plan on boosting either engine down the road fyi.

Anyone been down this road? Any suggestions on which route to take?
 
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#3 ·
I have a 04 Mach 1 4V in my 94 Cougar, with the marauder 4V you’ll need to find a 99/01 Cobra or Mach 1 upper intake lid to keep the passenger side Airbox location, and hood clearance is a problem either way, I had to use 3/4” shims between the I member and frame rails to lower the engine to do it, the Marauder lid sits higher so if you keep it and move the airbox over to where the battery is you’ll probably need a cowl hood. Exhaust is tricky too, bolt in wise you need SCPs Kooks midlength headers for the engine to fit the engine bay, and they’re pretty pricey, and because the EGR bung lines up with neither manifold configuration you’ll lose that unless you fabricate a custom tube. Other option I used is using 03-04 Cobra exhaust manifolds and relocating the steering shaft using a center pivot anchored to the chassis(like on mustangs), Mustang headers would work with this setup too.

Out of the box naturally aspirated the Marauder 4V wins, 2Vs can make similar power with ported heads, cams, longtube headers, and an intake manifold that flows past 6K RPM but that adds up, whereas the 4V can remain virtually stock down to the log exhaust manifolds. If boost is an inevitable plan though I personally favor the 2V for simplicity sake, it’s the cheaper engine to blow up if something goes awry, and it’s the cheaper engine to build up if you want to make serious power.
 
#4 ·
Thanks for the detailed response. I'm assuming if I went 4v that the mark viii 4v is an easier swap.

You bring up a good point on 2vs being cheaper to replace if anything goes. Looking into it, it'll probably cost about the same to do ported pi heads, cams, pi intake, etc on my stock 2v as the 4v swap would cost.

Is the 4v way more efficient under boost or is it irrelevant until the motor is fully built?
It seems most say stock rods are only good to about 450-500 rwhp I know a 2v is easily capable of this with boost.
 
#5 ·
Yeah, the Mark 4V is almost a drop in, but exhaust remains a bit of a roadblock unless you use the Mark’s weird integral catalytic converter exhaust manifold (It’s kind of hard to swallow $700 kooks headers on a $500 engine), plus you need a RPM switch to use the B head IMRCs. IMO for the power B head 4Vs make, a PI 2V with a tune and bolt ons will match it. Plus with boost in the cards a PI motor will have more suitable lower compression.

The 4V is more efficient but with boost you can work around it with overdrive pulleys and higher duration cams to make the best of it. Both engines respond very well to supercharging, the 2V boosts quite happily to 400 horsepower with little supporting mods, and 450-500 is achievable with ported heads, aeformentioned cams and cylinder cooling (intercooler, meth injection). That power level is definitely pushing the limits of the rods and pistons though, both 2V and 4V have the same rods and use hypereutectic pistons.
 
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