You don't need a new hood, Thomas. The '99 3.8 mustang upper intake manifold is a direct swap with the truck upper intake intake-- UNLESS you want to use a distributor, which is what I did. The 3.8 mustang split-port upper intake should fit under the stock hood with no problems but it does not allow for the use of a distributor. If your car currently has a distributor and you want a stock hood with a split-port 3.8 intake, you will have to switch to DIS.
I got the hood long before I did the truck swap. I figured I already had the clearance, and I might as well have something under the cowl to justify its presence. Otherwise, at a glance, people would say "V6 T-Bird with a cowl. What a ricer!" I got the hood because it was cheaper than buying a stock one after a stupid accident.
The 4.2 is a very smart and practical swap choice for V6 MN12 owners-- I think I will write an article on this soon (I am moving to SoCal this week so it will be a while). Rancherlee, will you help me write the performance potential segment of the 4.2 article, since I have more experience strictly on the installation side? I think an 11 second V6 is possible considering Pete is running mid 12s (V6 Mustang) with a stock 4.2 longblock + Procharger).
Answering the question regarding the difference between split-port and single port intake, lets look at a few facts.
The '98 single port 3.8L engine makes about 145 hp in stock trim. The '99 split port engine is basically the same engine with the following differences: returnless fuel system, split-port upper and lower intakes, and split-port heads. The split port works like having a secondary intake manifold. The longer runners are optimized for low-end torque, while the short runners are there for upper RPM horsepower (these are closed by the IMRCs until a certain RPM-- I chose 3400 RPM). The '99 V6 mustang engine makes 190 hp-- a 45 hp improvement over the single port equivalent. Rancherlee, what are the torque numbers of a stock single-port 3.8L?
Some of the '99+ V6 Mustangs do NOT have IMRCs (Intake Manifold Runner Controls)... a feature which I consider CRUCIAL to anyone putting a split-port in a heavy car. I will address IMRCs on a later day... Unless someone wants to beat me to it.
This does NOT mean that there is no potential for single port engines. Rancherlee might have more accurate figures, but the single port head, with a good porting job, will out-flow the split-port head. Maybe the single port plus a built lower-end will yield better results with high-boost... but there is always the dreaded head gasket...
I'm happy to say that I have no regrets over this swap. I finally can beat some of those cars I was ashamed to lose to with my 3.8, such as Camaro RS's, '99 V6 Mustangs, and 2.3L Preludes. My times are better than many 4.6 V8 T-birds, and I have yet to do any serious exhaust work. One of the benefits of sticking with the Essex based engine is that all of the aftermarket SC exhaust products work. I am expecting to receive some sweet Kooks headers and Supercoupe performance downtubes this week. I know I can run 15s with this car as it is in either cooler weather or lower alts. I ran a 16.31 @ 85mph in Tucson AZ (2800 ft??) at 105 degrees. Once in CA, I think I will be in low 15s with the new exhaust.
I am looking forward to boost in the future, so my exhaust will be optimized for that. A good NA oriented exhaust on a 4.2 with tall gears will most likely put the V6s in high 14s. This is more than respectable.
These are very exciting times for V6 owners. V6 T-Birds are a dime a dosen. Insurance is reasonable and they offer all of the comfort of their V8 counterparts. On top of everything, the V6 is lighter. The only downfall is that our drivelines are inherently weaker. I will let you guys know when I break a half-shaft or my current differential.
They're rebuilding 78 and 79 Ford pickups and figured they'd know some stuff on switching out engines. They said they'd help me if I had some mechanical questions.
