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5.0/351w vs 4.6 "Engine / Drivetrain" Platform

2.9K views 6 replies 6 participants last post by  Mike Braddock  
#1 ·
Please list the Pro's & Con's.
 
#2 ·
I like the 351W .There is still plenty of room to work around the motor, it is a very simple 1970's type carb set up and can be made to produce more than enough play time HP.
I also would have no problem with a SC'd 302EFI. Different look with but with other advantages and more than enough power. I don't know much about the 4.6 except is is quite wide and can really produce power with all the modern aftermarket goodies to make things easy. These are just my personal preferences. I will work with whatever is available next time and still be smiling wide each weekend !
 
#3 ·
Unless you can weld or fabricate to some degree the 4.6 is out until FFR releases the 4.6 kit.

There is a much narrower selection of appearance and performance items for the 4.6 - but this is changing rapidly.

The 4.6 is a neat motor, especially the DOHC. I had two Mustang Cobras with DOHC motors in them. Nice cars.

Between the 302 and the 351? It's mostly a cost issue if you already have 302 parts. Many of the parts are "bolt on" compatible. The only exception is the intake and distributor other than the obvious "Hard Parts (Crank/Rods/Etc). You get 49 extra cubes base, and most aftermarket 351's are stroked to at least 377 if not bigger.

The 377 was the smallest 351W coast really wanted to sell me.

If you're starting from scratch I would rule out the 302 in favor of the 351W.

A better discussion IMHO would be Windsor block vs Big Block vs DOHC. The SOHC 4.6 is just not worth the effort IMHO.
 
#4 ·
I thought there was some good reading on this "SB fans new "crate" 5.0 cammer" Club Cobra thread ( http://www.clubcobra.com/forums/t21487-15&pagenumber=1 ).

I thought the general concensus was a little harsh on the Ford cammer but I would still prefer it over the Chevy original "mouse" motor in a Cobra. The aluminum GM LS1 series is pretty tempting at 390 pounds, however.
Image
 
#5 ·
Capt Al,
I didn't want to hijack your other thread regarding kit differences in case someone actually had some input on the subject (I'd love for FFR to jump in and spill some beans!)

Here's my take on the differences in the powertrains:

302/351 Pros:
Tried and true. Lots of options for aftermarket performance in every category. You can put 500+ HP on the stock internals. Has a more period correct look when topped off with a carb. The donor stock T-5 tranny will take a lot more HP than people give it credit if treated reasonably well. The EEC-IV doesn't have a lot of emissions programming to cause problems with aftermarket parts.

302/351 Cons:
You have to change just about everything above the shortblock from a 302 donor motor and add a supercharger to get 500+ HP. (Or you could go stroker motor in place of supercharging.) Donors are almost always high mileage requiring a rebuild.

4.6/5.4 DOHC Pros:
Forged crank from the factory. 6 bolt mains. Aluminum block in the 4.6 variety. Heads you'll never need to replace to get more power. A more unique look and IMO cleaner appearance than the 302EFI. Lower mileage donors with cleaner parts. Just a supercharger away from 500+ HP

4.6/5/4 DOHC Cons:
Stock rods aren't quite as good as the stock Windsor. More expensive donors. T-45 tranny not quite as strong as the T-5. EEC-V has more emissions code but it can be defeated with a chip. Not as many aftermarket vendors and parts are still pricey. Luckily you don't need a lot of them to make a lot of power.

Several of my friends race the mod motors with turbos (1300+ HP) or superchargers (1000+ HP) using stock heads and cranks! Here's an example of what you can do with a stock block, ported stock heads, and a stock crank (click on the image for a little video):
http://www.athenasofttech.com/images/cobra/host/EPSN0081.avi><IMG

This car and engine were built by one of my friends, Randy Haywood, who also drove the car in NMRA Super Street Outlaw to 7.99@175. He did use the 5.4 DOHC from the Lincoln Navigator, but the 4.6 DOHC can get close to this kind of performance with the same stock block, crank, and heads.

Note that I left out the 4.6 SOHC engines. They have better power in the later years, but they just don't have as much potential as the DOHC. I don't see the point in using one when you can grab a DOHC from the junkyard instead.

For me it was just something different to do. I've had a 302 with bunches of mods (Vortech S-trim, heads, cam, intake, TB, MAF, injectors) making around 500HP. I've had a 351W stroker motor (403CI) with a carb making around 700HP naturally aspirated. But several friends have very tame and streetable 500+ Mod motors so I thought I would try one.

Another possible plus for for the 4.6 kit from FFR will be that the position for the Cobra spec T-45 tranny crossmember is very close to where it needs to be for those who want a T-56. If FFR didn't account for this in the redesign I'm going to be a bit disappointed...
 
#6 ·
Thanks to All for the Excellent Informative Posts.

I'm Contemplating a 2nd FFR build in the future and was looking for opinions on the 4.6 Platform.

You Guys definately Filled in the Blanks.
 
#7 ·
Aside from the additional complexity of the 4.6L build, the biggest 'con' of running it (IMO) is that few people have been successful road racing that motor. They are constantly toasting bearings due to oiling problems. The best solution seems to be a properly designed dry-sump setup which adds a hefty chunk of change to the bill. For "spirited street driving" they seem to do fine. This observation is not based on any personal experience but rather what I have read from the guys open tracking their cars over at corner-carvers.com.

Mike