351w swap in 2004 questions (set up like a 95 Cobra)

jonathansw1601

New Member
Mar 24, 2018
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Hello All,

I am currently in the process of swapping a 351w into my 2004 V6 mustang . I am posting on this forum because in order to make this build work, I am having to use a k-member, serpentine setup, T5 trans, headers etc. from a 94-95 Cobra because the body style from that car is basically the same as mine. Essentially, my car will be basically the same as a 95 Cobra R. The only difference is, I had to get a special-made flywheel and dampener that accommodates 4 bolt mains and the old 28 oz balance. With this setup, the engine bolts right on. As of now, the motor is a stock 69' 4v 351w with an original Shelby intake. The build cost me about half as much as it would've to upgrade to a 4.6 modular, and I like the 351 (and pushrod stuff in general) much better.

With the swap almost complete, I am currently planning the next stage of the build. I plan to switch to EFI and run a Kenne Bell supercharger, using a GT-40 lower intake off a Lightning. Ultimately I would like a steerable car with the max mpg possible for a boosted car that gets at least 400+ rwhp. Also I plan to emphasize low end power and torque over high end max power. This is because, as a street car, something thats good 0-60 matters much more to me than quarter mile times because the jerk your head back seat of your pants feeling is more fun/applicable than going 150+ mph and getting over 7000rpm. With all that said, I realize that mpg has much to do with how you drive, and I don't plan on goosing it across town everywhere. The car will be under 4000 rpm far more than its over it.

I plan to run higher gears and use the boost from the twin screw SC to create the torque to make up for loss of quickness off the line. Also, I've heard that shorty headers and an h pipe help with mileage because they create some back pressure for added torque low in the power band. Also, I've heard porting the heads and intake, as well as port matching the exhaust helps with efficiency. Finally, I've also read that a higher compression helps with mileage as well (although I realize that I will have to be careful with this high compression + boost) I don't want to blow up the motor and I also want to be able to run service station gas.

In order to achieve my 3 goals of:

1. 400 rwhp
2. Max mpg for a 351w at this horsepower
3. A build that emphasizes low end power/torque over high end/max power

What combination of things like EFI, chip, heads, cam, compression ratio, amount of boost PSI, etc would you run to achieve these goals? I ask all these things together because I all of these things work in tandem to achieve a specific goal.

Also, are there any other things you can think other than mentioned that would help. Perhaps methane injections? Cold air intake? Also, NOS is out of the question, and I'd be okay with running just enough boost to help me hit the numbers I want, if it means I can run a higher compression or do things in other areas that help with efficiency.

In advance, I realize, max MPG for a 400rwhp 351w may not be super impressive, but I plan to make this my daily driver and most efficiency mods increase hp anyway, especially low end power. I believe getting over 20hwy and 15 city is possible, as Ive seen people in the truck forums do it with 351s (albeit not boosted 400hp ones).

Thanks in advance!!!
 
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Noahwyatt48

New Member
Jun 26, 2018
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0
1
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Cowpens, South Carolina
Hello All,

I am currently in the process of swapping a 351w into my 2004 V6 mustang . I am posting on this forum because in order to make this build work, I am having to use a k-member, serpentine setup, T5 trans, headers etc. from a 94-95 Cobra because the body style from that car is basically the same as mine. Essentially, my car will be basically the same as a 95 Cobra R. The only difference is, I had to get a special-made flywheel and dampener that accommodates 4 bolt mains and the old 28 oz balance. With this setup, the engine bolts right on. As of now, the motor is a stock 69' 4v 351w with an original Shelby intake. The build cost me about half as much as it would've to upgrade to a 4.6 modular, and I like the 351 (and pushrod stuff in general) much better.

With the swap almost complete, I am currently planning the next stage of the build. I plan to switch to EFI and run a Kenne Bell supercharger, using a GT-40 lower intake off a Lightning. Ultimately I would like a steerable car with the max mpg possible for a boosted car that gets at least 400+ rwhp. Also I plan to emphasize low end power and torque over high end max power. This is because, as a street car, something thats good 0-60 matters much more to me than quarter mile times because the jerk your head back seat of your pants feeling is more fun/applicable than going 150+ mph and getting over 7000rpm. With all that said, I realize that mpg has much to do with how you drive, and I don't plan on goosing it across town everywhere. The car will be under 4000 rpm far more than its over it.

I plan to run higher gears and use the boost from the twin screw SC to create the torque to make up for loss of quickness off the line. Also, I've heard that shorty headers and an h pipe help with mileage because they create some back pressure for added torque low in the power band. Also, I've heard porting the heads and intake, as well as port matching the exhaust helps with efficiency. Finally, I've also read that a higher compression helps with mileage as well (although I realize that I will have to be careful with this high compression + boost) I don't want to blow up the motor and I also want to be able to run service station gas.

In order to achieve my 3 goals of:

1. 400 rwhp
2. Max mpg for a 351w at this horsepower
3. A build that emphasizes low end power/torque over high end/max power

What combination of things like EFI, chip, heads, cam, compression ratio, amount of boost PSI, etc would you run to achieve these goals? I ask all these things together because I all of these things work in tandem to achieve a specific goal.

Also, are there any other things you can think other than mentioned that would help. Perhaps methane injections? Cold air intake? Also, NOS is out of the question, and I'd be okay with running just enough boost to help me hit the numbers I want, if it means I can run a higher compression or do things in other areas that help with efficiency.

In advance, I realize, max MPG for a 400rwhp 351w may not be super impressive, but I plan to make this my daily driver and most efficiency mods increase hp anyway, especially low end power. I believe getting over 20hwy and 15 city is possible, as Ive seen people in the truck forums do it with 351s (albeit not boosted 400hp ones).

Thanks in advance!!!
Im looking at doing this swap also into my 02 V6 can you give me a rough parts list by any chance?.
K member?
Suspension?
things of that nature?
 

jonathansw1601

New Member
Mar 24, 2018
6
0
1
31
https://lmr.com/item/UPR-2005-95AK/...ember-And-Coil-Over-Kit-With-12-200Lb-Springs

There is the K member part. You basically need:

1. K-member kit that works for a 5.0 on a 94-2004 Mustang. You can also simply use a k member from a 94-95 mustang.
2. Serpentine belt for 351w Fox Body swap.
3. Headers for a 94-95 mustang with a 351 (this will be your hardest part to find)

Those are the basics. The rest depends on what transmission you have in the car, or what you plan on running. If you have an auto in your v6, it will bolt right on the the 351. You will just need an:
1. automatic transmission controller for a 4r70w. US shift makes one that is affordable. You will also need to get a throttle position sensor to go with it.
2. If you are running a manual, you will either need to run a t-5 from a 94-95 mustang or try to find an adaptor for your current manual.
3. If you are running a manual, you will also need a flywheel made for the t-5 that runs with a 28 oz balance. Tough part to find but if you go to a performance parts shop you should be able to order one. You will also need a dampener that runs a 28 oz balance with the newer engine setup. This can also be found via ordering at a performance shop. I think mine is a fluid dampener.

Hope that helps.