Advice Needed. 351 Or 429?

striker911411

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Jun 21, 2013
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My 86 GT has been around for 14 years now and between me and my dad working on it the car is pretty dang fast. But the bottom end is a stock 1986 from another car so at some point I know I will have to pull it again.

I had a chevy (no title) 4x4 with a 350 in it I was going to put in my Camaro (still needing a trans). I ended up trading that 79 chev for a 88 F-250 4x4 with a 351 and a title. Guy also threw in a $600 floor jack. Great deal right. The 351W will fit in the mustang and can stay FI using the same harness as far as I know. I would use my worked over 1995 302 heads and get a bigger cam plus swap parts id need to buy. This motor is also "Stated" to have been rebuilt.

Then my father in law and I was having some drinks last night when the topic came up about my 14 cars and what I was going to do with all of them. Then the 429 came up. He has one I would probably need to rebuild but I can have it for free. Would the power gain be worth it with the extra work I would have to put in for the 429? The 351 sounds good but lots of things are going to add up with it when you consider headers, mounts, lower intake etc, etc.... So I am looking for some sensible advice so I can say yes or no to the 429. I am looking for about 4-500hp on motor and maybe a 100 shot of nos in case I ever need it. I put like 2k miles on the car per year and dont really drag race it. Never been to a track with it but maybe I will. They just dont have many tracks near me.
So to the guys that know. What would you do? And I know the displacement saying well but my car already has traction issues (stock suspension) with my 302. Im not a OKC street outlaw but I would like to be like the shocker guy that pulls up in some junk and kicks some butt when the time comes. That's just my style. Not looking to spend 5k on the block.
 
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351W = IMO for a driver and can easily meet your goals

429 = Cool factor, but heavy

I would take the 302 pistons out of your current motor when pulled and buy a 3.85 crank for cheap and make a 393W

Either way you'll meet your goal, just 351W would be a lil easier

My vote 351W
 
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A 429/460 is a giant departure to consider as a possible swap when you already have a Windsor in the car.

Firstly, nothing you currently have, including the transmission, trans mount, and driveshaft will work. Additionally, you'll need to find a 385 bell transmission (no easy task) that will handle that duty.
Alot of guys have opted for a C-6 that came from the same donor, but a C-6 is one heavy pig, and is......unfortunately,..... a 3 speed.
To me that alone would be the deal breaker, but if you are industrious, you can find alternatives.

There is a C-4 bellhousing out there to fit that engine. In a drag car a C4 behind a 460 is a way faster transmission that the mega-pig C6. Not only is it about 50 pounds heavier, the internal mass of the C6 actually robs power just to spin all that junk.
However, that C4 bell is a needle in a haystack.

If it is a straight drag car, or very limited street you could also opt for a powerglide and use the available bellhousings that are out there to convert that 2 speed Chevy junker to your BBF.

(I'm thinking you're gonna want to go w/ a c6 here,......just my guess.)

You'll need a pan, headers, and swap mounts as well. (All of which can be bought from a kit)

The factory 429 cast iron heads came in two versions: Passenger car "Thunderjet" heads, and Muscle car "Cobrajet" versions.
The engine you can get will have T-jet heads. The exhaust port is restrictive as cast, but a die grinder, and about 40 hours can remedy that.

But once you remedy all of the above,.....this is what you can have.......If you'll be like Mike.

460 block bored .030.
Stock rotating assy.
TRW/Federal Mogul L 2404f dished forged pistons. 9.5:1 CR
Stock heads, hand ported, fitted w/ the "smaller stock size" stainless valves (2.19 I, 1.71E)
Flat tappet grind Comp cam 605L/ 248 dur at .050.
Weiand stealth dual plane intake manifold.
Holley 3310 vacuum secondary carb.

This was the single cheapest scratch build I've ever done,....did on purpose to counter the typical Southern Chevy Boy comments about how a Chevy was cheaper to build than a Ford.

The entire engine as described above was built for 2 grand, 800.00 in the short block.

In a 1980 notch with a C4 (and one of those rare assed bellhousings) and a 3000 stall converter the car ran 7.15 in the 1/8th.
Messing around with it I eventually managed consistent 7.10's on slicks.

I drove the car to the track, only using pump premium as my gas, beat it 5-10 passes, and then drove it back home. It never ran hot, and never needed any maintenance. And as it was built, was perfect as a sleeper capable of a consistent low 11 quarter mile.

So,...to answer your question,....A BBF will absolutely KILL a 351 W in the bang for the buck category, if you are capable, have the resources, and can find a transmission that'll work for you.
If not, put the 351 Windbone in there, and let that dog eat.
 
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351W = IMO for a driver and can easily meet your goals

429 = Cool factor, but heavy

I would take the 302 pistons out of your current motor when pulled and buy a 3.85 crank for cheap and make a 393W

Either way you'll meet your goal, just 351W would be a lil easier

My vote 351W
I like this idea but I wonder what else I would need to add in order to get a 393 eating properly. I have the Explorer injectors in the car now with a stock fuel pump, rail, and adjustable pressure regulator cause I had to bump it up 9PSI over stock. I can only assume the 393 would need a little more. Also have issues with my electronics working properly now since I have a stock computer. The car likes to surge until I rev it or just let it do its thing and surge like 12 times then its okay. Does the serge almost every time I start it even if I just run into the store for a minute and come right back out. Do I need to address that and get new computer if I go 393?
 
I like this idea but I wonder what else I would need to add in order to get a 393 eating properly. I have the Explorer injectors in the car now with a stock fuel pump, rail, and adjustable pressure regulator cause I had to bump it up 9PSI over stock. I can only assume the 393 would need a little more. Also have issues with my electronics working properly now since I have a stock computer. The car likes to surge until I rev it or just let it do its thing and surge like 12 times then its okay. Does the serge almost every time I start it even if I just run into the store for a minute and come right back out. Do I need to address that and get new computer if I go 393?

I can tell you this- stock 1995 mustang heads will choke a 393. You are going to have to buy some aftermarket aluminum heads to let it breathe.
 
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I like this idea but I wonder what else I would need to add in order to get a 393 eating properly. I have the Explorer injectors in the car now with a stock fuel pump, rail, and adjustable pressure regulator cause I had to bump it up 9PSI over stock. I can only assume the 393 would need a little more. Also have issues with my electronics working properly now since I have a stock computer. The car likes to surge until I rev it or just let it do its thing and surge like 12 times then its okay. Does the serge almost every time I start it even if I just run into the store for a minute and come right back out. Do I need to address that and get new computer if I go 393?

Is your goal 400-500hp flywheel or to the ground? The injectors needed to support that would be roughly 42lb'ers to the flywheel (500hp) and it would need to be tuned. Did you convert yours to MAF?

With the 393W you will need a larger set of heads like minimum example of heads would be TFS 170c, AFR 185cc, and etc. I seen some guys port older style heads and even covert 2 bbl Cleveland heads to try to make that kind of power. Most will say start at a 200cc+ head, but for the 400hp range I seen smaller head like that make similar power on a 302 base platform....take with a grain of salt.

There are more experienced people to talk to for engine builds like this and Woody at fordstrokers.com is a good one to talk too.


Anytime you start changing stuff on FIs cars you can run into issues, especially cam swaps. I'm not too familiar with what has to be done to tune it correctly. However, IMO making the 351W work is going to be more bolt in and figure out tuning than fabricate and shoehorn in the 429.

@jrichker ahs a surging checklist that may help you also.
 
Fuel injector sizing & injector photos

Revised 26-Dec-2014 to add statement about figures are for flywheel HP and not rear wheel HP

Injector HP ratings: this flywheel HP, not rear wheel HP.
Divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines at the flywheel.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP
36/.5 = 72, 72 x 8 = 576 HP
42/.5 = 84, 84 x 8 = 672 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

19/.5 = 38, 38 x 8 = 304 HP x .85 = 258 HP
24/.5 = 48, 48 x 8 = 384 HP x .85 = 326 HP
30/.5 = 60, 60 x 8 = 480 HP x .85 = 408 HP
36/.5 = 72, 72 x 8 = 576 HP x .85 = 490 HP
42/.5 = 84, 84 x 8 = 672 HP x .85 = 571 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

See http://users.erols.com/srweiss/calcpchg.htm to get the calculators used in these examples.


Here's the duty cycle explanation. Duty cycle is how much of the time the intake is open the injectors are turned on. The 85% figure means that for 85% of the time the intake valve is open, the injectors are spraying. The idea is that you want some percentage of the duty cycle left over so that you have some room to grow the process.

If you are at 100% and you need more fuel, all you can do is turn up the fuel pressure. That means the whole fuel curve from idle to WOT is affected. Maybe you are already too rich at idle, and turning up the fuel pressure makes it worse. If you had some injector duty cycle left to play with, a custom tune could use that where it is needed. That would not over richen the whole range from idle to WOT.

If you did turn up the fuel pressure, you might be able to change the injector duty cycle to get the air/fuel mixture ratio you want since the injectors will have extra fuel delivery capability.

With larger than stock injectors or higher that stock fuel pressure, you will need an aftermarket MAF that matches the injector size. The MAF “lies” to the computer to get a fuel delivery schedule that meets the engine’s needs and isn’t too rich or too lean. The best strategy is an aftermarket MAF and a custom tune to insure the best air/fuel ratio over all the RPM range.

Don't forget to increase the fuel pump size when you increase injector size or significantly increase the fuel pressure



Diagram courtesy of Tmoss & Stang&2birds
Ford_Injector_Guide.jpg





Copied from the FORD RACING PERFORMANCE PARTS catalog:

PROPERLY SIZING FUEL SYSTEM COMPONENTS


Fuel Pumps
The following information is presented assuming the above information has been taken into consideration regarding BSFC, fuel pressure and specific gravity of the fuel being used. Most fuel pumps for electronic fuel injection are rated for flow at 12 volts @ 40 PSI. Most vehicle charging systems operate anywhere from 13.2v to 14.4v. The more voltage you feed a pump, the faster it spins which, obviously, will put out more fuel. Rating a fuel pump at 12 volts then, should offer a fairly conservative fuel flow rating allowing you to safely determine the pump’s ability to supply an adequate amount of fuel for a particular application.

As previously mentioned, engines actually require a certain WEIGHT of fuel, NOT a certain VOLUME of fuel per horsepower. This can offer a bit of confusion since most fuel pumps are rated by volume, and not by weight. To determine the proper fuel pump required, a few mathematical conversions will need to be performed using the following information. There are 3.785 liters in 1 US Gallon. 1 gallon of gasoline (.72 specific gravity @ 65° F) weighs 6.009 LBS.

To be certain that the fuel pump is not run to its very limit, which could potentially be dangerous to the engine, multiply the final output of the fuel pump by 0.9 to determine the capacity of the fuel pump at 90% output. This should offer plenty of ‘cushion’ as to the overall “horsepower capacity” of the fuel pump.

To determine the overall capacity of a fuel pump rated in liters, use the additional following conversions:
(Liters per Hour) / 3.785 = Gallons
Multiply by 6.009 = LBS/HR
Multiply by 0.9 = Capacity at 90%
Divide by BSFC = Horsepower Capacity
So for a 110 LPH fuel pump:
110 / 3.785 = 29.06 Gallons
29.06 x 6.009 = 174.62 LBS/HR
174.62 x 0.9 = 157 LBS/HR @ 90% Capacity
157 / 0.5 = 314 HP safe naturally aspirated “Horsepower Capacity”

Safe “Horsepower Capacity” @ 40 PSI with 12 Volts
60 Liter Pump = 95 LB/HR X .9 = 86 LB/HR, Safe for 170 naturally aspirated Horsepower
88 Liter Pump = 140 LB/HR X .9 = 126 LB/HR, Safe for 250 naturally aspirated Horsepower
110 Liter Pump = 175 LB/HR X .9 = 157 LB/HR, Safe for 315 naturally aspirated Horsepower
155 Liter Pump = 246 LB/HR X .9 = 221 LB/HR, Safe for 440 naturally aspirated Horsepower
190 Liter Pump = 302 LB/HR X .9 = 271 LB/HR, Safe for 540 naturally aspirated Horsepower
255 Liter Pump = 405 LB/HR X .9 = 364 LB/HR, Safe for 700 naturally aspirated Horsepower

Note: For forced induction engines, the above power levels will be reduced because as the pressure required by the pump increases, the flow decreases. In order to do proper fuel pump sizing, a fuel pump map is required, which shows flow rate versus delivery pressure.

That is, a 255 liter per hour pump at 40 PSI may only supply 200 liters per hour at 58 PSI (40 PSI plus 18 lbs of boost). Additionally, if you use a fuel line that is not large enough, this can result in decreased fuel volume due to the pressure drop across the fuel feed line: 255 LPH at the pump may only result in 225 LPH at the fuel rail.


My Comments:

A lot of people oversize the fuel pump by buying a 255LPH pump thinking that the fuel pump regulator will just pass the excess gas back to the tank. It does, but… Did you ever consider that circulating the fuel around as a 255 LPH pump does will cause the gas to pickup engine heat? What happens to hot gasoline? It boils off or pressurizes the fuel tank! With most of the 5.0 Mustangs having the carbon canister removed or disabled, the car stinks like gas, and the gas mileage drops since the hot fuel evaporates away into the air.


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif