351W build

Topic: 351W build (Read 5534 times) previous topic - next topic

Reply #15 – July 26, 2010, 07:11:28 PM

I went out on a limb here and did some searching on the Corral for you and filtered out some of the BS:

http://forums.corral.net/forums/showthread.php?t=1209156

http://forums.corral.net/forums/showthread.php?t=1191407

Basically what everyone gets at is the motor will make 302W power (300 to 350 range) and about 50- 75 ft-lb more torque than a 302W but it will do it all under 5500 or so rpm. All that and a 100 lbs more over the nose of the car.

Now the one advantage I see here is if you are getting the P heads dirt cheap and are going to swap out heads and cam at a later date then this could be worth the work. Either way it sounds like a fun project as a day in the garage turning wrenches beats mowing the lawn.

Darren

351W build

Reply #16 – July 27, 2010, 09:29:35 PM

Aero

I have not dynoed the car yet because I was being stupid when I did the engine swap and did a full pull hard run on the street. Needless to say my AOD did not like me after that so I have alot of shifting issues and locked in gear issues. So next year I will put a Lentech or something in there. As it sits right now I can keep up to a supercharged Murauder with my 2.73 rear gears. But I do run fat and I have a really bad hunting idle after driving the car for 1/2 an hour or if I shut the car off then restart. I want to get to a dyno and get a chip burned for it. I will do this after I get a good trans in there and my 3.73 turbo coupe diff installed.

Now I know this is not exact numbers but we ran a buddies race car through a desk top dyno and the numbers were almost dead on for his engine. So we did mine and it came up with 357 hp and 418 ft lbs of torque. Like I said, not true numbers but it is a start.

I did build this car as a street car not a race car. So thats why I have a mild cam and only cleaned up the bowls on the GT40 Y heads. If I was going to do a race engine I just would have went with a Trick Flow package for the engine and used flat top pistions with valve reliefs in stead of a stock 351w truck engine. But if I do blow this engine up, I see a 427 small block stroker in its future.

351W build

Reply #17 – August 11, 2010, 07:56:52 PM

The "P" heads are only better than the standard gt40 iron heads due to a fast burn chamber(with smaller chambers) and slightly better exhaust port flow below .500" lift. A worked over set of P heads would be great for a stock stroke 351W destined for street duty.

Well ported gt40 iron heads would be worth much more than the P heads given higher lift on a larger(than 302) engine....but the money necessary to make either of those heads flow what you'll need will be equal to or greater than a new set of aluminum heads. Those heads are great for a low budget street build up....not much more.

MM&FF built a 351 similar to 86capri's and ran bottom 13's with a 2.73 gear and an ailing clutch...I can't remember rwhp numbers but it worked out to roughly 350hp at the crank and 420lb-ft at the crank....they even had a real lazy cam in it.....a hard working 350hp 302 would be lucky to make much more than 330-350lb-ft....and that torque makes all the difference.

AFR 185 heads and an appropriate cam will get you to 500+ hp on a 393. FWIW, all the 393 dyno tests I've come across out shine the larger 408...which seems weird...maybe a difference in rod ratio or piston speed.

Good luck,
Don

351W build

Reply #18 – August 11, 2010, 09:30:39 PM

If I was to do it again I would go ballz out and get nice flowing set of heads/intake and cam combo. I mixed and matched my stuff with used parts. I know places like Edelbrock make power packages for the fuelie 5.0L but carbed setups for the 351w engines.

I am running a stock 96 truck bottom end. The pistons are dished so many cc's already, and with the (I am guessing) 64cc GT40 Aluminum Y heads, I am only at 8.5-8.8 compresson ratio. May even be lower than that.

On the heads, most of the porting I did was in the bowl area. MM&FF and Mustang Monthly did some port work and tests a while ago on these heads. The best results were from cleaning the casting in the bowls and smothing out (and on my heads, the ports were terrible. I spent probably 8 hours total grinding and smoothing the bowls). After that the heads were at max flow and any port work actually hurt the flow. Not too sure how but the numbers showed it. But looking at my ports, they matched up to the gaskets very well. The hard parts was making sure the gaskets for the intake were in the proper position when the intake was installed.