521vs545

Need help on deciding on a 521 or a 545 for drag racing in a 88 mustang will be using p51 heads ?

drag only? If so go for cubes, street strip I like the 521, but 545 would be great. You have p51's go for 545. I am guessing a stock block?

Thats what i was thinking yes its a stock block.

the 521 will have a better rod, pistion ratio. There has been a few 545's exiting out of the bottom of the engine with stock 2 bolt engines. My 521 ran awsome for 2 years. The crank and rods didn't even need anything when it cam out of my d1VE block. Lem talked me into going with the 521 set-up. Hopefully others will chime in for ya to give you more info.

Thanks for ur help i was leaning towars the 4.3 stroke for that reason. I talk to lem other day for prices probaly be ordering tommorow. I want a solid 9 second car with some reliability if thats possible!!!! My buddy has 557 in a tube chassis car he wants me to a 521. Once again thanks this is my first bbf ford build

No problem, the 521 was my first build too.

What about a 521 compared to a 557 ? With stock block might as well go all the way am thinking, my first build also I like the 521 but a 528 sound a lot better 528SCJ .
ill be subbing here
what the differance weight for the iron block. Versus an aluminum block.?

my aluminum block weighed 556 pounds the way it came off the dyno

there is a sticky on engine weights

rmcomprandy wrote:

2fox wrote:What about a 521 compared to a 557 ? With stock block might as well go all the way am thinking, my first build also I like the 521 but a 528 sound a lot better 528SCJ .
ill be subbing here
what the differance weight for the iron block. Versus an aluminum block.?

In comparison, with all the same equipment, they will both usually make about the same peak horsepower BUT, the 557 will exhibit about 40 or so more lb/ft of torque.

Torque is what moves mass. A 557 with a set of super cobra jet heads from summit give me excellent Tq.? What's Max compression with 93 gas?
smaller heads give better Tq. And velocity right?

Torque is what moves mass.

So will 500 ft/lbs at 3000 rpm accelerate a car as fast as 500 ft/lbs at 6000 rpm then?

paulie

plovett wrote:

Torque is what moves mass.

So will 500 ft/lbs at 3000 rpm accelerate a car as fast as 500 ft/lbs at 6000 rpm then?

paulie

Well said.

HP = torque X rpm / 5252.

Just food for thought.

big Torque at a high RPM,moves mass fast. which is cu.in plus airflow=HORSEPOWER.