Looking for advice for a build up to 550 hp on my 5.3 with 799 heads with a 750 carburetor . I want it all motor going to be on the drag track only flywheel hp

 

Do you want 450 or do you want 550? There's a pretty big difference in cost to achieve either. Also, what fuel are you using? We need more information.

 

A N/A motor on pump premium can produce, AT MOST, something around 1.25 ft-lbs of torque per cubic inch, at its peak, at whatever RPM the particular motor's peak torque occurs at. MAYBE 1.33 if you're lucky and good (I'm neither of those things, but w/e, maybe you are both). Let's be generous and use the higher number.

Your 5.3 = 325 CI or thereabouts, can't recall the exact # for our specific motor but it's somewhere close to there.

325 × 1.33 = 432 ft-lbs

That's the most torque you can realistically expect to EVER get out of it. To get more, you'd need more compression (pump gas is a problem for that), more cyl pressure somehow (atmospheric density is the limit to that, in the absence of boost or nitrous), or SOMETHING that more or less defies the laws of physics. Still, that's A BUNCH of torque, CONSIDERABLY more than the factory's peak torque of what, 330 ft-lbs or whatever it was.

HP = torque × RPM × 2 × pi ÷ 33,000 (most people will refer to this as torque × RPM ÷ 5252.11; if you go back and look at the fundamental definitions of torque and HP, and the definitions of their units, it's obvious where those #s all come from)

That means, if you want your peak HP to be 550, you have to make your peak torque at the RPM where 432 × that RPM ÷ 5252.11 equals 550.

That means your peak torque of 432 will have to be achieved at an RPM equal to 550 ÷ 432 × 5252.11. That works out to about 6683 RPM. Call it 6700 for nice round numbers.

Now, this string of calculations could be a little bit off, one way or the other, but it won't be by much. Let's say, just for the sake of argument, that your peak torque will have to be SOMEWHERE in the range of 6500 to 7000 RPM.

Consider briefly the cam, heads, intake, exhaust, etc. you would have to use, to put your PEAK TORQUE into that range. Not your peak HP. Your PEAK TORQUE will have to be developed in the neighborhood of 6500 to 7000 RPM.

If you use a different fuel, the potential peak torque might change as well. Obviously adding nitrous will change all of this too: 200 HP of nitrous, for example, would allow your hypothetical motor to produce 550 HP under the same circumstances (cam, heads, RPM, etc.) that it OTHERWISE WOULD HAVE produced 350 HP. So that sort of thing can change all of this in a big hurry.

I'm thinking your goal is unrealistic. You need more CID to achieve that much HP in the real world without some form of power adder.

 

450 shouldn't be that difficult but 550 is pushing the upper limits even if using very expensive components.

 

anything from 450 and up

 

You better tell my engine builder he did something wrong by getting 1.44tq:cubic inch out of my pump gas 434 (626lb @ 6200). Speaking in absolutes can be dicey bc there's a number of shops who master the HP:CI game.

Now I'm not saying I'd try to get 500+HP out of 325ci but it certainly can be done.

 

Stock LC9 with gen 4 truck intake, 1 7/8" long tubes, and a Howards 222/225 cam/springs did 426 HP on my buddies engine dyno.
Was tuned on a little microsquirt too if I remember.

I'd recommend getting those 799 CNC ported, and make sure you're not running one of the bad carb intakes (there are some bad ones).
Then get a good cam/spring combo and some pushrods. 1 7/8" headers. You should be able to do ~475 at the crank pretty easily.

 

As you can see it can be done. To get closer to the 550 mark attention to detail would be needed.... ~Squeeze the max compression for your best octane.
~ Lightweight valves such as LS3 hollows. ~ Port match the intake to the heads.
~ Maybe run a bigger cam depending on your stall etc.
~ Run at least 600 on the lift. ~ use a good quality lifter.

 

I always love the rocket scientists who post long drawn out nonsense posts to impress us simple car folks with their vast amounts of knowledge.

 

Yup. 1.53hp per cube not that hard.
Doesnt even need anything all that special.
550 do able.

 

He is basically saying a stock Coyote motor shouldn't exist.....
Unless im reading it wrong

 

Right. He's saying 1.33 ft-lbs per cubic inches in the most torque you can expect to EVER get out of it, and a bone stock coyote is SAE rated to 1.39 ft-lbs per cubic inch.

 

Do you have a graph from that run? I'm planning to use that cam on a project.

 

I should be able to get one, but it was 3 or 4 years ago so hopefully the file is still saved.
I have one of them sitting on the shelf thats going in a TT 5.3 this spring.

 

If you're stuck on using the 799 heads and 750 carb you likely won't make over 480 ish. They dyno 380 ish stock at the flywheel with no accessories and using long tube headers. Big cam will get you 70 ish.

The intake you use with that carb will make a big difference too, which intake are you going to use?

How much are you willing to spend and how much of the setup are you willing to change?

The numbers you're looking for are doable, but it's gonna depend on how deep you wanna get into your pocket



It's really hard to say, because you'll need rpm to make the power you want, and turning high rpm is real expensive.

.

 

The stock heads flow enough to go almost 550hp. Porting would help make your number easier (lower rpm). You'll need some compression, cam and valve train setup to go at least 7K.