Trust the ET formulas on the Internet?

[Gmanuel11]

I'm thinking of taking my 355 out to 383 (it'll probably need to be .040 over actually). The motor is currently making around 420 fwhp, so I was wondering what E.T. people think I can get with it, if the truck weighs 3900 with me in it (I'm a little guy) and has a th350 with 3.73 rearend.
Also, what does everyone think about 195 AFR heads, 9.5:1 compression, a Holley 750 carb, performer rpm manifold, forged internals, and the below cam for my 383 build? The stroker kit will be from eagle.

http://www.compcams.com/Company/CC/c...?csid=161&sb=2
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[Gmanuel11]

Forgot to mention that the internet formulas claim I can run a low 13 with the current setup.
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[Super73]

Lets figure on this..

420 hp at the crank (not sure where you came up with that number, but lets role with it).

420 * .83 = a rough 350rwhp. .83 represents a 17% loss through the drivetrain.

Let's use this calculator as I find it to be one of the more accurate one for a well optimized set up (not a perfectly optimized one, but close): http://www.wallaceracing.com/et-hp-mph.php

13.0x at about 103mph.

Keep in mind, when I say a well set up combo, I mean one with:
a verter that is close to tq peak
a gear tire combo that is close to running out of rpm as you cross the traps
Correct shift points
Suspension that is set up correctly
Correct AFR
Good launch technique

Well, you get the point.
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[Gmanuel11]

The previous owner built the engine, following a build by a magazine, that claimed in the 430 range so I figured that after accessories, it'd be around 420. Thanks for the link, that'll be very helpful in the future for a point of reference! Would you say that the claim of 10 whp making a difference of around +/- .1 towards your e.t. is true? I hear that and that 100 pounds is a tenth so often that it seems like it must be true.
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[Super73]

Are we talking about a 4,000lb truck or a 2,800lb mustang?
In addition to that, are we talking about a 14 second ride or a 9 second ride.

Short answer, those rules are not always accurate.

The faster you go, the less accurate it is.
The heavier/lighter you are, the less accurate it is.
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[Super73]

Btw, here are more calculators for you.

http://www.wallaceracing.com/Calculators.htm
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[Gmanuel11]

Yeah I guess both extremes would impact how accurate that claim is. Thanks for all the help, mind if I ask a few more questions to try and gain a little more wisdom from someone who's down in the 10's?
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[Super73]

That's why we are here, ask away!
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[Gmanuel11]

Okay, well do you think you could give me an opinion on how well the truck is setup for the strip in terms of a mid/low 12 potential? It has Mickey Thompson slicks out back, a decent suspension, that seems like its pretty strip ready, but I could be a mile off in that thought. Would posting a couple side and rear views of the truck help at all in terms of determining how good the setup is? I believe it has some trac bars as well.
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[Super73]

Any idea:

What springs are in the front suspension?
Does it have Caltracs or a slapped bar? Big difference.
Does it have adjustable shocks?
Any other mods to the suspension?

Just so you know, stance has little / nothing to do with suspension set up.

How big is the converter?
Does it have a posi?
What size tire is on it?
What cam is in it?
What heads are on it?
What headers? Primary size and length.
Electric water pump and fans?
You sure it weighs 3,900? What does the front end weigh?

Lots to ask my friend.
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[Gmanuel11]

Indeed there is. I'm just now jumping into the game, with my first truck, coming from a low 13 car that I had barely done anything to, and I'm not very knowledgeable, but I'll see if I can figure all that out from the previous owner, and get back to you. Just one of the good things about buying from a close friend, is that most of the time you can trust that they'll be completely honest with you.
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[Gmanuel11]

I do know that it has electric fans and water pump, the rest that I can check without taking it apart, I'll check tomorrow.
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