416 and 243's
 

Goal of 550 on motor. able to be driven on long trips with ac, and road racing.
Give pros and cons of this setup before I buy.
Forged 416 or 427 about same price from Thompson with 1 year warranty.$4800
EPS custom cam $400
patriot ported 243's with 2.08, 1600 valves $500
new thompson lifters $160
new ls6 oil pump$160
ls2 timing chain, from old motor
Ls6 intake old motor
78 mm throttle body old motor
New upgraded fuel injectors $300
conversion kit ls1 to ls3 $400
tune $700
1 3/4 headers free
700 hp monster clutch new and already own
built t56 own
strange s60 4.11 1000 miles own.


I also still have my 78 mm nitrous plate and stand alone system which could get me to 700 hp if I needed it. I figured I'd save some money on the fast intake and Trick flow heads because I could get the extra hp from nitrous if needed. Let me know if i've listed all I need and your thoughts.

Are you "dead set" on the 243 heads? If I were you, I'd go with the 427ci if it's roughly the same price and go with some CNC'd LS7 heads. If you do that, you'll meet, and likely exceed, your goal of 550rwhp.

not dead set. I just already own the heads. with stock valves and patriot will change my springs and valves while they have them for $500. Plus, I may very well change my mind in 2 or 3 months after the car is done and buy something totatally new. I have very little time to sale parts and I often end up with a bunch of new and old sfuff ranging from new clutches to full motorcycles sitting around my garage. So I guess I'm trying to do a budget build.

I mean, the heads you have will work, but in my opinion, they aren't optimal for a 416ci or 427ci engine. My theory is to always put the best heads on the motor as possible, but, like you said, you're wanting to do this on a "budget", so since you've already got them, I can see what you mean. Plus, like you said, if you're going to be throwing Nitrous at it, that will give you all the extra power you'll need.

strokes longer than 4" can have skirt wear issues, keep that in mind.

Also, with the large bore, and added displacement, the ls3 heads should be a hands down win over the 243s

I'm not sure about the stroke. I think Thompson said 4.065 for the 416.
The conversion kit were relocation sensors etc that Thompson sales to get the motor to fit in fbody.
not really worried about dyno. I'm just pleased if I can run roughly 128 to 130 if i spray or 120 on motor.
I haven't sent the heads back to patriot yet. they are still connected to my tapping 346.
The long tubes are jet hots which are really hookers.
I'll even take 525 on dyno if it's running good and not running hot on the street.
Lastly, I'm not that educated about internal engines so what's a skirt issue?

I'm going with a 4" stroke and I would suggest it to anyone else for the reasons above....and fwiw my H/C/I ls1 trapped over 120 so that shouldn't be an issue

I'm not sure if 550 rwhp is very likely (no fast intake too?). I don't. I have a 427 (4.125" bore) w/ tfs 235s and it's trapped anywhere from 127 to as quick as 133. It has 12:1 compression. Not a monster cam but fairly big. I was hoping to trap 134-135 in cool weather and 130ish in the heat but it didn't work out that way.

You'll probably be in the 480-500 range with that motor. If you had TEA or AI 243s, you could certainly get much closer to 550 with the 416. The problem is the rest of the parts have are not up to the task.

As others have stated, the headers, intake, MAF, will not support that sort of power.

I'd save some money and do an Iron 408. You'll still be in the 480 range power-wise.

Either motor should easily trap more than 120. If they don't, then something is seriously wrong. 125-127 depending on the air and weight.

When your piston is at the very bottom position (with strokes longer than 4") part of the piston skirt comes out of the sleeve and creates a slightly "wobble" effect and causes premature wear around the bottom of your pistons.

and FWIW

you NEED:

1 7/8th headers
85mm (or larger) MAF, the z06 is a cheaper option
90-92mm TB, the 102mm TB wont show you any gains at this power level so a 92 will be plenty.
FAST intake 102mm version

With that much cubic inch, Mite as well sale the heads and intake and just buy stock ls3 heads and a ported ls3 intake or fast. I wouldn't worry too much bout dyno numbers unless you just wanna walk around with your dyno sheet bragging. What kind of times do you want to run?