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I've got the 468 pulled and already at the machine shop. It's gonna need 1 piston which HPR is sourcing to me.
Here's what the new build is gonna look like:
1) HPR 468 gen iv aluminum shortblock). 4.185 bore x 4.250 stroke. 13.5 compression.
2) Liberty LS3/LS7 hybrid heads with 2.185 Victory titanium valves, 1209x springs, heads were ported and flowed at 425cfm by Carl Quist competition engines.
3) TSP 1.72 roller rockers.
4) Cam motion .739/.739, 262/276, 114+4 hydraulic roller.
5) Johnson 2126 lifters.
6) 3/8, .135 wall pushrods
7) CID 4.5 intake.
8) Accufab 4500 throttle body.
9) 2" long tube headers.
10) 100 pound Fast injectors.
11) Magnafuel 4303 pump.
12) Mechman alternator.
13) E85.
Can I ask why the cam seems to small?? Seems like you would want 280/290 700 plus for that??
Looking at other 468 builds, Erik typically specs the cams in the 260/270 range and with 700+ lift. My goal is to have repeatable 9's without having to rev it to the moon. I think I will be fine with this set up, but If I don't get there, I will make changes.
Last edited by BigDaddy97; May 22, 2024 at 04:18 PM.
I hate to say this But I'll bet 5 bucks your engine is gonna like the Ls3 heads more... Why some may ask? With a engine this size it isn't CFM it's the CSA needed with CFM...
It's gonna have tq Regardless not saying a Ls3 is better than a Ls7 just it's happiness, & it's ability to Rpm with some Tq loss.
Depends on who ports it, but that's not a stock port anymore is it? The engine doesn't really even care about average csa anyways, does it? It's the minimum csa that matters more.
Not worried about the as cast Exact numbers. Rather the amount of CSA/MCSA wanted for a 468 @ 7k. Being this large wants a larger port...also may have gotten the Factory stuff as cast wrong.
Dennis Wheat ..
airflowdevelop wrote:My large port LS3 head is 3.24 at the intake flange, 3.58 at the short side and 3.05 at the venturi
Darin Morgan: personal camaro ls3 heads
Port volume stock 257cc
Port volume fully ported 262cc
These heads are a little to large from the factory. I tried to remove only the material needed to increase efficiency and no more.
Port opening 3.169in²
1" in 3.147in²
2" in 3.435in²
SSR apex 3.290in²
I hate to bother either for the MCSA...may send a sticky note question.
Not worried about the as cast Exact numbers. Rather the amount of CSA/MCSA wanted for a 468 @ 7k. Being this large wants a larger port...also may have gotten the Factory stuff as cast wrong.
Dennis Wheat ..
👍
Example of a Larger port head
Yeah, your numbers are off for an as cast factory rectangle port. This was posted months ago by a moderator...I save and bookmark good info too...
That ends up being about 2.72in2 in the throat. Usually with a 45 degree seat your throat diameter shouldn't be much more than 90% of your valve diameter, but If you hit 3.0in2, you're getting up over that 90% rule for a 2.165" valve.
The LS7 is just fundamentally a better head. Better shape, better valve location, more CSA..
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Hpr 468 2.0 
