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Here is a decent guesstimate for the flow data between the two. I got the 862 data off a Motortrend factory head flow test. Obviously, these didn't have the 2" valves but I don't think the 2" valves are worth a ton. The 243 data is straight off Wilkes website.
I know @RedXray you are saying cam dictates what rpm the motor will make power in and I totally agree I've watched 12 billion Richard Hooldner videos as well. Bear with me tho, if a set of heads flow 314 at .600 wouldn't that make more power than a set of heads that flow 231 at .600? No matter what RPM its at? Or am I over thinking?
Also, I do understand boost will work well with either and a better flowing head setup should make the same power at a lower level of boost because boost is just a measure of air the engine cannot consume naturally. Therefore answering my own question because obviously, the 243s should be even better under boost. It's just not fun answering my own questions.
The 243's leave you room to go more hotrod if the build snowballs.
The 862's are good too especially with the over size valves but not as good if the build snowballs.
I'd go 243's just for bragging rights... specs sounds faster on paper lol
Those are good numbers on the ported 243's they are close to my PRC 225's. The only advantage the aftermarket heads have is the 13* valve angle, thicker deck and the smaller 62cc chambers.
PRC 225cc As Cast Heads 2.06" Intake / 1.600" Stainless Valves
(4.00" Flow Plate - No Exhaust Pipe).
The 243's leave you room to go more hotrod if the build snowballs.
The 862's are good too especially with the over size valves but not as good if the build snowballs.
I'd go 243's just for bragging rights... specs sounds faster on paper lol
Those are good numbers on the ported 243's they are close to my PRC 225's. The only advantage the aftermarket heads have is the 13* valve angle, thicker deck and the smaller 62cc chambers.
PRC 225cc As Cast Heads 2.06" Intake / 1.600" Stainless Valves
(4.00" Flow Plate - No Exhaust Pipe).
I looked at those 225 as cast a bunch when deciding if it was worth it to get these and port them. The 225s ported or not are such a great value. I have the 225 CNC ported for my other truck, they look awesome on the motor stand .
Of course valve angle and thicker deck are awesome advantages that can never be gained on an OEM casting but, at best this motor will see 10* of boost. If the short block starts showing symptoms of death it will be replaced with an LY6, and probably a tad smaller cam (220/224 112lsa low lift or something similar) Stock motor with boost is hard to beat for a DD.
Back on track, a few weeks ago I calculated what CC the chambers would be but I can't remember what I came up with. Since the 243s are milled a tad I think I came to the conclusion it was 2cc or less difference which is not much and since the CR are virtually identical it wouldn't be a big deal.
I might go to plan C which is sit the 243s in a shelf until someone wants either set of heads or..... I dump the clutch, lq4 drops a valve and I need another set of heads .
As far as bragging rights go, 243s are so 200L8, where 862 are the cool under dog hipster heads that get the notable mention in all the hot rod mag tests. So maybe the 862s have more bragging rights or, both are lame and I should square port swap the lq, or even better LT4 swap the Gen 3 truck.
The 243s shouldn be delivered tomorrow I'll post a bunch of pics when they arrive.
Really depends on exactly how much better the 862s flow than stock with the larger valves. I'm guessing they'd be closer to stock 243s (which flow somewhere around 250cfm @.600" lift) unless they did some bowl work and valve deshrouding on top of it. That's about a 25% increase in flow for the ported heads which (if the rest of the combo supports), can add up to 25% more hp. Plus it's not just peak hp, but area under the curve. And boost adds a multiple factor when compared to N/A. Usually the big deal for 862s is the compression bump, which is nothing in your case.
I would think your currently combo should be good for 370-380whp. With the ported 243s closer to 460-475whp. And with an intercooled 10psi and a good tune ~775-800whp
Now if you want to stay with the 862s you would still eclipse your 500whp goal by at least 125hp once you add the boost, which is no slouch either. Heck, you'll probably have a problem keeping traction.
Really depends on exactly how much better the 862s flow than stock with the larger valves. I'm guessing they'd be closer to stock 243s which flow somewhere around 250cfm @.600" lift. That's about a 25% increase in flow for the ported heads which (if the rest of the combo supports), can add up to 25% more hp. Plus it's not just peak hp, but area under the curve. And boost adds a multiple factor when compared to N/A. Usually the big deal for 862s is the compression bump, which is nothing in your case.
I would think your currently combo should be good for 370-380whp. With the ported 243s closer to 460-475whp. And with an intercooled 10psi ~775-800whp.
Oh man I like your numbers! The engine does have an LS2 90mmTB, NNBS intake, long tubes, and straight through exhaust dual 3" to single 4" no cats. Injector DC is only around 70% IIRC but the pump is still stock. Not terribly worried about running out of fuel and with those mods I don't think anything would be a restriction. I currently shift it at 6,200-6,400 because I see the VE table start t fall off a tad before 6k, I have always felt the heads were holding the cam back but, that's just my uneducated guess. I'd love to be able to run it a little further without power dorpping off because I feel it has the valv train to support more and I'f I could push it to 6,700 I could run 2nd gear just past 60mph and improve my 0-60 time substantially by eliminating that 2-3 shift.
I was sorta worried the much better flow of the ported 243s would hurt low-end performance which is very important to me as I tow weekly with this thing and it kicks ***. Your saying under the curve would be better with the better flowing heads which would be awesome!
I was sorta worried the much better flow of the ported 243s would hurt low-end performance which is very important to me as I tow weekly with this thing and it kicks ***. Your saying under the curve would be better with the better flowing heads which would be awesome!
You will lose a little way down in the low range (<4k) due to the larger runner, but I doubt you'll miss it, especially once you add the turbo. Once you get out of first gear, you'll be making more power everywhere. Plus as you said, if you can stretch your rpm range high enough before you shift 2nd, your 0-60mph should be substantially faster.
07-23-2021, 03:05 PM
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