Increasing compression in a 6.0 L96?
12-13-2020, 11:17 AM
#22
Thank you for the calculation! I tried using the calculator but wasn't getting the result I thought I should be getting, I had listened to you and others on a thread I started and I'm glad I did, this really woke it up! ONLY regret is I didn't do it when I first put the heads on.
12-13-2020, 12:41 PM
#25
TECH Senior Member
Thank you for the calculation! I tried using the calculator but wasn't getting the result I thought I should be getting, I had listened to you and others on a thread I started and I'm glad I did, this really woke it up! ONLY regret is I didn't do it when I first put the heads on.
12-15-2020, 05:05 PM
#27
It's about getting the valve to peak flow as quickly as possible and keeping it there for as long as possible within a given duration window. That is, more often than not, going to involve lifting the valve past the point where flow no longer increases with additional lift. Unless you have a horrible port design (and they do exist) and flow actually decreases with additional lift (eg. port stalls), the port will continue to flow at max as you continue to lift the valve. But it will have spent a significant amount more time with that amount of flow, and you will have gotten to, say .150" or .200" lift (where flow is increasing very rapidly with increased lift) more quickly, and stayed above that amount of lift longer than you would by only lifting the valve to where flow stops increasing and then returning the valve to the seat.
going past will just increase your avg fill time..a cylinder now can only ingest what it can an that is controlled via valve events. a port may only be able to support so much flow an say 300 for ease at peak like hes saying but its not the limiting factor because the cylinder fill volume is the dictator. the longer you spend in a heads peak velocity range the quicker the cylinder will fill..not hard to get,its the very same reason why a engine with a good port will want a earlier ivc number in the valve events..much like a lazy exh port youll open the evo sooner to compensate..cough cough cath vs rec port cams for example 🙂
now o.p i have lq9 short block with rec ports milled .100" off the decks.i fly cut the pistons .150" an with a .051 gasket im rate around 12.5-1 comp..i ported a ls3 intake so itd be a sleeper combo an ment to rev to 7500..intake made 15 more hp on a cam only ls3 vs stock intake on btrs dyno an carried nicely..look in my for sale ad on it to see the crazy work i did an dyno graphs..i should make a how to on doing the port work an others..
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