Highest lift for stock engine?
03-14-2006, 02:33 PM
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Highest lift for stock engine? All the 1.8 threads and cam threads got me thinking.Does anyone know about what the highest lift cam is you can safely run without fly cutiing.I know more than lift play a role.
I'll use my set up as an example.I got a Comp shelf grind XR281HR.
Duration advertised is I-281 E 283, @ .050 I-228 E-230
Valvelift with 1.7 rockers I-571 E-573 Lobe sep. angle 112*
With 1.8's it should put me around I-604 E-606
I have 66cc perimeter ported 98 heads and the pistons come out the hole at .007.
I know heads and piston out of the hole makes a difference as well.But on average,what is the biggest cam without flycutting.
I'll use my set up as an example.I got a Comp shelf grind XR281HR.
Duration advertised is I-281 E 283, @ .050 I-228 E-230
Valvelift with 1.7 rockers I-571 E-573 Lobe sep. angle 112*
With 1.8's it should put me around I-604 E-606
I have 66cc perimeter ported 98 heads and the pistons come out the hole at .007.
I know heads and piston out of the hole makes a difference as well.But on average,what is the biggest cam without flycutting.
03-14-2006, 03:36 PM
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I just wanted to add that I read thru the cam sticky a couple of times.I didnt see anywhere in there about P to V clearance.So thats why i'm asking.I thnk that maybe I'm going to be real close beacause of the 1.8's.
03-14-2006, 03:45 PM
#3
For the most part, lift is not what gives you piston to valve clearance problems, it's duration. Think about it, at maximum lift, your pistons are just about at the bottom of the cylinder...not P to V clearance problems at max lift. But as the piston is coming up toward or departing from Top Dead Center, that's when P to V clearance gets tight. A cam with lots of duration is going to hang the valve open longer as the piston approaches TDC. Too much duration and BAM! Milling heads obviously tightens up P to V.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
03-14-2006, 03:59 PM
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I sorta understand what your saying.I'm kinda new to the cam thing even though I've been around cars forever.I've personally never got into cams big enough to have to worry.
Without having to clay,do you know about how much duration you can go.Like I said above,I just have ported perimeter bolt heads with a 66cc chamber.They have 2.05/1.60 valves.I also used stock gms gaskets.When I had the heads off I measured out of the hole and it was around .007.I dont know how to figure out if i'm going to have issues without claying.I guess now that the cam is on the way I'm getting a little nervous,wondering if I should of went a little smaller.Even though its not a huge cam.Maybe I'm worrying for nothing!I just dont want to have issues and I couldnt find alot of info when searching about piston to valve clearances.
Anyhelp would be as Ron Burgandy would say "super duper"!
Without having to clay,do you know about how much duration you can go.Like I said above,I just have ported perimeter bolt heads with a 66cc chamber.They have 2.05/1.60 valves.I also used stock gms gaskets.When I had the heads off I measured out of the hole and it was around .007.I dont know how to figure out if i'm going to have issues without claying.I guess now that the cam is on the way I'm getting a little nervous,wondering if I should of went a little smaller.Even though its not a huge cam.Maybe I'm worrying for nothing!I just dont want to have issues and I couldnt find alot of info when searching about piston to valve clearances.
Anyhelp would be as Ron Burgandy would say "super duper"!
