Originally Posted by Area47
(Post 2328578)
cam gears would be a better end route on the 272/272 set up
:) Even if the 272/264 is doesn't make as much power... it's lets the other 'un-cammed' guys make an educated decision as to whether they want a 272/272 set w/ adj.gears, to a 272/264 set w/o adj. gears |
it isnt going to make more power...just a longer powerband...just no one has compared them back to back to back on all cam durations..everyone has there own ideas on them and goes with it..our after market support is horrible
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there is a much deeper deal to this. you are still limited by the stock grind in it's base vs a blank grind. cam timing blah blah blah blah
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Originally Posted by Omega_5
(Post 2328597)
That's what I plan to compare to.
Even if the 272/264 is doesn't make as much power... it's lets the other 'un-cammed' guys make an educated decision as to whether they want a 272/272 set w/ adj.gears, to a 272/264 set w/o adj. gears |
Originally Posted by Witt
(Post 2328779)
My math might be wrong but those numbers you quoted for overlap will require adjustable cam gears. The LSA won't change between the grinds, even using the stock LSA there would be no overlap difference between a 264/272 and a 272/264. Whoever you quoted would require adjustable gears to achieve those numbers.
"lawl wtf" :cool: |
Originally Posted by Witt
(Post 2328779)
My math might be wrong but those numbers you quoted for overlap will require adjustable cam gears. The LSA won't change between the grinds, even using the stock LSA there would be no overlap difference between a 264/272 and a 272/264. Whoever you quoted would require adjustable gears to achieve those numbers.
I'll read though the whole thing and see how he figured it out. |
there is a fatal flaw in the thinking in said "email"
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Originally Posted by Area47
(Post 2328817)
there is a fatal flaw in the thinking in said "email"
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the flaw comes from a lot of things actually. look at the published numbers regarding every component of the valve train.
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Using the following published numbers, I did my own calculations....
264 Intake Max Valve Lift - 10.3mm (0.4055") Centerline at 0mm vavle lift 105 deg Intake Valve timing at 1mm (0.0394") Valve opens at 2 deg BTDC Valve closes at 28 deg ABDC Valve Centerline 103 deg 264 Exhaust Max Valve Lift - 9.8mm (0.3858") Centerline at 0mm vavle lift 117 deg Exhaust Valve timing at 1mm (0.0394") Valve opens at 42 deg BBDC Valve closes at -12 deg ATDC Valve Centerline 117 deg 272 Intake Max Valve Lift - 10.3mm (0.4055") Centerline at 0mm vavle lift 105 deg Intake Valve timing at 1mm (0.0394") Valve opens at 6 deg BTDC Valve closes at 32 deg ABDC Valve Centerline 103 deg 272 Exhaust Max Valve Lift - 9.8mm (0.3858") Centerline at 0mm vavle lift 111 deg Exhaust Valve timing at 1mm (0.0394") Valve opens at 36 deg BBDC Valve closes at 2 deg ATDC Valve Centerline 107 deg 264/264 -> OL -> -10*, Total LSA -> 137* 272/272 -> OL -> 8*, Total LSA -> 132* 264/272 -> OL -> 4*, Total LSA -> 132* 272/264 -> OL -> -6*, Total LSA -> 137* Not quite sure where the guy got his numbers from... but these still seem to show that a 272/264 combination will allow for a maximum intake charge, yet not allow for a large amount of blow though. |
Your numbers are from HKS DSM cams. The EVO ones that ours were ground from all use 110 centerlines for 264, 272, and 280 grinds.
Using the same centerline, a better flow can be had with less blowthrough via less intake duration. Your overlap numbers are also using @1mm duration. Overlap should be calculated at advertised duration. |
lift numbers are incorrect. unless said person was "dave" that sent you these numbers
Originally Posted by Witt
(Post 2329216)
Your numbers are from HKS DSM cams. The EVO ones that ours were ground from all use 110 centerlines for 264, 272, and 280 grinds.
Using the same centerline, a better flow can be had with less blowthrough via less intake duration. Your overlap numbers are also using @1mm duration. Overlap should be calculated at advertised duration. i guess we failed to mention that the evo had a slightly different "272" grind. also something else that was discussed. to find true numbers, one needs to know the ratio of the rocker as well |
People on this site need to stop looking at just advertised numbers. lobes have a profile, inorder to see what a lobe really is you need to look at the duration at .006, .050, .200. Lobes with the same advertised duration can have a suprisingly different duration at .200. I also suggest looking at comp they have a special line of lobes just for the ecotec.
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Originally Posted by fast98
(Post 2329326)
People on this site need to stop looking at just advertised numbers. lobes have a profile, inorder to see what a lobe really is you need to look at the duration at .006, .050, .200. Lobes with the same advertised duration can have a suprisingly different duration at .200. I also suggest looking at comp they have a special line of lobes just for the ecotec.
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fast98.
those are designed for the 2.2. not a direct deal for the lsj :) want cam info on all cobalt cams? google search a simple phrase. lsj cams one of the top two will be specs from gm on a pdf file. |
Originally Posted by Area47
(Post 2329513)
fast98.
those are designed for the 2.2. not a direct deal for the lsj :) want cam info on all cobalt cams? google search a simple phrase. lsj cams one of the top two will be specs from gm on a pdf file. |
the hex key in the end of the exhaust cam is the difference. lift and duration is also different.
you can stick them in an lsj and get away with it. if you have a weird desire to crank on the starter for a while to get it started. |
Originally Posted by Area47
(Post 2329866)
the hex key in the end of the exhaust cam is the difference. lift and duration is also different.
you can stick them in an lsj and get away with it. if you have a weird desire to crank on the starter for a while to get it started. |
Originally Posted by fast98
(Post 2330058)
You're missing the point. I know the cam cores might be for the 2.2 but the lobes you can have ground on any ecotec cam.
The lift rate can be inferred by comparing the advertised numbers to the duration @ 1mm as given by Omega earlier. His numbers were correct, just on a different centerline. We were simply comparing different combinations of the HKS Evo profiles, one of the few profiles that can be used on our stock cams. There are a very limited number of proven cam profiles that can be reground on our stockers while still maintaining proper lash without shims; the stock lash adjusters can only be stroked an additional 3mm maximum. Lifter shims cannot be used on the LSJ head, limiting available regrind options. |
Originally Posted by Witt
(Post 2329216)
Your numbers are from HKS DSM cams. The EVO ones that ours were ground from all use 110 centerlines for 264, 272, and 280 grinds.
Using the same centerline, a better flow can be had with less blowthrough via less intake duration. Your overlap numbers are also using @1mm duration. Overlap should be calculated at advertised duration. The posted overlap numbers are actually using the advertised duration, not the actual.
Originally Posted by fast98
(Post 2329326)
People on this site need to stop looking at just advertised numbers. lobes have a profile, inorder to see what a lobe really is you need to look at the duration at .006, .050, .200. Lobes with the same advertised duration can have a suprisingly different duration at .200. I also suggest looking at comp they have a special line of lobes just for the ecotec.
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how about some dyno numbers????? and Comp has the exhaust core, just no intake core for ours, our vise versa, i wrote it down somewhere.....
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Originally Posted by Omega_5
(Post 2329169)
From that I found the following (based on advertised duration and advertised opening/closing);
264/264 -> OL -> -10*, Total LSA -> 137* 272/272 -> OL -> 8*, Total LSA -> 132* 264/272 -> OL -> 4*, Total LSA -> 132* 272/264 -> OL -> -6*, Total LSA -> 137*
Originally Posted by Omega_5
(Post 2331127)
The posted overlap numbers are actually using the advertised duration, not the actual.
272/272 -> {[(272+272)/4]-110}*2 = 52 degrees overlap 264/272 -> {[(264+272)/4]-110}*2 = 48 degrees overalp 272/264 -> {[(272+264)/4]-110}*2 = 48 degrees overlap Theres the correct numbers using advertised duration. |
Holy crap you guys are super smart its scary. I want cams but I have no idea what to look for and you guys are throwing out big words and numbers and equations.... I need to do way more homework on this
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Originally Posted by racehtecobalt
(Post 2321870)
hi i want to know if any one here knows if there are any cams besides th jbp cams.....if not how well are the jbp cams.......also if i where to get cams could i run my stock cam gears or would it be best to replace them.....
Originally Posted by USMCFieldMP
(Post 2327128)
My JBP Stg2's are for sale WITH the Valve Springs. Never installed. $550 shipped for Cams and VS's... that's a fuggin deal.
Originally Posted by wisemanonice
(Post 2328222)
Originally Posted by USMCFIeldMP
My JBP Stg2's are for sale WITH the Valve Springs. Never installed. $550 shipped for Cams and VS's... that's a fuggin deal.
Either way... cams gotta go. |
Originally Posted by Witt
(Post 2331568)
264/264 -> {[(264+264)/4]-110}*2 = 44 degrees overlap
272/272 -> {[(272+272)/4]-110}*2 = 52 degrees overlap 264/272 -> {[(264+272)/4]-110}*2 = 48 degrees overalp 272/264 -> {[(272+264)/4]-110}*2 = 48 degrees overlap Theres the correct numbers using advertised duration. Yes... using 110 they are the right ones... The ones posted before were also the right ones... but not for our engines. Instead of looking up the EVO numbers, I just looked at the DSM spec sheet sitting on my hard drive.... much simpler and quicker in order to get the point across, considering I have stuff to do at work. |
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