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The most chatters online in one day was 3, 05-15-2008.
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08-01-2008, 04:37 AM
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#1
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Join Date: Nov 2006
Location: pensacola florida
Posts: 532
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3.6 dohc cam specs...somethings not adding up here
ok i was just playing around and trying to figure out what they are doing with the cams in the ly7. and its not adding up right at all! heres what they have listed in the gm spec sheet
- Camshaft Timing @ 0.15 mm (0.0059 in) Lift
-229 degrees BTDC14 degrees
ATDC
111 degrees ATDC
132 degrees ATDC9 degrees
ATDC
251 degrees ATDC
now how do i get from there to, duration at .050, intake centerline and lsa?
i did the math the old way, and its waaaayyy off. so i tried an online calculator, wayyyy off and entirely diff numbers this time.
whats the deal?
__________________
87 fiero gt 5spd 3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe, 2.5 inch ex, flowtech muff, gmtuners.com prom, 7730 ecm (GAVE TO BROTHER, divorce reasons.)
03 Trailblazer, cai.
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08-01-2008, 01:02 PM
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#2
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Join Date: Oct 2003
Location: south texas
Posts: 1,459
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Just a thought, but could the VARIABLE TIMING have something to do with it?
__________________
Taylor
1988 Olds Cutlass Supreme 3100 MPFI
1990 Pontiac Grand Prix STE 3.1 MPFI
1995 Cutlass Supreme SL 3.4 TDC
1996 Pontiac Grand Prix SE Mary Kay Edition (rest in pieces)
"find something simple and complicate it"
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08-01-2008, 04:38 PM
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#3
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Join Date: Nov 2006
Location: pensacola florida
Posts: 532
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ha, yes it could. very. im going to have to draw this out to get it right.
damn so much work just to know something
__________________
87 fiero gt 5spd 3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe, 2.5 inch ex, flowtech muff, gmtuners.com prom, 7730 ecm (GAVE TO BROTHER, divorce reasons.)
03 Trailblazer, cai.
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08-01-2008, 10:30 PM
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#4
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Join Date: Feb 2007
Location: NW indiana
Posts: 396
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Sombody should make VVT gears for the lq1... That would be awesome. That could totally make great hp/tq through the entire powerband. We could also raise the redline
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-1995 Pontiac Grand Prix GTP - 97 DOHC/6-Speed - Now running properly!-
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08-01-2008, 11:12 PM
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#5
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Captain of the Failboat
Join Date: Oct 2003
Location: warsaw,indiana
Posts: 9,228
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Its call a 3.6 DOHC. I just saved someone a ton of cash on R&D for the VVT 3.4 concept.
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08-01-2008, 11:47 PM
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#6
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Join Date: Feb 2007
Location: NW indiana
Posts: 396
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I would like a 3.6 but finding one is the hard part. Plus all the modding I would have to do to put it into my W. How does VVT work anyway?? how do the gears know when to adjust?
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-1995 Pontiac Grand Prix GTP - 97 DOHC/6-Speed - Now running properly!-
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08-02-2008, 12:01 AM
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#7
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Join Date: Nov 2006
Location: pensacola florida
Posts: 532
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Quote:
Originally Posted by SappySE107
Its call a 3.6 DOHC. I just saved someone a ton of cash on R&D for the VVT 3.4 concept.
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lmfao.
__________________
87 fiero gt 5spd 3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe, 2.5 inch ex, flowtech muff, gmtuners.com prom, 7730 ecm (GAVE TO BROTHER, divorce reasons.)
03 Trailblazer, cai.
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08-05-2008, 01:56 AM
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#8
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Join Date: Feb 2004
Posts: 434
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Quote:
Originally Posted by gpchris
I would like a 3.6 but finding one is the hard part. Plus all the modding I would have to do to put it into my W. How does VVT work anyway?? how do the gears know when to adjust?
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Not sure if its the same thing but on Honda's Vtec i know (or so i have been told) the larger lobe is locked in by a Pin when the engine reaches a cretin rpm the ECU uses oil pressure to lock in the pin to use the larger lobes... dunno if its the same on the GM's.. Or i could be completely wrong..
S
__________________
Shane "RedZMonte"
2004 Subaru WRX STI 13.8@98mph -5800 ft/alt.
-3" Dp, 3" Midpipe, Prodrive Muff., Cobb Access Port
1995 Monte Carlo Z34 14.38@101mph
-T04E, Borla Catback, OBDII, 42.5# Injectors
1992 L67 Lumina Z34 (SOLD)
1990 Turbo Grand Prix (SOLD)
1992 Lumina Z34 (RIP)
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08-06-2008, 12:18 PM
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#9
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Join Date: Aug 2008
Posts: 6
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Quote:
Originally Posted by merlot566jka
ok i was just playing around and trying to figure out what they are doing with the cams in the ly7. and its not adding up right at all! heres what they have listed in the gm spec sheet
- Camshaft Timing @ 0.15 mm (0.0059 in) Lift
-229 degrees BTDC14 degrees
ATDC
111 degrees ATDC
132 degrees ATDC9 degrees
ATDC
251 degrees ATDC
now how do i get from there to, duration at .050, intake centerline and lsa?
i did the math the old way, and its waaaayyy off. so i tried an online calculator, wayyyy off and entirely diff numbers this time.
whats the deal? |
The way that you have it layed out is confusing as hell. How about this:
Exhaust
Open: 229 BTDC
Close: 9 ATDC
Duration: 229 + 9 = 238
Centerline: 238 / 2 = 119 - 9 = 110 BTDC
Intake
Open: 14 ATDC
Close: 251 ATDC
Duration: 251 - 14 = 237
Centerline: 237 / 2 = 118.5 + 14 = 132.5 ATDC
LSA = (110 + 132.5) / 2 = 121.25
Measuring at .050 will change the duration and open and close events but it should not change the LSA or the centerline unless they are using some lopsided cams.
This engine does have variable timing so the centerlines can move which will change the LSA. I would assume that they would move the lobes closer at the higher rpms to get more overlap and seperate them at low speeds for a good idle and higher torque. I don't think they would put the entire range into those numbers. My guess based on the LSA is those are the numbers for idle and low rpms. "Street" cams have a LSA usually between 104-118. Since this engine has vvt, they can get away with 121. If it was fixed at 121, that engine would have no high rpm power.
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08-07-2008, 04:35 AM
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#10
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Join Date: Nov 2006
Location: pensacola florida
Posts: 532
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thank you. i feel stupid. but that makes perfect sense. i was thinking in a box
__________________
87 fiero gt 5spd 3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe, 2.5 inch ex, flowtech muff, gmtuners.com prom, 7730 ecm (GAVE TO BROTHER, divorce reasons.)
03 Trailblazer, cai.
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