New member looking for cam timing help.
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From: Nebraska
New member looking for cam timing help. Hey folks i need some help understanding cam timing events. Ive read some posts and looking for some info. Ive got a g8 gt with a small 220/227 112+2 cam, 3.27 gears, and 3000ish stall with headers. Looking to upgrade to a bigger cam and would like to run mid/low elevens and still take the occasional road trip. 0I Iive in crappy elevation at 2800ft and crappy humidity.
Is there any advantage to using a smaller cam with a narrower lsa over a wider one? How does an evo of say 50 or 51 degrees have an impact over one say using 54 or 55 degrees? Does the 55 degree evo help widen the power band or extend the torque curve? Would there be much difference in power and driveability in a cam with 6 or 7 degrees of overlap to one with 9.5 degrees of overlap? I know its alot of questions thank you guys. Ive got a couple of different recommendations for cam that seem to go about in different ways to reach that goal. My engine is an l76 6.0l
Is there any advantage to using a smaller cam with a narrower lsa over a wider one? How does an evo of say 50 or 51 degrees have an impact over one say using 54 or 55 degrees? Does the 55 degree evo help widen the power band or extend the torque curve? Would there be much difference in power and driveability in a cam with 6 or 7 degrees of overlap to one with 9.5 degrees of overlap? I know its alot of questions thank you guys. Ive got a couple of different recommendations for cam that seem to go about in different ways to reach that goal. My engine is an l76 6.0l
Last edited by Ewinder68; Feb 4, 2020 at 10:56 PM. Reason: Need to add engine specs.
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This is a loaded question.
Typically an earlier EVO improves top end power but if the exhaust is open too early it can bleed of torque in the low and mid range.
It's application specific.
What engine does your vehicle have?
I'm not familiar with the American vehicles.
Typically an earlier EVO improves top end power but if the exhaust is open too early it can bleed of torque in the low and mid range.
It's application specific.
What engine does your vehicle have?
I'm not familiar with the American vehicles.
Last edited by bortous; Feb 4, 2020 at 11:22 PM.
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There is a lot to be had but we need to see what behaviors you are willing to compromise. Intake opening is 0 degrees (tdc) and closes at 40 degrees abdc. Exhaust opens at 47.5 bbdc and closes at .5 btdc for basically zero overlap. Your best gains will happen by closing your intake later and opening a few degrees earlier (at the expense of idle quality -which is up to you). Exhaust opening is “in the zone”. The exhaust closing at zero is early. As Bortous mentioned, we need to see what the exhaust system looks like to make further recommendations. Can you tell us more about the car, gear, converter, engine, expected manners, and what you like to do with the car?
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From: Nebraska
Yes sir ive got 1 3/4 pacesetters ill be using a 3" mid pipe with x to 2.5" obx exhaust mid pipe. I've a 3000 multi disk stall, 3.27 gears and stock heads. I wanna get the car into the low elevens with a supporting drag pack. Originally i had a daily driver specd cam capable of 12s. Haven't ran the car yet. I know ive got a great tuner that can tune about anything. And already have a suggested custom cam specd with 9.5 overlap and an evo of 54 and an ivc of 44 degrees. Just wanted to see if theres any advantage of lowering the exhaust duration and and moving to a slightly smaller cam. I'm unsure of using tighter 51 degree evo vs the 54 degree evo and what effect thatd have on the way a cam behaves using a slightly narrower lsa with a bit less advance. The ivc would probably have to be closer to 42.5 degrees to lower the overlap. I do trust my tuner on his specs I'm just not sure the difference of a 9.5 degree overlap cam vs something with 7 degrees or if a person could even tell between the two power wise.
Last edited by Ewinder68; Feb 7, 2020 at 09:54 PM.
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Yes sir ive got 1 3/4 pacesetters ill be using a 3" mid pipe with x to 2.5" obx exhaust mid pipe. I've a 3000 multi disk stall, 3.27 gears and stock heads. I wanna get the car into the low elevens with a supporting drag pack. Originally i had a daily driver specd cam capable of 12s. Haven't ran the car yet. I know ive got a great tuner that can tune about anything. And already have a suggested custom cam specd with 9.5 overlap and an evo of 54 and an ivc of 44 degrees. Just wanted to see if theres any advantage of lowering the exhaust duration and and moving to a slightly smaller cam. I'm unsure of using tighter 51 degree evo vs the 54 degree evo and what effect thatd have on the way a cam behaves using a slightly narrower lsa with a bit less advance. The ivc would probably have to be closer to 42.5 degrees to lower the overlap. I do trust my tuner on his specs I'm just not sure the difference of a 9.5 degree overlap cam vs something with 7 degrees or if a person could even tell between the two power wise.
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How would a 227 275@.050, 236 287@.050 111+2 compare to that power wise, torque and rpm range? Would it make as much torque without having to shift as the your stage 2 cam? My 10" patc multidisk 3000 stall shifts at 6700rpm with a shift extension of 5500rpm currently. Overall i want to be able to have a weekend road trip car with an overall goal of low elevens with 118mph+ trap speeds.
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How would a 227 275@.050, 236 287@.050 111+2 compare to that power wise, torque and rpm range? Would it make as much torque without having to shift as the your stage 2 cam? My 10" patc multidisk 3000 stall shifts at 6700rpm with a shift extension of 5500rpm currently. Overall i want to be able to have a weekend road trip car with an overall goal of low elevens with 118mph+ trap speeds.
If the lobes were equal intensity, the 227 grind would have a slightly more aggressive idle. The powerband will basically be identical with the 42.5 vs. 43 intake closing, but the custom is hampered a bit up top with later exhaust opening. On the plus side, the custom would make slightly more torque in the 2500 to 4000 range. The custom's 5 degree atdc exhaust closing creates a bit more overlap (10 vs. 6) when coupled with the earlier intake opening. This makes it a little more sensitive to exhaust backpressure. As you said, it's not going to tune as easily as the Stage 2, but overall not too bad.
Again, with Seat timing being nearly the same..we think the Stage 2 is likely going to out do the custom pretty much everywhere, but the exercise above was to describe what the theoretical changes would be. It's hard to say how well the customs lobes are in terms of stability at high rpm...but we know the Stage 2 is stable in the 7000 plus range.
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What if I told you to save your money, stall it up to 3600-4200 range and gear it to 3.73?
I do not think your cam thoughts are bad. A 227 range intake lobe and 43 IVC are good ideas. But that cam swap will not help your car ET better without more stall and gear. More stall and gear will help the cam you have ET better.
To answer your OP question, earlier evo will compromise low end off idle grunt for more power past peak up top. 51 to 54 will not make a huge difference to either though. If you are really wanting to use EVO to manipulate the power curve, you'd want like a 60 EVO, which would mean your cam in the range of 228/240. Back of napkin math, so calcs are in my head. You would also need to mill heads to 11.5 as higher compression helps earlier EVO work better and make fewer compromises.
But there again.... none of that does you any good until 3.73 gear and 4200 stall.
I do not think your cam thoughts are bad. A 227 range intake lobe and 43 IVC are good ideas. But that cam swap will not help your car ET better without more stall and gear. More stall and gear will help the cam you have ET better.
To answer your OP question, earlier evo will compromise low end off idle grunt for more power past peak up top. 51 to 54 will not make a huge difference to either though. If you are really wanting to use EVO to manipulate the power curve, you'd want like a 60 EVO, which would mean your cam in the range of 228/240. Back of napkin math, so calcs are in my head. You would also need to mill heads to 11.5 as higher compression helps earlier EVO work better and make fewer compromises.
But there again.... none of that does you any good until 3.73 gear and 4200 stall.
I have the Lingenfelter GT1-1 cam in the LS3 in my '95 Impala.....229*/242*, 114* + 0*
With all the other bold-on goodies, it puts out about 495hp/440tq to the wheels.
That's with 11.4:1 SCR, a 2 1/2" exhaust and a 4L60e transmission. 7.5* overlap.....very streetable daily driver. Haven't raced it yet....but I already know it's a high 11-second car at 4300+ LBs.
I love it....but if I knew in 2015 what I know now, I'd probably have gone with the BTR Stage 3 LS3 cam....229*/244*, 113* + 4*.....would likely yield more HP...AND....torque. 10.5* overlap, though.
Best of luck.
KW
With all the other bold-on goodies, it puts out about 495hp/440tq to the wheels.
That's with 11.4:1 SCR, a 2 1/2" exhaust and a 4L60e transmission. 7.5* overlap.....very streetable daily driver. Haven't raced it yet....but I already know it's a high 11-second car at 4300+ LBs.
I love it....but if I knew in 2015 what I know now, I'd probably have gone with the BTR Stage 3 LS3 cam....229*/244*, 113* + 4*.....would likely yield more HP...AND....torque. 10.5* overlap, though.
Best of luck.
KW
Last edited by KW Baraka; Feb 15, 2020 at 06:10 PM.
….To answer your OP question, earlier evo will compromise low end off idle grunt for more power past peak up top. 51 to 54 will not make a huge difference to either though. If you are really wanting to use EVO to manipulate the power curve, you'd want like a 60 EVO, which would mean your cam in the range of 228/240. Back of napkin math, so calcs are in my head. You would also need to mill heads to 11.5 as higher compression helps earlier EVO work better and make fewer compromises......
KW
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From: Nebraska
Thank you all for the suggestions. May have to run my car as is to see what benchmark I'm at and go from there. Probably the right way to go about it before stabbing in another cam. My tuner says he can tune a 9.5 degree overlap cam he specd thats just a bit smaller than the btr stage 3 so thats always a comfort.
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The two cams ive been specd are both custom from different companies with mid to low 11 second slips can anyone give a run down of both and advantages or disadvantages of them? Ones a 226 /.625 236/.625 113+4 and the others a 229/.626 238/615 112+3. Any thoughts? i know its another cam question but you all have way more knowledge than i do just weighing the options. Sorry i mistyped the 238 exhaust duration.
Last edited by Ewinder68; Mar 4, 2020 at 10:48 PM. Reason: Mis typed a duration number
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Thanks darth i appreciate it. I dont think i can get the compression that high but i believe ive got room to mill the heads with the 226 cam and use a .040 compressed gasket. Will the added ovelap of the 229 cam really make that much more power with a slightly larger exhaust duration?
Last edited by Ewinder68; Mar 4, 2020 at 10:50 PM.