Next mod: Cam!
10-10-2013, 01:27 PM
#1
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Next mod: Cam! Ok so for my next mod I was thinking of doing a cam set up. I love the sound of a nice lope. I don't mind losing some drivability to the car. How big is too big? Also I am running nitrous so is there a cam that would be more beneficial than others to nitrous? I know daveGXP has a tread somewhere about his cam and the options he looked at, i just can't find it 
. I am a noob! I am just looking to be pointed in the right direction.
Here is a clip I found that I love the sound of
. I am a noob! I am just looking to be pointed in the right direction.Here is a clip I found that I love the sound of
10-10-2013, 01:46 PM
#4
If it's your DD I wouldn't go bigger than 220 224. I have a 216 220 in my GXP and I lost quite a bit of power down low even with a high SCR. My last fill up was 12.3mpg where I was getting 16.5mpg stock. So it's really how much more do you wanna pay at the pump for some more HP?
And the LS4 is just like any other 5.3 internally just with a bit more compression so they shouldn't have issues spec'ing out a cam.
And the LS4 is just like any other 5.3 internally just with a bit more compression so they shouldn't have issues spec'ing out a cam.
10-10-2013, 01:48 PM
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They'll be able to help based on all your parts - you'll want to decide what intake your gonna use and if your doing any other motor changes before you ask for help on a cam spec.
Last edited by x11 nut; 10-10-2013 at 02:47 PM.
10-10-2013, 02:52 PM
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Pat G will spec a cam considering all you mods and trans setup up for $40 I think, then you decide to get a custom grind or see if any of the cam suppliers have one that matches. I see most go for @ $400. Comp's techs will help recommend which of their catalog cam will work best with your setup.
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11-15-2013, 12:16 AM
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These heavy *** cars with long gearing need low to mid range torque. Stick with a tight lobe separation, with no more then 216* intake duration. It's all about valve events, so bigger duration cams can work, as long as the cam is designed to work with your combination.
243 heads will always put peak torque above 4000 rpm, that's why I decided to go with 205 gen x tfs heads.
243 heads will always put peak torque above 4000 rpm, that's why I decided to go with 205 gen x tfs heads.
12-18-2013, 10:20 PM
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Here is what they Recommend http://www.compcams.com/Company/CC/c...csid=1089&sb=2 What do you think @davidGXP ?
12-19-2013, 05:39 AM
#13
I am running the NewEra High Lift DoD camshaft with it advanced a significant amount to bring the hp peak down to 6800 rpm. The cam, pushrods, springs and timing tension were $750 and the camshaft is 224/232 and still DoD compatible. It would likely need a larger stall and gears in the stock application with an auto, but I have a manual transmission and a 2800 lb fiero.
12-19-2013, 12:22 PM
#15
Before removing my stock LS4 camshaft, I went ahead and degreed it so I could see where the valve events were for (cylinder 1).
Stock LS4 cam (everything at .050 lobe lift)
IVO (BTDC): -18
IVC (ABDC): 35
EVO (BBDC): 31
EVC (ATDC): -14
When I got the new camshaft, I installed it dot to dot and degreed it so I could see exactly what it was. This camshaft was designed for the 6L and larger engines so I took the dot to dot valve events and put them into desktop dyno and ran a series of tests with the camshaft installed at various degrees of advance vs. dot to dot as well as comparing them to the stock LS4 camshaft. Now Desktop dyno isn't a perfect tool, but all I was looking for were some directional indicaters for the change, and not focused on the actual hp #'s.
Below 3500 rpm, at dot to dot the new camshaft was giving up 60 lb-ft of torque below 3500 rpm and the HP peak was well north of 7K. With advancing the camshaft I was able to get the low RPM loss down to 15 lb-ft, the new camshaft was gaining on the LS4 one at 2500 rpm and higher, and the HP peak dropped 1000 rpm (yes, I advanced it quite a bit!). The valve events I ended up with were:
New cam installed advanced (everything at .050 lobe lift)
IVO (BTDC): -3.5
IVC (ABDC): 47.5
EVO (BBDC): 46
EVC (ATDC): 5.5
Concerned about the amount I was advancing the camshaft, I looked at other off the shelf grinds and found two that were similar which helped confirm the engine would actually run with those valve events.
MTI Stealth II 224/220 (everything at .050 lobe lift)
IVO (BTDC): -4
IVC (ABDC): 48
EVO (BBDC): 46
EVC (ATDC): -6
Comp Cams xer 224/230 (54-444-11 XER273HR)
IVO (BTDC): -1
IVC (ABDC): 45
EVO (BBDC): 50
EVC (ATDC): 0
Here is my dyno chart so you can see how flat the torque curve is, and remember this is through a manual transmission with a lightweight flywheel:
If I had to do it over, I would have Pat G spec a custom camshaft, as the DoD lobes are lazy and shorter to protect the lifters vs. a real performance camshaft. However, I would still try to keep the 6800 RPM power peak!
Stock LS4 cam (everything at .050 lobe lift)
IVO (BTDC): -18
IVC (ABDC): 35
EVO (BBDC): 31
EVC (ATDC): -14
When I got the new camshaft, I installed it dot to dot and degreed it so I could see exactly what it was. This camshaft was designed for the 6L and larger engines so I took the dot to dot valve events and put them into desktop dyno and ran a series of tests with the camshaft installed at various degrees of advance vs. dot to dot as well as comparing them to the stock LS4 camshaft. Now Desktop dyno isn't a perfect tool, but all I was looking for were some directional indicaters for the change, and not focused on the actual hp #'s.
Below 3500 rpm, at dot to dot the new camshaft was giving up 60 lb-ft of torque below 3500 rpm and the HP peak was well north of 7K. With advancing the camshaft I was able to get the low RPM loss down to 15 lb-ft, the new camshaft was gaining on the LS4 one at 2500 rpm and higher, and the HP peak dropped 1000 rpm (yes, I advanced it quite a bit!). The valve events I ended up with were:
New cam installed advanced (everything at .050 lobe lift)
IVO (BTDC): -3.5
IVC (ABDC): 47.5
EVO (BBDC): 46
EVC (ATDC): 5.5
Concerned about the amount I was advancing the camshaft, I looked at other off the shelf grinds and found two that were similar which helped confirm the engine would actually run with those valve events.
MTI Stealth II 224/220 (everything at .050 lobe lift)
IVO (BTDC): -4
IVC (ABDC): 48
EVO (BBDC): 46
EVC (ATDC): -6
Comp Cams xer 224/230 (54-444-11 XER273HR)
IVO (BTDC): -1
IVC (ABDC): 45
EVO (BBDC): 50
EVC (ATDC): 0
Here is my dyno chart so you can see how flat the torque curve is, and remember this is through a manual transmission with a lightweight flywheel:
If I had to do it over, I would have Pat G spec a custom camshaft, as the DoD lobes are lazy and shorter to protect the lifters vs. a real performance camshaft. However, I would still try to keep the 6800 RPM power peak!
12-19-2013, 01:06 PM
#16
so if im understanding correctly ordering the off the shelf grinds you just posted
MTI Stealth II 224/220
Comp Cams xer 224/230
they could be installed dot to dot without advancing the cam?. if thats the case since im in the market for a cam i might spring for the comp cam
MTI Stealth II 224/220
Comp Cams xer 224/230
they could be installed dot to dot without advancing the cam?. if thats the case since im in the market for a cam i might spring for the comp cam
12-19-2013, 07:55 PM
#17
Correct.
Using those cams would require a complete DoD removal, but should be able to produce a few more HP with the more aggressive ramp rates and higher overall lift numbers. In a heavier car, they would benefit from a larger stall and more gear.
Using those cams would require a complete DoD removal, but should be able to produce a few more HP with the more aggressive ramp rates and higher overall lift numbers. In a heavier car, they would benefit from a larger stall and more gear.
12-19-2013, 09:52 PM
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A large stall converter is not fun in a daily driver. Been there done that.
Most of these cars are pure street. My car was only driven at the track a few times a year, and was not a daily driver.
When choosing a cam for the track be cautious. Transmission gear and the finial drive ratio sucks in the 4T65E. Before installing 3.69 gears, I was just topping 2nd gear at 6500-6800 rpm when crossing the line. 2nd gear was slow, and the 2.93 gear caused a slow launch with a crappy 330. The 3.69 gears were hard to launch, but when they did my 1/8th mile mph jumped upped 3 mph. The 330ft times dropped big time, and ET/mph pretty much stayed the same, since the trans would shift into 3rd and cross the line at 5400 rpm. More gear was needed. 1.9 60ft times were the best I could do with drag radials.
I strongly recommend going with Pat G instead of assuming, or using off the self cams that are generic unless you know what you are doing.
Most of these cars are pure street. My car was only driven at the track a few times a year, and was not a daily driver.
When choosing a cam for the track be cautious. Transmission gear and the finial drive ratio sucks in the 4T65E. Before installing 3.69 gears, I was just topping 2nd gear at 6500-6800 rpm when crossing the line. 2nd gear was slow, and the 2.93 gear caused a slow launch with a crappy 330. The 3.69 gears were hard to launch, but when they did my 1/8th mile mph jumped upped 3 mph. The 330ft times dropped big time, and ET/mph pretty much stayed the same, since the trans would shift into 3rd and cross the line at 5400 rpm. More gear was needed. 1.9 60ft times were the best I could do with drag radials.
I strongly recommend going with Pat G instead of assuming, or using off the self cams that are generic unless you know what you are doing.
