Thinking on New Cam - LS7
01-11-2009, 11:02 PM
#1
Thinking on New Cam - LS7 236/248 .637/.652 116LCA 114ICL (116+2)
Looking for better drive ability compared to my old 242/256 .646/.668 113+2 camshaft, while maintaining similar power and rpm band.
This new cam decreases my overlap at 50thou from 23 to 10, while building more torque downlow, a slight loss in upper rpms hp, but powerband still maintaining a 7K rpm redline. True? Or no?
Funny thing is these two cams maintain the EXACT same DCR, but the new one has less overlap/duration/lift but same split...
427 - LS7 headed motor. 11.4:1 SCR Daily Driver...
Let the debate begin.
(Reason for new cam is motor threw a rod
, so I'm probably getting a new shortblock)
Looking for better drive ability compared to my old 242/256 .646/.668 113+2 camshaft, while maintaining similar power and rpm band.
This new cam decreases my overlap at 50thou from 23 to 10, while building more torque downlow, a slight loss in upper rpms hp, but powerband still maintaining a 7K rpm redline. True? Or no?
Funny thing is these two cams maintain the EXACT same DCR, but the new one has less overlap/duration/lift but same split...
427 - LS7 headed motor. 11.4:1 SCR Daily Driver...
Let the debate begin.
(Reason for new cam is motor threw a rod
, so I'm probably getting a new shortblock) 
01-13-2009, 08:33 AM
#7
I like the looks of the new cam much better as well. I think i'll build a little more torque, bring my redline down slightly (6700-6800 instead of 7K rpms) while only losing a few ponies (maybe 10) up top, and maintaining much better driveability. Everything I'm looking for....
Any other suggestions?
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01-13-2009, 09:06 AM
#8
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I ran a 242/256 a couple years ago in my LS7, I went to a 238/260 (nitrous motor) and the power is on sooner, slighly less bucking at lower rpm (none now that I am auto/stall). I think that 242 is about the max for that intake manifold, but that cam made 559rwhp/520tq. Could not give u a direct comparo right now as I am now 441ci, but 589rwhp and 549tq all below 6400rpm (I have issues). If it were me and not spraying, 232-236int/244-248 exh. for a 427 w/ those heads. Do a search on "Lethal cam" from ragin' racin', u might be surprised. Shawn from Ragin' and myself were on the same dyno the same day, him w/ the lethal (smaller) and myself running 242/256. Though my peak #s were a tad higher, his usable power was insane, and the car drove so much better than mine as a DD. Ohh yea, his all motor e/t was a tenth quicker and his mph was dead nuts. The very reason my cam cam out......
01-13-2009, 09:12 AM
#9
Ideally, you want your IVC between 46-48 degrees ABDC at .050" for best power down low and in the mid range. Both cams you're talking about are at 52 degrees ABDC at .050". The 236/248 116 +2 cam you're looking at has close to the same IVC and EVO as your current cam, but with earlier IVO and EVC. The only gain you'll get down low will be at very low rpm (1200-2500) from reduced overlap. With the same IVC as your current cam, don't expect huge gains in mid-range torque. In fact, they will probably be less. But if your main goal is better street manners with similar rpm range of your last cam, and you don't mind taking a hit in power, then you should be pleased.
__________________
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.
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.
01-13-2009, 04:06 PM
#10
Ideally, you want your IVC between 46-48 degrees ABDC at .050" for best power down low and in the mid range. Both cams you're talking about are at 52 degrees ABDC at .050". The 236/248 116 +2 cam you're looking at has close to the same IVC and EVO as your current cam, but with earlier IVO and EVC. The only gain you'll get down low will be at very low rpm (1200-2500) from reduced overlap. With the same IVC as your current cam, don't expect huge gains in mid-range torque. In fact, they will probably be less. But if your main goal is better street manners with similar rpm range of your last cam, and you don't mind taking a hit in power, then you should be pleased.
My old cam did make very good power, and the torque was near tabletop flat across the board never dropping below 400 rwtrq from 2700 rpms and up to 7K. But, i could never manage to squeeze out all the bucking, although it was minimal at times depending on weather. Just looking for something more consistent.
I would like to put it on a 113+3, but I believe that would defeat the purpose of better street manners, although overlap drops from 23 to 16. Not sure how 7 degrees less overlap compares to 13 degrees less on the other LSA/ICL. Maybe compromise at a 234/248 114+3?
Was able to take a peek through the porthole in my oil pan/block, major damage. Looks like the rod on the number 7 or 8 hole (hard to tell) broke in half....wtf
Should have the motor out by late tonight...will try to post pics tomorrow.
01-17-2009, 12:26 AM
#14
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We have been using our Lethal Cam for most LS7 application with excellent results. The cam has 13 degrees overlap and has excellent torque and power. It usually dynoes in the 550rwhp area and runs mid 10's.
Lethal - 230/248 113+3
Lethal - 230/248 113+3
01-17-2009, 04:32 PM
#16
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If you want to increase the driveability and torque of your LS7, why not try something a little different..... keep the lobe sep at 113-114 and instead use a slower lobe profile on the exhaust with less lift. The big exhaust valve on those heads coupled with the 1.8:1 rocker move the valve off the seat WAY too fast to produce good VE. Try something around 24x duration @ .050" with about .550 - .570" lift.
01-17-2009, 05:31 PM
#17
If you want to increase the driveability and torque of your LS7, why not try something a little different..... keep the lobe sep at 113-114 and instead use a slower lobe profile on the exhaust with less lift. The big exhaust valve on those heads coupled with the 1.8:1 rocker move the valve off the seat WAY too fast to produce good VE. Try something around 24x duration @ .050" with about .550 - .570" lift.
01-17-2009, 06:29 PM
#18
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It's about the valve speed off the seat.... too much opening too fast kills exhaust velocity at the end of the cylce (right where it's important to help scavenging/ prevent reversion). That's why most racing engines have a lower rocker ratio on the exhaust side than they do on the intake. Superstock small block chevys for example, making about 625 HP and needing to wind very high, routinely use a 1.8 ratio on the intake but only a 1.6 on the exhaust. Since the LS7 is pretty much stuck with the 1.8, you need to change the lobe profile to create the controlled opening of the exhaust. This usually (but not always) means a lobe that winds up having less total lift. Big block chevys also have this problem (1.88" valve and 1.7 rocker) and seem to perform much better when used with a softer lobe profile.
01-17-2009, 06:56 PM
#19
It's about the valve speed off the seat.... too much opening too fast kills exhaust velocity at the end of the cylce (right where it's important to help scavenging/ prevent reversion). That's why most racing engines have a lower rocker ratio on the exhaust side than they do on the intake. Superstock small block chevys for example, making about 625 HP and needing to wind very high, routinely use a 1.8 ratio on the intake but only a 1.6 on the exhaust. Since the LS7 is pretty much stuck with the 1.8, you need to change the lobe profile to create the controlled opening of the exhaust. This usually (but not always) means a lobe that winds up having less total lift. Big block chevys also have this problem (1.88" valve and 1.7 rocker) and seem to perform much better when used with a softer lobe profile.
