yet another L92 build - GET IN HERE!
Thread Starter
Launching!
Joined: May 2005
Posts: 210
Likes: 0
yet another L92 build - GET IN HERE! Car is 2007 corvette with STOCK L92 heads with 918 springs mated to an L76 complete intake assembly, then with B&B headers connection to the STOCK h-pipe and mufflers. Car will retain stock converter on 6-speed auto. Z-51 Gearset.
The cam i have chosen is an XE-R 220/232 581/595 112LSA 108ICL (4 deg advance ground in) Yielding 2 degrees overlap and 8.64:1 DCR from 10.66:1 SCR.
A very close second place is an LSK- intake lobed 218/230 XER .605 int/.592 ex 111 LSA 107 ICL (4 degrees advance) Yielding 2 degrees overlap and an 8.73:1 DCR from 10.66:1 SCR.
thoughts? this will be a stock combustion chamber which i have found to be 70cc, with a .041 mls head gasket.
1. With cats (starting out it won't have them) who wants to take bets this car will pass vegas/CA emissions?
2. Will it need to idle fast enough to effectively 'push' through the stock converter when stopped? i'm projecting 800 rpm or perhaps 850-875 rpm maximum idle speed.
3. Are there any suggestions regarding cam specs/valve events/SCR/mild head porting that someone could justify for me?
EDIT: this car/motor should be completed in the next 5 weeks.
The cam i have chosen is an XE-R 220/232 581/595 112LSA 108ICL (4 deg advance ground in) Yielding 2 degrees overlap and 8.64:1 DCR from 10.66:1 SCR.
A very close second place is an LSK- intake lobed 218/230 XER .605 int/.592 ex 111 LSA 107 ICL (4 degrees advance) Yielding 2 degrees overlap and an 8.73:1 DCR from 10.66:1 SCR.
thoughts? this will be a stock combustion chamber which i have found to be 70cc, with a .041 mls head gasket.
1. With cats (starting out it won't have them) who wants to take bets this car will pass vegas/CA emissions?
2. Will it need to idle fast enough to effectively 'push' through the stock converter when stopped? i'm projecting 800 rpm or perhaps 850-875 rpm maximum idle speed.
3. Are there any suggestions regarding cam specs/valve events/SCR/mild head porting that someone could justify for me?
EDIT: this car/motor should be completed in the next 5 weeks.
Lots of questions. First off, why in the world would you put a lightweight 918 spring over a heavywieght L92 valve (especially when considering those fast ramped cams)?
Second, why run such a low compression ratio when milling is worth so much power?
Third, is your goal to remain emissions legal?
If emissions compliance is your goal, then you might be pleased with those cam selections. Otherwise, they are really, really small. Basically, subtract 10-12 degrees of duration and you'll have an equivalent cam in a 346. We're talking 208/220 cams here. The cams will make your motor very torquey and fun to drive around town, but will lack a little bit up top because of the very early intake valve closing point. Really depends on your goals. If you want stump pulling torque and emissions compliance, then you're on the right track. If you want emissions compliance and top-end pulling power, I think you're off the mark.
If you don't care about emissions compliance, I think you're leaving lots of power on the table with your current selections.
Second, why run such a low compression ratio when milling is worth so much power?
Third, is your goal to remain emissions legal?
If emissions compliance is your goal, then you might be pleased with those cam selections. Otherwise, they are really, really small. Basically, subtract 10-12 degrees of duration and you'll have an equivalent cam in a 346. We're talking 208/220 cams here. The cams will make your motor very torquey and fun to drive around town, but will lack a little bit up top because of the very early intake valve closing point. Really depends on your goals. If you want stump pulling torque and emissions compliance, then you're on the right track. If you want emissions compliance and top-end pulling power, I think you're off the mark.
If you don't care about emissions compliance, I think you're leaving lots of power on the table with your current selections.
__________________
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
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
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
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Thread Starter
Launching!
Joined: May 2005
Posts: 210
Likes: 0
tell me where YOU would want to be, the primary factor here is we have to do this on a stock converter, it would be nice if the car were able to meet emissions, but not necessary.
i personally thought the 918 was weak for the 2.160 valve also BUT that was simply how SDPC was selling them.
i'll bounce yet another off you here:
EDIT:
XE-R 230/244 116 LSA 112icl heads milled to 64cc acheiving 11.47:1 SCR and 8.61:1 DCR. I'm trying to stay away from too much overlap in order to contend with fuel mileage and smooth idle/NVH.
i personally thought the 918 was weak for the 2.160 valve also BUT that was simply how SDPC was selling them.
i'll bounce yet another off you here:
EDIT:
XE-R 230/244 116 LSA 112icl heads milled to 64cc acheiving 11.47:1 SCR and 8.61:1 DCR. I'm trying to stay away from too much overlap in order to contend with fuel mileage and smooth idle/NVH.
Last edited by stevewix; Feb 14, 2007 at 04:37 PM.
If you're wanting to cut back overlap, you may want to consider running a little bit less of a split between intake and exhaust. Something more like 230/236 114LSA +2 might satisfy your drivability and emissions goals while still putting down some good power with nearly stock street manners.
For maximum area under the curve, you would want to narrow the LSA more and run another 10-15 degrees of duration, but it doesn't sound like you want this type of build.
For maximum area under the curve, you would want to narrow the LSA more and run another 10-15 degrees of duration, but it doesn't sound like you want this type of build.
__________________
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
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
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
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
On The Tree
Joined: Dec 2006
Posts: 126
Likes: 0
From: Indianapolis, IN
918 Valve Springs I ran the Comp Cams 918 valve springs, push rods and XR275HR 222/224 duration, .566/.568 lift, 112 LSA on my 2005 GTO. The 918 valve spring broke, allowing my valve to drop into the #3 cylinder, ruining my whole longblock. Yeah, I'd say the 918 valve spring is way too weak to run on the L92 heads. I'm running the 921 springs on my L92 heads.
Originally Posted by cybernco
I ran the Comp Cams 918 valve springs, push rods and XR275HR 222/224 duration, .566/.568 lift, 112 LSA on my 2005 GTO. The 918 valve spring broke, allowing my valve to drop into the #3 cylinder, ruining my whole longblock. Yeah, I'd say the 918 valve spring is way too weak to run on the L92 heads. I'm running the 921 springs on my L92 heads.
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