What's the ideal DCR for LSx Engines
What's the ideal DCR for LSx Engines What is the ideal DCR for our cars? Is there one?
I know many things affect it (cam ,heads, bore, stroke, head gasket, pistons)
I know there is always a trade off somewhere when you want power, usually at the expense of idle quality.
Would you want a certain DCR for a 346 CI vs. a 408 CI?
Thanks in advance,
Bill
I know many things affect it (cam ,heads, bore, stroke, head gasket, pistons)
I know there is always a trade off somewhere when you want power, usually at the expense of idle quality.
Would you want a certain DCR for a 346 CI vs. a 408 CI?
Thanks in advance,
Bill
8.5:1 seems to be the limit for 91 Octane and 8.8:1 seems to be the limit for 93. If you're running higher octane than this, you can bring up DCR.
__________________
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.
So basically play around with the calculators till I get close to 8.5 - 8.8.
The values you gave me, are those like an average compression for the whole stroke, just want to understand why it's so important and the full meaning of DCR.
The values you gave me, are those like an average compression for the whole stroke, just want to understand why it's so important and the full meaning of DCR.
At one point you guys will start to run into detonation with increased VE levels. LT1 motors can take a ton of static and dynamic compression due to the good cooling of the GM castings and the revearse cooling. Even with that older chamber design, but if you get the Vol Eff% up high enough you can even have issues with 8.3:1 DCR on pump gas, it's not going to knock at low loads and low RPM but once the motor starts making over 110% VE (210+BMEP) it will start rattling. You cna help this out by reducing engine temps with lower thermostats, colder intake air etc... So a lot of how much your motor can take depends on other factors as well. Different chamber designs can have a impact on the amount of compression you can run and in LS1 land we have a pretty big assortment of chambers, just look at what GM gives us in a LS1, LS6, L92 castings. Not to mention the ET, AFR, TFS and Darts.
Bret
Bret
Trending Topics
Originally Posted by SStrokerAce
Even with that older chamber design, but if you get the Vol Eff% up high enough you can even have issues with 8.3:1 DCR on pump gas, it's not going to knock at low loads and low RPM but once the motor starts making over 110% VE (210+BMEP) it will start rattling.
Bret
Bret
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
10 Reasons the LS7 Is GM's Most Extreme Naturally Aspirated V8 Engine Ever
Verdad Gallardo "Without question, the most common mistake in racing is to buy parts impulsively without having a clear vision of where you want to end up. The result is often a pile of mismatched pieces that will never work together properly." - David Reher
I know its a lot to ask but when buying parts for a strong running LS1 LS2 LS6 346ci street car what would be a wise choice to make? Heads, Intake, and Cam timing
Could you also suggest a good 402 street build also?
I know its a lot to ask but when buying parts for a strong running LS1 LS2 LS6 346ci street car what would be a wise choice to make? Heads, Intake, and Cam timing
Could you also suggest a good 402 street build also?
TECH Resident
Joined: Dec 2004
Posts: 881
Likes: 1
Originally Posted by SStrokerAce
At one point you guys will start to run into detonation with increased VE levels. LT1 motors can take a ton of static and dynamic compression due to the good cooling of the GM castings and the revearse cooling. Even with that older chamber design, but if you get the Vol Eff% up high enough you can even have issues with 8.3:1 DCR on pump gas, it's not going to knock at low loads and low RPM but once the motor starts making over 110% VE (210+BMEP) it will start rattling. You cna help this out by reducing engine temps with lower thermostats, colder intake air etc... So a lot of how much your motor can take depends on other factors as well. Different chamber designs can have a impact on the amount of compression you can run and in LS1 land we have a pretty big assortment of chambers, just look at what GM gives us in a LS1, LS6, L92 castings. Not to mention the ET, AFR, TFS and Darts.
Bret
Bret
TECH Resident
Joined: Dec 2004
Posts: 881
Likes: 1
Originally Posted by Patrick G
8.5:1 seems to be the limit for 91 Octane and 8.8:1 seems to be the limit for 93. If you're running higher octane than this, you can bring up DCR.
Originally Posted by DavidNJ
Are you using the seat times or the .050 times? If the seat times, your calcs would show a huge advantage for a solid lifter camshaft with its 15-20° smaller major intensity.
__________________
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.
Cost is the current detriment to going solid roller. Probably at least $2,000. With all the advantages though, I'm sure I'll be there again someday. It's like having your cake and eating it too, huh?
__________________
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.
TECH Fanatic
Joined: Mar 2004
Posts: 1,017
Likes: 0
From: Laguna Niguel, CA
Originally Posted by DavidNJ
There is an issue with hammering the needle bearings at idle...but yes...the whole hydraulic lifters in performance cars is an emissions thing IMHO.
TECH Fanatic
Joined: Aug 2005
Posts: 1,691
Likes: 1
From: Sunny London, UK
There is your answer (or at least a good view on it). Read the full article as well http://www.popularhotrodding.com/tec...power_squeeze/
As mentioned there are lots of things to consider with max DCR including quench, chamber design, intake temps, efficient exhaust. Engine temps have a large effect as noted in the diagram above.
Last edited by ringram; Jul 2, 2006 at 02:57 AM.
