AFR/ETP/etc. Aftermarket Heads --> Can they handle higher DCR?
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AFR/ETP/etc. Aftermarket Heads --> Can they handle higher DCR?
I was having this discussion with a friend over the weekend, and we came to a subject where we didn't think anything was substantiated (yet).
Will an aftermarket head, ie AFR ETP or others, support a higher DCR than an as-cast GM 243 LS6 head? (Using the 243 head because it presumably has the best chamber design of the LS1/2/6 heads) Are the combustion chambers in the aftermarket heads that superior to the 243 casting - and do the combustion chambers then allow the aftermarket heads like AFR & ETP to support a greater dynamic compression ratio (knock-free) than the *exact* same setup with GM-243 heads?
(For the sake of discussion, we were presuming the car would also already have a well-flowing exhaust (longtube headers) and some sort of upgraded intake, like a ported LS6, FAST, etc.)
So, take two engines (or use the same engine and repeat the experiment, doesn't matter), set them up identically (same cam, same intake, same exhaust, etc.), but on one engine install AFR205s (or ETPs, whatever) milled to 64.67cc, and on the other engine install GM-243's unmilled at 64.67cc. Use the same head-gasket, etc., so that the DCR and SCRs are identical. If the timing were also identical between the two - and the 243-engine had "X" degrees of KR, would you assume the AFR-engine to have A) More KR, B) Less KR, or C) Same KR....?
The question: All else being EQUAL, will the aftermarket heads suppress detonation to a higher DCR than 243 heads?
What if the 243 heads were ported vs. unported (but the combustion chamber untouched)? Any change in your answers?
Will an aftermarket head, ie AFR ETP or others, support a higher DCR than an as-cast GM 243 LS6 head? (Using the 243 head because it presumably has the best chamber design of the LS1/2/6 heads) Are the combustion chambers in the aftermarket heads that superior to the 243 casting - and do the combustion chambers then allow the aftermarket heads like AFR & ETP to support a greater dynamic compression ratio (knock-free) than the *exact* same setup with GM-243 heads?
(For the sake of discussion, we were presuming the car would also already have a well-flowing exhaust (longtube headers) and some sort of upgraded intake, like a ported LS6, FAST, etc.)
So, take two engines (or use the same engine and repeat the experiment, doesn't matter), set them up identically (same cam, same intake, same exhaust, etc.), but on one engine install AFR205s (or ETPs, whatever) milled to 64.67cc, and on the other engine install GM-243's unmilled at 64.67cc. Use the same head-gasket, etc., so that the DCR and SCRs are identical. If the timing were also identical between the two - and the 243-engine had "X" degrees of KR, would you assume the AFR-engine to have A) More KR, B) Less KR, or C) Same KR....?
The question: All else being EQUAL, will the aftermarket heads suppress detonation to a higher DCR than 243 heads?
What if the 243 heads were ported vs. unported (but the combustion chamber untouched)? Any change in your answers?
#2
LS1 Tech Administrator
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With the AFRs, the answer is yes. The dual quench pad combustion chamber is a step above the best cathedral port factory casting (241,243,317). So yes, you will get a faster burn and yes, you will be able to handle increased dynamic compression.
Take my setup for example: I have around 11.50:1 static compression and 8.73:1 dynamic compression. I run 26 degrees of timing at peak torque and 30 degrees of timing at higher rpm. Zero knock, even in the Texas heat. This would be hard to do with a factory casting.
Take my setup for example: I have around 11.50:1 static compression and 8.73:1 dynamic compression. I run 26 degrees of timing at peak torque and 30 degrees of timing at higher rpm. Zero knock, even in the Texas heat. This would be hard to do with a factory casting.
__________________
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.
#5
LS1 Tech Administrator
iTrader: (14)
Yes, when running a 160 stat, my coolant temps hover around 180-190f with the ac blasting, and 175-180 without. Getting cool air in through the sealed Ram Air hood also helps.
__________________
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.
#7
LS1 Tech Administrator
iTrader: (14)
Ideally, you want the block as hot as possible and the cylinder head as cold as possible. With engine temps around 180, the 160 stat seems to strike a happy medium with the hot/cold thing.
__________________
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.
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#8
7 Second Club
iTrader: (11)
Originally Posted by 02RedHawk
Yep, that's what I was figuring.
PatrickG - This with a 160 tstat?
Phil99 - That DCR (9.45) seems awfully high. Can you share your calcs?
PatrickG - This with a 160 tstat?
Phil99 - That DCR (9.45) seems awfully high. Can you share your calcs?
3.62 stroke
3.905 bore
-2cc reliefs
52cc heads <== not mistyped
3.910 x .045 gasket
.007 out of hole
254/260 111 +0
Let me find the valve timing @ .006, its written down somewhere here. If memory serves me correctly my SCR is around 12.5:1
Phil
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