Quench - Would .035 with 9.1DCR or .046 with 8.9DCR be better?
01-04-2008, 03:49 PM
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Quench - Would .035 with 9.1DCR or .046 with 8.9DCR be better? I'm looking at a TSP 402 Shortblock with -2cc pistons.
.005 out of the hole.
63cc Heads
and either a 236/240 or a 236/242 cam on a 113+2
After doing many searches and much reading, those two cams produce the best valve events for a 402 motor with 49* IVC@.050 and 55* EVO@.050. One has 12* of overlap and the other 13*
I'm sure a lot of you think this is a baby cam for a 402, but bigger cams throw off the valve events too much and I've had better luck with smaller cams in the past rather than large ones.
The only problem I forsee is too much compression for pump gas.
With the .040 gasket I'm showing a 12.41:1 SCR and 9.12:1 DCR - .035 quench
With the .051 gasket it drops to 12.06:1 SCR and 8.9:1 DCR - .046 quench
It seems to me that even though the CR is higher with the .040's they may work better that the .051's because the quench is so much tighter.
What do you guys think?
.005 out of the hole.
63cc Heads
and either a 236/240 or a 236/242 cam on a 113+2
After doing many searches and much reading, those two cams produce the best valve events for a 402 motor with 49* IVC@.050 and 55* EVO@.050. One has 12* of overlap and the other 13*
I'm sure a lot of you think this is a baby cam for a 402, but bigger cams throw off the valve events too much and I've had better luck with smaller cams in the past rather than large ones.
The only problem I forsee is too much compression for pump gas.
With the .040 gasket I'm showing a 12.41:1 SCR and 9.12:1 DCR - .035 quench
With the .051 gasket it drops to 12.06:1 SCR and 8.9:1 DCR - .046 quench
It seems to me that even though the CR is higher with the .040's they may work better that the .051's because the quench is so much tighter.
What do you guys think?
01-04-2008, 08:36 PM
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Your cooling system needs to be up to the task (radiator and oil cooler), aftermarket heads with a good chamber design, a consistent supply of good gas, coatings on everything. Even then I think your really gonna be pushing it.
01-05-2008, 05:53 AM
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I decided on a slightly different cam. A Magic Stick 3 off the shelf on a 114 LSA looks like it will yield 8.89DCR with .035 quench. It has a slightly later IVC and dropped the compression just enough to be on the safe side with 93 octane. That should be just about perfect.
Thanks for the replies.
Thanks for the replies.
01-05-2008, 04:21 PM
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I'll be using the heads I have on my current motor: PRC Stage 2.5 5.3L and they have 63cc chambers. They unshrouded the valves to work on a 4" bore motor when I bought them. Wishing I had gone with the LS6 version now, but hindsight is always 20/20.
I could go with the dish pistons, but with their -10cc's I'd lose something like a full point of compression and would need to go with a really small cam to get the right numbers. I just didn't want to be running out of breath at 6000 rpm.
I wish they offered a -4cc flat top. That would have been a perfect compromise.
I could go with the dish pistons, but with their -10cc's I'd lose something like a full point of compression and would need to go with a really small cam to get the right numbers. I just didn't want to be running out of breath at 6000 rpm.
I wish they offered a -4cc flat top. That would have been a perfect compromise.
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01-05-2008, 06:24 PM
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I'll be using the heads I have on my current motor: PRC Stage 2.5 5.3L and they have 63cc chambers. They unshrouded the valves to work on a 4" bore motor when I bought them. Wishing I had gone with the LS6 version now, but hindsight is always 20/20.
I could go with the dish pistons, but with their -10cc's I'd lose something like a full point of compression and would need to go with a really small cam to get the right numbers. I just didn't want to be running out of breath at 6000 rpm.
I wish they offered a -4cc flat top. That would have been a perfect compromise.
I could go with the dish pistons, but with their -10cc's I'd lose something like a full point of compression and would need to go with a really small cam to get the right numbers. I just didn't want to be running out of breath at 6000 rpm.
I wish they offered a -4cc flat top. That would have been a perfect compromise.
01-05-2008, 06:36 PM
#10
Is your ultimate goal to end up with a 5.3 headed 402? If so, then consider the custom pistons for $350 to get the exact dish you need.
I'm assuming that you really want a different head later. You may be able to get by with your stock LS1 castings for a while as you save for the final head you desire. That way you get a larger chamber to drop compression and don't have to rely on an excessive quench with a small chamber, high DCR combo that will be more suceptable to detonation.
Using PianoProdigy's DCR calculator, I modeled a 4.00 x 4.00 engine with .005 positive deck, 66.67cc (stock volume) heads, .045 thick gaskets, and 2 cc dish (more like valve reliefs) - and came up with a 11.71:1 SCR and 8.7:1 DCR using a 236/242 113+2 XE-R cam. You could push it to an 11.81 SCR and 8.8 DCR with .040 gaskets.
Then, all you have to do later is have your final head finished in a 67cc chamber. Looks like TSP has 67cc available in their ported L92 heads, or ET 240cc, or AFR 225.
I'm assuming that you really want a different head later. You may be able to get by with your stock LS1 castings for a while as you save for the final head you desire. That way you get a larger chamber to drop compression and don't have to rely on an excessive quench with a small chamber, high DCR combo that will be more suceptable to detonation.
Using PianoProdigy's DCR calculator, I modeled a 4.00 x 4.00 engine with .005 positive deck, 66.67cc (stock volume) heads, .045 thick gaskets, and 2 cc dish (more like valve reliefs) - and came up with a 11.71:1 SCR and 8.7:1 DCR using a 236/242 113+2 XE-R cam. You could push it to an 11.81 SCR and 8.8 DCR with .040 gaskets.
Then, all you have to do later is have your final head finished in a 67cc chamber. Looks like TSP has 67cc available in their ported L92 heads, or ET 240cc, or AFR 225.
01-06-2008, 05:44 AM
#11
I have found that 50-52 degrees ABDC at .050" to be a better window for IVC on a 402. You could retard your cam 2 degrees and get you right where you need to be. 
Keep the high compression setup and get your cam right. 
Keep the high compression setup and get your cam right.
__________________
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.
01-06-2008, 08:58 AM
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This is what I came up with using a Magic Stick 3 (237/242 .603/.909 - 114LSA XER Lobes) installed straight up on a 114 LSA:
Valve events at .050
Intake Valve opens - IVO - 4.5
Intake Valve closes - IVC - 52.5
Exhaust Valve Opens - EVO - 55
Exhaust Valve Closes - EVC - 7
Exhaust Centerline - ECL - 114
Overlap - 11.5
Deck Height: -0.005
Piston Dome or Dish: 2
Compressed Head gasket thickness: 0.04
Cylinder Head Chamber Volume: 63
Static Compression Ratio 12.41:1
Dynamic Compresion Ratio 8.89:1
I could push some more numbers around, but it looks like this off the shelf cam has everything I need to get the job done. Thanks for the input everyone.
Patrick: After the last cam I had you spec for me, I learned that there is more to this than I thought. So when I decided to go 402, I did a few searches to find everything I could about 402 cam specs and your posts cam up a lot. Consequently, I used some of your recommendations to other people to help pick out the right cam for me. So thanks for the help even though you didn't know you were helping. Haha
Valve events at .050
Intake Valve opens - IVO - 4.5
Intake Valve closes - IVC - 52.5
Exhaust Valve Opens - EVO - 55
Exhaust Valve Closes - EVC - 7
Exhaust Centerline - ECL - 114
Overlap - 11.5
Deck Height: -0.005
Piston Dome or Dish: 2
Compressed Head gasket thickness: 0.04
Cylinder Head Chamber Volume: 63
Static Compression Ratio 12.41:1
Dynamic Compresion Ratio 8.89:1
I could push some more numbers around, but it looks like this off the shelf cam has everything I need to get the job done. Thanks for the input everyone.
Patrick: After the last cam I had you spec for me, I learned that there is more to this than I thought. So when I decided to go 402, I did a few searches to find everything I could about 402 cam specs and your posts cam up a lot. Consequently, I used some of your recommendations to other people to help pick out the right cam for me. So thanks for the help even though you didn't know you were helping. Haha
