So I built this motor
I have your same Lunati Voodoo cam in my 383 with CNC ported stock heads, ported stock intake 52mm ported stock TB, and mid tube headers and it's a beast; your compression is far too low; mines a very conservative 11.3:1 CR. That cam likes compression, as does any NA LT1. Why such low CR since stock is 10.5:1
Slap a supercharger on it!
That or get those heads milled and run a thinner head gasket, for a performance NA LT1 you want 11:1CR MINIMUM, 12:1 + would be even better. Keep in mind this is a reverse cd engine and it's not 1970 anymore. I think that is the main thing holding yours back, who tuned it also? Does it pull hard to 6700 RPM or so (mine does)? What valve springs are you running? 1.6 Roller rockers?
Slap a supercharger on it! That or get those heads milled and run a thinner head gasket, for a performance NA LT1 you want 11:1CR MINIMUM, 12:1 + would be even better. Keep in mind this is a reverse cd engine and it's not 1970 anymore. I think that is the main thing holding yours back, who tuned it also? Does it pull hard to 6700 RPM or so (mine does)? What valve springs are you running? 1.6 Roller rockers? Not to throw too big of a monkey wrench into this discussion, but GM rated them at appox 10.5:1 and they were nowhere close to that in all reality. All of the LT-1's that have went through my machine shop were closer to 8.8:1 on average due to the deck height of the blocks being measured at 9.028"-9.038" depending on the cylinder.
I call BS on that....if that were the case, LT1's would love some boost and that's not the case. They run like crap and spark knock if you don't run 93 octane, and I trust GM more than some dude at a machine shop. Where's your "proof" on this wild unsubstantiated claim? How specifically are you calculating CR??? ^To further elaborate:
Combustion chamber volume = 54 cc's
Bore size = 4.000"
Stock deck height is 9.025" = i.e. piston is .025" "in the hole"
Compressed head gasket thickness = .042"
Crank stroke = 3.48"
Piston "dish" volume = 8 cc's
DO THE MATH! I wouldn't want this guy working on my engine!
http://www.summitracing.com/expertad...ion-calculator
Combustion chamber volume = 54 cc's
Bore size = 4.000"
Stock deck height is 9.025" = i.e. piston is .025" "in the hole"
Compressed head gasket thickness = .042"
Crank stroke = 3.48"
Piston "dish" volume = 8 cc's
DO THE MATH! I wouldn't want this guy working on my engine!
http://www.summitracing.com/expertad...ion-calculator
The .039 gasket is probably a Felpro 1074 if I remember correctly.
Here's the most accurate info I've collected for stock LT1 specs:
Stock shortblock
9.025" deck height, sometimes a hair taller
4" bore
3.48" stroke
1.559" compression height of stock Mahle piston
-5cc piston head volume from valve reliefs
Aluminum heads
54cc chamber
.048-.051" stock head gasket compressed thickness
.026" piston to deck clearance (in the hole) or a little more
10.5:1 static compression give or take
Here's the most accurate info I've collected for stock LT1 specs:
Stock shortblock
9.025" deck height, sometimes a hair taller
4" bore
3.48" stroke
1.559" compression height of stock Mahle piston
-5cc piston head volume from valve reliefs
Aluminum heads
54cc chamber
.048-.051" stock head gasket compressed thickness
.026" piston to deck clearance (in the hole) or a little more
10.5:1 static compression give or take
I call BS on that....if that were the case, LT1's would love some boost and that's not the case. They run like crap and spark knock if you don't run 93 octane, and I trust GM more than some dude at a machine shop. Where's your "proof" on this wild unsubstantiated claim? How specifically are you calculating CR???Left bank at cylinder #1 (9.027"), cylinder #7 (9.038")
I have decked a lot of SBC'S, GEN 1 & Gen 2's. I'm sorry that you don't agree with the facts that I have seen, but then again I could care less if you agree or not. BTW, the heads are not always 54cc if you had ever taken the time to cc a set of stock heads.....
Last edited by 1997bird; Feb 24, 2014 at 12:41 AM.
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........that's about the norm for LT1 heads. The guys looking for 54cc chambers must be thinking of LT4 heads. Right bank at cylinder #2 (9.028"), cylinder #8 (9.030")
Left bank at cylinder #1 (9.027"), cylinder #7 (9.038")
I have decked a lot of SBC'S, GEN 1 & Gen 2's. I'm sorry that you don't agree with the facts that I have seen, but then again I could care less if you agree or not. BTW, the heads are not always 54cc if you had ever taken the time to cc a set of stock heads.....
Left bank at cylinder #1 (9.027"), cylinder #7 (9.038")
I have decked a lot of SBC'S, GEN 1 & Gen 2's. I'm sorry that you don't agree with the facts that I have seen, but then again I could care less if you agree or not. BTW, the heads are not always 54cc if you had ever taken the time to cc a set of stock heads.....
Really dude?? You CLAIM to work at a machine shop which you're just further embarrassing yourself, I would think someone who works at a machine shop would know how to calculate CR, it's basic engine building 101 
I never claimed to work at a machine shop, and no, I have not personally cc'ed LT1 heads....it's not my job. Playing devil's advocate here, let's say we use your numbers to be REALLY conservative:Combustion chamber volume = 58 cc's (complete BS just to round up A LOT, LT1 actually has 54cc combustion chambers )
Bore size = 4.000"
deck height is 9.038" = i.e. piston is .038" "in the hole" (for every single cylinder...would never happen
)Compressed head gasket thickness = .048"
Crank stroke = 3.48"
Piston "dish" volume = 5 cc's (I stand corrected on this)
9.8:1 CR = [{(B/2)^2 * S*Pi}+Vcc+Vp+{(B/2)^2*Pi*(DH+TG)}]
[{(B/2)^2*Pi*(DH+TG)}+Vcc+Vp]
9.8:1 CR is a entire point higher than your ridiculous 8.8 CR, I'll ask you again....how are you coming up with this 8.8:1 CR nonsense? I don't care either if you believe GM, me, or anyone else who knows what they are doing, you don't seem to have any business working on engines! You are the one who can't agree on facts (how to calculate CR)! Must be smokin that GOOD isht
Hook me up bro! Last edited by ahritchie; Feb 25, 2014 at 12:39 AM.
A moderator really should update the "The Ultimate LT1-Newbit FAQ -Basic Engine specifications" sticky on this very site claiming 54cc....the internet has enough misinformation on it already! https://ls1tech.com/forums/lt1-lt4-m...ml#post2682252
Does the LT1 section even have moderators anymore? Or is it like "Lord of the Flies" around here now? No no no no no no NO NO
Here's a quote from the man himself:
His chambers are usually a little bigger because they get a little work.
Here's a quote from the man himself:
stock is 54.5cc and the typical LE2/LE3 haeds get milled .010 and end up at 55 cc after the chambers are unshrouded and polished.
If you are wanting a smaller/larger chamber, just ask and we can get you what you are looking for (as large as 59 cc, as small 50 cc).
Lloyd
If you are wanting a smaller/larger chamber, just ask and we can get you what you are looking for (as large as 59 cc, as small 50 cc).
Lloyd
I don't know where 58cc came from but it's definitely not right.
http://www.grandsportregistry.com/lt1vslt4.htm
"Combustion chambers are almost identical with a negligible .4cc increase in volume for the LT4 Combustion chambers at 54.4cc's." That would make the LT1 aluminum heads right around 54cc.
http://www.grandsportregistry.com/lt1vslt4.htm
"Combustion chambers are almost identical with a negligible .4cc increase in volume for the LT4 Combustion chambers at 54.4cc's." That would make the LT1 aluminum heads right around 54cc.
I don't know where 58cc came from but it's definitely not right.
http://www.grandsportregistry.com/lt1vslt4.htm
"Combustion chambers are almost identical with a negligible .4cc increase in volume for the LT4 Combustion chambers at 54.4cc's." That would make the LT1 aluminum heads right around 54cc.
http://www.grandsportregistry.com/lt1vslt4.htm
"Combustion chambers are almost identical with a negligible .4cc increase in volume for the LT4 Combustion chambers at 54.4cc's." That would make the LT1 aluminum heads right around 54cc.
As does Chevy high performance magazine....got a bunch of misinformed jokers on this forum
http://www.chevyhiperformance.com/te...1_engine_info/
Last edited by ahritchie; Feb 24, 2014 at 03:48 PM.
Combustion chamber volume = 58 cc's
Bore size = 4.000"
deck height is 9.038" = i.e. piston is .038" "in the hole" (for every single cylinder...would never happen
)Compressed head gasket thickness = .048"
Crank stroke = 3.48"
Piston "dish" volume = 5 cc's (I stand corrected on this)
9.8:1 CR = [{(B/2)^2 * S*Pi}+Vcc+Vp+{(B/2)^2*Pi*(DH+TG)}]
[{(B/2)^2*Pi*(DH+TG)}+Vcc+Vp]
Stock parts most definitely do vary.
I have heard one trustworthy report of a single Fleetwood engine being .032 down in the hole but at least in my experience .022-.025 seems to be most common. One report I am not sure I trust that was .009 down.
Round all volumes up and you can't get the number anywhere near low 9s much less high 8s.
11 Second Club
Joined: Jan 2010
Posts: 1,707
Likes: 13
From: New Orleans, LA
I think the aluminum heads are 58cc, I also think that the iron headed LT1 has even larger combustion chamber heads and less compression than the aluminum headed LT1. 10.0:1 for iron, 10.5:1 for aluminum
Last edited by NewOrleansLT1; Feb 24, 2014 at 08:36 PM.
Prove it! Where's your source on this? I think a lot of things....doesn't make them true! 
Here's my references...where's yours?
http://www.grandsportregistry.com/lt1vslt4.htm
http://www.chevyhiperformance.com/te...1_engine_info/
https://ls1tech.com/forums/lt1-lt4-m...ewbie-faq.html
http://www.fierolt1.com/lt1_vs_lt4_1.htm
http://www.miataturbo.net/engine-per...chamber-64407/
Here's my references...where's yours?
http://www.grandsportregistry.com/lt1vslt4.htm
http://www.chevyhiperformance.com/te...1_engine_info/
https://ls1tech.com/forums/lt1-lt4-m...ewbie-faq.html
http://www.fierolt1.com/lt1_vs_lt4_1.htm
http://www.miataturbo.net/engine-per...chamber-64407/
Last edited by ahritchie; Feb 24, 2014 at 08:45 PM.
11 Second Club
Joined: Jan 2010
Posts: 1,707
Likes: 13
From: New Orleans, LA
Prove it! Where's your source on this? I think a lot of things....doesn't make them true!
Here's my references...where's yours?
http://www.grandsportregistry.com/lt1vslt4.htm
http://www.chevyhiperformance.com/te...1_engine_info/
https://ls1tech.com/forums/lt1-lt4-m...ewbie-faq.html
http://www.fierolt1.com/lt1_vs_lt4_1.htm
http://www.miataturbo.net/engine-per...chamber-64407/
Here's my references...where's yours?
http://www.grandsportregistry.com/lt1vslt4.htm
http://www.chevyhiperformance.com/te...1_engine_info/
https://ls1tech.com/forums/lt1-lt4-m...ewbie-faq.html
http://www.fierolt1.com/lt1_vs_lt4_1.htm
http://www.miataturbo.net/engine-per...chamber-64407/
Last edited by NewOrleansLT1; Feb 24, 2014 at 09:33 PM.