L83 component images
No most cars do not (except for diesels, but they usually use electric driven ones). Most cars do use manifold vacuum. LS engines did not have them.
Staging Lane
Joined: Apr 2013
Posts: 74
Likes: 0
From: Chino, Ca
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
Vacuum pump The vacuum pump is needed because the engine doesn't generate enough vacuum in order to maintain proper brake pedal assist.
The likely causes of this are cylinder deactivation (Active Fuel Management) and the camshaft phaser (VVT), both of which can impact engine vacuum.
Engine manifold pressure was often in the 88 to 92 kPa range (6 to 10 kPa vacuum) when driving the vehicle at highway speeds. This is not enough vacuum to generate enough vacuum assist for the brake system.
The DI V6 engines have been using vacuum pumps for several years in the Lambda trucks and in the Camaro.
If I recall correctly, on the Gen IV V8 engines that had AFM (and no vacuum pump), they would disable cylinder deactivation if brake booster vacuum wasn't high enough. I assume by having a vacuum pump they can extend the use of AFM.
The likely causes of this are cylinder deactivation (Active Fuel Management) and the camshaft phaser (VVT), both of which can impact engine vacuum.
Engine manifold pressure was often in the 88 to 92 kPa range (6 to 10 kPa vacuum) when driving the vehicle at highway speeds. This is not enough vacuum to generate enough vacuum assist for the brake system.
The DI V6 engines have been using vacuum pumps for several years in the Lambda trucks and in the Camaro.
If I recall correctly, on the Gen IV V8 engines that had AFM (and no vacuum pump), they would disable cylinder deactivation if brake booster vacuum wasn't high enough. I assume by having a vacuum pump they can extend the use of AFM.
Last edited by Jason Haines @ LPE; Jun 22, 2013 at 10:17 PM. Reason: typo
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
Vacuum pump Some of the previous generation (1999-2013) gasoline CK trucks also used the hydroboost. Easy to identify when you look under the hood - no big vacuum booster.
Not sure what GM does on car based diesel applications but I would assume it is an electric pump.
The truck braking duty cycle is probably different from a car, especially when you include towing or loading up the vehicle with payload in the mix.
Last edited by Jason Haines @ LPE; Jun 22, 2013 at 10:17 PM. Reason: typo
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
Staging Lane
Joined: Apr 2013
Posts: 74
Likes: 0
From: Chino, Ca
The vacuum pump is needed because the engine doesn't generate enough vacuum in order to maintain proper brake pedal assist.
The likely causes of this are cylinder deactivation (Active Fuel Management) and the camshaft phaser (VVT), both of which can impact engine vacuum.
Engine manifold pressure was often in the 88 to 92 kPa range (6 to 10 kPa vacuum) when driving the vehicle at highway speeds. This is not enough vacuum to generate enough vacuum assist for the brake system.
The DI V6 engines have been using vacuum pumps for several years in the Lambda trucks and in the Camaro.
If I recall correctly, on the Gen V V8 engines that had AFM (and no vacuum pump), they would disable cylinder deactivation if brake booster vacuum wasn't high enough. I assume by having a vacuum pump they can extend the use of AFM.
The likely causes of this are cylinder deactivation (Active Fuel Management) and the camshaft phaser (VVT), both of which can impact engine vacuum.
Engine manifold pressure was often in the 88 to 92 kPa range (6 to 10 kPa vacuum) when driving the vehicle at highway speeds. This is not enough vacuum to generate enough vacuum assist for the brake system.
The DI V6 engines have been using vacuum pumps for several years in the Lambda trucks and in the Camaro.
If I recall correctly, on the Gen V V8 engines that had AFM (and no vacuum pump), they would disable cylinder deactivation if brake booster vacuum wasn't high enough. I assume by having a vacuum pump they can extend the use of AFM.
Ok, that makes sense.
We will likely publish that data in the next few days.
I will try to remember to post it to this forum. I am posting everything to our own web site forum and then posting the specific information people ask for on other forums to those specific forums but I might miss some.
I will try to remember to post it to this forum. I am posting everything to our own web site forum and then posting the specific information people ask for on other forums to those specific forums but I might miss some.
Is the VVT operation similair to the Gen IV design?
Locked at 7 degrees advanced in the park position?
Thanks again for sharing the Gen V inernals!
Mike
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
I would assume for the VVT as manifold vacuum would drop when it kicks in.
Edit: As Jason stated.
I was speaking in general terms. I've seen Ford applications (such as the Excursion) use electric pumps for their diesels.
Edit: As Jason stated.
On the diesel trucks that I am familiar with GM uses the power steering pump hydraulic pressure (Hydroboost) for brake assist instead of using vacuum.
Some of the previous generation (1999-2013) gasoline CK trucks also used the hydroboost. Easy to identify when you look under the hood - no big vacuum booster.
Not sure what GM does on car based diesel applications but I would assume it is an electric pump.
The truck braking duty cycle is probably different from a car, especially when you include towing or loading up the vehicle with payload in the mix.
Some of the previous generation (1999-2013) gasoline CK trucks also used the hydroboost. Easy to identify when you look under the hood - no big vacuum booster.
Not sure what GM does on car based diesel applications but I would assume it is an electric pump.
The truck braking duty cycle is probably different from a car, especially when you include towing or loading up the vehicle with payload in the mix.
Last edited by 93Z2871805; Jun 24, 2013 at 05:34 PM.
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
L83 flow data L83 chamber volume: 57.6 cc
Intake runner volume: 248 cc
Exhaust runner volume: 102 cc
Fairly large intake runner volume when you compare it to the previous 5.3L heads.
Note, we flow tested on a 3.900" bore instead of the stock 3.780" bore size because we don't currently have a 3.780" size bore sleeve for our flow bench fixture.
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
L83 valve sizes and weights The stock L83 intake valve size is 1.928" and weighs 99.5 grams. Here is an image of the valve:
The stock exhaust valve measures 1.556" and weighs 90.3 grams. Here is an image of the valve:
Here is an image of the combustion chamber with stock valves:
The stock exhaust valve measures 1.556" and weighs 90.3 grams. Here is an image of the valve:
Here is an image of the combustion chamber with stock valves:
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
LM4 vs L83 flow data comparison Here is L83 compared to the LM4 5.3L heads (Gen III 5.3L V8).
Intake data:
Exhaust data:
Some of the other comparison data for the LM4 heads:
The chamber volume was 62.6 cc.
The intake runner volume was 204 cc.
The exhaust runner volume was 76 cc.
Intake valve size was 1.890".
Exhaust valve size was 1.550".
Intake data:
Exhaust data:
Some of the other comparison data for the LM4 heads:
The chamber volume was 62.6 cc.
The intake runner volume was 204 cc.
The exhaust runner volume was 76 cc.
Intake valve size was 1.890".
Exhaust valve size was 1.550".
TECH Regular
Joined: Feb 2008
Posts: 458
Likes: 1
From: Keller, Texas
Thanks for the exact data I was looking for.
What do you think is causing the sharp cfm decline at .400 lift on the intake side? That's very peculiar.
What do you think is causing the sharp cfm decline at .400 lift on the intake side? That's very peculiar.
Last edited by texas94z; Jul 3, 2013 at 12:38 AM.
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
Exhaust flange The exhaust flanges are different.
Here is an image of the L83 Gen V exhaust flange/exhaust ports on the cylinder heads:
Here is an image of the L83 cylinder head with a Gen III/IV exhaust gasket for comparison. With the evenly spaced exhaust ports and the same bore centers it makes sense that the exhaust ports line up but note that none of the bolt holes do:
Here is an image of the L83 Gen V exhaust flange/exhaust ports on the cylinder heads:
Here is an image of the L83 cylinder head with a Gen III/IV exhaust gasket for comparison. With the evenly spaced exhaust ports and the same bore centers it makes sense that the exhaust ports line up but note that none of the bolt holes do:
Thread Starter
LS1Tech Sponsor
Joined: Oct 2002
Posts: 603
Likes: 1
From: Decatur, IN
Intake flow data It is likely that at that particular valve lift/valve location in its travel, the air is not able to make the turn as well as it can at the other valve lift points. We see this from time to time in different cylinder head configurations. On some heads it flat lines, sometimes it drops and comes back up like it did in this case.