Some customers have asked us the difference between the L76 and the LS3 intake manifolds. We thought it would be helpful to forum members to post some pictures showing the differences.

First, side by side they look virtually the same. The throttle body opening is 90mm on both.


L76 on left LS3 on right



The runner port dimensions are identical (1.25"w x 2.475"h).

Illustration courtesy of CompCams


The part numbers are different.


L76 Part Number



LS3 Part Number


The easiest way to distinguish them is to look at the MAP Sensor mount on the left side of the throttle body opening as you face the front of the manifold. The L76 is mounted with a clip whereas the LS3 is mounted with a screw.


L76 MAP Sensor mount


LS3 MAP Sensor mount

Other than the MAP Sensor, the two manifolds are interchangable and they flow the same.

 

What do these flow?

 

LG Motorsports shows a non-ported stock manifold flows at about 325 CFM.

 

Other identifiers;

1) Compression limiters for intake bolts in LS3, L76 doesnt.
2) Passenger side PCV is different. L76 is hose clamp style, LS3 has a clip on barb.
3) Looking down the throttle body, L76 has the PCV tube (above) protruding into the plenum about 1/2 way.

 

Awesome info! Internally, are they the same? What does a ported LS3 manifold flow?

 

Ported these intakes don't pick up anything hardly. The only thing that is changed when porting is cross-section which can shift the power up a few rpm. I am the only one who has picked up 10-20 cfm on these intakes that I know of. It isn't from porting either.....

 

We actually see an average of 12-16 rwhp gains from radically porting the LS3/L76 intake manifolds. Go to our website for customer feedback and dyno results. http://www.peakspeedshop.com/

 

Just thought I would update this.

I just pulled the intakes off of two L76 '09 G8 GTs yesterday, and they both had the bolt on MAPs, compression limiters for the mounting bolts, and the barb-style hose connectors. Didn't think to check the PNs, but they were both ~50K mile cars that the intakes had never been off of, so they were stock on the cars. Maybe GM changed to intalling all LS3 intakes somewhere along the way.

 

Thats what ive heard and seen on most cases when some one ports their LS3 inatkes.

 

Some other tuners say its more like 4-5rwhp...still not too bad for the price.

 

Sure aint, its a good deal if you think about it. In most cases it depends on the tuner and the porting job to see the power gains on porting LS3 intakes, some might see little difference others will see big gains.

 

Any chance of rehosting the photos?

Tipsy