Upgrade Your LS7 Cylinder Heads for Huge Gains!
- mamomotorsports
- Nov 12
- 5 min read
If you are new to Mamo Motorsports, then it’s important to understand that we don’t take a “one-size-fits-all” approach to our products. While we engineer our products quickly for our customers, we take the time to speak with them before we ship a product, so that we know what has been done to a vehicle, what is planned, and what the overall goal is. This approach allows us to deliver the very best product and achieve the best results. This has built up a family of repeat customers, cemented our reputation as experts, and allows us to sleep soundly at night knowing we sent the perfect product to our customer for their build. This story is an example of the results of our company philosophy.
The test results we are sharing are from Chris, one of our customers, on his OEM 427cid LS7 short block. Simply put, are the most impressive "verified" results that we have seen to date in one of our E85/flex fuel HR cammed street packages.
Chris and I started out with much smaller cam specs in our initial discussions (we were discussing low 230's on the intake lobe, initially) but after a few phone calls he decided that he would be willing to compromise some of the stock-like drivability for bigger numbers with more top end power and a little more "charisma" at idle (let's face it.....most guys LOVE the chop!).
I initially told Chris we were looking around 650 RWHP based on the build specs below:
OEM 427 LS7 Short block
Mamo Motorsports 265cc Stage 3 heads (2.230 Ti intake / 1.615 hollow stem exhaust) milled to create 12.5 to 1 with a thinner .040 head gasket (E85/flex fuel builds love compression!)
103 NW TB Yella Terra Ultralite rockers (the "Pro" version with the 10mm hardware upgrade)
Mamo Custom spec 3.2 camshaft with 241 intake @ .050 / 25X exhaust @ .050 on a 114 LSA
Mamo custom ATI 10% U/D dampener with the taller belt guides (no kicking A/C belts at high RPM!)
Johnson Link Bar Slow bleed HR lifters
Cometic Head gaskets
Rollmaster Timing chain
Manton Pushrods
Bosch 72lb/hr injectors
Aftermarket Headers (unknown specs)
CAI (do not know the brand)
THE INSTALL AND DYNO TESTING
The installation, baseline and power testing was performed at Hawks Motorsports in Easley, South Carolina, and the baseline dyno was done right before the car was taken apart to install our 265 LS7 cylinder heads. Hawks is a full-service facility for everything GM performance, and they use a Dyno Jet 224X dynamometer, with an Eddy current brake for testing under different load conditions, as they also perform tuning services. I often refer my clients to Hawk if they are even remotely close, or willing to trailer their car there. They are a family-run establishment with good, knowledgeable people and are excellent tuners. We highly recommend them if you are in the Southeast part of our country.
The baseline power numbers for Chris’s car netted 470 RWHP and 449 lbs/ft RWTQ with a cold air intake, aftermarket cat-back exhaust, and a tune, which is what was on the car when Chris bought it. Those baseline dyno numbers are right in-line with a mostly stock engine with a few minor mods, netting about a 20 HP gain over the 450-ish RWHP these cars typically produce in bone-stock trim.
Hawks installed our parts after baseline testing, then started tuning for the improved airflow from the new Mamo cylinder heads and ported intake manifold. They started by optimizing the tune for 93 octane pump fuel with very conservative timing (this is a flex fuel car after all, not straight E85), and achieved 630 RWHP and 542 lbs/ft RWTQ, which are very solid numbers for a build that is still enjoyable to drive. However, the next round of testing using E85 fuel really let this engine stretch its legs.
Keep in mind this is in South Carolina in the summer, so it’s unbearably humid, and this car was putting down 665 - 685 RWHP on E85 as they kept tweaking the timing and the fuel curves.
When all was said and done late in the day (the hottest time), Hawk finished with a very respectable 685 RWHP being the best run. For us, if this was the final number we would have been over the moon – but it gets better!
The next morning Chris’s car was still strapped to the dyno, and was scheduled to come off so Hawk could start on their next project car, but the dyno operator was curious to see what kind of power it would make in the cooler early morning air with no heat soak from back to back test runs. And are we glad he took the time to do that! The final numbers speak for themselves, 701 RWHP and 600 lbs/ft RWTQ, which are simply incredible the gains with E85 and this parts combination! These are the biggest N/A numbers on an LS7 seen at Hawks to date. Everyone there was pleased with the outcome.
If you asked us to duplicate this exact same build tomorrow, we would tell you it would make 40 RWHP less, and even that would be a solid number by anyone's standard. Obviously, we are stoked about this build. It exceeded expectations by a large margin. In full disclosure, if we didn’t have the baseline numbers, we would call BS on them and attribute it to a generous dyno. But in this case, we have the baseline, which was perfectly in-line with what you would expect to see, and we know Hawk is a very capable facility. The planets aligned with this build, and it will be fun to see what a different car with close to the same package can do somewhere else in the country, since the installer, the tuner, and even the dyno all play a huge role in the outcome of a project.
THE DRIVING IMPRESSION
We’ll leave the driving impressions to Chris to speak about on the forums, but the guys at Hawks told me it spins the wheels in 3rd gear at 80 MPH with the traction control on. Chris already has put over 500 miles on the car and says he doesn't dare take the traction control off, as the car scares him and leaves black tracks even with it on.
Stickier tires and more seat time will let him experience what this combo is fully capable of. Our only regret is that we wish we had the opportunity to drive this car. It’s extremely explosive, and the cam in it is not massive.
The dyno results are below and show the power numbers for baseline, on pump gas, on E85 in the heat of the day, and on E85 with cool morning are and without a heat-soaked engine. If you want to step up the performance of your LS7 contact us! We will work with you to build the right combination, and work with your builder to get you the best results!