One thing I learned so well from Ron Sutton while doing my suspension upgrades is to not make a WAG (wild ass guess) when making performance upgrade decisions. Don't just run what your friend runs or what someone on the internet said is the
best cam out there, input all of the data and review real world dynamic results BEFORE you start buying parts. I did this with Ron on my suspension and not only am I very happy with how it turned out, it also turned out exactly as the data said it would right out of the box.
By asking these cam choice questions on a few different message boards, I stumbled across a very helpful friend that has some good engine dyno simulation software that he uses every day when building high performance engines. For the past couple of days we have been working together to get the data input into the software (as best as we know) and running different simulations to see exactly how my engine will react to different cam lobe designs.
Since I bought these new to me heads used, we aren't exactly sure of their flow numbers...but we have a pretty good idea that they flow comparably to the newer design CNC ported Bowtie Fastburn heads, so we used those flow numbers in all of the simulations. We ran simulations many different ways with the different crate engine cam choices as well as with the dual plane vs the single plane intake manifold choice.
Like was done when I worked with Ron on my suspension, I had some sacred cows that we chose to deal with along with some budget constraints (as always). We found that there are certainly ways to make more peak horsepower and torque, but the trade offs weren't worth it for me. I want to run my dual plane intake and Q-jet so that was one sacred cow and I don't want to make any changes on the bottom end engine nor do I want to change the headers. I wanted to find the best cam design we could find using the new heads and everything I already have.
Here is a chart showing 3 simulated dyno charts, the purple and yellow lines are my current setup, the dark blue and green lines are the cam design we are currently looking at and the lite blue and red lines are a stock LS2 with headers for comparison.
As the graph shows, this combination makes a huge increase in peak horsepower over my current setup while at the same time keeps my idle Vac at 20.3" and makes more torque from 3000 RPM and up as well.
At 4000 RPM it makes 20 hp more than my current setup, 5000 RPM 80 hp more and the big one at 5500 RPM 116 hp more.
The lines are actually pretty similar to stock LS2 numbers which should make it much easier for me to keep up with them on the straights which is what I need.
The cam we are looking at is a Comp Cams custom grind on a 114-degree lobe spread:
Intake on a 110 intake center line
Lobe#3014
Rated Duration 268
Duration @0.050 218
Lift with 1.5 rocker .534
Exhaust on a 118 exhaust center line
Lobe#3015
Rated Duration 274
Duration @0.050 224
Lift with 1.5 rocker .537
This makes a 4-degrees advancement in the cam which lets me run my timing chain straight up.
The heads are at my local engine shop to give them the once over and mostly check the valve springs real well. I need to make sure they'll handle a .550 lift with no issues and have around 350# of spring pressure before ordering the cam (if that's the final choice). If there is any question at all about the condition of the springs, I'll likely go ahead and have a new set of springs and retainers installed...just because. That way I can be sure they are healthy with no issues and also make sure they match up with a cam with this much lift.
Curious of your thoughts on this? Do you think we are headed down the right path? See anything we should address? I'm learning as we go here and I appreciate everyone's input on this.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
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