One of the reasons I emphasize calling instead of e-mailing is because a lot can be learned in a conversation. They ask questions not on the form, and you might ask a few of your own. For instance, the fella at Lunati learned that "streetable" to me is nothing like downtown Chicago at 5:15PM. That gave him a little more freedom to be aggressive. Also, they're probably more likely to believe you'll buy a camshaft if you take the time on the phone.
I don't think there's anything wrong with Howards' cam choice for your car a'tall, mind you, but they might've gotten a little more aggressive had you spoken with them. It pays to play it safe for those guys; I truly doubt you would hate the 710031-12 but the one I have seems to build significantly more power and torque, both average and peak, than the split-pattern they chose... but, most of the difference is above 4,800RPM. Between peak HP and 6,000RPM, the smaller cam loses 22 horses, where the big boy only loses 9. Below 4,000RPM the torque is essentially a wash, but at and above that number the 711451-08 walks away and never looks back. This is always the case with larger camshafts: You have to spin to win. There's actually a slightly-larger difference; read the notes below. Interestingly, in this case, you're giving up very little on the low end for the substantial upper-RPM gains. The flip side of that is more aggressive valvetrain movement in that area. I don't consider either camshaft wild enough for that to be a serious concern, honestly.
Another consideration is your willingness to
use those gains. Some guys put a lot of stock into the factory redline, which on a stock 360's best day was 5,000RPM. They're not comfortable above that number. I'm
not one of those guys; I've pushed a stock E58 well beyond that with a little creative tuning. If anything beyond 5,000-5,500RPM is out of your comfort zone, there's little point in getting the larger cam. Looking at the curve the 711451-08 would be pulling like a freight train beyond your happy place. It's
really hard to convince yourself to leave the party just when you're having the best time. The 710031-12 is tapering off pretty quickly at that point, so it'll remind you to shift where you like to if you're doing so by ear.
Now, on to the graphs and charts.
There are a few things I'd like to note about what follows:
- "Valiant Dumper 3" has the Howards camshaft I own. "Valiant Dumper 360 6:08PM" is Howards' recommendation.
- The modeled engine was a "stock" 3.58"-stroke shortblock at 4.030" bore.
- I did not research ports. They're ported J-head flow numbers, better than stock Ed L. Brocks.
- Intake: 750CFM carb on the program's generic single-plane intake.
- Exhaust: 1-5/8" long-tube headers with low-restriction mufflers (I used DynoMax flow numbers).
- Rocker-arm ratio was 1.5:1.
- Compression was 9.72:1, which is where my low-effort 360 landed. It's a pain to change, so I left it.
- I did not model valvetrain losses, which are significant in an LA engine due to pushrod angles and worse yet on a Magnum due to rickety, flexible-flyer rocker mounting.
- I forgot to change the ramp profile when I entered the 710031-12 cam file. It is not optimized for large-diameter lifters like the 711451-08. Changing that had little effect on the averages, but there was a minor yet noticeable increase in torque between 2,000-3,600RPM. It slightly flattened the HP curve at peak with no loss--it hit peak a tick earlier and maintained it to 5K--which was surprising. Regardless, above 3,600 the divergence was even greater in favor of the larger cam. Spin to win, remember?
- Increasing total timing from 34° to 36° did virtually nothing except raise the knock index. Maximum survivable timing is not always the best timing.
- These are not figures to wave around at your friends as gospel. This is a simulation, and while the software I'm using is the best available, it is still modeling software. The point of this exercise was a camshaft comparison, not hard numbers. There is no replacement for an actual dyno sheet and/or timeslips.
- Actual intended use for the car is far more important than ultimate numbers. The figures are positively bewitching on my W2 engine, but few would want to drive it to work daily.
- I am neither a camshaft engineer nor a guy who makes cam recommendations. Howards gave you a recommendation that I have no doubt would make you happy. It would be a better car for ice-cream runs with B-body-babe, but the larger cam is a party animal above 4K--and that's my kind of party.
- If you're reading this and are not @b-body-bob, don't ask me to do this shit for you. It's time-consuming--never mind the hour-plus I have in making everything appear in one image--and rather tedious. If I hadn't had an engine already modeled that's so similar to Bob's, I wouldn't have done this.
Without further ado, here you go Mr. Robert:
