Torque Monster !
Lets use my high top conversion van as an example for a minute. When I put the fresh rebuild in, it was 165psi with stock 5.9 pistons, .028 head gasket, Hughes prepped EQ heads as cast chamber size with 1.92 intakes, and a Hughes 0814 roller cam. That was with only the one plug pulled for the gauge, not all 8.
That's a really nice combo.
With 3.55s and 30.6 tires, that is the equivalent of running 2.98s with 26.5s, to put it into perspective for me. For you to laud the 5.9 at 2700, is proof of that engine's capabilities.
I'm assuming that 5.9 is still equipped with the factory EFI system, which has timing control, a knock sensor, and that wicked keg intake, which is basically a reshaped tunnel-ram.
As already mentioned, that's a great way to go. That 0814 cam is also a good pick for torque.
The only way you can run more pressure with that 5.9 which is already at or near the pressure limit, is to run in conjunction, either a detonation suppressant like water/meth injection; or to run alloy heads. But in the Travco case, IDK if that is such a great idea.
Firstly, to get 165psi with iron at sea level points to 9.5Scr and an Ica of 56*, with a resultant PV predicted to be
148, a very nice number for a streeter.
To beat this with alloy,is gonna take about 10.5Scr Which points to a total chamber size of 77.6cc, and you can't get away with that .028 gasket anymore unless you can figure out how to keep the pressure from blowing the Fire-ring into the valley. So you are "stuck" with the FelPro .039s (8.8cc). You are gonna have to mill the decks to get the pistons up to at least zero-deck. Mine are at .003 to .007, above deck. This means everything has to be machined just about perfect. My stuff has been to three different machine shops, each saying they could do better than the last one. Well not one of them could. The stack up gets critical when you want to run .030 or less Q. The block could be off a tad. the rods could end up resized to 8 different lengths, the crank could be off a hair, and if you line-hone the block, all bets are off. It took me more than a full morning to get my deck-heights to the range they are in. Only the KB107s were the same to 3 decimal points. But you know; they say .040 is as close as you need to get. My tightest is .032, by the math after measurement. So at zero-deck, the KB107s are listed at 5cc.The total now is 8.8+5=13.3, leaving 63.8 for the heads. easy peasy; so the compression and Q problems are solved, and 10.5 at stock 4.0x3.58 is done.
Here's the problem as I see it;
With that 0814 cam the Ica is sorta predicted to be 56*, and if that is true, then the pressure is predicted to be 187psi at sealevel. I say sorta because Hughes, as is their policy, does not publish the advertised duration specs; so I guessed.
I guessed that the 0814 cam is 256/264/110 advertised.
Now there is nothing wrong with 187 psi with alloys either, but in this case it comes with a P/V index of 168; read about PV here;
V/P Index Calculation
A PV of 168 is flipping huge. That is what my engine runs, and she's a parts breaker in my 3650 pound Barracuda, with a manual trans. It has at one time or another, broken every member behind it, and is particularly hard on clutch discs. It broke;
2 of A833 overdrives
a 5.13/5.38 Crown gear, Can't recall exactly which
a 3.91 crown gear.
a 7260 u-joint was no match
the 7290 held up better
and the 1350 finally solved it.
She can blow up a factory 340 disc in just hours.
On the street! mind you, every one on the street. with those BFG/Cooper 295/50-15s yet, that everyone rightly calls crappy,lol.
For comparison, the 1968 Chrysler 440Magnum maths to a VP of 150.
Now if you read the supplied PV link, you already know that VP is a measure of Low-Rpm Performance, the purpose of which is to be able to bring that performance comparison into a useful apples to apples relationship. Like saying the 440M has 150Vp, and it will compare well to a 5.9M with 148VP, like yours. And this has nothing to do with Horsepower; but is instead trying to tell you something about the low-rpm performance. Obviously if you hung a 3500TC on the back of that 5.9, VP would be meaningless.
So the question then is:
is 168VP a good fit for your Travco? Or better asked is this;
is it a better fit than the 148VP of the 165psi Magnum you already have?
Sometimes more is not the best answer.
If you run a 2-speed rear as previously talked about, you will never have to floor this Magnum during the run to 70 mph. You can, but you don't have to.
So hang on a sec; what good reason can you then give, to justify the cost of replacing perfectly good iron EQ heads, with alloy anything? See what I mean.
OK I'll answer that;
Because now you can pitch that wiener 0814 cam, sacrifice some of that excessive bottom-end VP, and pick up some serious power up top. That's why.
But is that a good thing?
Heck ya for a 3650 pound streeter like mine, which is why I did it,lol. But for your Travco? Not hardly, because that power comes at or near 5000 rpm, which, with the current combo and a 727 gearing, will come exactly once/maybe twice, on the way to 70mph, namely at the top of First gear. and then; even with 4.56s out back, 70 in Second gear with 33s is 4700/no slip; perhaps 5200 at 10% slip.
Will it be fun?
Heck ya.
But there is
another reason not to go to a bigger cam; namely efficiency. As you go to ever bigger cams, you are pushing the operating rpm up. The useful, power-making rpm. But it comes at the expense of eating up the bottom end of that useful operating rpm, each bigger cam size (about 7*) will move the power about 200rpm higher at the top, while simultaneously taking about 100rpm off the bottom, in terms of driveability. And so begins the march into gas-hog territory. If the march ends up in your chosen cruise rpm, well then, you can kiss fuel-economy good bye.
Now in your case a cruise rpm of 2400 is still fairly high, and I think there is room for nearly two more cam sizes, from the 0814 before getting into trouble with the alloy heads. But two more sizes will plummet your PV back to about what you have now.
So, all in all, if it doesn't mess up your fuel-economy, it could be a good deal.
But, then comes the price tag. Is it worth it to you to purchase the alloy heads and the new cam kit, which may need all new valve operating gear; while simultaneously pumping up the Scr to get 30/40 horsepower at 5000 rpm, which you will only go to when you need to satisfy your own personal need to hear the engine screaming? I mean that's exactly why I did it,lol.
And then, after all that, unless you have a computer controlled timing map, You still will have major hurdles to solve, to get adequate Cruise-Timing.
Once again, jus spitballing ideas around.
