[TheGrudge]

Here's my theory. I'm sure I'm not the first to think of this. Maybe it's a known "thing". Maybe it doesn't work.
Through a strange twist of events a 4.25/6.8/4.181 build became 4.50/6.7/4.195.
RPM vs longevity has become something I've pondered a lot. Conventional wisdom would suggest that keeping RPM to a safe level would necessitate selecting cam/intake/heads etc matched to the intended operating range ie if you don't want to spin it past say 6000 pick parts that work from 2500-5500 and maybe shift at 5800 to keep it all together.
Problem there is of course that 2500-5500 is 067-068 territory and I'm not building 497 cubes to pull a Winnebago.
My idea is to use airflow limitations/choke point to make the motor "run out of air" before 6,000rpm thus making peak power earlier (obviously giving up some top end power) but using a much more aggressive cam that would otherwise maybe peak at say 6500.
I got to thinking about fast Ponchos in the pre-E head era (or pre Wenzler). 250cfm headed 450-some cid motors deep in the 10's clearly making more than the old rule of thumb
HP=Cyl head intake cfm x2 kinda thing. Anyways, as things have turned out I'll be testing this theory first hand in the coming months as I finally get this lump together. I'll post details, but wonder if this is something others have tried/done or if a specific class of racing has led racers down this path before. Fire away, I won't be offended!

[taff2]

Contact one of the cam manufacturers and tell them what you want to do, you'll probably end up with a roller with lots of lift but short on duration I imagine.

[pastry_chef]

What will the compression ratio be?

What heads will be run?

[Lee]

"Running out of air" is not going to miraculously re-make low-end power, which was sacrificed by a too-large intake duration.

The big cam will lose low-end. The "choke point" will just kill the upper-rpm power, the motor will not really notice it until becomes the limiting factor. You'll end up with a large engine that performs like a much smaller, weaker engine.

Get a custom cam for sure. A properly chosen cam will extract the most power possible over the rpm range you wish to utilize, and not "tricks" will be needed.

[TheGrudge]

Thanks for your replys. Motor is almost ready to assemble. Custom cam already ground.
I know that if I posted the specs straight up I'd get responses like "you need more cyl head flow/Northwind/Victor/Dominator" etc. Probably still will. What I'm getting at is that if more airflow/bigger ports etc will raise peaks then less airflow/smaller ports/higher velocity will lower peaks and keep rpm range safer as a byproduct. Stepping up to 4.50 stroke was something that wasn't part of the original plan so rather than re-spec the entire build I've tried to work with what I have, knowing that some more port work & an intake/carb swap down the line won't be major surgery if it comes to it.
Goal was always 550hp/550tq/5500-6000 rpm at 467cid.
Specs as they stand are:

YC 455 block
3 centre program billet caps
Spotts windage tray & scraper
Butler pro series oil pump 80 psi
Scat 4.50 steel crank
Manley 6.7 H-beam rods
Icon 2618 4.195 slugs 17cc dish
87cc E heads 285cfm / right on 10:1 comp
Torker 2 blended approx 1.5" in to Felpro 1233
Carb shop stage 3 4150 vac sec 925cfm no choke horn etc
Comp custom solid flat tappet ( card below )
Comp 800-16 lifters w/edm hole
Lifter bore brace
Comp 1.65:1 gold roller rockers
PRW stud girdles
MSD ignition

[pastry_chef]

Thanks for sharing, will you dyno this?

The cylinder pressure differential will increase horsepower / CFM.

[TheGrudge]

Will definitely dyno, yes. Just love a bit of bench racing/like to pretend I understand physics. All will be revealed on dyno day. A trillion calculations have me thinking this thing may make some torque.

[Skip Fix]

My pump gas 455 in the 78 TA is about there with an UD HFT 296/304 T2 Holley 850.

[john marcella]

Give it lots of cyl head and back up on valve timing.! VE will be better over the whole curve.

[Probird]

Looking at the bottom end parts you are using that thing will be plenty safe to 7000 or more. I wouldn't hesitate to turn up to 6800 and let that be the rpm upper end.

[TheGrudge]

Thanks for your input guys. If the bottom end is likely to safely/reliably spin up past 6500 then will the T2 let it get there? When I was at 467cid I would have thought so, at 497 I wonder. Will the cam still be pulling at 6500?