Eddie Blackwell's Vengeance Racing built C5 Z06 features a N/A powerplant that fits that bill

https://www.thedrive.com/watch-this/...vs-to-9200-rpm

 

This really isn’t obscure once you get into actual race engines.

Now THIS is where you start getting into obscure

https://www.dragzine.com/tech-storie...s-race-engine/

For what you mentioned, I’d run these puppies any day of the week. Throw them on a tall deck block and huge cubic inches it’d run ~8000 rpm and make over 1000 horsepower. Probably could make 900 on pump gas.

http://dartheads.com/dart-product/ra...-10-368cc-cnc/

https://www.enginelabs.com/news/vide...-stock-engine/

 

I've looked at both the mozez and dart heads. I've also looked at RFD LSR heads, which look to kill both of those in terms of raw flow (500 cfm)

it goes to show you how big the intended use changes your head selection. You also start getting into some crazy stuff when you start aiming for >2.5 HP/CI performance goals.

 

Those Edelbrock heads are serious business as well.

 

Yeah, problem is the deck to port height is taller than the stock LS7 head! You see it called the Big Johnson head...

 

All of these heads need their own unique intake. When you take the restrictions away from a stock port location things get crazy expensive lol.

Whats really worth pondering is that these heads are still utilizing a 2.2x” intake valve... you need to use ~1” lift to keep it all happy.

What does that say about our baby street heads using the same valve size?

 

Yup. It says our crappy street heads are pretty damned efficient and effective. I meant to add the BES/CID heads to the list too.

But notice how once the rpm goal changed, nobody talked runner volume or anything else. Straight to 350+ cc heads. The whole equation changes. All those heads flow 440+, but have humongous runners and would be very lazy until 5000 rpm. Maybe even 6000 rpm

 

There's a sweet spot which is going to be the high 200's low 300's cc's but maintain a conventional valvetrain and intake setup. Our big LS stuff really isn't that much different than small BBC's, we just don't have the bore size they do - but push that out to 4.200 and you start getting into the same realm. I'd kill for a 4.500 bore, but our pistons would be occupying the same space lol. The weight and size of a BBC is much less appealing.

The COPO LSX427 package uses the LSX-LS7 head punched out to 289cc's. You can easily do a 427 up to 8500 rpm with a big cam.

 

funny i was having a conversation earlier today and said the same thing -- love to have a 4.5 spacing and 4.3 bore. But if we did, we'd all be asking why GM didn't do 4.6" bore spacing. The small BBC is an interesting way of looking at it. If you look at the splayed valve LS heads, the ports even start to look a bit oval-ish. Just out of my league until I build one

 

What sort of percentages do people look at?

MCSA = ~85% intake valve
Someone mentioned intake valve = ~52% bore
CFM/CC = 140+%
I/E ratio = ~70+%

I am a huge fan of port velocity and prefer the smallest port that will meet the requirements. As well as the smallest cam that will get you where you want to be. I also like the longest intake runners that can be used without inhibiting peak. This is true regardless of application, in my opinion.

I also believe that you should cam for the heads best flow, and also have to consider that factoring in what your heads see with the intake attached is important. The cam has to blend the pressure waves in the intake runners and the flow of the heads into a sensible symphony of efficiency and power.

Your assessment of bore and stroke being far more important than just displacement is spot on, in my opinion.

Coefficient of discharge is also a huge factor for me. I love the small bore heads and using stock castings on the next size larger bore. I don't believe in putting heads on smaller bores, but that is just me.

 

David ~ Brian Tooley speaks on Coefficient and discharge all the time but it goes in one ear and the other ear of most people.

 

It's one of my biggest concerns when thinking about head selection, honestly.

I barf a little every time I hear about LS3 heads on 4" bores, but I love hearing about them on 4.125" bores. For the record, I find it the same sort of gross that the 799 head is on the 3.78" bore, but love them on the 4" bore.

Big valves shrouded by the cylinder wall don't do nearly as great as people seem to think.

 

Agreed. The LS3 head on a 4.125" bore is very good. On a 4.00" bore, it's limited. Probably to 640HP at the engine or so with a plastic intake and hydraulic roller. There's just not much you can do--solid roller and single plane opens it up to probably 700HP or so. The 4.065" opens it up to closer to 670HP with the Plastic/Hyd combo and another 50-60 for Single Plane/SR.

Moving to a 4.125" plus bore... well 750+ is attainable with a hydraulic/plastic manifold setup. And over 800 can be had with the move to a single plane and SR.

And that's between a 402/408, 416, 427. The difference in cams, heads, and CID isn't much. But you're looking at a good 100HP more out of the 427 vs a 408 with the same topend. Just from unshrouding the valve.

 

What about having LS3 heads on a 4.030 bore?
That would work better compared to a 4 inch bore I wonder.
Would that make it about 660hp limited?

 

Most powerful heads I ever seen on a 4.030 bore wasn't LS3 heads. MOST LS3 headed 402-408s make 62X horsepower at the crank using a plastic oem style intake and a hydraulic roller.

 

4-4.03" is close enough that they make about the same power.

 

More air and fuel on top of a larger area = piston is what makes hp. Shrouding is small fries.

 

How do I know? ER racing and the 430ish emc build. With a .060 over bore and ls7 heads. Think I asked about this before I shrunk the exhaust valves. Intake valve is where the HP's at. We can add exhaust duration to get all that burnt $h!+ out

 

If I have 505rwhp now through a 3200rpm stall and a 4L65E auto how much power would that be at the crank?

 

So you like extra exhaust duration?