I wonder whether there is a retired Chrysler employee
who saved a dyno room graph that plotted
the Octane rating of pump gasoline versus the Compression Ratio of a test engine,
hopefully the 1992 Magnum 5.2 V8?

Octane could be Research, or Motor, or EPA Anti Knock Index.

Compression Ratio could be either static, or the more predictive Dynamic.

I am not sure if Willem Weertman is alive or answering questions,
but he was the chief engineer
and he cared enough to write a book.

Since we are in the “Incredible Transition” to battery electric vehicles
you would think secrecy about such cylinder head knowledge would have lessened to near nothing.

I'm not worried, I think it is all a very useful discussion sort of related to the topic. My personal thought is it helps evaporate the fuel better so it burns faster and more completely before the ex valve opens and relieves the pressure, anything burning after the ex valve open is not contributing to power or MPG. Secondly a higher temp evaporates out sludge forming moisture in the oil faster so it should help longevity, probably more of an issue on engines that get driven a lot of short trips and don't see max temp much. Also just having a thermostat in the system makes tuning easier as it holds at one certain operating temp instead of continually fluctuating based on load and outside temp and such. My heater feels a little hotter with a 205 stat and it gets cold a lot here. All things considered it is not a huge deal but they are cheap and easy to swap so a fun thing to play with.

Any idea where to get headers made for this? I have ran the numbers in several on the line calculators and seems I need primary pipes around 1" X 105" long, aiming for most TQ boost around 1500-2000 RPM. Seems like I could even run opposite firing cylinders into each other with this long of primaries.

This is the premier long tube header maker,
but the prices will widen your eyes.

https://burnsstainless.com/blogs/articles-1/not-all-tubing-is-created-equal

Before sending that level of $
perhaps fab up a “proof of concept” with thin wall aluminum electrical conduit you can bend yourself,
and try it out for a few thousand miles,
not expecting it to last beyond a MPG testing period?

I doubt even having the correct pulse arrive back at the exhaust valve seat at low rpms will improve BSFC more than a few percent.

I would spend the $ on some wind tunnel testing time,
or cheap coasting down steady grade hills.

this is what I need https://burnsstainless.com/blogs/articles-1/bundle-of-snakes-180-degree-headers-1

I don't expect it to be a huge thing by it self but combining many tricks the whole thing should be pretty cool. My main thing i if I can improve the low end TQ of the engine it can operate at a lower RPM reducing friction and giving more time for the pressure to work on the crank before being released.

I already have a great hill I do red-neck wind tunnel testing on, I figured out I can block 1/2 the grill and a few other things on the front end and pick up a few MPH at the bottom. I think I may have gotten that idea from you years ago.

My builder uses an 8 into 1 arrangement on a very successful Hydroplane Program. Obviously won't work in a conventional automotive application but if you had a mid or rear engine...

Kevin

When you say “this is what I need”
you need the Caldwell Development restricted Dodge V8 header, near the end of the article, right?

sample quote

The last photo shows a header we built for Caldwell Development for a Reynard chassis Lemans Prototype powered by a restricted Dodge V-8.

Because of the restrictor, the engine rpm was limited making it an ideal application for the 180 degree header layout.

end quote

I still have doubts,
but agree “it ain’t the craziest experiment ever funded”

Before welding metal
I would try computer modeling the torque gain of such a header in the rpm range of 1200 to 1600.

Article that shows those Caldwell Development headers... among other things.

--> Bundle of snakes article <--

HRD I think there may be a simpler path than 8ftlong primary tube headers. An anti reversion chamber in the exhaust near the end of the collector would likely give you some of the increased low end torque you are looking for without the huge expense and pain in the [censored].

Some 4/2/1 headers and longer than normal collectors may also help.



https://www.youtube.com/watch?v=HNeY_Vge5gs

Anyone know of intake and exhaust valves that will drop in a magnum head but not be concave? Flat valves would give me just a little more compression...

Do the original valves need replacement? If you need to bump compression a little bit then mill the heads or run a thinner head gasket. Seems like a lot of expense for little gain.

I see you're looking at custom built headers too. I haven't read the entire thread, but you might want to think about adapting one of the new eight speed transmissions. Expensive, but a lot to be gained from it. There are controller setups to shift it manually.

I'm trying to get ridiculously high compression while keeping a perfect flat top piston, milling the heads as much as possible (about .030), zero deck the block, .028 composite head gaskets or .010 steel shim and piston about .020 down then retard the cam to bleed off excess pressure and increase time the combustion pressure presses on the piston before opening the exhaust valve (similar to a miller cycle engine).

Since you are going all out for compression have you considered having the heads angle milled?

I had not considered it yet, my first thoughts about it are all the head bolt holes being at an angle as well as the seating surface for them, same with the intake bolts, dowl pins will be crooked... I have never done it maybe I am over thinking it???

Depends on how far you take it.

https://www.onallcylinders.com/2016...f-head-milling-to-gain-more-compression/

Sodium filled valves are bigger and would both increase static compression AND reduce pre-spark mixture temperatures.

What SRT valve sizes/stem lengths did Chrysler factory install lately?

Thermal barrier coating would also “suck up” additional CC’s

USA economy needs stimulus desperately Hot Rod Dave,
we propose your checking account sacrifice itself.......

Are they stock pistons? Stock pistons where not flat they where dished on the magnums. Similar to this...

360's are dished like that. 5.9's have a soap dish shaped dish. 5.2's are flat tops with no dish.

The sodium hemi valve stems are about .200 longer than a magnum exhaust valve. There are some older small block chevy sodium valves about the right length but 11/32 v/s 5/16 stem and 1.55 diameter. If a valve job and guides were needed they would likely work but I have not test fit one. If hardened seats were wanted or needed they would work for sure.

The 6.4 is the only one I know of with sodium ex valves and they are 1.65 VS 1.6 magnum valves butt like you mentioned just eyeballing them next to a magnum valve are about .200 longer. They are also dented in so no compression bump.