The end is near...

Rat Bastid said
I’ll see if I can answer some of these. If I miss one or some let me know and I’ll answer them too. I’m not afraid of being questioned BUT just giving a standard answer may not be the BEST answer. That’s why a couple of times I said to go back and read what I said very close. If you are focused on the wrong thing, I’d rather correct your focus and then deal with the question. I’ll leave it at that for now.

So what does the W8 and W9 flow? The answer is I have no idea. Those heads, just like the W5 and W7 were designed to be ported per the application. That way you don’t have a port that is too small for 400 inches and too big for 340 inches. And once again I say to you and everyone else, Flow is very low on what makes a head make horsepower. Chad Speier just released a YouTube video a day or two ago where he flow tested a port and he was talking about port noise. I suggest you look up that video and listen and watch closely. What he says in that video is so critical it can’t (or shouldn’t) be ignored IF making horsepower matters.

Head costs are again based on how much port work goes into them. Some engines may need very little porting and just a nice valve job and others may need a full port job. So nailing down the cost is near impossible to do without knowing exactly what the combination is.

All those heads will fit any LA a lock. You don’t need a Ritter or the all elusive R block. I would suggest if you are spending money on a head as developed as the W8-9 it’s worth every penny to invest in an aftermarket block.

In NA form, the Hemi has the valves in line. Which can be a good thing IF you understand what happens when they are lined up.

When the valves are opposed (like a Hemi) you have a straight path for the intake charge to go through the chamber and out the exhaust at overlap. That isn’t a bad thing except that you have to know it’s there and you have to control it with cam timing. Or you piss power (and fuel) out the headers. To be clear, YOU need to pull the fuel/air charge into the chamber at overlap, but the Hemi (again in NA form) allows to easy a path for that and you can over scavenge the chamber and throw away power.

To that end and to control that over scavenging you have to open up the LSA. I’d be lying if I said I understood exactly why this is, but it is. And that is when you open up the LSA (even for a purpose) you kill mid range torque like a ****. And that’s where the wedge kicks it’s ***.

I think (abut again I can’t say for 100% sure) that opening the LSA on the Hemi to control over scavenging that it wouldn’t kill mid range torque because it would seem you are just correcting that one issue. But it surely does. It just kills it. Don’t get me wrong in that a too wide LSA kills a wedge engine too, but the Hemi is very touchy about LSA. Of course you can use RPM to get past that but most guys don’t have the stomach to turn anything tight enough to overcome a wide LSA on a Hemi.

This is a whole area of ICE function that I don’t even remotely understand. All I know is what happens. I just can’t explain it because it doesn’t make sense in my mind. So flaw 1 in an NA Hemi is valve arrangement/overlap flow/LSA. You can’t separate the three. They go togehter.

Issue two is rocker gear. Any Hemi will always have problems with rocker gear, geometry and such just because of valve layout. Steve Morris has videos of this on his YouTube channel and he covers it very well. If you’ve ever been around a blown alcohol Hemi and have seen the RPM they turn to make power and what that does to the valve train it blows the mind. NHRA a for years now has allowed injected nitro to compete against blown alcohol dragsters. And for 2023 injected nitro will be allowed in blown Funny Car as well. And you may ask so what? And the so what is very interesting.

And that is a blown alcohol Hemi is now turning 11,000 RPM and maybe a skosh more. And they make power up there. But valve spring life is near zero. And the rocker gear gets its *** kicked every pass. Thats a function of RPM and valve layout.

If you chose injected nitro (very cool injected nitro is…even watching them get one started is amazing) then the last time I knew for sure they only turn 6800-7000 RPM to run with the blown alcohol stuff. And they both run the same basic Hemi. And even if the injected nitro engine was turning 8k (and I don’t think they are based on MPH and tire diameter) the difference that 8k and 11k is HUGE.

So overlap flow and what happens around that hurts the Hemi (NA) unless you wind it up. And the valve layout isn’t as good when you have to RPM the hell out of to make power when it comes to getting stable, reliable rocker gear.

I haven’t seen the G3 in a while but pushrod geometry is also a big compromise for the Hemi. It rarely gets mentioned but it’s a thing. Guys making power spend a huge amount of money to get the lifter/pushrod/rocker in line. With the Hemi it’s another compromise because of the opposed valve arrangement.

And then there is the skirted block. Since I was around and paying attention in 1999 (and I was just dumb lucky enough to run into the guy tasked with making the “new” Hemi in Pro Stock run a year before it actually happened I had a good idea what was coming. And that included the killing of Pro Stock Truck.

So when Chrysler did the research on how to sell what became known as the 99 Hemi as a Hemi what mattered most to the consuming public was two things. One was the spark plugs had to go through the valve covers. If the average guy at the drag strip looked at the engine and it had the spark plugs through the valve cover they knew it was a Hemi.

And a close second was the dreaded skirted block. The vast majority of spectators (and therefore likely buyers of the product on the Monday after a race) could identify the engine as a Hemi IF it had those two things. With the skirts off the block a good number of spectators didn’t count the Hemi as a Hemi without that skirt. Against the objections of the guys who had to build and race this thing, the Hemi got skirts.

The skirt is a bona fide power killer. That’s a known fact. The skirt makes it almost impossible to control crankcase windage. And that sucks horsepower like a ****. As long as the skirt is there (the passenger side is the most critical because of crank rotation and oil throw off the crank) the skirted block will give up a significant amount of power to a block without skirts.

It was so bad that the guy running the Pro Stock program (I don’t want to name drop because I get gigged for that) milled off the skirt on the passenger side and built a pan that fit the skirt on the drivers side and no skirt on the passenger side. And it was a royal pain in the *** to get that pan off. And it was double as hard to put it on. Per the guy doing it, it took 2 hours just to pull the pan and FOUR HOURS to get it back on and sealed up.

And yet Chrysler could have eliminated the skirts off the G3, marketing said they had to stay.

Hell yeah, this is the kind of explanation I was looking for when I asked you a few pages back.

A few points, and I'm just trying to have a convo here not claim you're wrong at all... first, the included valve angle on the G3 is much narrower than the G1 and G2, I think it's around 35 degrees instead of 58. Is it possible that would reduce the tendency for the excessive overlap flow since the air is flowing at a more downward angle into the cylinder? I also think that's partly where the dual-spark-plug came into play; there was no room left between the valves and just putting one plug in would have required it to be really far off the center of the chamber. The dual plugs also give the "extra" benefit where G3 Hemis require very little ignition timing advance for max power, as in 26-28 degrees. I dug around the web a bit and found an interview with an engineer who worked on the development who said they actually started with the air-cooled 2-valve Porsche combustion chamber as opposed to the previous Chrysler Hemis and worked off of that. Filling in the chamber on the sides of the valves further reduced chamber volume and provided some quench area without shrouding the valves and also allowed for flat-top pistons with good compression ratios.

One neat feature of the G3, the stock pistons have a slight dome in the center. When I was in grad school I took a class on fluid dynamics and had access to SAE publications; I did my final project on air flow through the modern Hemi engine and found the original article submitted to SAE by the Chrysler engineers at the time (late 1990s). They explained and showed through CFD cross-sections that there was significant flow going down the side of the cylinder by the intake valve and putting a slight dome on the piston increased the intensity of the tumble flow and allowed that air/fuel to continue mixing throughout the intake stroke and for much of the compression stroke. Swapping to true flat-tops takes away most of the tumble flow which is probably better for max power since less kinetic energy of the flow is "wasted" due to turbulence.

Regarding the valvetrain, apparently the designers consulted with Tom Hoover and Willem Weertman (by then in retirement) who worked on the G2 426 and they recommended raising the cam tunnel to shorten the pushrods and improve geometry. Which they did and also did a lot of Finite Element Analysis on the rockers, springs, retainers, valves to make them as light as possible without sacrificing strength. A few years back when I was looking at building up the 2014 5.7 I have, everything I was seeing from the guys who were building them up confirmed the stock G3 valvetrain is good to 7000 RPM at least. You mentioned you haven't seen one spin that fast though so jury's out on that one I suppose.

And then the skirted block, I think that had more to do with NVH like you said regarding the LS and also carrying over a strength feature that had proven to work in the past. I think now it's known there are stronger and better ways to beef the lower structure than deep skirts and cross-bolted mains but in the 1990s it probably seemed like a good idea for a production engine where 8k+ RPM windage wasn't really a consideration.

Being an engineer, someone saying "it can't be done" is the biggest motivating statement one could make lol. Now more than ever I want to build my 5.7 to make 600 N/A HP, or at the very least 570 to hit the 100hp/Liter mark all the import guys look down on pushrod V8s for lol.