Ultra4

Completely counter to all of my expectations, not only are Johnny Utah and Contestant #3 responding to me, but they're also giving me the exact same feedback about how the 4GR reacts to having the high-tumble roof cut into a bowl and the short side tumble feature left alone: not very good. It pulls like a freight train until about 4k RPM, then it slowly falls on it's face until feeling like it's not making enough power to shift, shifts, then chirps the tires and activates VSC in the next gear, pulls hard for a few hundred RPM, then goes back to stumbling. Utah says he likes it as long as he's short-shifting it manually and wants to keep playing with it over the summer, but I will be sending both of them another set of heads with a return label and hopefully will get theirs back so I can do what I already know is going to fix that problem: epoxy-in the short turn and give it the radius I want it to have. This is pretty much the perfect use scenario for JB Weld, which I've already learned the do's and don'ts of off-label usage in the 2-stroke world...primarily I was using it to fill boxy voids in the intake paths, take up dead volume in the crank case ("stuffing"), and reshape intake/transfer ports (essentially cam detail tuning for a 2 smoke, the relation of the top of the exhaust port to the opening of the transfer ports determines duration, port shape/volume effectively determines lift/ramp...but that's not relevant here). While you can get creative in potting methods to keep it in place, you pretty much cannot use JB Weld in the hot side of any engine...which seems quite obvious, but hey, you'll try just about anything once in your 20's. As far as using it to shape a 4GR intake short turn, I'll need to grind a pocket into the apex and at a few points along the hypotenuse of the tumble cut in order to get a drill bit in there for some potting anchors (y'know, to keep the puck of epoxy where it belongs and not tryna get loose or eaten by the intake valve over time), but that is well within my wheelhouse.

To explain what's happening in the port a little better: the 4GR cylinder head (and I assume the 3GR, still haven't washed that one down yet) has a very well-designed mass-production high-tumble port. With no machining outside of the seat pocket and guide hole, the tiny little scrunched-down snakehead-shaped intake port achieves it's objective as-cast of causing as much turbulence in the chamber as possible. The turbulence is engineered-in to help with stratification of the fuel charge, while good in theory, the practice in reality makes a low-flowing port with lots of dead zones, as evidenced by all the carbon that just so happens to build up in this engine thanks to other engineering decisions. The effect of a high-tumble port is to focus pulling the air charge from the axial center of the primary while the intake valve is at maximum lift, and stall airspeeds everywhere else at all other valve lifts...when your intake air is laden with combustion gasses that slipped past the rings and oil vapors kicked up by windage, those contaminants line the walls of the primary and negate the tumble features of the port, turning it instead into a very small traditional-shaped port. I'll be taking pics of every 4GR port as I get them, after cleaning, and after reworking from now on just as a manner of tracking my own work, which I'll probably turn into collages to post here, so as to save overall pic count. That'll probably show you what I've said here a little better than I just did. What's happening in the two live engines I described in the first paragraph is that the sharp ridge of the short-turn tumble cut is ramping turbulent air into the smoother-flowing air along the roof, and as the speeds increase, the angle of that ramp changes until it's back to being a full-tumble port again, only with bad flow characteristics everywhere. My guess is that it's making a lot more torque, but a little less power, which inverts the power curve the wrong way and behaves as described. I was hoping leaving the tumble feature on the short turn would still allow enough air past at peak RPM to work, but hey...that's what I get for being scared of the unknown. Like $400 of shipping.

Anyway, I'm never moving my grinding bench ever again, almost 40 is too old to be moving 350+lbs of stainless steel solo, no matter how FUBIJAG you are. When I have my air, electric, and lighting sorted, I'll be filling this thread back up with pics...the album I removed no longer represents my abilities, anyway.

Til then.

Ultra4

So both shots have splashed and now I'm waiting to hear target effects. Contestant #3 is quite displeased with having to open his engine back up, so I doubt he'll be participating further, and Utah's likely not swapping for a few weeks/months.

I originally wanted this post to be a "watch me port the F outta 4GR-FSE heads", turning them into 4GR-GSE, but the free oven I've had in my garage decided to remind me I've gotten more than my money's worth out of it when I went to bake a fresh set of heads (so I can pull the guides). I've anodized, parkerized, hot salt blued, and metal plated with the help of that poor range...I'm a little afraid to move it and kick up the eleventy billion cancers lurking in the dust...

The real purpose of this post has to do with vaseline. For a good 2 years now, I've been crucifying myself for not understanding what went wrong when I went to measure the combustion chamber and primary port volumes. I've gone to four different shops and talked to their head grinders about my process and while they all sounded like they were being helpful, ultimately all I got was some tooling advice from them. The guy who told me I ovalled my seats is of the opinion that valve jobs can't correctly be done without his specific $7 million umpteen-axis machine, and his machine alone...to him, every running engine out there is garbage because he didn't do it. I figured this out when I went back to him asking to pay full shop price to be shown how much my seats were ovalled, and his bumbling response gave me the feeling I was dealing with the pill-sniffers on the sikorsky assembly line again...anyway, youtube came to the rescue, and the first vid that showed someone applying petroleum jelly to the seats and stems just about gave me a stroke. I have a giant tub of vaseline not even 10 feet away from where I made that UV dye mess. That's life, I s'pose.

So while I'm trying to find another free oven, I'll also be setting up the water bench again to get some before/after volume measurements. If nothing else, it'll tell us how consistent each casting is from one batch to the next.
Anyway, all I got.

LCH91

What a great read! Nice to see someone explore the potential of the engine.
I got my IS250 '08 MT a couple years ago and since recently started wondering and exploring what could be done to give it a slightly more spirited character. Somewhere along the way I stumbled upon a forum/thread from a guy in newzealand who is exploring the high revving capabilities of the 4gr-fse. Part of his thread is about modding the intake side and the potential restriction of the 4gr heads/intake valves pose at high rpm. It seems he's considering the 3gr head as a a solution. Thought I'd share although it might be old news to most. The pictures and text below are copied from his thread on a different forum.



This pic below is how a 3GR head would fit onto a 4GR bore size. So the valves would fit without conking the bore.
Based on my dubious scaling the valves are approx 33mm on intake side, 28mm exhaust side.
Compared to from memory 31mm intake side, 25mm exhaust side.

It would be interesting to see if the intake side geometry/port sizes are any different as well.

Ultra4

I'm glad you saw some value in all this.
My hoard grew larger by some more 3GRs, intakes, 4GR heads/cams and whatnot, but the too-clever-by-half galaxybrains over at audi made me walk off a job and hand back a down payment. Just google pics of their 4.2l v8 timing chain setup; after overcoming that hurdle, we were stopped in our tracks by the seeming fact that each wire harness is bespoke to each vehicle or something. I dunno, I went back to gunsmithing to fund this cylinder head project for the time being. Nobody antagonistically designs a firearm to be built and maintained in it's own microcosm of technicians (who, I might add, are utterly useless outside of their microcosm). Just like gunsmithing and every other generalist career, the job of being a mechanic is soon to be reduced to a piece of paper you can buy to "prove" you can do the job. Not that I'm exceptionally bitter about it or anything. Just ask for my opinions of the stinky dingleberry inspectors or whoever sponsors your favorite guntuber.

Things'll have to unfreeze for me to get the ball rolling again. Contestant #3 3GR swapped and went silent, Johnny Utah's doing zoomer things in mormonsville right now, so I'm in my own head about if the epoxy floors are gonna work or not. Great topic to get stuck on for those 12hr checkering sessions...

LCH91

That timing chain alone does not look like a good time ... let alone the wiring harness to go with it ....
Regarding that tumble cut on the shortside, would it be possible to reshape it to where it would allow for high rpm flow and keep tumble properties for low rpm? Assuming the 3gr intake port have the same tumble cut, I wonder if it has the same effect in the slightly larger intake throat? Below picture is probably not very accurate but it looks like there's some material to work with in the apex of the short side.

Ultra4

Yeah, the tumble cut on the short turn seems like it's going to need to be filled in in order to get any kind of increase in port velocity. When I cut a bowl and blended the whole pocket into the throat (which I left at factory dimension), it made the engine breathe very well down low, but quickly ran out of air as the RPMs increased. The two sets of heads I have floating out there in the wild have short turns that I copied (using my mk1 calibrated eyeball) from a high-angle racing head, and the aforementioned bowl/blend work. I'm hoping that's all I need to do, but I'm not committing to cut up another head until I have a better understanding of which direction I should go. If I can stop myself from telling people on facebook marketplace how to fix their 2IS/3GS, I'll have one of those to do whatever the heck I like to, instead of catching another pp-smack for using my wife's car as a guinea pig.

Come next month or month after, when the snow's starting to thin out up here, I'll be separating the heads from the 1st $50 3GR I have laying around (looks like it faceplanted the asphalt during extraction, timing cover's donezo) and doing an actual side-by-side of the two engines' airways. My original suspicion was that the same head package was on both 3GR and 4GR, but just from the intake side down, it's evident the port's 2mm larger, and I suspect the valve is equally as large...like those smallport SBC heads you'd find on chevy 262ci, 283ci, 305ci, et al, versus a head meant for a 4" bore SBC. I wanna say that's a 1.84" int, 1.5" exh for the smallport chevies, 2.02" and 1.55" for your standard SBC head. My suspicion is that something similar is happening here, and as such, the valves of the 3GR would be too big for the bore of the 4GR and will at the very least shroud a quarter to a third of the air path into the outsides of the cylinder, which would likely lead to worse carbon issues in the port. The flip side of that combo--4GR heads on a 3GR bottom--would probably produce 2GR torque numbers, but have the same max horsepower as the 4GR. I'm completely in the theoretical here, so I won't really know until I tear into the 3GRs I have.

LCH91

Sounds like a good time leaving the stoplights with an odd 70lbs.ft extra!
From the pictures I found on the newzealand forum it does look like 3GR valves would just about fit the 4GR bore, perhaps the angle of the valves would be enough to minimize shrouding?
Found a picture from a 3GR-FSE intake (screenshot from a carbon cleaning video on youtube). Looks like that shortside tumblecut practically terminates right at the valveseat .... Is it similar to the 4GR? IF so I see what you mean about needing to add material.



I have no Idea what the policy of clublexus is about posting links to external websites but here's the buildthread from the guy in new zealand trying to get max RPM from the 4GR. https://oldschool.co.nz/index.php?/t...carina/page/2/ Might be worth taking a look at.

Ultra4

That kiwi and I think in broadly similar ways, I'll be spending some time in his thread and probably contributing, so thanks for the link.
Yeah, the shortside throat is just a cylinder on the valve side. Intentionally bad airflow in the name of charge stoichiometry, which--after some carbon buildup--just turns into really small good airflow and the carbon starts caking inside the combustion chamber; so while I now owe toyocorp a bunch of apologies for things I've said in this thread, I still don't fully buy into their stoich argument. I'm worried that the two sets of heads I have out there are over-ported for the camshafts they have in them because I opened up the bowl area first, then filled and formed the shortside. I'm hoping the combination of ACIS, SCV, and VVT will be able to provide enough low-to-mid range RPM port velocities to provide the grunt we expect from these mills and not turn it into a Honda power curve.. I'm thinking the higher velocity going into the port will give us "good enough" stoich to not build carbon in the chamber, while increasing volume going into the cylinder greatly. Won't know until I find out.

Edit: I'm stupid. Replace mentions of "stoichometry" with "charge stratification". They wanted the fuel charge to evenly distribute in the pocket they made for the explosion between the head and piston. Fuel outside of there (in the quench area) is wasted and ends up as carbon.

LCH91

I've been reading up a bit on direct injection in the hopes of coming across something that would be applicable here. Ironically, reading about 101 different ways of creating and utilizing swirl and tumble has left my head somewhat spinning.
I came across a few research publications regarding the development of the D-4 injection system. One of them was mainly about improving the injector form a swirl spray cone nozzle to the (current?) fan spray slit type nozzle, which was better at atomizing and thus saw improvement across the board. They briefly mention varying intake shapes to test the effect of various rates of tumble during stratified combustion(low rpm/warm up). Interestingly increased tumble ratio deteriorates performance...

https://www.jstor.org/stable/4463424...71a42163&seq=6


From below picture it seems you were right on the money with stoichiometry, at least for higher engine load/rpm.


Wondering if anything can be done further up the intake system to increase velocity in the port? Something along the lines of opening up the runners a bit, from bottom half of the plastic part to first bit of the port or so.
I might have to get some tools and used parts to mess with, as I'm finding this increasingly intriguing.

MikeFig82

iTrader: (13)

I stumbled across these from another thread from late 2014 a few days ago.

I'm sure they can be used here for intersted parties as well.

LCH91

Literally all the papers I was finding snippets and parts from! Having them on hand in pdf will definitely come in handy, if not sooner then later for sure!