posted on March 03, 2013 21:00
|The car's been sitting at Modified by KC since May of 2012, when the engine mishap happened. It's really dirty.
Project Supra, Part 3
Extreme Engine Tech—The Cylinder Head
By Pablo Mazlumian
It's been a couple of months since our last update, but with many of our awaited products now in hand, things should start to move more swiftly. To bring you up to speed, in Part 1, we ended up with a stronger and lighter shortblock. In Part2 we took care of the crank damper and had our oil pump modified for improved flow. Follow the links to catch up on the build:
Extreme Engine Tech: 2JZ-GTE, Part 1 – More strength, less weight
Extreme Engine Tech: 2JZ-GTE, Part 2 – Good vibrations and better lubrication
Waiting for our long anticipated intake and exhaust manifolds, we were stuck. Jeff Gerner—our engine builder—of FRP Engineering, needed our intake manifold before returning the head to Noland's Cylinder heads for final assembly. When the intake manifold arrived from Hypertune, I think everyone's jaw dropped at not only the beauty of it, but also the build quality. More on that in Part 4, but I've given you a sneak peek of it, and a couple of other very exciting products, in the last page.
Because we ordered Hypertune's intake manifold with larger runners for maximum flow, the first order of business for Jeff was to port-match the intake ports of the cylinder head to the intake manifold. This process is imperative because, if you think about it, when air flowing one direction encounters a smaller opening with sharp edges, the results to flow are detrimental.
I experienced something similar with a turbo M3 I built over a decade ago. The then engine builder over ported the exhaust ports of the cylinder head, making the openings too large for my turbo manifold. At first, I didn't notice, but when that issue was fixed by going back to a stock cylinder head, the results were staggering. The flow—and, therefore, the spool-up—was so greatly improved I had wheel spin at a boost level I could never spin the wheels with before, and nothing else had changed.
|The big port Hypertune intake manifold is anodized in red with CNC machined ports (the base one is all silver). Sorry, I couldn't help it—this article is about the cylinder head. More on the manifold in Part 4.
|The first order of business was to match the manifold's ports with the cylinder head. While it's hard to see from this angle, it turned out that the Hypertune manifold's ports match up to a stock Supra intake manifold gasket. This meant that no modifications were needed on the manifold's flanges themselves.
|The cylinder head's intake ports, on the other end, are much smaller. See what I mean about air hitting those edges as it enters the intake ports? It would turn the air toward the center, leaving a large percentage of unused space near the edges and causing unwanted air turbulence. It was time to grind away.
|After applying a dye, and tracing the inside edges of the gasket, Jeff has something to go by with his grinder.
Monday, March 04, 2013 6:20 AM
It still amazes me to see what parts sharing OEMs use on various vehicles and improvements they make along the way. Those MR2 buckets seem to be a huge improvement. Hopefully in the next installment you'll also show us how shiny those combustion chambers are. They looked pretty good in the partial shot you gave us. And a 7 cylinder diesel motor? Those diesel guys never cease to amaze me either.
Monday, March 04, 2013 6:30 AM
I think the port on the far end of the shot is either a coolant passage, or the exhaust ports are divided in a strange way between each cylinder. I only count 24 valves on that cylinder head.
Monday, March 04, 2013 7:21 AM
I'd like to request a discussion about the claim in this article that a rough surface will have a lower drag than a smooth one due to a thinner boundary layer. I'm not sure that the comparison which was drawn to golf ball aerodynamics is valid. The benefits that a golf ball realizes have nothing to do with boundary layer thickness, but flow attachment. It's done in an effort to reduce low pressure "wake" behind the golf ball. In my experience with ducted flow(theoretical only), higher surface roughness equates to thicker, turbulent boundary layer and higher drag.
I'm not doubting that the rough texture has some flow benefit, because this isn't the first place I've read it, but I don't think it has anything to do with golf balls. So what is actually causing it?
Monday, March 04, 2013 8:01 AM
Did you happen to weigh the valve springs by chance? Because they no doubt negated some of the gains realized in the reduced reciprocating mass of the lifters themselves. In my mind, a heavier spring would have less of an effect than a heavier bucket, but I can't really say why. Somebody here must be able to speak to that. This is something I want to do to my 4AGZE too as the Vitz lifters are an identical upgrade for me.
Monday, March 04, 2013 8:09 AM
@ Crarrs: Agree. The spacing on that last port being odd is what gave it away for me.
Monday, March 04, 2013 10:48 AM
@ Supercharged111: You are right that a heavier spring has less effect than a heavier lifter. The overall mass of the spring doesn't move as much because one end of it is fixed, so less of the total mass of the spring has to be accelerated up and down each time.
It's the same as suspension, with upright/brakes/wheels/tires' mass ("Unsprung mass") effecting handling a lot but springs (sometimes called "Semisprung mass") not as much.
Monday, March 04, 2013 12:31 PM
HudsonMC, I am with you on that one. I was always under the impression that a smoother and area is, the better the air flow (the higher the air velocity).
I'd like to see some data (from anyone) backing up those statements if possible.
@Supercharged111, the 4AGZE and the Toyota Yaris/Vitz do share the same size buckets and shims, and so does the Toyota Tacoma's 2RZ (and 3RZ as well).
Monday, March 04, 2013 1:17 PM
@jeffball610 In a continuation of the 7 cylinder diesel topic, while that head is certainly for a 6 cylinder engine, there are 7 cylinder diesels out there. The one example that comes to mind is a 9.8 liter made by Sisu which is a Finnish company owned by AGCO. Those engines can be found in Massey Ferguson, Caterpillar and Fendt branded combine harvesters and output about 450 hp.
The engine was made because Sisu was lacking an engine for the 400-500 hp range and thus far had built modular engines. So rather than increasing bore or stroke to make a bigger six cylinder engine, they just combined a 3 cylinder and 4 cylinder head with a 7 cylinder inline block. The 6 cylinder 8.4 liter employs a similar strategy with two 3 cylinder heads mounted inline.
Continuing in that theme, they've just released a 12.8 liter V-12 for tractor applications complete with quad turbos and two ECMs. Madness!
Monday, March 04, 2013 3:24 PM
The whole thing with roughish intake ports is to keep fuel in suspension by having a bit of turbulence at the port walls where it might otherwise drop out of the air stream.
Not sure how valid it is on modern port injected engines, but I honestly doubt it much matters either way as far as flow numbers so what the heck.
Monday, March 04, 2013 6:55 PM
That is what I remember reading as well. The rough walls promote turbulence, which assists with maintaining a more homogenous air/fuel mixture when it enters the cylinder.
Tuesday, March 05, 2013 5:04 AM
Thanks for reading, guys. I've asked the engine builder to further explain and this was the reply: "I used the golf ball example because I thought it would be easy to understand for the largest number of readers. The truest technical explanation is as follows:
The roughness applied to the port wall is actually only rough at a micro level. It is applied with 100 grit sanding rolls. The micro roughness grabs at the very edge of the boundary layer. In doing so, it causes a microscopic "rolling" of the air molecules (think micro vortexes, much like ball bearings) at the port wall. This rolling of the outer most part of the boundary layer "supports" higher velocity of the main air column."
Hope this helps.
Tuesday, March 05, 2013 7:27 AM
So, I've always wondered this...Why with dual spring setups is one spring primarily coiled clockwise and the other counter clockwise? Is it hopes that perhaps the spring wont bend out sideways if theyre different?
Tuesday, March 05, 2013 8:14 AM
Dual springs have an interference fit; it's done to try to induce a but of damping to combat spring surge and thus not float the valves.
Wednesday, March 06, 2013 9:39 PM
The "semi truck" head pictured is off a 6 cyl Cat C15 (also called 3406e if its old enough) that powers trucks, ag tractors, all manner of equipment, and probably generators, even if they are junk.