2016 Tacoma Dyno Time!!!

Has anyone actually felt the power band dip while driving?

 

The dip is not caused by the fueling. Engines are not as sensitive to fuel mixture as many people think, and Toyota would do a better job on the fuel map than that. The dip is more likely due to the variable cam timing - and maybe variable intake tract if it has that. What you are seeing is not really as much of a dip, but the area below the "dip" being a bulge from the advanced "low end" cam timing being in effect. Lock the cams and intake (if it has that) in one position as many people are used to seeing and it is highly likely that the "dip" goes away. When you are dealing with variable geometry systems, it isn't unusual to see torque curves like this. Without it, we'd have no dip, but that low end bulge would be gone too. Either that, or they would tune it for the low end, and the top end would not be as good. This way, we get the best of both. It's a good thing.

 

The load on that dyno is whatever the dyno operator tells it to be. If you want heavy load, it will do it. As far as the engine management system is concerned, load = manifold pressure. Maximum throttle = maximum load. As far as the dyno is concerned, load = rate of acceleration. More load = slower rate of acceleration. That dyno has enough load capability to stop the axle at full throttle if you wanted to.

 

I know it's a different engine, but I saw some posts somewhere that the mid-range dip was smoothed out for the FR-S/BRZ by changing headers and doing a tune. I wonder if it's an emissions issue to make more power in that RPM band with D4-S for some reason?

 

I completely disagree.

A: Engines are very sensitive to fuel mixtures. If my theory is correct, Toyota can very easily tune out the "dip" but it would require a time of overlap between the two fuel injection methods which will result in a period of rich running that will marginally increase emissions and decrease fuel efficiency.

B: The variable valve timing system on the FKS doesn't use profiles but continuously adapts to the engine speed therefore there won't be any noticeable profile changes in the dyno.

C: As I mentioned before, the ACIS system can also be a factor but since this is common with all D4S systems, I'm pretty sure its the fueling transition that is causing this.

 

That's your choice, but pretty much everything in your post is incorrect.
At WOT in this RPM range, it is not transitioning between two fuel modes on this engine, that happens at lower throttle levels, but you refuse to accept this for some reason.
Nobody is arguing that the actual cam profiles change, their phasing does - if there were no noticeable change in the torque profile on the dyno they wouldn't be doing it. That is the main advantage to having variable cam timing.
It isn't the fuel transition, that doesn't happen at WOT as pointed out above and previously to you. Believe what you want, but the facts aren't supporting your argument.

 

Similar wave on the FA20 engine's torque curve. Exacerbated with the addition of the twin scew s/c.




***Edit*** Both the Tacoma and this car were dyno'd using a dynapac dyno.

 

First, I refuse to accept it because Toyota says differently @Torspd may be able to help out here, but I don't know may dynos that put a "Heavy Load" on an engine. The mustang dyno is about as heavy a load you get and the OP used a dynopack.

Do you understand how the Toyota's VVT-i works? It literally adjusts the valve timing on the fly. Its not a two or three profile cam that kicks down at a certain RPM. '

Try to look up the facts before saying they don't support my argument.

 

Example of variable cam timing: (not the actual torque curve but a reasonable example to demonstrate the principle)

Blue line represents likely torque with retarded cam timing only
Red line represents likely torque with advanced timing and reduced lobe separation for high rpm
Black line represents the sum of both with variable timing.
At high torque (throttle) engine is operating on direct injection only.
At lower settings, and until a certain rpm point, both systems are used.

 

I disagree. If you want to go fast in a truck, do it in a truck that is fast. Or make the truck you have fast. Saying "just get a sports car" is a cop out and total BS for most anyone on this forum who has ever done any sort of performance modifications. Tell guys on XRU that and they will you the same shit. The comments you made were so generalized that they can not be appropriately applied to any person who has ever considered themselves a motor head or enthusiast. Some times you also have to make due with what you have, or bought.

 

The dyno load on a Dynapack is user defined. It can be very light, very heavy, or wherever you want in between. A Mustang dyno is also somewhat user defined, and it nowhere near as heavy as you can get. You obviously don't know much about how different dyno operate.

Yes I do understand it - fairly well actually. Like I said believe what you want. You're still wrong on most points.

 

Ok, all you idiots out there spouting off motivated me to actually look into this deeper, not speculate.

From the D-4S development papers for the 2GR-FSE:



Its due to intake port designs. We were all wrong.

/discussion

 

Was the dyno ran at "part loads"...that would be unusual

 

I purchased a Tacoma to go off-roading. Must have purchased the wrong parts because it turned into a race truck. With 400+ whp and 450+ wtq. (@~8 psi.Hehe.)

Curious to see what a motivated person like me can do with this engine in the 3rd gen.....

 

fair enough, my opinion is based on experience. I've been in fast trucks, fast cars, modded and un-modded but the only vehicle that I ever felt the most speed in was a motorcycle (175mph). Sure motorbikes may not be for everyone and IMO the next best thing would be a sports car then a modded car or truck.

 

This is the kind of data all these conversations should start with.. thanks for looking that up.

 

Pfff....facts....

 

He just proved my point. (ignoring the fact that he posted info on a different engine)
It says right there in the highlighted area that it uses both set of injectors "at part loads" - meaning less than full throttle.
Dyno tests (and nearly all power and torque graphs published for public viewing) are done at full throttle - a.k.a. full load. The dyno test being argued was at FULL throttle.
Case closed on that one. I hope...