2016 Tacoma Dyno Time!!!

Lurkin'

 

Toyota uses two injectors per cylinder on the D4-S, a port injector and direct injector. The transition between the way they fire causes the dips. IIRC, they fire both at low RPM's and DI takes over %100 in higher RPM's.

The FKS also has a variable length intake runners that transitions between lower and upper RPM's that probably affects the torque curve as well.

No, torque is NOT power. Two different things horse POWER is power.

The problem with this argument is HP increases with torque. HP = Torque x RPM/5252 IIRC.

To dumb it down, torque is force, HP is force per unit time.

 

Torque is measured, HP is calculated

 

It still has no relevance when your actually driving. Smooth torque delivery gives you a predictable and controllable throttle input.

 

While this is sort of true, its not exactly complete. Torque is force. Power is force per unit time. HP is a very obscure unit of power.

So break it down: Torque is measured (in the US) as lbs/ft

HP = (Torque(lbs/ft) x RPMs (Rotations/min)/5252Rotations (the calculation to get this is complicated)

So cancel out the units and you get HP=(lbs/ft)/Min

 

It has all the relevance when driving. Torque only measures and takes into account 1/2 of the equation. HP is the inclusion of both factors that account for acceleration, the force exerted from the air/fuel mixture detonation and the amount of detonation per unit time. People always say "low end torque" which is fine, but low end torque is also low end HP.

Yeah, I know Tomatoes, Tomatoes, but understanding how torque and HP relate to each other and relate to the engine will keep you from making stupid ass "van motor" comments.

 

Not arguing, the point I was trying to impart was that HP is not measured. To your point, torque is measured, rpm is measured, HP is calculated based on those measurements.

 

The later wasn't exactly for you.

Yeah, it has two transitions that take place as the engine rpms increase, the injectors and the variable intake runners (ACIS Acoustic Control Induction System), and for some reason, the stock tune doesn't smooth it out too well; not sure why

 

"In theory" this should be much better since when in port injection mode fuel sprayed will hit the valves and clean them. Unclear if its enough to keep them fully clean though.

 

BLUF: You don't have to worry about carbon build up on the Toyota D4S engines.

There are two issues with carbon build up to worry about on a DI engine.

One is carbon build up on the valves. This can be mitigated by running a catch can so blow by from your PCV doesn't coat your valves. Port injection engines don't have this issue as the fuel from the injectors "clean off" the valves. Since Toyota's D4S system uses port injectors during low RPM running, in conjunction with the DI (for a more efficient burn), you don't have to worry about this.

The other place carbon can build up is on your Direct Injectors. It doesn't just clog the injectors but it can heat up and act as a glow plug of sorts and cause pre detonation. Toyota's D4S uses side ports on the injector to clean them off during a Cleaning cycle that occurs at idle when the ECU decides its due for one.

 

I think you are confused with the difference between overall measured power / torque output vs power / torque output at a given RPM. All I'm saying is that the torque curve is more important because it will determine how power / torque is delivered throughout the rev range.

Here is and example what I mean, and I've actually experienced this.

Your driving a big horsepower v-8 RWD car down the straight on an oval track. As you approach the banking you have to shift the weight of the car forward to increase your front tire grip. After you pointed the car properly, you use the throttle to shift the weight towards the back so that the rear does not loose grip. Without a smooth torque delivery, the transition of weight from front to back would be allot more dangerous and difficult to manage.

Please understand I'm not trying to win an argument here, but unless you've driven on a track at high speeds this concept is difficult to comprehend. If your experience at a race track is different than mine, then I'm happy to hear how.

 

We're splitting hairs. You can't make an argument about "low end torque" or "flat torque curve" as each equate to low end HP and a linear HP curve respectively. They are both the same thing; all I'm saying is people that make that argument (generally the people that say "torque win's races") are not getting the whole picture.

 

Who likes videos????

Horsepower and torque explained! animation!

http://www.dailymotion.com/video/x2no8x6

 

We are splitting hairs..

What kind of racing are we talking about? I'm talking about the ones that have corners that need to be steered.

Straight line speed requires good torque and horsepower output.
High speed cornering requires good throttle control, good throttle control requires smooth torque delivery.

This at least has been my track experience. Not only that, its what I've been told by some top engine tuners and pro racers in the country.

 

Yeah, a catch can won't fix it as many ford Ecoboost owners are finding out. And intake cleaners are blowing up their turbos

Since Toyota uses both direct and port injectors pretty much most of the time, unless you are driving around at 3-4k+ rpms all day, the port injectors will keep your valves clean. My theory with the dip is when they tuned the engine when for the eco transition. I'm sure you can make the transition smooth by overlapping the DI and PI injectors during the transition, but at the expense of running rich during the transition. I'm not sure its the intake valve duration as the dip is common across all D4S engines, including the Scion FRS. When I get entirely too board, Ill probably read more into it; for now I'm happy with my "no technology" 5VZ

There's a few around here. Lots in Va Beach, Hampton, Newport News/Yorktown ways. I think Tanner and Clint (who drives a Honda DD) are the only ones that live in Portsmouth.

Exactly but the D4S system still uses port injectors (in conjunction with DI) during idle, up to about 3-4k rpms.