Engine technology thread.

[Ryephile]

...or both, or tires, or driver, or launch method, or the fact that 0-60mph or 0-100kph times are relatively stupid unless you're simply comparing drivetrain strength and tire stickiness.

[Hasjwandje]

I think i've mentioned the clio specs in some other thread because it is pretty similair to the ft86.

I know for a fact that the gearing is quite good in the new clio, 1ste second and third are short. Also the torque is band is pretty good 5400 rpm max torque and 80% of that is available from 2000rpm.

So it would all come down to front wheel drive vs rear wheel drive.

But im pretty sceptical.. friend of mine drives a bmw 120i (150bhp) and it is just as fast as my Aud A3 2.0fsi (150)bhp. But on paper it should be much much faster 0-100 is rated at 8.4 for the bmw and 9.1 for the audi, so that's 0.7 seconds. And yes we traded cars to take out the driver variable.

so to make a long story short... i dont see the ft 86 go from 0-100 quicker then 6.9 seconds which is to be honest a bit of a disapointment to me.

[Levi]

Toyota has better drag and can better put the power to the ground thanks to RWD and LSD.

[Dimman]

Originally Posted by Ryephile

From The Toyota UK Press release:



Another confirmation of 197 HP @ 7k RPM and 151 LbFt @ 6600 RPM. Still no word on the rest of the power band.

What's that thing that the Mythbusters guy says about refusing reality and substituting his own? I'm doing that right now.

I think Toyota UK is jumping the gun with the training manual. I'm telling you guys, the power/torque separation is not right...

[Dave-ROR]

Originally Posted by Dimman

What's that thing that the Mythbusters guy says about refusing reality and substituting his own? I'm doing that right now.

I think Toyota UK is jumping the gun with the training manual. I'm telling you guys, the power/torque separation is not right...

Your reality is not right...

[Dimman]

Originally Posted by Dave-ROR

Your reality is not right...

My reality is better...

Seriously, look at the most recent Yamaha-touched motors, 2GRFSE, and the LFA's motor. 2GRFSE puts out more torque to displacement (BMEP), with the same tech and less compression, and the spread between peaks is decent.

The LFA's approach is a bit different, but without the combustion benefits of D4-S (which can be significant), and a half-point less compression than the FA20. Their torque to displacement is less than the 2GRFSE, but they spread 90% out over more than 5000 rpm (90% of peak from 3700, and it is still making over 90% of peak torque at power peak). Plus it has to fight with more friction at the revs it uses, AND it still manages ~2000ish rpm (can't remember off the top of my head) between torque and power peak. Torque is FLAT, but also somewhat symmetrical in terms of where the peak is. Goes up slow, then down slow.

400 rpm separation, doesn't make sense.

[Dave-ROR]

It does if that's what the designers wanted. I'm perfectly fine with the specs as they are. They tell us what two numbers are at two different RPMs. That's it.

Just move on, test drive the car, if you like it, buy it. If not, buy something else. Numbers don't mean crap.

[Ryephile]

Originally Posted by Dimman

400 rpm separation, doesn't make sense.

Sure it does, it's dictated by the VE curve the engine designers settled on.

[Dimman]

Originally Posted by Ryephile

Sure it does, it's dictated by the VE curve the engine designers settled on.

It's out of fashion design-wise as well.

[Dimman]

Ok, so I'm going to (temporarily) let go of my lack of understanding of the torque issue, and ask some more wave tuning stuff.

I've ordered the book, but now I have to wait, and I'm pissy about (maybe) being wrong about the torque thing, so I'm trying to distract myself with the confusing wave shit.

What I'm looking at right now is we have 3 issues that we are trying to tune with/around. Exhaust open, Ex/In overlap and intake closed.

Starting with Exhaust Open:

Valve opens an we get a pos+ wave firing out the port and down the primary tubes at whatever the speed of sound in hot exhaust gas is. (1500 feet/second?)

That wave reaches a collector (2-1 or 4-1), and because of the volume/area change (???), the wave expands in all directions (???) including sending a now neg- wave back up the tube towards the port.

It also continues on its way as pos+ down the secondary tube (or exhaust pipe) until it reaches the next change (exhaust pipe or atmosphere) and again expands/reverses sign and direction.

Now if the time of the valve's open duration (which is rpm dependent) and the travel time of the wave match, a neg- wave will reach the port before the valve closes and suck out a bit more exhaust gas, creating less work for the piston (more power/less loss) and pulling out more exhaust gas that can screw with the next cycle's intake charge.

In/Ex Overlap:

If that wave arrives when both the intake and exhaust valves are open (overlap period) the neg- wave will expand in the combustion chamber (will it reverse again here, and also fire a pos+ back down the exhaust primary???) and since the intake is also open, suck in more intake charge on its way up the intake runner. When the neg- wave hits the plenum, the volume/area change again makes it expand/reverse and fires a pos+ wave back down (hopefully intake is still open) and stuffs in more good intake air/fuel to make more power. (But the wave speed in the cooler intake air would be slower than the hot exhaust right? So what speed range 1000-1200 feet/sec?)

Also what happens with a really short runner? If there is enough open time for the wave to cycle again? From the pos+ reaching the combustion chamber, will it expand and send another neg- up/pos+ down???

And how much energy do these waves lose when they are bouncing/reversing/changing sign?

Intake Closes:
Finally the intake valve shuts, and the fast-moving intake air keeps going and slams into the closed valve. This creates a pos+ (?) pressure wave that goes up the intake runner and expands/reverses at the plenum, but since the valve is still closed it reverses direction, but doesn't change sign in this case? So now we have to match the waves with the intake runner length, and keep them bouncing back and forth until the intake opens for the next cycle, and hopefully a pos+ wave is on its way down.

But with a plenum, and pos+ waves going up an intake runner, and expand, can they end up going down another runner of another cylinder? And is plenum size/volume going to affect this?

That's it for now, a mostly torque-conspiracy-free post.

(Book hasn't shipped yet...)

[chulooz]

Yamaha? ... Can you hear the crickets chirping? So much for that rumor.

[arghx7]

^^ You are describing things that certainly can happen. But it's hard to say what the deal is with a given engine without expensive proprietary computational fluid dynamics (CFD) models. That's how engines are developed now.

Originally Posted by chulooz

Yamaha? ... Can you hear the crickets chirping? So much for that rumor.

Well we know they helped develop the 2GR-FSE engine but I suppose we can't be sure if they had a hand in the development of the FA boxer engine

[Levi]

I don't know if you already noticed this, but this is the torque curve of the GT86.

We can see the 205 Nm at 6.600 RPM.

[Ryephile]

Yes, that page has been around for a while now. The problem is, the text on the left doesn't match the graph on the right. There's no way to scale that graph linearly to represent the 6600 RPM torque peak and 7000 RPM power peak while having a 7400 RPM redline.

If you scale the torque and power peaks, redline is at about 7100 RPM, and there's a torque plummet below 6k RPM. If you scale the power peak and redline, then torque peak is at 5500 or something, and the engine falls off a cliff below 3k. It really doesn't make sense. Add to that the graph torque curve very much resembles a 2-stage cam lift setup [i.e. VTEC or VVTL-i]

Based on all that, I'm pretty confident the graph is simply a "here's an abstract example of how D-4S improves the torque curve" and not a literal FA20 engine performance graph.