Production Toyota FT-86 Details and Design Previewed by Toyota Sports Vehicle Boss

[Matador]

Does this forum have an ignore button or list or something of the sort? Anway...

Originally Posted by WingsofWar

valve train balance? piston height + compression? Displacement? bore size? economy?

just because a engine has low reciprocating mass and a short stroke doesn't automatically mean it will REV high. There are other determining factors and safety measures engineers place on the engine to determine its rev range.

im guessing the fact that the 2GR has a big bore and its displacement is a 3.5 liter, makes its peak HP around 6k and peak TQ at in the lower 4k RPMs. Probably makes the 83mm stroke not that impressive when considering all the other elements.

The 2GR CAN rev higher. Quite a lot actually. How much? Couldn't tell you yet, but you wouldn't believe how much Power Toyota left on the table with these engines (as usual-Cosworth to a 2GR without DI, stroked it to 4.0 and tuned to 440hp with a 7000rpm redline). Why doesn't it leave the factory revving higher? Toyota (and most other manufacturers I assume) Rarely ever surpass a mean piston speed of 20m/s for engine longevity. Toyota rarely chooses to stress their engines from the factory.

[bofa]

Originally Posted by MatadorRacing_F1

Does this forum have an ignore button or list or something of the sort?

It does actually... click on their name, click on user lists, and select ignore member. But where's the fun in that. :happy0180:

[1660]

Originally Posted by MatadorRacing_F1

Why doesn't it leave the factory revving higher? Toyota (and most other manufacturers I assume) Rarely ever surpass a mean piston speed of 20m/s for engine longevity. Toyota rarely chooses to stress their engines from the factory.

This is the first I've heard of mean piston speed, having to do with longevity. Why would 20m/s be a cut off? (I assume m/s means meters per second?) Does it mean reducing stress on bearings by reducing reciprocating stress? Does this apply to some kind of stress formula?

[madfast]

Originally Posted by Driftster

i just can't stand direct injection.. It completely ruins the tuning aspect of the cars it's installed in..
You're basically left with very very very standard bolt on changes and ecu reflashes...

How does DI ruin the tuning aspect exactly? it only becomes a limitation when you start making serious hp. and MOST people wont go that far...

anyways, the D4-S system is the perfect solution, theoretically....

[Exage]

Originally Posted by 1660

This is the first I've heard of mean piston speed, having to do with longevity. Why would 20m/s be a cut off? (I assume m/s means meters per second?) Does it mean reducing stress on bearings by reducing reciprocating stress? Does this apply to some kind of stress formula?

To put this somewhat basic:

Typical piston acceleration forces become quite great, recommended maximum mean piston speed for most piston internal combustion engines is at ~20m/s, (I'm also thinking combustion expansion rate has something to do with this as well): Hence stroke length and RPM relationship is one of the pieces to a high revving engine.

Obviously if you increase the piston speed the greater distance the piston has traveled (easier to understand linearly) the more wear it will cause in the cylinder bore and hence why engines wear faster at high RPM, particularly if they are not designed for it.

Hope this helps.

[Giccin]

Originally Posted by MatadorRacing_F1

Does this forum have an ignore button or list or something of the sort? Anway...



The 2GR CAN rev higher. Quite a lot actually. How much? Couldn't tell you yet, but you wouldn't believe how much Power Toyota left on the table with these engines (as usual-Cosworth to a 2GR without DI, stroked it to 4.0 and tuned to 440hp with a 7000rpm redline). Why doesn't it leave the factory revving higher? Toyota (and most other manufacturers I assume) Rarely ever surpass a mean piston speed of 20m/s for engine longevity. Toyota rarely chooses to stress their engines from the factory.

Click on User CP > Edit Ignore List > Add Name > Confirm

I'm surprised hachi hasn't banned yet. Lol

[Matador]

Originally Posted by bofa

It does actually... click on their name, click on user lists, and select ignore member. But where's the fun in that. :happy0180:

Originally Posted by Giccin

Click on User CP > Edit Ignore List > Add Name > Confirm

Got it already, thanks.

Originally Posted by 1660

This is the first I've heard of mean piston speed, having to do with longevity. Why would 20m/s be a cut off? (I assume m/s means meters per second?) Does it mean reducing stress on bearings by reducing reciprocating stress? Does this apply to some kind of stress formula?

Originally Posted by Exage

To put this somewhat basic:

Typical piston acceleration forces become quite great, recommended maximum mean piston speed for most piston internal combustion engines is at ~20m/s, (I'm also thinking combustion expansion rate has something to do with this as well): Hence stroke length and RPM relationship is one of the pieces to a high revving engine.

Obviously if you increase the piston speed the greater distance the piston has traveled (easier to understand linearly) the more wear it will cause in the cylinder bore and hence why engines wear faster at high RPM, particularly if they are not designed for it.

Hope this helps.

^What he said.

Originally Posted by madfast

How does DI ruin the tuning aspect exactly? it only becomes a limitation when you start making serious hp. and MOST people wont go that far...

anyways, the D4-S system is the perfect solution, theoretically....

Dude, didn't you hear? We just ought to go back to using carbs.

[Spaceywilly]

it works for NASCAR

[serialk11r]

With D4-S if you want to make SERIOUS power, you could theoretically turn on both the port and the direct injectors couldn't you? Well if you could coax the ECU into it. That should be more than enough fuel.

[madfast]

Originally Posted by serialk11r

With D4-S if you want to make SERIOUS power, you could theoretically turn on both the port and the direct injectors couldn't you? Well if you could coax the ECU into it. That should be more than enough fuel.

exactly. DI is not a problem until you look for crazy power. with D4-S you basically get the best of both worlds: the high compression possible with DI, and the limitless amounts of fuel possible with port injection. provided of course that you have full ECU control...

so if the rumors are true that the next WRX will use toyota D4-S tech? it could be a monster of an engine...

[serialk11r]

Yup, it decreases the work the piston does during the compression stroke by the value of the latent heat of vaporization of the fuel (times the amount of fuel obviously). This work is directly saved from the compression stroke and the rest of the cycle is for the most part unchanged. Depending on fuel you basically get a few percent more power for free. With a fuel like methanol or ethanol this number becomes very significant and you get a crapton more power. Oh and that's not factoring in the increased compression you can run.

[serialk11r]

I don't think it's just a "few joules", given that part of the reason people adjust their air/fuel ratios rather rich is just so the fuel can provide a cooling effect. If you have port injection, (assuming performance oriented engine) at the bottom of the intake stroke your valve closes off so you have basically atmospheric pressure, and the temperature is slightly cooler than ambient due to the fuel vaporization. So the compression stroke works as an adiabatic process. If you have direct injection, you pull in pure air at ambient temperature, atmospheric pressure into the cylinder. If this were it, the compression stroke would consume slightly more power due to the lower heat ratio. However if you add fuel gradually as the compression stroke happens, you cool it off and it loses pressure. Depending on how it's done, this is somewhere between adiabatic and isothermal compression. In the first scenario, the charge was essentially cooled isobarically, then compressed adiabatically, and this requires more work. If you're not convinced you can go draw some T/S diagrams and convince yourself.

A second benefit is that you can probably cram a tiny bit more air/fuel mixture in, since the fuel is added after the intake valve closes. A third benefit is higher compression like I said. A fourth benefit is as you said, better fuel atomization, although I'm not too sure about this one since port injection allows the fuel to pass through the relatively narrow intake opening and experience some turbulence. The higher pressure used in direct injection probably helps with this, at least at the start of the compression stroke where the pressure difference between fuel system and cylinder is very large.

EDIT: Gasoline's heat of vaporization is about 3% of its heat of combustion. I wouldn't call that insignificant.

[Allch Chcar]

Originally Posted by Driftster

Please madfast, show me a stock DI piston capable of producing some good numbers, that means a DI piston that isn't compressed powdered steel.....that's a good big crowned low wrist pinned piston... ..

How many companies are producing high performance DI dish pistons?

Or did you forget DI pistons are completely different from standard dishes...

There's more to producing power from an engine than just spewing gas into the cylinder...

Go back to carb? hardly...

but is there a reason we need hundreds and hundrends of pounds of pressure in the fuel line and fuel added directly to the cylinder?

Do you keep up on current ICE tech like Gasoline Direct Injection?

[madfast]

Originally Posted by Driftster

Please madfast, show me a stock DI piston capable of producing some good numbers, that means a DI piston that isn't compressed powdered steel.....that's a good big crowned low wrist pinned piston... ..

How many companies are producing high performance DI dish pistons?

Or did you forget DI pistons are completely different from standard dishes...

There's more to producing power from an engine than just spewing gas into the cylinder...

Go back to carb? hardly...

but is there a reason we need hundreds and hundrends of pounds of pressure in the fuel line and fuel added directly to the cylinder?

First of all, i doubt most people would go as far as swapping internals. but for those that do, there ARE aftermarket pistons...