Engine build

[WingsofWar]

its like trying to build an already built motor..

[Maxim]

Originally Posted by WingsofWar

its like trying to build an already built motor..

That's my main worry with the car.

If Toyota/Subaru don't include a turbo, and they actually meet their goal of 200hp in the base model.....there's going to be VERY little room for improvement. We'd wind up with a repeat of the situation that happened with the RX-8. The Renesis was already so optimized from the factory that it was almost pointless to try to do anything other than a full re-build with a turbo if you actually wanted power gains.

I love modifying my car....I've done a myriad of things to my GTI and I love the car more each time. I'd have to think hard about getting a vehicle that I couldn't enjoy that same process with.

[Levi]

You are right everybody. I think the wait is just making me mad. I just am afraid that the production car might disapoint.

[82mm 4g63]

What kind of experience do you folks have with Toyota's DFI systems? I have none. However, I have seen some nightmares from Porsche's DFI and when I first heard the Subieyota was going to have DFI I was nervous.

It seems to be a safer way to increase compression/boost and control knock, but it's not like the non-DI engines are lagging much. This is from an 08 Porsche Cayanne:

I'm not 100% positive that build up is a result of the fuel being dumped on the valve or if it is PCV crud.

I've heard a lot about fuel dilution in the oil with DFI. Seems to be a big problem. I remember reading a Nissan study on it and I'm guessing that is why they still use port injection. I also know it was a huge problem with the CX-7 and Mazda not covering it under warranty.

Question for you, is the FR-S getting Subaru's AVCS and if so how does Subaru's AVCS compare to BMW's VANOS/Double-VANOS?

[WingsofWar]

Originally Posted by 82mm 4g63

What kind of experience do you folks have with Toyota's DFI systems? I have none. However, I have seen some nightmares from Porsche's DFI and when I first heard the Subieyota was going to have DFI I was nervous.

It seems to be a safer way to increase compression/boost and control knock, but it's not like the non-DI engines are lagging much. This is from an 08 Porsche Cayanne:
I'm not 100% positive that build up is a result of the fuel being dumped on the valve or if it is PCV crud.

I've heard a lot about fuel dilution in the oil with DFI. Seems to be a big problem. I remember reading a Nissan study on it and I'm guessing that is why they still use port injection. I also know it was a huge problem with the CX-7 and Mazda not covering it under warranty.

Question for you, is the FR-S getting Subaru's AVCS and if so how does Subaru's AVCS compare to BMW's VANOS/Double-VANOS?

I haven't had a lot of personal experience with Toyota DFI, im a little more familiar with Mazda's Direct Injection. They practically work the same with a few different variations.

While port injection guys have same issues, I think the major problem (atleast just with more frequency) some mazdaspeed3 guys have been having was carbon deposits from oil coming back into the intake charge. Since Fuel isn't injected at the intake manifold anymore to clean the intake valves..they get murked up. I'm really only seeing this kind of build up with people who baby their car and turbocharged vehicles. I am not sure if flogging the motor would help, but its worth a try. I have to rev my rx7 at least once a day to break down carbon.

As far as AVCS....im not entirely sure if the FT86 will use AVCS...especially if Yamaha might be in charge of the head design, we might see a Toyota VVTi in the FR-S if this is a case. But if they plan to further boost torque and economy, having a VVTi will help. Vanos is just BMWs technology...they virtually all accomplish the same thing.

[Exage]

Originally Posted by 82mm 4g63

Question for you, is the FR-S getting Subaru's AVCS and if so how does Subaru's AVCS compare to BMW's VANOS/Double-VANOS?

I would anticipate the use of Dual AVCS considering that the Subaru FB engine is currently employing that system.

From what I read the AVCS system it is very similar to VVT-i (and most Variable Valve Timing Systems). Hydraulic pressure (engine oil) is used to rotate the camshaft/s. I'm going to go out on a limb that this is done at the cam gear and has ~30 degrees of maximum rotation.

[serialk11r]

30 degrees? :O I think the intake valve timing isn't changed that much, wikipedia says BMW VANOS varies +6 or -6 degrees. Exhaust timing on double VANOS varies a lot more though, I think up to 15 degrees or something.

Valve phase shift mechanisms are more or less all the same, it's a pretty simple thing. Anyone know how much of a difference electrical actuation makes? Seems like hydraulic isn't as optimized and possibly has "lag".

What I read on the direct injection thing was that the carbon builds up on the valves since there's no fuel to wash them, but Toyota D4-S has port injectors as well which would solve that problem right?

[Exage]

http://www.scribd.com/doc/54981523/2...ne-Description

Look at the 2nd and 3rd pages of the 2ZZ-GE, Intake valve events with cam phase is 43 degrees maximum rotation on both low and high cam lobes (hence VVT-i system).

[serialk11r]

Oh crap my bad. I guess that does make sense, if exhaust event advance traps a lot of exhaust then the intake opening a lot later is a good idea.

[Dimman]

Found an epic site about the old Toyota Twincam motors:

http://www.3sgte.com/page_1.htm

Shows Toyota was experimenting with eVVT-i using stepper motors instead of hydraulics back in the 80's!!! Starts on page 20: http://www.3sgte.com/page_20.htm

[witchatookie]

Id like to see an FB20/25 Frankenstein
In the latest News the head engineer said that they would be placing a variant ob the fb20 series engine into the ft-86. That engine has the exact same bore pitch as the FB25. I'm willing to bet it also has the same head bolt specs as th fb25. With the ds-4 Head from the FB20 and the Fb25 short block could create a killer combo. Tuned correctly I believe an engine like that could pump out 280-300 streetable horses easily. Think about it, the ds-4 direct/port injection mixed with some itb's, ecu, Header, and a catback exhaust would be a killer engine.

[witchatookie]

bore and stroke on the FB20
84mm X 90mm

Bore and stroke on the FB25
92mm X 90mm

The FB25 shares the same stroke as the Fb20 but has a larger bore which, make me think that the FB20/25 would have no problems with high revs. It being slightly oversquare and all.

[Marrk]

'tookie,

The Tada interview says it's going to be a new engine.

>>>
In the maniac, well, enthusiast scene, it is pretty much gospel that the cars use Subaru’s flat four “D4-S” boxer engine. Depending on whom you believe, the production engine ranges from a tried & true to a refined & modified D4-S. That elicits protests from Tada, as loud as the softspoken man can manage:

“No,no, no – it is a completely new engine. The engine is still a boxer. The technology, even the engine block are completely new. Everything is new. The only thing that remained are the mounting points.”
<<<

So, it looks like everything is up for grabs.

[ryridesmotox]

Hey fellas, sorry to ressurect a thread from a month ago but I'm new to the forum and I have a thing or two to possibly add for discusison.

#1) DI is great! It's been around since the late 40s/early 50s with diesel engines and such. The problem I run into with my car is that I can't get enough fuel into the cylinders due to the High Pressure Pump not being able to keep up (granted I run a 91 octane/E85 blend). Now I do have forced induction and that is what I will be doing on the FT-86 if they ever release the darn thing.

#2) I think WingsofWar put it best "it's like trying to build an already built motor". I run into the same thing with my car. I run just bolt ons and a tune. Its too much of a pain/expense to go internals on some cars.

#3) I am gonna have to go forced induction. Love me some turbo. Hopefully the motor will be "built" nice and solid. If chevy can do a good 4banger with my car then Toyota/Subaru should be able to do even better.

The way a turbo helps with volumetric effeciency in a 4 banger is awesome. The new formula 1 cars are now going to be turbo 4s (yea obviously alot different then our little dream machines). Depending on how strong the block and rotating assembly is I could see 400hp fairly easily. I get about there with my ethanol mix with a stock turbo on my cobalt. A more effecient turbo would be even better. Hopefully the High Pressure Fuel Pump and injectors are up to the task. Those will be the costly modifications (at least they are on my car) since most of that is custom work.