SCOOP: Subaru didn't want D4S (and neither do I)

[Homemade WRX]

Originally Posted by Dimman

I'd start with doing some D4-S research rather than pricing bigger port injectors. Current 2GRFSE's D4-S runs on DI alone at full throttle. And it has varied injector use % at different load/rpm ranges. It's not 50/50 port/DI all the time.

If it's as simple as it just has 2 maps (DI and port) then being able to activate the port injectors at full throttle may be all that is needed for enrichment. Pending pump capacity, of course.

Sorry, I was a bit unclear by simply stating 'injectors'. I meant GDI injectors and not port. I've researched D4-S and their 101 on fuel strategy but that really doens't shed much light from an engineering level of the software, mapping and intergration.

Originally Posted by Ryephile

As long as you understand that adding port fueling will likely lower chemical quench and reduce combustion uniformity. Otherwise, it's foolish advice.

You don't have to preach to me. I'm a GDI junky. I started working with it in my senior project in college in early 2006 (though largely aimed at E85 usage). I've since kept my ear to the ground on new advances in the field both at work, SAE print and through colleagues in the field. However being a large Subaru guru, I don't hvae much GDI but strictly diesel DI work now.

Since I'm however one of those engineers who is bored doing the 40 hour a week production work and also burned out in the motorsports environment of being gone 180 days a year on short notice.
So now I do the easy 40hr/wk and run my own company for taylored Subaru race engines.

I'm really excited about the pre/post injection technology finally crossing over into the GDI world from diesel technology. If a pre-main-post injector comes out, oh the possibilities of that paired with a VGT turbo!!

...but back to simple NA and fixed FI talk for now

[Ryephile]

I was simply bringing up the point that mixing strategies isn't as cut-n-dry as MotoIQ's generalization.

[Altezza_86]

didnt you guys know? direct injection is the new thing for eco cars? better fuel economy!

[Dimman]

Originally Posted by Homemade WRX

Sorry, I was a bit unclear by simply stating 'injectors'. I meant GDI injectors and not port. I've researched D4-S and their 101 on fuel strategy but that really doens't shed much light from an engineering level of the software, mapping and intergration.



You don't have to preach to me. I'm a GDI junky. I started working with it in my senior project in college in early 2006 (though largely aimed at E85 usage). I've since kept my ear to the ground on new advances in the field both at work, SAE print and through colleagues in the field. However being a large Subaru guru, I don't hvae much GDI but strictly diesel DI work now.

Since I'm however one of those engineers who is bored doing the 40 hour a week production work and also burned out in the motorsports environment of being gone 180 days a year on short notice.
So now I do the easy 40hr/wk and run my own company for taylored Subaru race engines.

I'm really excited about the pre/post injection technology finally crossing over into the GDI world from diesel technology. If a pre-main-post injector comes out, oh the possibilities of that paired with a VGT turbo!!

...but back to simple NA and fixed FI talk for now

Awesome. My fault for assuming port as well, as that seems to be the majority of the posts here. "I'll just put bigger port injectors in and leave the DI alone." Uh-oh...

As for the DI injectors it sounds like they are a Denso and D4-S-specific design, having a special nozzle for a different spray pattern than Toyota's normal D4 injectors. So choices may be limited for a while.

[gt86vx]

good to know, can we move on with life now.

[mspeed6]

Originally Posted by carbonBLUE

if you dont want direct injection, go int the ecu and turn if off and turn up the port injectors...

great idea. Do that on a engine with this kind of high compression. Nice paper weight.

[tranzformer]

The more I read about DI the more apprehensive I am about it. Other guys with DI state that they have had to deal with intake valve gunk buildup and misfiring. Wish their car wasn't DI. I have never owned a car with DI but some of the downsides sound like a pain in the butt.


Edit: Should add that this is mostly from Mazda and Audi owners so hopefully this version is different.

[carbonBLUE]

Originally Posted by tranzformer

The more I read about DI the more apprehensive I am about it. Other guys with DI state that they have had to deal with intake valve gunk buildup and misfiring. Wish their car wasn't DI. I have never owned a car with DI but some of the downsides sound like a pain in the butt.


Edit: Should add that this is mostly from Mazda and Audi owners so hopefully this version is different.

Port injection is the answer to carbon buildup on the intake valves that's why the car has both

[tranzformer]

Originally Posted by carbonBLUE

Port injection is the answer to carbon buildup on the intake valves that's why the car has both

Is that in theory or actually been shown in real world experience? Asking cause I don't know.

[fatoni]

Originally Posted by tranzformer

Is that in theory or actually been shown in real world experience? Asking cause I don't know.

id guess in theory since there probably isnt enough of a history of this kind of fuel system in the real world to collect suffiecient data to come to any reasonable conclusion

[serialk11r]

PCV catch can or filter? Port injectors? I think we've discussed this in detail already...
Although I guess one new thing that's been pointed out since is the DI/PI ratio at different loads. If you drive only highway miles the load might be too low to get the port injectors to turn on.

Even with the "disadvantages", I think people should wake up and see that there is almost no other way to get high rpm power, low rpm efficiency, and strong midrange torque, while passing emissions.

[carbonBLUE]

Originally Posted by fatoni

id guess in theory since there probably isnt enough of a history of this kind of fuel system in the real world to collect suffiecient data to come to any reasonable conclusion

actually the detergents in gas clean the intake valves as the port injectors spray

Originally Posted by serialk11r

PCV catch can or filter? Port injectors? I think we've discussed this in detail already...
Although I guess one new thing that's been pointed out since is the DI/PI ratio at different loads. If you drive only highway miles the load might be too low to get the port injectors to turn on.

Even with the "disadvantages", I think people should wake up and see that there is almost no other way to get high rpm power, low rpm efficiency, and strong midrange torque, while passing emissions.

exactly, this tech is revolutionary, its only good for us, if you want a hand in tuning D4S, then find someone who has tuned a few IS-F's, they will have the best solutions for you, probably the safest route when tuning D4S

It WILL be pricey but it will be done right

[Jeff Lange]

Originally Posted by fatoni

id guess in theory since there probably isnt enough of a history of this kind of fuel system in the real world to collect suffiecient data to come to any reasonable conclusion

There is enough history. Almost all DI engines without port injectors seem to have at least some sort of carbon build-up issues on the intake valves.

Lexus has dealt with this with the D4 4GR-FSE in vehicles like the IS250, while other engines with D4-S (such as the 2GR-FSE in the IS350), do not have any carbon issues.

There may be another way to solve the carbon build-up issues with a DI system, but the addition of the port injectors do take care of it.

Jeff

[fatoni]

Originally Posted by Jeff Lange

There is enough history. Almost all DI engines without port injectors seem to have at least some sort of carbon build-up issues on the intake valves.

Lexus has dealt with this with the D4 4GR-FSE in vehicles like the IS250, while other engines with D4-S (such as the 2GR-FSE in the IS350), do not have any carbon issues.

There may be another way to solve the carbon build-up issues with a DI system, but the addition of the port injectors do take care of it.

Jeff

my point is that there isnt enough of this combination. how much is port injection contributing? whether we know how it should work or not, we dont know how it works. im sure it will be fine but to say anything about this car as being fact and not theory or whatever is kind of hasty