[Diy_efi] direct injection

Tue Sep 27 18:56:14 UTC 2011

Phillip,

It might be that they think they have to do all the special redesign of the
combustion chamber, but they did not test it with a normal combustion
chamber.  Did he say that had tried the normal type and it did not work
well?

Bobby

2011/9/23 Phillip Kuhn <pmkls1 at yahoo.com>

> I know that this topic has gone kind of cold, but I spoke with a field
> engineer that came to the shop today and he had some information I thought I
> would share with you. When I told him about your inquiry and the information
> that I had been unable to obtain he also had some additional information
> that I was unaware of as well. He told me that the injector placement was
> critical and that was one of the major obstacles that took GM engineers some
> time to overcome. Evidently, the location of the injector in the combustion
> chamber and more importantly where the spray is focused is crucial to the
> engine performing properly. Since they were modifying existing engine
> designs with the intention of making as few major modifications to the
> cylinder heads as possible it was quite difficult to get the injectors
> spraying fuel into the right part of the cylinder for the engines to run
> right. As a matter of fact I have replaced a cylinder head on a DI 3.6 v6
> recently. I noticed the injector actually came in through the side of the
> combustion chamber ( this was probably due to the only available location to
> mount the injectors ) and the top of the piston and combustion chambers were
> very specifically shaped. They were profiled so that the fuel spray focused
> into a recess in the middle of the combustion chamber directly under the
> spark plug. I am guessing that this was to get the flame to start in the
> middle of the chamber and spread outward in a controlled manner. Anyhow, I
> thought this information was important enough to pass on. Don't get me
> wrong, I would love for you to successfully utilize a DI system on your
> project and anyone else for that matter. I just want to provide enough info
> so as to aid in this being completed successfully without running into so
> many obstacles that anyone who attempts this will not give up. I also don't
> want to see someone ruin a possibly rare and/or expensive cylinder head just
> to mount the injector and find out that the rest of the project is too
> difficult to complete. Good luck and feel free to ask anymore questions that
> come to mind.
>
> Phil
>
> *From:* "ScottyGrover at aol.com" <ScottyGrover at aol.com>
> *To:* diy_efi at diy-efi.org
> *Sent:* Friday, September 9, 2011 12:15 AM
>
> *Subject:* Re: [Diy_efi] direct injection
>
>  Thank you very much for the information.  I am designing a system for an
> air-cooled, 2.7L flat six and haven't been able to get any co-operation from
> Delphi or from my local dealer (he says I don't need to know.)
> I have studied the patents (Delphi and others) and have a good idea of the
> layout but I need the physical size (particularly the diameter) and the
> application (HP rating, engine size, and of course the part number.)
>
> Scotty
>
>  In a message dated 9/8/2011 7:46:41 P.M. Pacific Daylight Time,
> pmkls1 at yahoo.com writes:
>
> I have been a tech at GM dealerships since 2001. I don't have the slightest
> clue about the other manufacturers using DI, but know a decent amount about
> the GM systems. So far I haven't seen any common issues at all with the GM
> stuff. I have seen a few injectors go bad and some issues with the high
> pressure pump leaking fuel into the crankcase ( just like the old mechanical
> pumps did), but nothing major or widespread overall. As far as the systems
> themselves go I will give a detailed description of how they work etc.
> Currently, only the Ecotec engines have DI versions, and all late model high
> feature v6 engines (2.8, 3.0, 3.6) are DI. They all use an in-tank electric
> pump running at ~60 psi to send fuel up to the high pressure pump. The high
> pressure pump is mounted on the engine, is driven off of a camshaft, and
> operates exactly like the regular old mechanical fuel pumps do ( save for
> the pressure output ). The entire system is a returnless system and
> like most newer vehicles has no serviceable fuel filter. The supply
> pressure is regulated by the ecm and a fuel pump flow control module via a
> pwm signal to the electric in-tank pump. The fuel pressure on the high
> pressure side of the system is also controlled by the ecm too via an
> actuator mounted inside the high pressure pump. The system operating
> pressures on the high pressure side are 500-800 psi at idle and around 2500
> psi at max output iirc. From the high pressure pump forward they use heavy
> stainless lines with flare and ball connections and are supposed to be a
> one-time use deal. Anytime we take a line loose it is supposed to be
> replaced, although I have reused several without any leaks. There is also a
> fuel rail pressure sensor located on the fuel injector rail to send pressure
> readings back to the ecm and there is no other means of testing pressure on
> the high pressure side. The injectors look like normal injectors on the fuel
> rail side and
> use o-rings that appear to be the same size or similar to that of regular
> fuel injectors( I still can't figure out how the seals don't blow out at
> those pressures). The other end of the fuel injector is very long and narrow
> and uses special teflon seals to seal it into the cylinder head as they go
> directly into the combustion chamber through the intake side of the cylinder
> head. Special tools are required to install and size the teflon seals
> similar to the tools used for non-cut teflon seals used in transmissions.
> There are also special tools required to remove the injectors from the
> cylinder head as carbon will quickly cause them to get stuck in the
> close-tolerance bores. Every time the injectors are removed all of the seals
> have to be replaced. The injectors do require a special high voltage driver,
> but I do not know the specs right now. Overall, the systems operate like a
> regular sequential port system does and are designed similar to a diesel
> system. Both fuel economy and power are improved on the engines GM is using
> DI on currently. The latest 3.6 in the base camaro is up to something like
> 317hp now. As far as being able to fit DI to any other engine, I suppose it
> may be possible on some engines. Even then it would require significant
> cylinder head modification and some fabrication. You would also have to use
> an ECM designed for DI and be able to modify the calibrations and flash the
> ecm which I am unsure if that is possible currently. Hope this answers a few
> questions.
>
> Phil
>
> ----- Original Message -----
> From: Avery Nisbet <anisbet at gmail.com>
> To: Fred Cooke <fred.cooke at gmail.com>
> Cc: ScottyGrover at aol.com; diy_efi at diy-efi.org
> Sent: Thursday, September 8, 2011 4:07 PM
> Subject: Re: [Diy_efi] direct injection
>
> I have heard from VAG mechanics that they still have trouble with
> this. This is with the current TSFI engines found in the audi's and VW
> in the US.
>
> Though TDI engines have been around for years I only hear of them
> clogging up the EGR system not the intake ports.
>
> I think most of this is due to EGR issues and dirty air.  Where else
> would any substance that would/could coke on the intake port/valve
> come from if you have DI.  The washing action of Port injection
> probably helped with badly designed EGR systems in the past.
>
> For DIY at home "testing" of DI, EGR systems could probably be avoided.
>
> -Avery
>
> On Thu, Sep 8, 2011 at 1:00 PM, Fred Cooke <fred.cooke at gmail.com> wrote:
> > Early examples, from at least 1998, perhaps earlier, are to be avoided as
> > they are usually prone to coking of the intake manifolds. Very bad coking
> -
> > to the point of blockage! The earlier cars had a lot of trouble in many
> > areas and were not reliable at all. If we're talking about DI. if we're
> > talking about BMW Piezo DI, I have no idea.
> >
> > On Fri, Sep 9, 2011 at 7:18 AM, Avery Nisbet <anisbet at gmail.com> wrote:
> >>
> >> A lot the current car have these.
> >>
> >> GM has been using them in the eco-tec(FWD 4 cylinder) engine for a
> >> while.  Im sure there a few different injector styles.
> >> The prices should come down in a few years.  You may be able to find
> >> specs by looking up after market replacements.
> >>
> >> The cruze should have these depending on market.   The later model
> >> year US market cobalts had them too.
> >>
> >> -Avery
> >>
> >> 2011/9/8 Mike <niche at iinet.net.au>:
> >> > All I know its pretty high pressure, the latest bmw twin turbos use
> this
> >> > with piezo driven
> >> > injectors that cost $2200+ (AUD) each !  But they do get pretty
> >> > reasonable
> >> > fuel consumption of
> >> > around 6L/100Kms with sizable power on demand - straight six 2 to 3L,
> >> > seems like the next tech step but geesh does it cost !
> >> > regards
> >> > Mike
> >> >
> >> > At 02:48 AM 9/9/2011, ScottyGrover at aol.com wrote:
> >> >
> >> > Has anyone done any work on this type of fuel injection? I can't get
> any
> >> > data from Delphi, even as to the physical size (length, stem
> diameter.)
> >> >
> >> > Scotty from Hollyweird
> >> > _______________________________________________
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> >> >
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-- 
Toward freedom,

Bobby Yates Emory
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