[Diy_efi] direct injection
Phillip Kuhn
pmkls1
Fri Sep 23 02:39:52 UTC 2011
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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