Thoughts on Direct Injection
Thread Starter
|
Road Warrior
Joined: Nov 2007
Posts: 1,984
Likes: 7
Thoughts on Direct Injection
I expect Harley is working on this.
The thread about Throddle Body size got me thinking again about this subject.
DI is supposed to be a good thing and some Auto's do pretty well with it.
How can we apply DI to what we have?
I expect some on this forum have giving this a though.
My thoughts are:
If the TB is big enough to flow all the necessary air needed, then the question is the fuel delivery.
If we can get all the fuel in during the time the intake valves are open we are doing about as good as we can. With our old time FI.
This means--and this seems to me---the bigger Injectors are the way to go if you have a modified engine.
All in every time. Nothing left to raddle around till next opening.
I figured it up once but the math hurts my head now, the time the intake valve is open, but I thing at 6000RPM comes to 0.0016 of a second max for injector pulse.
May be off a few decimal points.
Anybody thinking about this DI?
Probably be a GM or Borsch thing Harley will use.
The thread about Throddle Body size got me thinking again about this subject.
DI is supposed to be a good thing and some Auto's do pretty well with it.
How can we apply DI to what we have?
I expect some on this forum have giving this a though.
My thoughts are:
If the TB is big enough to flow all the necessary air needed, then the question is the fuel delivery.
If we can get all the fuel in during the time the intake valves are open we are doing about as good as we can. With our old time FI.
This means--and this seems to me---the bigger Injectors are the way to go if you have a modified engine.
All in every time. Nothing left to raddle around till next opening.
I figured it up once but the math hurts my head now, the time the intake valve is open, but I thing at 6000RPM comes to 0.0016 of a second max for injector pulse.
May be off a few decimal points.
Anybody thinking about this DI?
Probably be a GM or Borsch thing Harley will use.
Last edited by Old Gunny; Apr 29, 2011 at 11:37 AM.
Ultimate HDF Member
Joined: Feb 2007
Posts: 7,663
Likes: 7
From: Northeast Ohio
You are going down a path that just makes sense. But, I don't think larger injectors are a must to accomplish this. In monitoring pulse width, if it is in the 40% range, enough fuel is bing delivered, at least what is being called for by the ECm is being delivered. In running 4.89 Gm/sec injectors in my 120, they were in the 75% range. Going to 5.3gm/sec, they were in the 40% range.
With direct injection, less fuel will be "hung up" on the manifold walls and in the intact tract, so you actually may be able to go a bit smaller in injector size to get the proper a/f ratio. It depends on how much you want to load the cylinder, and will be very dependent on cam timing and exhaust.
This hurts my head too...too much math and theory!
With direct injection, less fuel will be "hung up" on the manifold walls and in the intact tract, so you actually may be able to go a bit smaller in injector size to get the proper a/f ratio. It depends on how much you want to load the cylinder, and will be very dependent on cam timing and exhaust.
This hurts my head too...too much math and theory!
Elite HDF Member
Joined: Jun 2008
Posts: 4,109
Likes: 9
From: Connecticut
with DI you can run higher compression, more camshaft without fear. It is the wave of the future. Have to run high pressure fuel system to make it happen if I remember right it's like 2000 psi they run off an engine driven high pressure pump. They can run clean with high HP output. The car makers are making some big HP figures with it now and so far pretty trouble free.
Cruiser
Joined: Aug 2007
Posts: 117
Likes: 0
They've been running it in the 2-stroke field on boat motors and sleds for years now. Check it out on Evenrudes and Ski Doo snowmobiles from BRP, very low emissions(even better than 4-pokers in comparasion) and keeping it lightweight and with high horsepower. Been very interesting.
Cruiser
Joined: Feb 2008
Posts: 114
Likes: 0
From: Southern Indiana. (Louisville KY Metro Area)
It's time.
Yes, higher pressure in the norm for GDI.
While Delphi makes injectors for GDI systems that operate in the 200+ bar range, one of the leaders in GDI and engine management systems is Bosch.
For EFI Harley's, MM for the years 1995 to 2001, Delphi 2001 to present.
Bosch engine management for Harley's with GDI to debut soon??
While Delphi makes injectors for GDI systems that operate in the 200+ bar range, one of the leaders in GDI and engine management systems is Bosch.
For EFI Harley's, MM for the years 1995 to 2001, Delphi 2001 to present.
Bosch engine management for Harley's with GDI to debut soon??
Thread
Thread Starter
Forum
Replies
Last Post
TriGeezer
Ignition/Tuner/ECM/Fuel Injection
25
Sep 12, 2018 06:47 AM
