Automobile Mag. Dyno Test of Sky Red Line - Page 5 - Saturn ION RedLine Forums
Reply
 
LinkBack Thread Tools Display Modes
post #41 of 44 (permalink) Old 09-28-2006, 04:43 PM
Senior Member
 
matt's Avatar
 
Join Date: Nov 2003
Posts: 2,012
That dyno is crap. The horsepower and torque are crossing way before 5252 RPMs.
matt is offline  
Sponsored Links
Advertisement
 
post #42 of 44 (permalink) Old 09-28-2006, 04:48 PM
Senior Member
 
jpapa's Avatar
 
Join Date: Feb 2005
Location: SE MI
Posts: 2,041
Quote:
Originally Posted by Shabodah
I think you're confusing diesel direct injection (16-24:1 compression) to gasoline direct injection (8.5-11:1).

Edit: but looking at how the duramax has been tuned is a good idea to determine where to go with this.
Nope, diesel direct injection and gasoline direct injection share the same type of mechanics in fuel/air injection. In both, the fuel injectors are have to feed the fuel directly in the cylinders, where air is already shoved in with a pretty high pressure. In order to overcome that pressure and shoot the fuel where it needs to go, a much greater pressure on the magnitudes of 1000s bars is needed.

I'm not exactly sure when the fuel is injected in this Ecotec, whether its simultaneously injected when the intake valves are open and air is rushing in, or if it's right after the valves close and the piston compression stroke is already coming up. Either way, the fuel has to have enough of a pressure and trajectory to aim at the different type of piston head in this engine so that it can mix with the air properly in the cylinder (like a diesel, a bowl shaped head).

That brings me to my next point with your compression ratios. Yes you are right with the gasoline (8.5:1-11:1) and diesel (16:1-24:1), those ranges can very with different engines too. But the compression ratio doesn't determine the fuel pressure, the type of mixing and air/fuel ratio does. You see, you're used to our pre-mixed port injection Ecotecs where the fuel and air mix together BEFORE they enter the cylinders. This makes the air/fuel mixture homogeneous (a constant, even mixture) all throughout the cylinder.

Direct injection (in both gasoline and diesel) have a stratified charge of fuel/air in the cylinder, which is differing fuel/air ratios all throughout the cylinder. The mixture will be near the 14.6:1 near the spark plug for proper ignition, but since the rest of the fuel and air mix in the cylinder during the piston's upward compression stroke, the mixture will not be even like that of our Ecotecs.

THIS is the reason for the different piston head design, so that the injected fuel aimed at the piston head bounces off and mixes properly near the spark plug for proper ignition. THIS is the reason the fuel injected needs to be at such a high pressure, so that the fuel is in a turbulent state which allows for better mixing with the air. And THIS is the reason why tuning will be harder: any change in the fuel flow will cause the mixing to be a lot different than designed for, and can cause improper ignition. So people really have to know what they're controlling in order for the tuning to work right. A lot of light will have to come from diesel tuning if it is to be done properly because this is a much different field of engines that most people are used to.

Wow sorry for the long explanation, but a lot of people aren't going to understand this direct injection like this. I figure I'd spread a little bit of what I've been learning in my internal combustion engines class

Quote:
Originally Posted by Ahriman
this makes me very sad... and mad... im sad and mad.... im smad
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Cyanide & Happiness @
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jpapa is offline  
post #43 of 44 (permalink) Old 09-29-2006, 10:07 AM
Superd00d
 
Sp00ner's Avatar
 
Join Date: Jan 2005
Location: Chicago
Posts: 22,040
Quote:
Originally Posted by matt
That dyno is crap. The horsepower and torque are crossing way before 5252 RPMs.
The HP and TQ are using different scales... they're still crossing there, just not on that graph... Just about 220 hp/tq at 5250...




'05 Stage 2 Redline -One of the few Red REDlines

Sp00n's HP Tuned GM Stage 2, K&N CAI, SFPH 2.8" Pulley, GMPP Exhaust Manifold, B&M Shifter, GMPP Clutch, Eibach Drop, Stillen Rotors, ZZP Stage1 Axles, URC-Subframe, TqForward Strut Bars.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


260whp 225wtq
1/4 - 14.0 @ 103.7

Red Red Line Club #001
Sp00ner is offline  
 
post #44 of 44 (permalink) Old 09-29-2006, 10:15 AM
Senior Member
 
Shabodah's Avatar
 
Join Date: Aug 2005
Location: Walker's Kingdom
Posts: 11,403
Quote:
Originally Posted by jpapa
Nope, diesel direct injection and gasoline direct injection share the same type of mechanics in fuel/air injection.
A little knowledge can be more destructive than no knowledge.

Cylinder pressure determines the amount of fuel pressure necessary. Compression ration is the main factor in determining cylinder pressure.

GM has already stated what the fuel pressure ranges are on both the direct injection gas engines, and obviously, the diesels. They shave the same basics, indeed and most of what you're saying is correct, but the direct injection gas engines are not running anywhere near 1000 bar.

Edit: I mentioned static compression ratios in my example as a generalization. Dynamic compression ratios are what are going to give you the most accurate idea of what's going on, and as you stated, they change very much, even in the same engine on the same day.

Ok, so, like, yeah, umm....

Last edited by Shabodah; 09-29-2006 at 10:17 AM.
Shabodah is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Saturn ION RedLine Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Aug 06 Automobile GXP first drive Axel Sky Discussion 7 07-09-2006 08:55 PM
Inside Line Full Test DeYanko ION Redline Discussion 5 10-17-2005 09:26 AM
Ion Red Line TV Test drive.... Blu_Redline ION Picture/Media Post 17 10-16-2005 04:11 PM
Red Line on Dyno * VID * DaytonaGTS ION Picture/Media Post 24 05-02-2005 07:30 PM
Vita's Red Line on the Dyno. Aeain ION Picture/Media Post 9 01-28-2005 07:59 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome