Slant *       6       Forum
Home Home Home
The Place to Go for Slant Six Info!
Click here to help support the Slant Six Forum!
It is currently Tue Oct 28, 2025 2:42 pm

Unanswered topics | Active topics


» » Tech Q & A » Fuel Injection

All times are UTC-07:00



Post new topic  Reply to topic  Page 2 of 2
  [ 20 posts ]  Go to page Previous 1 2
  Print view Previous topic | Next topic 
Author Message
FrankRaso
 Post subject:
PostPosted: Fri May 16, 2008 4:32 pm 
Offline
Turbo Slant 6

Joined: Fri Apr 16, 2004 10:50 am
Posts: 660
Location: Stevensville, ON
Car Model:
It would seem to me that you could buy a wide band O2 data logging system for less than the cost of all that dyno time. Basically, you are aiming for a power fuel mixture that gives the best power at full throttle and a cruising fuel mixture that gives the best fuel economy at part throttle.

For the best power, you could simply find a empty stretch of road and use a stop watch to measure 0-60 mph times. Alternatively, your data logger should very accurately be able to tell you how long it takes to reach whatever RPM you pick. For the best fuel economy, adjust the cell that your car operates in on the highway until you get the best fuel economy. I'm not sure if this is where your manifold vacuum would be the highest. You could also optimize your timing this way too.

As Joshie suggested, the only reason to maintain 14.7:1 is for emission control with a catalytic converter. However, your fuel economy will be better with a leaner mixture.
Top
   
Reply with quote  
Sam Powell
 Post subject:
PostPosted: Fri May 16, 2008 6:51 pm 
Offline
Supercharged

Joined: Sun Jun 04, 2006 4:53 pm
Posts: 4295
Location: Gaithersburg MD
Car Model:
A wide band set up for the ECU would be good for many reasons in addition to data logging. But these guys at Maryland Performance are reputed to be really great. Plus, when I was talking to him about the set up on my Dart, instead of laughing at the turbo slant, he said he has seen engines built this way turn 10's all day. Whether he is right or wrong (just smart marketing?) , he is not going in with negative expectations. If he could tune this engine for that kind of power, the first thing to break would be the transmission.

I need to get the things I have already stockpiled, on and working before I buy anything else. I might eventually do the wide band thing.


EMS, I don;t know if the coil is oil or epoxy filled. I guess I could drill into it and find out.

Sam

_________________
Image
Top
   
Reply with quote  
emsvitil
 Post subject:
PostPosted: Fri May 16, 2008 8:08 pm 
Offline
Supercharged

Joined: Thu May 12, 2005 11:50 pm
Posts: 6291
Location: So California
Car Model: 64 Plymouth Valiant
Quote:
EMS, I don;t know if the coil is oil or epoxy filled. I guess I could drill into it and find out.

Sam
Just shake it.......

You can usually hear/feel the oil sloshing around. :wink:

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

8)
Top
   
Reply with quote  
Sam Powell
 Post subject:
PostPosted: Sun May 18, 2008 4:50 am 
Offline
Supercharged

Joined: Sun Jun 04, 2006 4:53 pm
Posts: 4295
Location: Gaithersburg MD
Car Model:
OOPS! Too late, the trash man comes Saturday morning. It had a solid feel to it. If memory serves, the only sloshing was coming from my brain. :lol:

Sam

_________________
Image
Top
   
Reply with quote  
10sec_rx7
 Post subject:
PostPosted: Wed Jun 04, 2008 4:55 pm 
Offline
1 BBL (New)

Joined: Wed Jun 04, 2008 4:48 pm
Posts: 2
Car Model:
Quote:
Sam,

I would shoot for nearly as lean as the engine will tolerate without misfiring under low load conditions. More of a weak (lean) mixture is more efficient than a less of a rich mixture as it reduces pumping losses. If you can run 16-18:1 under light load cruise I'd do it. The only reason to run 14.7:1 is to keep a catalyst happy. Catalytic converters do not like excess oxygen if you can believe it. Once you get below about 4" of Hg vacuum I would switch to a richer mixture just as a carburetor with a power valve does. You can have an intermediate step or taper up to say 13:1 at higher loads and go slightly richer from there as you get into boost. Believe it or not you can run lean under boost and have the engine live, but it has to be lean enough that it's also cool enough to not burn parts. I wouldn't try it in a passenger car application, but it was done reliably with supercharged piston aircraft engines.

The SDS EFI web site has lots of good info on tuning.
most of the time shooting for as lean as it will go on cruse will actually increase the fuel used, you need to find the happy medium of ignition timing and fuel mixtures to get the engine in the mose efficent state, sometimes this will be with mixtures at 14.0:1

to do this you really need a dyno that will tell you a torque reading, then it is just a matter of playing with the timing and fuel to get the peak torque at that throttle position and revs,

if your running in closed loop then it will more than likley be fine but if in open loop you can generally get better economy by giving the engine what it wants.

these old motors dont have the best design heads and dont like a lot of ignition timing and wont run well when leaned out,

VE safari's car is a perfect example of this, lean it out and it gets hot and looses a lot of power, run it a little richer and it is perfectly normal
Top
   
Reply with quote  
Display posts from previous:  Sort by  
Post new topic  Reply to topic  Page 2 of 2
  [ 20 posts ]  Go to page Previous 1 2

» » Tech Q & A » Fuel Injection

All times are UTC-07:00

Who is online

Users browsing this forum: No registered users and 2 guests

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited