The Oldsmobile Connection

[andrewk]

Hi all,
I am hoping to get some info from some of you guys... on another board that I am a member of, there is a debate on fuel systems and their effiency. There is a member that says at high rpm closed throttle operation, the injectors dont fire at all, and no fuel is put in the cylinders. Something seems weird there... Ill post the thread.

http://strangetalk.net/viewtopic.php?t=87804

Any thoughts?

Andrew

[88 Coupe]

Hi andrewk, hello everyone,

Quote: ........ Any thoughts?
Not a topic I'm interested in. It deals more with theory than useful fact.

Since it is you who is asking, here is my opinion based (as always) on my own personal experience, not what I read on the internet.

During deceleration, a small amount of combustion is necessary for several reasons. One is to control oil deposits.

Computer controlled fuel mixtures and spark timing can maintain the minimum required A/F ratios. A stand alone carb cannot. A computer controlled carb is not as effective as TBI or later, but it's closer than most realize.

Theory behind shutting off the fuel completely, would probably include a belief that the small amount of time spent on compression braking would do no harm. In this area, fuel savings and lower emissions are not significant.

In the discussed time frame, the design engineers using different philosophies, might have debated their positions. If I was actually interested, I'd check all the current specs to find out if one side prevailed.

The subject thread wrote: I wonder what the difference is between a rotary and piston motor ........
A Wankel (rotary) is a two stroke. Any comparisons to normal 4 strokes should be made with that in mind. In this case It's not revelevant.

The subject thread wrote: ........ It's a manual transmission. When the vehicle is moving, the clutch is engaged, and the transmission is in gear, the vehicle moving will continue to turn the engine even with no fuel/ignition ........
As it applies to the topic, there is no difference. An automatic turns turns the engine until the TC unlocks and it reaches stall speed. Both occur at a low speed.

The subject thread wrote: ........ I don't ever engine brake in my cars ........
Anyone who would advocate "clutch in/trans in neutral" braking, for any reason, should be confined to the General/Off topic area, and/or be limited to asking questions.

The subject thread wrote: A properly double clutched (or even rev matched) downshift has almost zero clutch wear, and there's no clutch wear when it's fully engaged. It's NOT a case, as people seem to make it, of "wear the brake pads or wear the clutch" unless you suck at driving a stickshift and use the clutch to drag the engine up to the new RPM. It's a case of "wear the brake pads, or wear nothing."
Correct . . . . . A good driver can make a clutch (and trans) last the life of the car.

The subject thread wrote: ........ emissions crap is largely responsible for the lack of fuel economy lately.
As stated, his point is not valid. It can be partially applied to American cars made from '71 through the late '80s.

"emissions crap"? Two unrelated subjects. Kinda like saying "crappy Qjet" or "crappy 3800". Translated, the poster is referring to a subject he doesn't understand.

The subject thread wrote: Do a search on google for "deceleration fuel cut" There's all kinds of stuff out there .........
Answering a question by telling one to "do a Google search" indicates the poster is not knowledgeable on the subject. Posting a link, because the answer would require a lengthy answer, is acceptable.

A personal aside: "Do a Google search for my answer to your question" was DrJays method of commiting Hari-Kiri.

Sorry, I couldn't help it. Back to business.

The subject thread wrote: ........ I used to keep my car in 1st gear, run it to about 5,000 rpm and let it decelerate. It made for a pretty good flame show under the car.
Not relevant, however, a decent tuneup would take care of that.

Regards, Norm

[88 Coupe]

BTW, if you quote any of this, I'll deny I said it.

[andrewk]

88 Coupe wrote: BTW, if you quote any of this, I'll deny I said it.

I wouldnt put you in that position. Thanks for your help!

Andrew

[88 Coupe]

andrewk wrote: I wouldnt put you in that position . Thanks for your help
Read it again, then think about it. Do I really need to learn how to use those smilies?

You're welcome.

Norm

[andrewk]

88 Coupe wrote: andrewk wrote: I wouldnt put you in that position . Thanks for your help
Read it again, then think about it. Do I really need to learn how to use those smilies?

You're welcome.

Norm

Touche salesman... :wink: I should know better by now, huh? :D