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Author Topic: Optimizing 8v71 High Altitude Performance  (Read 3965 times)
technomadia
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« Reply #30 on: July 08, 2013, 09:46:16 AM »

Chris, I sent the file to the email in your profile.. I guess, like a lot of things in life, you have a lot of choices on how to time your injectors!  Smiley

Brian

Sweet.. thank you Brian!

For anyone who'd like the PDF as well, I have placed it on our Dropbox server, which is available for download here:

https://dl.dropboxusercontent.com/u/5589663/detroit%20tune%20up%20instructions%20-.pdf

(It may take a few minutes for it to show up...)

 - Cherie
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« Reply #31 on: July 08, 2013, 09:56:51 AM »

Maybe you could install a tow hitch in the front and hook up the Jeep to pull you through those long climbs!
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« Reply #32 on: July 08, 2013, 10:11:44 AM »

 Give serious consideration to bumping up the governor to 2400 plus to extend the range of your gearing, this works very well for the V730.>>>Dan
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« Reply #33 on: July 08, 2013, 12:03:26 PM »

N70's are 1.496 for standard timing for no smoke some old timers use 1.500  for coaches it's in da book

It is so confusing when the books say different things, as do the experts.  The book Brian posted shows 1.460" / advanced timing for an non-turbo N70, and standard timing only with a turbo.

One old tech here says N70's always get advanced timing.  But the most experienced 2-stroke tuning guy hasn't been consulted yet, and I haven't told them to dive into their books either.

Luvrbus - you've got more real experience than just about anyone, what book / settings are you referring to? I'd love to be able to point the guys here in the right direction.

Cheers,

  - Chris
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« Reply #34 on: July 08, 2013, 12:28:18 PM »

FWIW my Detroit manual shows 2300 full load rpm for the 1970/71 era 8V-71N engine with the N65 and N70 injectors.  I would guess that would be around 2450 no-load accounting for droop.  By no fault of mine that is what my 8V-71T is also set to, that's they way it came and I didn't change the high speed setting, just measured it.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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« Reply #35 on: July 08, 2013, 01:19:49 PM »

Guys I am not going to get into to the debate with your shop but the N70 with standard timing I found 1.484,1.496,1.500 and 1.520 been that way most if my life the 8v71T has more setting for the N70, was your engine A timed or not

 I also found 4 setting for the N65 with standard timing they have those books or should that shows the fuel curve, injectors,hp increases or decrease with setting
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« Reply #36 on: July 08, 2013, 03:42:33 PM »

Per my Detroit Diesel Field Service Data book, copyright 1983 rev. 6SE266 / June 1987 mailing # 46 inclusive. ( just so you know, this possession gives me no credibility.... Kiss )...there are 105 different injectors listed in the identification section....for 53 /71/ 92 series engines. ( Series 149 and 8.2L...not so many. )
The N series units are N55, 60,70,75, 80, 90, and 140.
the N55 and N60 uses an 8 hole @.0055", 165*degree A tip, as do ALL N series units.
the remaining units have 7 hole variants ranging from .006" /.0065" / to .0075"
the N 65's ARE NOT even listed as of 1983-6...for highway use,  they are listed as suitable for marine and stationary applications.
all plunger and bushings are unique to the individual and are not interchangeable IIRC, as are the plunger design.

incase you wish to know....7E65 injectors have built in Adv., C/S Timing.... but are not listed in a coach application Grin

If you need to know, 2.25 / .50 quarts of lube oil consumption
(recommended average) per 10 hours run time at 2300 rpm....AFTER 200 hrs or 35,000 hwy miles post rebuild/break in. probably....(indoubitably more during break-in )

 And # 2 diesel makes more  horsepower.... Roll Eyes
« Last Edit: July 08, 2013, 04:20:54 PM by eagle19952 » Logged

Donald PH
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« Reply #37 on: July 08, 2013, 04:09:16 PM »

You take it from here Donald these guys are wearing me out on the injectors and timing 

 I have all my injectors built for the middle range I never worry about the low end or high end in a bus ,it's probably me not explaining clearly but for what ever reason they don't get it that one injector can have 20+ configurations 
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« Reply #38 on: July 08, 2013, 04:13:17 PM »

You take it from here Donald these guys are wearing me out on the injectors and timing  

 I have all my injectors built for the middle range I never worry about the low end or high end in a bus ,it's probably me not explaining clearly but for what ever reason they don't get it that one injector can have 20+ configurations  

lol I am  probably falling on deaf ears. I may be a little rusty but it's like sex and bicycles...
it all comes back to you if you don't fall off... Angry Grin Angry

ps the mid range custom injectors of which Clifford speaks are probably not available to the general public...to know someone with the skills to produce same x's 8 ( in balance ) are more rare than 2 stroke > dudes <snort snort chuckle snort.. and for sure possess skills equal to or surpassing gunsmiths able to accurize 4000 yd sniper rifles.. but I digress....
« Last Edit: July 08, 2013, 04:34:15 PM by eagle19952 » Logged

Donald PH
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« Reply #39 on: July 08, 2013, 04:31:06 PM »

This is exactly what makes ME want to give up on this and the other chat groups.  I try to share what I know and what I've learned, and others offer cryptic references to secret documents and unknown manuals, and indeed don't explain things well at all, but obfuscate and obscure with every post.  It's obvious that there are many ways to set up this injector or that one, but if all you say is there are 20 ways to do it, I know how but I'm not going to tell you, what good does that do anyone at all?  I have asked a dozen times on this chat group what is the effect of different injection timing settings.  I have never gotten an single answer.  Anything I know I found to from SAE engineering publications and other papers elsewhere.  I'm also pretty fed up with this whole topic, I'm out.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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1972 NTM MK-4 B/SR
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« Reply #40 on: July 08, 2013, 04:41:49 PM »

Brian, I think all that I am saying is that there are many people here that are qualified to speak, that not all are eloquent in delivery..but ALL seem to reinforce the correctness of the specs.. you especially...but the people asking are seemingly wanting reinforcement after reinforcement....I know that you know and we know that Clifford knows...and you would probably understand what he says..
I can DO a lot of things that I can't explain in words to others...very well.
so I hope you don't think I am trying to out smart you...cuz I can't.
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Donald PH
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« Reply #41 on: July 08, 2013, 04:51:12 PM »

I am not talking about Brian I think you are a sharp guy I don't post all the info because it becomes a pissing contest 99% of the time. I tried to explain how you read a injector here before to help people that was a big mistake we had pink,yellow every color in the book  

 Hell I may will you all my manuals when I die
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« Reply #42 on: July 08, 2013, 04:59:23 PM »

Actually, seconds after I posted I considered this: A secret chord that David played...  (Leonard Cohen)

Now I've heard there was a secret chord
That David played, and it pleased the Lord
But you don't really care for music, do you?
It goes like this
The fourth, the fifth
The minor fall, the major lift
The baffled king composing Hallelujah

This reminds me that there are always secrets, if only because one person knows something yet cannot put into words to transfer that knowledge.  My life has been, as much as it has been anything, teaching but I got paid for selling.  David played a secret chord that pleased the Lord, yet he could not explain how he played it.

Peace, all.  In my little piece of world we have over 40 families waiting to hear if their loved ones were literally incinerated in a fireball from a train derailment that may have been caused by vandals, and many other much more serious things to really worry about.

Edit: in the completely off topic category, there is a pair of bald eagles that have been hanging around my place today.  There is something in the primate brain of a man that makes him just freak out when a bald eagle shadow flies over at around 60 - 70 feet off the deck, you just jump!  Anyway, I always think of Clifford and other Arizona people when I see a bald eagle, and I hope you are doing well with the heat wave.  I have no idea why a bald eagle makes me think of Arizona, but my bus did come from the Navajo nation...

Brian
« Last Edit: July 08, 2013, 05:12:37 PM by bevans6 » Logged

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« Reply #43 on: July 08, 2013, 05:30:55 PM »

I gave up long ago trying to get very much help from these bus boards. Some of the "gurus" can't write English to explain anything meaningful, or they throw in what seems like secret intel as a favor, but without explanation. I find the manuals and technical publications pertaining to what I need far more useful. And I go directly to the people whom I know have the correct information. Some of them I have met on these boards.

I still read every day mostly for entertainment, but hardly ever post, to stay out of this circus.

Have fun.

JC
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JC
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« Reply #44 on: July 08, 2013, 05:52:15 PM »

I know for me, the thing I most enjoy learning about are the "why's" -- I love digging deep and understanding how things work.

What are the changes that come from changing injector x to injector y, or timing A to timing B?

Why would someone choose one option over another?  What are the tradeoffs?  What are the tricks of the trade?

It is interesting to learn from the old timers and experts the ways that they would do something, or what they have done in the past. And this is invaluable information.

But there always seems to be a lot of the "why" missing - when luvrbus says he does it one way but "some old timers use 1.500  for coaches it's in da book" -- I am left wanting to understanding not just what the old timers have done - but why?  What were the reasons, and the tradeoffs?

There are decades of experience (and some instinct) at work here - it is probably nearly impossible to summarize.  But this sort of greater depth in answers is I imagine what some of us crave here on the forums.

We ask so many questions not out of disrespect, but because we value our predecessors in busnutting, and want to learn as much as we can.

  - Chris
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