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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Lin on July 06, 2013, 08:12:33 PM



Title: Optimizing 8v71 High Altitude Performance
Post by: Lin on July 06, 2013, 08:12:33 PM
A lot of the trips we have been taking involve mountains. A non turbo 8v71 is really doing its best at around sea level, so we are getting poor performance a good part of the time.  We are not going to turbo it, so forget that option.  My question is whether there is a way to tune the engine's performance at some altitude, like 3000 feet so we would get some better power higher up, but not cause problems lower down.


Title: High Speed Blower Gearing And Smaller Injectors
Post by: HB of CJ on July 06, 2013, 08:21:51 PM
Not much you can do, other than going to a smaller injector and the rare high altitude blower gear train that speeds up the blower.  I am not sure if that is going to help at ALL altitudes; setting up the N engine for high altitude helps up high, ( a little) but MAY not improve things down low.  HB of CJ (old coot)


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: RJ on July 06, 2013, 08:43:41 PM
Lin -

The BEST way to get the most performance out of your 8V71N while playing around on Rocky Top is to remember which character you're driving based on Aesop's Fables "The Tortoise and the Hare" - and it's NOT the Hare!

 ;D


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia on July 06, 2013, 09:06:14 PM
Since we opted not to turbo our 8V71 during our rebuild...  we're making sure our music and podcast collection is well stocked for helping get through the high altitude roaming :)

 - Cherie


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: Lin on July 06, 2013, 09:43:33 PM
It is not so much the speed of the ascent that I am concerned about.  On the last trip, the bus did not have the power to pull the Jeep through a hairpin turn at 6000 feet.  We had to disconnect to continue.  This is always an option, but it would be nice to have been able to just keep on going.  Of course, as mentioned it is not worth the cost of a turbo for me.


Title: Re: High Speed Blower Gearing And Smaller Injectors
Post by: technomadia on July 06, 2013, 11:41:37 PM
Not much you can do, other than going to a smaller injector...

I'm curious how the injectors affect performance at altitude.  In the next day or so we need to decide what injector to use in our 8V71 rebuild, and I am still weighing whether to go N70 or N65... 

Will the N65 outperform an N70 driving at 6,000 - 8,000 feet elevation?  How about doing a pass at 10,000?

  - Chris


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: chessie4905 on July 07, 2013, 01:15:10 AM
 If given the choice, I'd prefer turbo with smaller injectors over non turbo with bigger ones. Being a newly rebuilt engine in the hot summer weather, I'd go with N65's. You could always upgrade down the road when you decide to turbo it or desire more power and/or tune-up. You can use a lower boost turbo with standard compression pistons.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: 06 Bill on July 07, 2013, 02:26:07 AM
When we have been in not enough power spots, we put a non steering driver in the toad, start her up and actually help push the bus. A few hundred feet will usually do it, stop, reset toad, retrieve driver and off you go. Amazing how much this helps. Just the ol' country boy way.     06 Bill


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: bevans6 on July 07, 2013, 03:47:48 AM
Power is roughly based on fuel and air, so when you put more fuel in than the engine can burn based on availability of air, you run out of steam.  You kind of hit a wall where more fuel doesn't add much power.  So optimizing the airflow with the turbo is always the first option, second might be over-speed the blower, always have the intake filters and exhaust optimized, and then at the end of the day turn the engine faster.  More RPM equals more bangs per minute, equals more power until you hit the intake and exhaust limits.  Mostly this doesn't work in a bus, you only have a few gears, the road tends to dictate speed so your rpm is what it is.  You could usefully raise the high idle setting a few hundred rpm, maybe to 2400 or 2500, and get to stay in a lower gear longer with good effect climbing a hill but there are other impacts from that change.  Different injectors will add more or less fuel per stroke, maybe change the curve of how they add fuel as the rack opens or closes, maybe change the atomization of the fuel in the chamber and affect burn speed but at the end of the day when it starts to roll coal (smoke heavily) from too much fuel for the amount of air you have, you are getting all the power your combination can make.

Brian


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: lostagain on July 07, 2013, 06:43:40 AM
Before I turboed the 4-71 in the Courier 96, I built a ram air scoop for the air intake on the roof. Remarkable how well it worked starting at 20 mph: a lot less smoke out the tail pipe.

JC


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: Lin on July 07, 2013, 07:31:56 AM
I like the idea of the Jeep giving the bus a boost in a jam.  I do not know if it would have worked in last weeks situation, but I'm sure it could help sometime.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: TomC on July 07, 2013, 07:56:54 AM
When I turbo'd my engine, I went all the way by having a custom air to air intercooler made and went with larger injectors. I know you don't want to turbo, but consider this-if you do install what we call a "smoke turbo" it will put out about 5psi, you keep the same injectors, don't have to change anything on or in the engine and it keeps the same power from sea level up to altitude. It is the only real way you'll get the same performance. Yes you could go with a different gear ratio on the blower to spin it faster-but then you'll have a hit on fuel mileage all the time. The nice side benefit of installing a smoke turbo with the same injectors is you'll have more power coming from the same injectors. For instance, with the same N65 injectors, the non turbo engine will be 304hp and 800lb/ft torque. Add the turbo and you'll be at 325hp and 975lb/ft torque-just more efficient.  Talking from experience-turbocharging really wakes up the 8V-71 even without changing the injectors. Good Luck, TomC


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus on July 07, 2013, 08:11:13 AM
I don't think Don will work on a bus now but find someone to install a high capacity blower they made 14 different blowers for a 8v71 just for different operations and altitude they do fine with the different blowers at lower altitude turboing one is &&& even with out a after or inter cooler 


The best way to go is the turbo if you need or want all the power


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia on July 07, 2013, 08:45:18 AM
Thanks everyone for the great tips!

I never knew there were different blowers for the 8V71. Are they just geared differently, or do they have different lobes as well? Our Detroit book makes no mention of any options other than "Blower Speed is 2.05 Times Engine Speed". If there are 14 different types, is there a way we could tell whether or not ours might already be different than stock? Where can high capacity blowers be found?

I am still a bit confused though as to the tradeoffs between injectors. All things being equal (standard blower, no smoke turbo, no full turbo) - are there places/cases where an N65 will outperform an N70?

The shop here is happy to install either - we just need to figure out the tradeoffs and pick one.

Cheers,

   - Chris



Title: Re: Optimizing 8v71 High Altitude Performance
Post by: muldoonman on July 07, 2013, 09:29:46 AM
Hey Cris, just tell the shop what you want, the most power you can get safely and reliable. If they are Detroit 2 stroke guys they should have a solution for you. 


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia on July 07, 2013, 09:36:51 AM
Hey Cris, just tell the shop what you want, the most power you can get safely and reliable. If they are Detroit 2 stroke guys they should have a solution for you. 

The shop here thinks that both N65's and N70's are good options.

The old 2-stroke expert here thinks N70's - but he admits he doesn't care much about making smoke or fuel economy.
The younger 2-stroke guy thinks N65's - should still be plenty of power, and potentially less smoke and a bit better economy.

In the end - they suggest comparing notes with other bus guys and letting them know which way we want to go...

  - Chris


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: Lin on July 07, 2013, 09:58:18 AM
When we replaced my old C60 injectors, Don went with the N65's.  I do not remember discussing N70's but I believe he wanted to give me the safest upgrade.  I think that my engine having the older dry block my have been part of the decision.

Now with regard to getting more air to the engine, would a toggled booster fan at the air intake make any difference?  I have sometimes thought of spraying propane in the intake also, but wonder whether, since lack of air is the issue, it would make any difference for this problem.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: muldoonman on July 07, 2013, 10:44:32 AM
I have the 8V92TA in my 40,000 lb. coach and have all the power we need  but have heard of the propane addition on Detriots but does it start affecting reliability? More heat and pressure in engine? Wondering if it was like my old drag car days when we first tried nitrous. Blew a engine or two up before we figured it out. Just curious.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: Barn Owl on July 07, 2013, 10:52:45 AM
The difference between the injectors is one allows you to put more fuel into the engine if you choose. The 65 will take that choice away. BTW, you can still make both of them smoke at altitude.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: Ed Hackenbruch on July 07, 2013, 11:35:35 AM
Can't remember for sure, its been awhile since i looked, but i think that i have N60s in my 8v71. Get some smoke at altitude even with those, i just let up on the pedal and or gear down as needed.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia on July 07, 2013, 11:35:56 AM
The difference between the injectors is one allows you to put more fuel into the engine if you choose. The 65 will take that choice away.

This is what I have been trying to understand - will the N70's with a light foot on the throttle end up with the economy and smoke characteristics of an N65? But if I punch it (and there is enough air), the N70's will give me a little more oomph?

That seems like a good plan.

  - Chris


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus on July 07, 2013, 12:13:32 PM
You guys are out to lunch on the injectors the 65 will produce more smoke it has 8 holes (brown tag) on a angle, the 70's have 7 holes straight same size holes in tip 006 only major difference is the plunger the N65 uses a N65 plunger the 70's use the 7N plunger now the white tag N65 is a totally different animal 

Go with old guy he can set the 70's where there is not much smoke if he sets those at a 304 hp which is the max for a N65 the 70's you can go to the full 318 hp and then they do smoke 


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: bevans6 on July 07, 2013, 12:33:58 PM
That is my theory too - my N80's can smoke with the best of them at full throttle, full load, but are clean clean clean at part throttle part load.  Don't forget that the throttle control (actually sometimes called the speed control in the manual, since there is no throttle) only has a tangential impact on where the governor sets the injector racks and hence the amount of fuel injected.  If you set the speed control lever to let you run at 60 mph on the flat and you start to climb a hill the governor will try to maintain that speed and will increase fuel to do so.  It will eventually have the racks full open while you haven't changed your foot position at all.  I never felt this with the 8V-71N but it is quite apparent with the 8V-71T, I could really hear the engine note change when I got to a hill and the feeling of power being added was tremendous.  What I do is adjust the mirror so I can see the smoke.  If I want the power I ignore it, if I am being polite I vary my foot to adjust.  Don't forget that where you set the injector timing can have an impact on power and smoke.  If you advance the timing you can inject the fuel earlier, which has the effect of starting the combustion event earlier, increases cylinder pressure and heat, makes more power and burns more of the fuel reducing smoke and some other pollutants.  The downside is you can burn up the engine.  It's all a balance.  I have no clue which injectors you should have, btw.  If it was me I'd just keep what I had if they were good, and use the N70's.  If not, I'd install the set of brown tag N65's I have on my shelf, left over from my engine swap which need a good home...  :)

Brian


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: pvcces on July 07, 2013, 09:53:59 PM
Chris, I didn't see where you said which cam timing your coach has. As I understood it, standard timing used N60 injectors and advanced timing used N65s. The best fuel economy that I know about occurs with standard timed engines. With advanced timing, RPM has to be kept higher and more heat is generated. It seems like the power band is wider with standard timed engines.

Our coach uses standard timing and N60s, and it will smoke plenty at 6,000 feet. It's quite noticeable at 3,000 feet. I would not consider going to larger injectors without a very good reason. I do understand that adjustment of the rack can make a big difference.

I figure that the hydrogen in the fuel is stripped off first and then the carbon is burned only if there is enough oxygen left. When you're at high elevation, there is a bunch of leftover carbon, hence the soot in the exhaust. Since we get no work out of the carbon in the exhaust, it stands to reason that power output is reduced accordingly at high elevation.

Imagine what the effect might be if oxygen was added to the air intake at high elevation. Since no one that we know of is using that setup, there may be some unwanted effects that go with it.

I did see that propane injection seemed to be well tolerated by the people that tried it.

Tom Caffrey


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: TomC on July 08, 2013, 06:56:26 AM
If you do alot of altitude driving, DON'T go with the N70's-you'll be smoking like a locomotive. Mine had N65's that I had to pull up on the accelerator about an inch to keep it from smoking at altitude. But then you don't have much power. Once again-turbocharge the engine and you don't have to worry about smoking at altitude plus you'll get better fuel mileage. If you're going to keep the bus for a while, you'll be very pleased with turbocharging. Good Luck, TomC


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus on July 08, 2013, 07:33:45 AM
Their engine had 70's it's well documented by the 2 they had no smoke I setting up a 8v71 NA now with the 70's it had no prior smoke either just don't use A timing

A timing You don't A time a 92 series N/A or turbo it can all be done through the injectors


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia on July 08, 2013, 08:32:08 AM
Their engine had 70's it's well documented by the 2 they had no smoke I setting up a 8v71 NA now with the 70's it had no prior smoke either just don't use A timing

Very good point - we hardly had any smoke with our old engine setup and N70's when we first bought the bus, and took it up to Flagstaff, AZ to escape the heat. That was near 7,000ft elevation.

As for A-timing though...  The shop here seems to think that A-timing is a must for N65's and N70's.

What is the reasoning not to go A-timing?  Is there some documentation I should point them to in order to convince them that standard timed N70's are a good idea?

  - Chris


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: bevans6 on July 08, 2013, 09:31:53 AM
Chris, I will email you directly a PDF file that shows the recommended timing settings for the two injectors, and has a great description of how they work.  The N65 brown tag non-turbo has a recommended setting of 1.484 with advanced cam timing and 1.460 with standard cam timing.  The N70 non turbohas only one recommended setting, that is 1.460 with advanced cam timing.  You can see that 1.460 is more advanced than 1.484, so the N70 is, compared to the N65, getting advance from both the timing setting and from the cam gear setting.  This is in line with my earlier comment that a more advanced setting allows more fuel more time to combust, increases power and reduces smoke.  Also recall that the advanced cam setting also advances the exhaust valve timing so the exhaust valve opens and closes sooner, starting the compression event earlier and ending it earlier.  This should have the effect of increasing dynamic compression but reducing the length of the power stroke interval.  I honestly have no idea what effect that would have, probably reduces efficiency and increases fuel consumption.  But it's clear that the recommended cam wheel timing is advanced for both injectors.  I think standard timed N70's are a quite bad idea, and it might be a good idea to let the experts you have hired do their thing.  If you don't believe they know their craft, why are you letting them work on your engine?

You are far better with computers than I, maybe you can post the PDF file in a manner that all can access it who care to.  I think the server I took it from it gone now, it was on George Brown College in Toronto.

Brian


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus on July 08, 2013, 09:35:58 AM
N70's are 1.496 for standard timing for no smoke some old timers use 1.500  for coaches it's in da book


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: bevans6 on July 08, 2013, 09:39:08 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!  :)  FWIW, the numbers I quoted match those in my 1980 Detroit Diesel manual for 1970/71 engines with N65 and N70 in natural engines.  Clifford rightly points out that there is more than one way to skin a cat, and you can get different results with different settings.

Brian


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia 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!  :)

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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: treeplanter 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!


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: Utahclaimjumper 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: bevans6 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: eagle19952 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.... :-* )...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.... ::)


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus 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 


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: eagle19952 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... >:( ;D >:(

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....


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: bevans6 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: eagle19952 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.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: bevans6 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: lostagain 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia 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


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: Lin on July 08, 2013, 06:01:28 PM
I am definitely not an expert here, but it would seem that one has to have some confidence in experience promoting the best compromise.  There is no perfect injector and setting; it is all compromise.  This means that, in most cases, close enough is good enough.  You will either never notice the difference or adapt to using the machine as you learn its idiosyncrasies.  If one is unwilling to do that, your other option is to swap engines to one with so much power that you will never feel any issue and convert the bedroom to a radiator.  As mentioned before, there was a guy near here selling an 06 with an 8V92 (could that do wheelees?).

C&C, I understand what you are going through.  I have a strong tendency to want to define the very best option in purchases; especially high dollar ones that I will have to live with for a long period of time.  However, it is not as if you can program some algorithm that will adjust to every situation.  Which is better, 80 degrees at 50% humidity or 75 degrees at 60 % humidity?  At some point, if you have confidence in the mechanics doing the work, you will have to let them make decisions.  If you do not have any confidence, that's a problem since you will not be able to train them with second hand information.

I hope that this is not one of those shops that posts an hourly rate, a higher one if you watch, and a higher one if you offer suggestions.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: eagle19952 on July 08, 2013, 06:40:10 PM
Here is a factoid that might win a round of final  Jeopardy....
All Detroit Diesel engines nominal hp ratings are determined at 500' elevation @ 85*F.
 ;D


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: luvrbus on July 08, 2013, 06:54:35 PM
It really doesn't make any difference what is said here people do what they want to it's their bus and JC is probably referring to me about with the writing and it true I just don't take the time then I have Canadian friends I don't understand them 1/2 the time plus I never had to write and explain things a good secretary is hard to beat

I watched him get beat up when he installed high compression pistons in his 471 when he tubroed it all the experts said he was doomed I bet the engine is still running I didn't have a problem with it because I do it all the time then another DD guy may say it's crazy


 My buddy Don Fairchild question me about the 20:1 on my 92 it's still running we disagree from time to time he is not always right neither am I but we remain friends if he doesn't come pick these engines up soon that will be questionable lol

 My motto is  if one doesn't get off the coach and outside the box it's a waste of time  

Very few here do their own engine work so what's the point of posting every little detail

Don doesn't post here he doesn't care for it, Geoff is a sharp guy he doesn't like it either, Dr Detroit,Dallas,Cole,Andy and others are long gone what I am trying to say C&C ask 5 DD guys you get 5 different answers we all do it different  

We are finishing up a 8v71 rebuild I let Doyle do most of his own work including the injectors,valves,rack and governor I just check behind him he is doing good, the problem will be he will do it oneway the way he was shown by me

 I should have stayed off the board but Lin shamed me into coming back and that won't happen again lol take it over Donald


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: eagle19952 on July 08, 2013, 07:13:27 PM
Clifford I can copy stuff out of books and I know where to find my tools and service manuals.
and I can tell when some mechanic is bs'ing. I get what you are saying....people need to pick one horse and go with it to the finish.
you keep doing what your doing ... ;)
and i'll keep using K&N FILTERS.... :o
I will say that running a 2 screw rack is an art well learned...but every time I lost my favorite big fisted stubby screw driver I had to re develop my touch  ;D.....and I never could balance the bounce of each control rack with anything but my finger...and as I rotate a rack I watched for the ball to lift and rotate each rack simultaneously...before I start tho I was taught it's best toloosen and free up the balls in the rack stands and oil them.
I used a buck knife or o pipefitters welding wedge spacer to spread the stands....
like you say everyonre is different.


Title: Re: Optimizing 8v71 High Altitude Performance
Post by: technomadia on July 08, 2013, 07:16:07 PM
At some point, if you have confidence in the mechanics doing the work, you will have to let them make decisions.  If you do not have any confidence, that's a problem since you will not be able to train them with second hand information.

I'm not digging up information to second guess the mechanics here - I am doing it because I am loving learning about the inner workings of our engine. It is a wonderful beautiful machine - and we are loving the chance to literally see and touch every single piece of it.

I love being able to actually refer to books, wisdom and experience.

As luvrbus said - five different DD guys might give five different answers.  It is interesting to learn how they came to their conclusions, and to learn from their years of experience. This is exactly why I love having luvrbus on the forums, and I love that so many other experts are willing to share their experience and wisdom here and via phone.

Learning about these engines is a blast - that is why we are nuts, right?

I hope that this is not one of those shops that posts an hourly rate, a higher one if you watch, and a higher one if you offer suggestions.

Actually - much to our delight this shop has been incredibly welcoming, inviting us to watch, and going out of their way to not just show us everything but to explain the inner workings. They love that we are so interested, and they encourage us to tap into other experts and they are eager to hear what we learn.

They have capped the number of hours on the estimate too, so they are not running up the clock in the process - and they even lowered their hourly rate & hours when they gave us the final quote.

And they have given us access to tools and equipment and help for tackling a few other projects while we are here too.

Overall I couldn't be more pleased with this shop.  They aren't the cheapest, but they are being extremely thorough, and providing us an invaluable education too.

  - Chris