Any info on the 6-71 Detroit?

[Goofyexponent]

the old 6-71...they came as an inline (6-71) and as a V configutation (6v-71). As said before, you hold them to the mat and let them scream. The turbo'd version made 238 HP, which is why some of us truckers call them 238's. We also call them screamin' deamons, controlled oil leaks, etc.

They work fine, not the most powerful thing on the road, but one of the toughest!

 

[RampageFSJ]

Thanks a bunch for the information. I'm starting to think that I'm going to pass on the truck now. For some reason, the owner hasn't been answering his phone when I called him several times this weekend and he never sent me the pictures that he said he took on Friday. What irks me is that when I called his shop and an employee said the owner was away, he told me that his cell phone was working fine since he had just gotten done talking to him on it before I called.

I'm not sure if he's sold it and doesn't want to bother with me or what, but I'm not sure I want to deal with somebody who won't answer the phone for a potential buyer. Either way, I'm probably going to pass on this one and concentrate on building a shop.

 

[geonc]

The turbo'd version made 238 HP, which is why some of us truckers call them 238's.

Er...that is incorrect 238 bhp was in stock trim "naturally aspirated" with N60 injectors....power can be upped from there using N65 Brown Tag injectors and even N90 inj but the gear train will need to be advanced requiring removing the flywheel housing, also different inj timing....

In marine trim the last HP I recall working on was 450hp using 9215inj along with a fat turbo and raw water intercooling, along with different piston crowns, rings and liners....sadly that much fuel being forced in did not allow for a decent lifespan at all due to fuel wash in the cyls....

Also the term "318" used for 8V71 naturals referred to the hp....

 

[DeepRoots]

http://www.adieselengine.com/new_page_1.htm

It isn't perfect, but it's a good start.

 

[ameristar1]

Er...that is incorrect 238 bhp was in stock trim "naturally aspirated" with N60 injectors....power can be upped from there using N65 Brown Tag injectors and even N90 inj but the gear train will need to be advanced requiring removing the flywheel housing, also different inj timing....

In marine trim the last HP I recall working on was 450hp using 9215inj along with a fat turbo and raw water intercooling, along with different piston crowns, rings and liners....sadly that much fuel being forced in did not allow for a decent lifespan at all due to fuel wash in the cyls....

Also the term "318" used for 8V71 naturals referred to the hp....

Can you get more power out of these engines without killing them? Are there any injector, blower, timing combinations that are reliable?

 

[geonc]

dup post....

 

[geonc]

Can you get more power out of these engines without killing them? Are there any injector, blower, timing combinations that are reliable?

Blower does not change---except when you turbo the eng then just the rotor seals change from lip style to piston ring style...

For nat aspirated...N65 brown tags and advance gear train timing is a safe bet....but you can go if memory serves up to N80 but then you will get cyl wash...different piston crowns with keystone style fire rings, stellite valves---

note--most engines will most likely have them as they were introduced originally for turbod units but it was found that even the natural aspirated units did not burn them after they started removing the sulpher from the fuel...

the marinized units can make more power due to generally stablized load as opposed to hwy stop and go, along with less intake air restriction ---no filter just an air silencer, and a virtual unlimited supply of raw water cooling that not only flows thru the intercooler, but fuel and oil coolers as well.


Just what are your looking to do

 

[ameristar1]

This is later down the line after I get bored, as a toy more so than anything. I would like to put together a tribute rig to the guy who got me excited about trucking. It had a 8V-92TA (435 hp) and an Allison, and it was all in a stretched, double wide KW K100.
I loved that truck.

Tuning a 4 stroker is not hard to me, I have a pretty good grip on them. The two strokers I don't, and there aren't a lot of books to read on the subject that you can get easily. Can the blowers be overdriven, can the cams be made with more lift to push the injectors further and raise the exhaust valves higher to help scavenge the exhaust, can the liners be ported to improve performance?

 

[geonc]

Blowers already turn 2.5 times eng speed....no "special" grinds for the cams so you will have to provide some R+D on those if you want to change the ramp.... liners are "ported"--knife edged to assist swirl....if the exh valves open any more they are get real cozy with the pistons

Another thing to keep in mind is 71 series don't like getting over 3k turns....blower drives strip/grenade, cam followers rotate..........even the marine units have a MNL of 2650 for a 2500 rpm full load......

Now I have seen series 92 rods in 12v71's along with some over clocked blower drives, stoopid big injectors-145's , turbos, jacked up fuel return pressures etc... on some .....er....eh ....drug boats but of course they were not built with longevity in mind

 

[gatorman21218]

yeah on our marines we couldnt turn over 2150

 

[ameristar1]

Blowers already turn 2.5 times eng speed....no "special" grinds for the cams so you will have to provide some R+D on those if you want to change the ramp.... liners are "ported"--knife edged to assist swirl....if the exh valves open any more they are get real cozy with the pistons

Another thing to keep in mind is 71 series don't like getting over 3k turns....blower drives strip/grenade, cam followers rotate..........even the marine units have a MNL of 2650 for a 2500 rpm full load......

Now I have seen series 92 rods in 12v71's along with some over clocked blower drives, stoopid big injectors-145's , turbos, jacked up fuel return pressures etc... on some .....er....eh ....drug boats but of course they were not built with longevity in mind

Thanks for the response. What about the set ups used by the tractor pullers? I'm not talking about using the same thing, but some of these guys are spinning the 71s to almost 6000 rpms, but how the heck do they do that?

Hey, a 92 series with twins and lots of polish and chrome can be fun. And a 1000hp.

 

[DeepRoots]

ameristar, also remember regarding cams, there are no intake valves.

Geo... I have no experience with them, but didn't the 92 have a bypass for when the turbos were making alot more air pressure than the blower? If so, how was that arranged?
The engines "can" turn faster. Did I ever tell ya about the 12v149 that got stuck at 2600-2800rpms?

 

[ameristar1]

ameristar, also remember regarding cams, there are no intake valves.

Geo... I have no experience with them, but didn't the 92 have a bypass for when the turbos were making alot more air pressure than the blower? If so, how was that arranged?
The engines "can" turn faster. Did I ever tell ya about the 12v149 that got stuck at 2600-2800rpms?

True about the intake valves, I was just thinking adding some lift would help with the scavenging and porting the heads do the same.

A 12V-149 at 2800 rpms? She went on a runaway?

 

[Captain Morgan]

ameristar,

I have just the ticket for something for you to "tinker" with. My 1970 Pete 358S-T
with a 8v71 (N/A of course) and a lovely 4X4 duplex transmission. It is part of my last load from MT, still gotta go get it and my IH 4700.

I have only worked on a few 6-71 and several 4-53 and 4-71 and I am still no expert by any means. I will have to stick with the Yellow ones!

 

[geonc]

Geo... I have no experience with them, but didn't the 92 have a bypass for when the turbos were making alot more air pressure than the blower? If so, how was that arranged?

Drew, Yes but not in a way many would think---ie; blow off valve style---this may get long winded

Theroy of operation was that due to turbo'd Detroits being 2 cycle[actually needing the blowers to start and pump air at low speeds] and not using any form of boost limiting device ie; wastegate plus the fact that there is so much air box pressure 50 psi+ the blowers would actually interfere,restrict or in effect "choke" the incomming air from the turbos.......



What you are referring to was called "by-pass blowers" and they were your normal roots style blowers that had each end plate milled for a "small" beveled window approx 1.5" square on the lower [block end] inside face where the rotors met, and then vertical bored for a spring loaded piston that was splash lubed from the end plate oil galley that fed the rotor end bearings.

Seeing that there is no real way to "disengage" the blowers, it was a neat solution

The operation is regulated by air box pressure [boost]

When the eng is running at idle or low speeds, the bypass valves remain seated until the air box pressure is high enough to unseat them and allow "some" of that compressed air to sneak past the rotors and go directly into the airbox for combustion.


Damn...my brain hurts now