711 Turbo

[michael57]

Hi I'm new to this site and not much time on the computer at all so if i dont do this right, sorry. Well i'm from Austraila just west of Brisbane in Queensland, i have just got an old R600 What we call a Flintstone it's got a 711 motor with a 5x4 transmission 38 boggie backend And i way thinking about turbo ing the 711 or putting in a 370 hp V8 If anyone knows anything about what i will have ahead of me please reply Thanks R600

[Freightrain]

With the issues with 711's I'd probably just replace it. Does it have the big head bolts in the corners?? They had had gasket problems and the bigger bolts were to help hold it all together better.

I can't say that the 711 had oil cooled pistons, so If you plan on running it hard I would again just replace the motor than try to turn it up.

Good luck and WELCOME to BMT!

[terry]

The first engine with oil cooled pistons was the 673C engine with 250 hp. Terry

[HK Trucking]

With the issues with 711's I'd probably just replace it. Does it have the big head bolts in the corners?? They had had gasket problems and the bigger bolts were to help hold it all together better.

Actually, the ones with the big studs at the corners were the ones with the older type non fire ring head gaskets.

The 711's with all 5/8 head studs were the later model (about '65 on up) which had the fire ring head gaskets.

None of the 711's had piston coolers.

I once bought a junkyard engine which turned out to be a 711 which had a turbo added on.

Reportedly Mack had a factory conversion kit for this back in the mid 60's.

Hopefully Rob will respond to this thread, as he has a 711 turbo motor in a B61 which he has done some modifications to.

[theakerstwo]

Actually, the ones with the big studs at the corners were the ones with the older type non fire ring head gaskets.

The 711's with all 5/8 head studs were the later model (about '65 on up) which had the fire ring head gaskets.

None of the 711's had piston coolers.

I once bought a junkyard engine which turned out to be a 711 which had a turbo added on.

Reportedly Mack had a factory conversion kit for this back in the mid 60's.

Hopefully Rob will respond to this thread, as he has a 711 turbo motor in a B61 which he has done some modifications to.

You are right about the head bolts I worked for a mack dealership when that engine came out and it is ok to turbo them but do not set up the fuel because it has a hi copression piston and it is still hard on head gaskets .I would be ok to set up fuel if the truck does not have to work but just play. glenn

[terry]

Are you sure the 711 had fire rings? Never seen a 5 inch bore with fire rings, but you never know. Terry

You are right about the head bolts I worked for a mack dealership when that engine came out and it is ok to turbo them but do not set up the fuel because it has a hi copression piston and it is still hard on head gaskets .I would be ok to set up fuel if the truck does not have to work but just play. glenn

[HK Trucking]

Are you sure the 711 had fire rings?

Only the later models with all 5/8 head studs.

[Rob]

Actually, the ones with the big studs at the corners were the ones with the older type non fire ring head gaskets.

The 711's with all 5/8 head studs were the later model (about '65 on up) which had the fire ring head gaskets.

None of the 711's had piston coolers.

I once bought a junkyard engine which turned out to be a 711 which had a turbo added on.

Reportedly Mack had a factory conversion kit for this back in the mid 60's.

Hopefully Rob will respond to this thread, as he has a 711 turbo motor in a B61 which he has done some modifications to.

Hi Herb, still need to get up your way but just can't get away from broken equipment.

My B-61 with the turbocharged 711 is a 1964 model. It was not built as a factory turbocharged engine but rather the "official" Mack factory conversion. The engine is back to stock configuration now as I ran out of time and patience till another day with the project.

Many of us with B model trucks have similar powertrains so I started with a simple goal in mind: To make 300 reliable horses at 1800rpm from a "Thermodyne" series engine without any exotic modifications to make it more durable, hence a bone stock 711 that had a notoriety to it. I have several other non fire ring 673 engines, but only this one 711. It therefore did not matter a lot if it blew up. A friend of a friend that builds sprint, and stock car engines had a chassis dynamometer which was mine to use at the time but was not set up to set up semi tractors, so we had to be a little creative.

I sent a "reasonably good" Garret T-18 turbocharger (large) to another friend in Texas that I went to high school with, along with an injection pump from a Maxidyne series ENDT-676 engine, injectors and an exhaust manifold from the 676 engine, along with the horsepower, and torque specifications I was trying to achieve. The injection pump was sent to someone that does a lot of "trick" pump work as my friend only builds/tests turbochargers for a living. What I got back was a "cored out" exhaust manifold that was "Jet Hot" coated, a special machined adapter to mount the turbo to the manifold, the original injection pump recalibrated with 11mm barrels, modified injectors with more spray holes, and a different turbocharger (smaller) mapped to fit the engine characteristics.

When assembled, and with the exception of some different plumbing to get everything married up, the engine did not idle any different than before. It was a different story upon stepping on the throttle though. Older Mack trucks and black smoke seem synonymous, so I didn't think too much of it but the increase in power was very noticable. I also think the oil bath air cleaner was a little restrictive. After driving to the dyno shop and figgering out how to chain the truck to the floor, removing the rear driveshaft, and outer rear tires, I was almost ready to obtain some measurements. This dynamometer was not set up for tandem drives, or the width needed for duals.

Unfortunately, I broke the cable needed for the pyrometer, (my big feet) at first so was unable to obtain exhaust temperature readings but the engine was making 312 horsepower at 1825 rpm, and almost 790 ft. pounds torque at 1630 rpm. All seemed to be happy until near 1875 rpm the engine was again loaded, the engine started to develop a miss that turned out to be a head gasket let go between the number 2&3 cylinder as I watched a flame shooting out the side of the engine at the back side of the turbo. After unchaining, unhooking, evaluating figures, I then decided to change the headgaskets the next day. The engine was pretty warm at this time from the loading.

After removing the cylinder heads and carting them to the machine shop, they were rebuilt. The ports and bowls were matched to the exhaust manifold, all new valves, springs, retainers, keepers, and guides were installed. The mating surfaces were also planed .010 to ensure a perfectly flat sealing surface for the new gaskets. The block deck was "straight edged" and had about .006 from one end to the other and well within specs.

The engine was assembled, and a compression check made on all six cylinders and all were within 10% of each other I thought I was good to go. After the rechaining, wiring and all needed things to test the engine again, we were ready to go. It was really surprising to achieve almost the same result as before but a little more horsepower (317 as opposed to 312) at 1875 rpm when the new head gasket let go at the same exact spot. Well after spending nearly a $1000.00 at the machine shop and parts house, I was ready to conquer this challenge. I called Victor-Reinz corporate direct and spoke with one of their engineers to come up with a solution (hopefully) to why this engine would blow two sets of head gaskets in the same place twice at damn near the same operating parameter. It was recommended that I use one of the graphite based gaskets with the stainless steel ring around the cylinder(s) as my engine did not have fire rings. After acquiring two of these $86.00 gaskets, and installing them we then hooked the truck up again to have the same exact thing happen again!! At this point it was time for a breather to figger out where the project was jinxed so I put standard gaskets back in and the original turbo, manifold, injectors, and pump back on the engine which has now run fine for a couple of years.

The truck for all practicle purposes is past prime but runs well so I keep it around for a "yard dog". I can only assume the head gasket(s) blowing at the same point and operating parameter are due to a non fire ring engine coupled with the deck sealing surface having a bit of warp to it even though it is within factory specifications. As we can tell, I was way outside the design parameters of the engine, so in my opinion there is no fault to be concerned with. On the final engine run on the dyno, I did have a boost pressure gauge hooked up and 28psi was the reading at 1875rpm. The original Schwitzer turbocharger runs between 9-11psi which is nowhere near maximum loading.

This was just my "playing around" to both learn and see if all could benefit from anything. I think one could get a reliable 275 horsepower from a 711 engine but would be sure to fit a pyrometer and drive by it. I don't know if a hobby truck would need improvements in power or not but by today's standards, 170 horsepower is a little lacking. I basically wanted to see if it could be done.

Just one of my many varied experiences. Enough spouting off for now.

Rob

[terry]

Rob i believe if you would have used a 673 engine you can put the fire ring liners in it and have the heads scored for the fire ring, you can have an old style engine with the newer style head gasket. terry

[Rob]

Rob i believe if you would have used a 673 engine you can put the fire ring liners in it and have the heads scored for the fire ring, you can have an old style engine with the newer style head gasket. terry

Hi Terry, I have heard a person could do that. I was not trying to develop something solely for my own use but rather something that anyone could accomplish on their engines with little effort such as bolt on parts. There are a lot of old 673, and 711's still out there and are underpowered, and non fire ring. Often the cost to rebuild an engine exceeds the value of the truck hence the thought process on this idea.

Thanks,

Rob

[HK Trucking]

Rob, do you think it would have stayed together if it was a later model 711 with the fire ring heads?

The original poster has an R model, so I'm thinking he would have the later style 711 with fire rings.

[Rob]

Rob, do you think it would have stayed together if it was a later model 711 with the fire ring heads?

The original poster has an R model, so I'm thinking he would have the later style 711 with fire rings.

I believe it would have as I was only using about 2/3 throttle via a remote cable. I can't say for sure because there was no pyrometer installed so I don't have/know all the available information. My thoughts are that I hit the mechanical limits of the design. I also purposely did not incorporate any charge air cooling because of underhood room in the average B model.

Rob

[michael57]

I believe it would have as I was only using about 2/3 throttle via a remote cable. I can't say for sure because there was no pyrometer installed so I don't have/know all the available information. My thoughts are that I hit the mechanical limits of the design. I also purposely did not incorporate any charge air cooling because of underhood room in the average B model.

Rob

Hi and thanks for all the replies, yes my motor is the later one with all the same size head studs. Rob could you tell me what the original turbo was and what i would have to get to set my motor up as per Mack had the kits for Regards Michael R600

[Rob]

Hi and thanks for all the replies, yes my motor is the later one with all the same size head studs. Rob could you tell me what the original turbo was and what i would have to get to set my motor up as per Mack had the kits for Regards Michael R600

I'll get some pictures for you along with part numbers. The tag is still on the turbo, and the manifold piping has casting numbers on the pieces.

Rob

[michael57]

I'll get some pictures for you along with part numbers. The tag is still on the turbo, and the manifold piping has casting numbers on the pieces.

Rob

thanks regards Michael

[jackson.hancock.@gmail.com]

Okay so just wondering I haven't seen anyone do this yet can you just ,fire ring, the head and block to seal these old motors like you would a 12valve cummins that way you could maybe get 225hp to 300 without blowing head gaskets 👍

 

Edited October 15, 2019 by jackson.hancock.@gmail.com
Added

[terry]

Bet you can if you can find the tools, when they true up the head surface they have to cut new fire rings in.     terry

[jackson.hancock.@gmail.com]

So even if the block nor heads came with the grooves you can have them machined into them

 

[theakerstwo]

1 hour ago, jackson.hancock.@gmail.com said:

So even if the block nor heads came with the grooves you can have them machined into them

 

The block would be same and yes the heads can be cut.I have never seen fire rings on a 711.When the 673b and c first came out it did not have fire rings but same engine as a maxsidyne did have fire rings so when guys over hauled the 673 b and c they used the maxidyne liners and cut the deck on the heads for fire rings.