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Mack Engines 06 Oct 2010 11:54 #35198

  • GM Diesel
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Can someone explain what Mack engines were in what in the 60's-70's.
The B model had the thermodyne which I think was also known as a 711 ??....did this engine get used in the Flintstone.
The tip turbine intercooled engine was known as the Maxidyne. Was this the ENDT237 ?...what years or models was this used in.
Some of the R600's Ive looked at have an air - air intercooler in front of the rad....was this the coolpower ?

Confused Basil :-?
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Re: Mack Engines 06 Oct 2010 13:04 #35199

  • bigcam
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Hi Baz, I'm not right up on them, but I've seen a few. A 237 has no intercooler and a pressed inlet manifold. The coolpowers started at 285hp, with the tip turbine air to air, but there was also a 320, and a 350 coolpower with water in the tip turbine as well. The econodyne's have the intercooler in front of the radiator, about 1984 on I think, and in the old motors there was a 711 and a C motor, I thought the C motor was turboed but I not 100% sure.

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Re: Mack Engines 06 Oct 2010 17:25 #35200

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Gidday Cam,

I found alot of info on the Mack forum but I still cant tie it all together....eg I found a picture of an EM6-285 which has the charge air cooler up on top and the tip turbine setup.
Found a picture of a EM6-300 and its completely different to look at.
The M is for Maxidyne in the notation.
Another site reffered to the the donk with the charge air cooler on top as a Coolpower...
Buggered if I can work it out.

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Re: Mack Engines 06 Oct 2010 17:30 #35201

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I think the B61 had a END673 Thermodyne which might stand for Engine, Naturally aspirated, Diesel, 673 cubic inch. Swishy will know anyhow.

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Re: Mack Engines 06 Oct 2010 17:49 #35202

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Hi Pete,

I have this list Ive been putting together of the R models but im trying to understand whats unique from one Mack donk to the next. There was a model in the 400 series with a Scania engine also thats not in the list yet.
The EM6-285 comes up on the net but doesnt show up in the Mack info Ive been reading and using to put this list together.
Model Engine E/Man Fuel

R401 END475 Mack Diesel
R403 END465C Mack Diesel
R411 EN414A Dodge Petrol
R482 3208 Cat Diesel
R483 6V-53N Detroit Diesel
R487 ENDT475 Mack Diesel
R493 V555 Cummins Diesel
R567 END465D Mack Diesel
R607 END673P Mack Diesel
R609 EN707 Mack Petrol
R640 EN707 Mack Petrol
R679 6V-71N Detroit Diesel
R685 ENDT675 Maxidyne Mack Diesel
R686 ENDT675 Maxidyne Mack Diesel
R686R ENDT675 Maxidyne Mack Diesel
R688 ENDT675 Maxidyne Mack Diesel
R688R ENDT675 Maxidyne Mack Diesel
R690 ENDT675 Maxidyne Mack Diesel
R690R ENDT675 Maxidyne Mack Diesel
R709 END711 Mack Diesel
R711 ENDT673C Mack Diesel
R712 ETAZ673"300+" Mack Diesel
R715 END864 V8 Mack Diesel
R719 Twin Turbo ENDT 864 V8 Mack Diesel
R731 NH-230 Cummins Diesel
R737 NHC-250 Cummins Diesel
R747 NTC-290 Cummins Diesel
R763 NTC-335 Cummins Diesel
R766 NTC-400 Cummins Diesel
R767 NTC-350 Cummins Diesel
R769 8V-71N Detroit Diesel
R770 8V-92 Detroit Diesel
R771 12V-71 Detroit Diesel
R773 8V-71N Detroit Diesel
R785 ENDT 675 Maxidyne Mack Diesel
R785R ENDT 675 Maxidyne Mack Diesel
R786 ENDT 676"300" Series Maxidyne Mack Diesel
R788 350 Mack Diesel
R795 ENDT 865 Maxidyne Mack Diesel
R795R ENDT 865 Maxidyne Mack Diesel
R797 ENDT 866 Thermodyne Mack Diesel
R797R ENDT 866 V8 Mack Diesel
RL755 1693TA Cat Diesel
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Last edit: by GM Diesel.

Re: Mack Engines 06 Oct 2010 18:12 #35203

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I've forgotten ,more than eye kno
Bazza seems to have fathomed it out me thinks
the early macks had the Scania Vabris Lanova type motor ( n U can spl th@, any way u wanna)
the number is the Displacement Cu In
the B series macks were odd number for diesel B41, 61,63,65,75,81,LRX
Diesel Engines EN672, END 672, ENDS 672, END673, ENDL 673, ENDT 673, ENDLT 673,END 711,

Even number for B model Mack gas motors
Gas Engines EN-291,331, 401,
all the above gets U up to the 1960's
then after th@ all new ball game



There's more WORTH in KENWORTH

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Re: Mack Engines 06 Oct 2010 18:17 #35204

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Confused Basil - Geez, how many dozens of pages do ya want written up?? - and let me see how much I can get wrong.
Mack have more models of engines than any other manufacturer, I reckon .. with no rhyme nor reason, to any model numbering or nomenclature.
In America, the range of engines was mind-boggling. Fortunately, here in Oz, they kept the engine range to a smaller number of models.

In the era of which you speak, there are basically 3 engines in Oz Macks - the 672 cu in 6 cyl .. the 707 cu in 6 cyl, and the 866 cu in V8.

Let me go back .. way back. In 1950, Mack produced a new diesel engine, with a lot of fanfare. It was called the END672, and this engine was to be a major feature of Mack power for a long time.

This engine was 4 7/8" bore x 6" stroke for 672 cu. It wasn't long before Mack coined the "Thermodyne" name for their diesel range.

This engine used Lanova combustion chamber fuel injection. The injectors are stuck into the side of the head, squirting the fuel across a figure-8 shaped combustion chamber, into a precombustion chamber that is screwed into the opposite side of the head.

Engines using Lanova injection were rattley and limited to about 1800 RPM. The Lanova system could not be made to operate satisfactorily at the new, more efficient, high speed diesel requirements of 2000-2100RPM.

About 1957, this engine was redesigned with a totally new head and new fuel injection, using direct injection .. with assistance from Scania (Scania had the best, new, direct injection, combustion chamber design) .. and it became the END673. The engine used an in-line American Bosch fuel injection pump.

Mack turbocharged this engine a little later on and it became the ENDT673.
Mack were very conservative and continued to offer both non-turbo and turbo engines well into the 1960's.

I think the engine nomenclature sort of follows this style .. but I could be wrong a lot here, too ..

Front letters ..

EN = Engine model
D = Diesel
T = Turbocharged
B = Dynatard fitted
M = Marine version
A = ?
Z = ?

Numbers ..

672 = Original Lanova injection engine
673 = Upgraded, re-engineered, new model, direct injection engine
675 = Re-engineered, improved Maxidyne model engine
676 = Re-engineered, up-dated, improved Coolpower model

Letters after the numbers ..

A .. Original engine
B .. Upgraded, re-engineered model
C .. As above
D .. As above
E .. As above

In 1962, a new model of engine appeared. This had a 5" bore and 6" stroke, for 707 cu inches. This was the END711. Rated at 211 HP in Naturally-Aspirated version, it later became 250HP when the turbo version appeared, the next year. This became commonly known locally as the "C" engine, when the revised ENDT711C model became a common local engine.

The first Mack V8 appeared in 1962 as well. It was 866 cu inches and called the ENDT864. Later models were the ENDT865 and ENDT866. These engines were plagued with problems and were unreliable.

The Maxidyne engine appeared in late 1966, for the 1967 model year.
This engine was called the ENDT675 .. and it was re-engineered again with bigger head bolts, stronger crank, stronger conrods, heavier pistons .. and it used totally new design principles that involved a turbocharger that produced more air, as the RPM's dropped off .. and a fuel pump that continued to inject the same amount of fuel as the RPM's dropped.

The design idea behind the Maxidyne, was to produce a new, extremely-high-torque rise engine, that would reduce the number of gears, and therefore, the amount of gearshifting required.

This engine appeared with a brand new design, triple-countershaft gearbox, designed to match the massive torque of the new Maxidyne engine .. the Maxitorque.
The Maxitorque initially only came with 5 or 6 speeds .. however, a little later, 10 and 12 speed versions appeared.

The Maxidyne engine produced a staggering torque rise of 53%, when most engines produced about 20% torque rise. The Maxidyne produced 237 HP at 2100 RPM .. but it churned out a massive, shaft-twisting 906 ft lbs of torque at 1200 RPM.
Compare this, with the biggest Cummins available at the time .. the NTC-335, which produced 900 ft lbs of torque, along with its 335 HP.

The 711 engine was still offered along with the Maxidyne, well into the early 1970's.
The next version of the Maxidyne, produced around about 1973, was the Coolpower. There were two Coolpower engines initially .. the 285 HP and the 320 HP versions.

The Coolpower still used the Maxidyne principle .. but added a tip-turbine, air-to-air intercooler, mounted on the engine.
The tip-turbine intercooler used bleed-off air from the turbocharger to drive it. Here's a good diagram of the tip-turbine intercooler on the Coolpower engines ..


I can't recall exactly how the 320 Coolpower got its extra horses, whether it was bigger turbo, more fuel or a combination of both.
The next series was the E6 series engines. These were 2 valve engines (E6-300) .. and 4 valve versions (E6-350) appeared later. These were termed the Econodyne.
These engines dispensed with the problematic tip-turbine intercoolers, and used straight air-to-air intercoolers mounted in front of the radiator.

The R-model appeared as the Flintstone in 1965. I seem to recall that the fibreglass front was offered as an option, but it took a while for it to catch on. When it did, the Flintstone died a natural death. Not sure on the dates when the fibreglass-bonnet first appeared .. maybe 1966 or 67? .. or when the last Flintstone was built? 1970? ..

So .. getting back to your query .. yes, the Flintstone used the ENDT711 or the ENDT673 engines.
Not sure how many Flintstones came out with the ENDT675 Maxidyne. I suspect some of them were fitted with it. Most Flintstones seemed to be fitted with the ENDT711, because it was Macks "biggest" 6, and produced 250 HP, as against the 237 HP of the Maxidyne.
Not many Flintstone owners obviously looked at the torque figures, because the 711 engine produced substantially less torque than the Maxidyne.

Remember that an engine you're looking at in a truck isn't necessarily the original. Every second truck doesn't have an original engine.
Engines blow up or wear out every 5 years on average .. and many a repower is done using an engine from another model truck .. often a totally different year truck .. and often a different HP truck.

Bear in mind, that Mack re-engineered their engines constantly. They would produce new modifications every couple of years. Even with the Maxidyne, they actually cast a new block by the mid 1970's, as the early blocks were prone to cracking at the lower rear, near the bellhousing.

I hope this helps a bit, it's the best of my knowledge and fading memory. I guess someone will come along now, and tell me I got half this wrong.

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Re: Mack Engines 06 Oct 2010 18:55 #35205

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Swish - Scania had nothing to do with the design of the Mack Lanova engines (the early model -November 1938, and the later model, END672, in 1950).

Scania did not come into the picture with Mack until the mid-1950's, when Mack paid Scania for their direct injection diesel engine design.
In 1963, Mack produced the END465 & END475 in conjunction with Scania, and it was labelled the Mack-Scania (or Scania-Vabis) END465 or END475. The 465/475 was actually built by Scania in its entirety, it was the Scania DS8 engine in Sweden.
The link between Scania and Mack came about when Mack licensed Scania to build Mack buses in Sweden.

This turboed END475 engine was 190 HP as against the bigger END673's 225 HP. I'm not sure we saw the END475 in Australia?

Bazza - Here's some more help, from the ATHS forum. Don't forget that Aussie-built Macks diverged substantially from the American models, due to Mack Australia having a lot of independence, and building trucks to Aussie requirements.


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Re: Mack Engines 06 Oct 2010 19:22 #35206

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Ron youve earned yourself a couple of beers for that effort. What a good read. Makes it clear now what is what.
Not that im up to anything but I just wanted to try and understand what all the numbers, letters and Dynes, maxies, and cooly pops reffered to.

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Re: Mack Engines 06 Oct 2010 19:54 #35207

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Baz - No worries .. I'll be over shortly to pick up the award .. ;D

Here's a little more "gold" on the Mack Model B numbers and engines, from a fella on bigmacktrucks.com. It's just a PDF file with all his gathered (but incomplete) data from Mack spec sheets.

It's well worth saving, and maybe someone will be able to fill in the "holes".

I have a sneaking suspicion I made an error with the NTC-335 torque figure, too .. and I think it was actually only 830 ft lbs .. but I can't find it written down anywhere .. :(


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