Yep, even Cat and Cummins tried their hands at V block engines in trucks. In the end they all stuck with the inline 6. Simple reason is in order to get the power needed out of the V blocks to compete you had to sacrifice longevity and dependability. The biggest thing the old two stroke Detroits had going for them is they were cheap to buy, cheap to maintain and cheap to operate. Power was not one of their strong points. They were often refered to as "Water trucks", as in, they would run down hill. LOL

 

One of the local guys around here claims he tuned his 8V-92 up enough to make 600HP on an engine dyno. Not sure how credible that is. Anyone else heard of detroits making nuts horsepower?

 

I always thought bore/stroke ratio and valvetrain mattered more than now the cylinders are arranged.

 

Don't forget about the MONSTER! The 3408 CAT ... Puts Detroits in their place, The SCRAP YARD!

-Enjoy
fh : )_~

 

Some of the 8V-92 TA's were rated for 500 HP. I suppose you could tune one up to hit 600 with some timing, injector, turbo and fuel pressure tweaks. Keep in mind tho, a engine dyno is not the same as putting it to the rear wheels. I wouldn't be a bit suprised to see Syco's IDI hit 250 or more HP on an engine dyno.

 

That is true when you are talking about getting the most out of an individual engine but has no bearing when both blocks are using the same basic valvetrain technology as a comparison of the two. An inline 6 has more main bearings, the crank is heavier, the stroke is longer. All that is good for torque and long life. Racers have a saying, Horsepower is how fast you hit the wall, Torque is how far you move it. LOL

 

I'm calling BS on that one. Either your odometer, your math or both are off. A 20K lb combined and 16+ mpg?
Maybe the 6% grades were downhill...

Jason

 

How do we know that anything is actually wrong with my stock N/A 7.3 IDI? It starts OK,doesnt smoke,and doesnt burn oil so most will say the compression must be decent even though I think it pulls like its down on compression.A mechanic friend listened to my truck and said theres nothing wrong with it.

I just got home from a local tractor pull where I talked to several people with lots of IDI experience as they used to own them.They all agreed the stock IDI's were good old motors that fall flat on their face when hooked to a loaded gooseneck trailer.

In the three years that I've owned my 1991 F-350 I've talked to numerous people at truck stops while fueling,at farm sales,at tractor shows,and at tractor pulls.When you drive a decent looking older truck it seems to get peoples attention and they come over and want to visit..I've yet to find one person that used to own one that said their stock 6.9 and 7.3 IDI pulled a trailer good and got decent mileage.

I live in farming and cattle country where trucks earn their keep pulling loaded gooseneck trailers and cattle trailers.Rural people arent bashful when talking about how a truck pulls.When I bought my IDI I made the mistake of listening to a loyal Ford man that thinks that Ford never did anything wrong.

The only way to make my truck pull is to completely rebuild the motor using 17-18 compression pistons and turbo it so I can run lots of boost.I really dont care to plow lots of money in to a $2500 truck.If anyone is interested my truck is for sale and it has had lots spent on it.The list is endless.

As for the old 2 cycle Detroits I love them.There are two on my farm right now.One is a 1967 Oliver 1950 farm tractor with a 4-53 that I tractor pull with.The other is a 1966 IH CO-4000 Transtar road tractor with a 8V-71 (318) Detroit in it.Theres what I should be pulling my trailer with but 4 mpg would be it.They are the sweetest sounding engines ever built.

 

you dont until you actually do a compression check and have the timing set properly.
guessing/assuming,and poor fuel economy while empty are all reasons to actually investigate to see if there is actually any thing wrong with it.
until you do,your not going to know.only guess and assume.your not going to hear low compression.id suggest a new mechanic (no offense to your friend.)
besides this,there was a post with 7.3l N/A IDI truck here that hauled 20k+ down the interstate,hauling a large dyno machine on a trailer.he had no issues cruising right along at 70 mph plus.something you claim is not achievable with yours.
i just remembered that story/thread and didn't tell ya before.
hang tight.i'll look for the thread now.

 

here you go SWMO,
see how his results compare to yours:
https://www.ford-trucks.com/forums/9...hlight=hauling

ok i was off a little.he claimed 65 mph,and 55 up most hills.a couple 3rd gear 45 mph,with 14/10 mpg.
skip to post # 37 for his results.

post #43 claims:
"its a 7.3 non turbo w 305/70 tires"

using posts 1's info.that w/ 4:56 gears and:
"with the 38s, it pulls a 3600lb car on an open trailer at 75 no problem. in the hills of PA, it will pull them 50-60 mph with the load and big tires."
the math shows,thats = to 3.80 actual rear gearing with his 38's on and for 20k load run getting 10 mpg he had 4.40 gearing with his 305/70 sneakers on.

a section of your story with 4.10's goes like this:
"It does OK empty and gets 13-14 mpg but 98% of the time its on a 25 ft gooseneck trailer.A 5000 lb empty trailer is a moderate load for it and it gets 11 mpg.Put 5-6000 lbs on the trailer and it absolutely works it to death and 6.5-7 mpg is all you will get.The slightest grade seems like Pikes Peak."

to me,these results are drastically different,and i would be inspecting the truck.real tests with compression and timing to start with,so you know where you stand.

compression:
https://www.ford-trucks.com/forums/9...a-7-3-idi.html

timing info in your other thread.though i suggest taking to a shop who has proper timing light.

how does your rig compare to John's w/3.55's in take off when empty?
https://www.ford-trucks.com/forums/9...ifference.html

 

I'm calling BS on that one too! None of the Power Strokes,Cummins,or Duramaxes pulling a combined 20K load in my area get 16 mpg on level ground. Most say they get 13-15 mpg with 14 mpg common.It all depends on the load they are pulling and the wind.

I know a guy that has a Duramax dually that pulls tall loads with lots of wind drag and he gets from 10-13 mpg depending upon the terrain and wind.

 

Stroke length has nothing to do with the arrangment of the cylinders. Maybe as a general rule inline engines tend to be "taller" but there is no law of physics that dictates a V8 (or V6 or V10) can't have the exact same bore and stroke of an inline 3, 4, 5, or 6 engine.

Maybe I am not following what you are trying to say.

I agree inline engines have more main bearings though. Number of cylinders +1 for inline, and 1/2 the number of cylinders +1 for V block.

 

Google RB Slagle or the Phoenix (worlds fastest diesel truck)

I know of a couple 8V-92's putting over 600 hp to the ground in this area. One of his other trucks is a IH log truck with a twin turbo 12V-71.

Jason

 

I know that story well because if you read it all you will see that I made a comment on it.One thing in his favor is that he was pulling a bumper hitch trailer and a low load with no wind drag.Few if any on here pulls a 5000 lb gooseneck trailer with tall and heavy loads.Thats a whole new ball game.IDI's that can pull a 20K load and get 10 mpg are few and far between.

If anyone wants to come by my place with a stock 7.3 IDI we will hook it on to my gooseneck and load up a 12,000 lb tractor.Theres a fairly level 4 lane 3 miles from me and we will see what you have.

I'll bet my timing is close.The sweet spot seems to be 1-2 dimes width to the passenger side of the timing mark.The Ford dealer around here doesnt have a mechanic that could even properly time an IDI.

 

i go by my gps for the miles. 275 or so round trip miles... 20 total 6% grade miles up hill, and the same down hill. on the down hill im in 3rd gear at like 2500 rpm or so just keeping me cruising. 16.7mpg is my average. i was at 12mpg before the turbo.