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Trivia question on Heavy truck engines

 
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TheDriver




Joined: 18 Dec 2015
Posts: 198
Location: America

PostPosted: Mon Feb 01, 2016 2:05 am    Post subject: Trivia question on Heavy truck engines Reply with quote

Okay I want some trivial info on Engines used on the Heavy trucks. (Cummins VT903 vs. 318 Detroit Diesel?) Class 8 Diesel trucks that used Cat, 335 Cummins or 318 Detroit Diesels.
Here's some background info on me.
I used to drive and service 18 wheelers and have assumed to know a lot about them but it seems that I lack the true facts on certain engines and how each one stacks up against each other.
Like I say I drove many different types of truck and many sizes and configurations and engine sizes and trannys. I have driven a lot and in many different situations so I am qualified to form an opinion on the subject yet I found a very interesting thing that I want cleared up but I have no way of getting the facts on my own. The internet is great for most common things but not good for trivia.

I have always loved the Detroit Diesel for it's sound in a truck or bus and in the wet fields it actually is more able to keep the wheels from spinning. The Detroit Diesel is nimble and small and is quick off the line. Quick off the light and quick in the low gears and light load situations.
This describes a Chevy 350 truck engine on a farm truck but it does not have the torque so you have to give it gas when you want to go from a stop. Sort of like driving a toyota.
Caterpillar has been a heavy but a strong and fast engine that guys use to go fast. I mean over 100 MPH. I also operate heavy equipment so I know that this engine is solid. I don't like it on a truck for it's inability to properly respond to my throttle. All it knows is full on and full off.
Cummins has been a very dependable engine with great fuel economy.
Slow at the takeoff but torque soon kicks in at about 40 MPH and you see the speedometer move from there up.
We Know that the Detroit Diesel is a light engine and I have assumed that it was because it was poorly made but I found out from the internet that by most standards the Detroit Diesel was a solidly built engine. It was light because it has a small displacement even though it burned fuel like a big dog. Cummins would burn so little fuel and climb the hills much better than any Detroit Diesel. Cat never made any excuses for being a fuel hog. It was just that. But folks didn't care since they could leave everyone behind.
Now this being a "BUS" forum and me being a bus fan I also think about engines in buses and It has been my assumption that the Detroit Diesel was chosen for it's light weight and it's ability to boogie since buses are not heavy like the 18 wheelers tend to be.
This is the area where I am not very well informed.
The Cummins VT903 V8
1) I thought it might be a great replacement for the 2 stroke Detroit Diesel for better fuel economy, longevity and hill climbing ability.
2) I assume it would be a more solid engine and not weigh much more than the Detroit Diesel.
3) I assume that it would fit in the same space that the Detroit Diesel would occupy.
What I have found from other forums is that
1) You cannot beat a Detroit Diesel for it is a better built engine and more reliable.
2) Cummins VT903 has a lager bore and shorter stroke which results in less torque and higher fuel use. I thought the Detroit Diesel had the short stroke.
3) The Cummins VT903 seems to be a heavy engine.

Since I am having trouble finding info on the web I thought I'd post this here.
I sure would like any info on this subject
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traildriver




Joined: 26 Mar 2011
Posts: 907
Location: Queens, NY

PostPosted: Tue Feb 02, 2016 12:39 am    Post subject: Reply with quote

I find your comment about the CAT engine's interesting....
Our fleet used to have a few MCI 102C3's (purchased used) with CAT engines, and your comment hit home....I too found it difficult to modulate smoothly the throttle on them...they did seem either "on or off", resulting in an uncomfortable ride for passenger's. The Detroit throttles were much easier to control. I don't know if it was the engines or the type of throttle linkages that were responsible for that difference....
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TheDriver




Joined: 18 Dec 2015
Posts: 198
Location: America

PostPosted: Fri Feb 05, 2016 7:59 pm    Post subject: Reply with quote

I believe it was the floating rail. It seems to adjust to the changing loads not the feed from the throttle.
And as as the vehicle speeds up going down hill the need for your throttle to go farther down is needed to keep up with the engine so it makes your foot useless.
Going uphill the engine meets the load and so even as you may want to slow down the engine may want to go faster..
This engine really was made for the field and on a slow moving dozer.
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TheDriver




Joined: 18 Dec 2015
Posts: 198
Location: America

PostPosted: Sun Mar 20, 2016 11:37 am    Post subject: Reply with quote

Here's an update: just talked to a mechanic who isn't too familiar with truck engines but he thought that the Cummins was a lighter engine although it had a larger displacement. He says it was probably a better built engine than a Detroit Diesel and ran at a low R.P.M.
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