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Chevy 454 TBI diesel conversion


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TJKako
New User

Mar 4, 2017, 7:04 PM

Post #1 of 8 (4073 views)
  post locked   post icon Chevy 454 TBI diesel conversion  

1994
Chevrolet
K2500
7.4L

I left for a jobsite the other morning after realizing my gas gauge was bellow the half mark. It was 6:30am, the jobsite was 30 miles away in the middle of nowhere, and the only gas station in the one horse town I live in was closed. Normally this wouldn't be very exciting, except for the fact that I drive a 454 TBI and get what seams like -20mpg. long story short, my truck was almost on empty by the time I arrived at the job and it turned out there wasn't a drop of gasoline available. In a pinch I needed to get to another jobsite 45 miles away from the first and the only fuel around was some #1 diesel. I dumped 2-3 gallons in and went about my day. My truck was slightly boggish but seamed to run surprisingly good once up to running temp, and got double the mileage (possibly due to the diesel being thicker and not pushing through the injectors as easily).

This got me thinking, how hard would it be to convert a throttle body injected 454 to run off diesel? I'm assuming it's because it's TBI that it ran so good off diesel? Would it take much internal work or would diesel destroy a stock engine setup? I know the basic difference between diesel and gas being diesel uses compression and gas uses spark, but is there a way to do it? And make it reliable and not cost an arm and a leg? Maybe using components along the lines of a GM 5.7L 350CI diesel engine?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 4, 2017, 7:24 PM

Post #2 of 8 (4067 views)
  post locked   Re: Chevy 454 TBI diesel conversion  

Sorry for that disaster but diesel and "gas" are totally different in how they fire and work. It's just a maybe that adding diesel to a gas engine's tank just went to bottom for a while and unusable remaining gas floated up for a while and would eventually mix and not fire well or at all.
The one 5.7 GM diesel I knew of was an Olds block not Chevrolet at all and was a failure with the super high pressures couldn't take it. By that it was originally a gas engine converted with stronger but not strong enough head bolts in particular. They did get a real 30MPG no problem but few made it to 40K without total failures.


For a 100 reasons it's not feasible to change to that but rather work with what you have which will mean clearing out all diesel it has in it now.


Other is fuel pumps in tanks when run low enough get hot and fail quickly. If totally dry can't last at all new out of a box.


Suggestion is keep what you have and carry extra fuel if needed and never drop below 1/4 tank if possible. Know that when you really do run out there's still a couple gallons on bottom that will not pick up by static spot of the pick up sock and tube,


T



(This post was edited by Tom Greenleaf on Mar 4, 2017, 7:29 PM)


TJKako
New User

Mar 9, 2017, 7:54 PM

Post #3 of 8 (4019 views)
  post locked   Re: Chevy 454 TBI diesel conversion  

You are correct, I did a little more research and the GM 5.7L diesel, otherwise known as the LF9, isn't related to the 350 in any way. Although, the diesel in my pickup did burn quite decently and there was no need to clean it out. This isn't the first time it's been run off of diesel. Before I purchased the truck, I drove it for work at my old job, where it was ran off of diesel MANY times when ran low on fuel. Also, I know of a guy who has ran hundreds of gallons of diesel thru a Dodge 318. Both trucks are still running great after running diesel and they're both well over 20 years old!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 9, 2017, 8:13 PM

Post #4 of 8 (4015 views)
  post locked   Re: Chevy 454 TBI diesel conversion  

If you have all the answers, why are you asking us?

The bottom line is you can't make a diesel out of an engine with an 8.5:1 compression ratio.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 10, 2017, 2:00 AM

Post #5 of 8 (4007 views)
  post locked   Re: Chevy 454 TBI diesel conversion  

Keep it up and have two trucks permanently impossible to fix for the bucks it would cost, T



TJKako
New User

Mar 12, 2017, 7:32 PM

Post #6 of 8 (3991 views)
  post locked   Re: Chevy 454 TBI diesel conversion  

Never said I have all the answers! Just stating that diesel doesn't destroy an old gas engine when it is occasionally ran through.


TJKako
New User

Mar 12, 2017, 7:37 PM

Post #7 of 8 (3987 views)
  post locked   Re: Chevy 454 TBI diesel conversion  

Both trucks have been doing this for 15plus years. The only thing the diesel could ruin over time is the fuel system. I wasn't asking for a know it all to tell me that I'm ruining my truck, I am asking what all would need to be done to do a conversion. because I don't see why it's not possible, even if it were to take allot of work!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 12, 2017, 7:42 PM

Post #8 of 8 (3983 views)
  post locked   Re: Chevy 454 TBI diesel conversion  

This thread is not going anywhere so we'll close it now.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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