hello,
Can anybody tell me what's the best way to convert a fresh rebuild 460EFI engine to propane?
Wich system to use?
What's giving best milage?
Brands/types, preferrably DIY conversions?
Any info is highly appreciated, thanks.

 

Please note mileage will decrese when you switch to LP. That being said. What year is it? An IMPCO CA425 Mixer and either a Impco Model E Vaporiser or Century M6 Vaporiser will do ther job on a stock engine. Depending on the year/electronics involed you made need some addl "support" Also I recommend you NOT to use the Impco vacumn Fuellock (shut off) Use a century 2384B or equivilent. To answer yor main question start by contacting your local LP Gas Supplier to locate a conversion shop. If you dont have LP Experiance Its not a DIY job. If I can help any more let me know.

Regards
Gasman

 

Moderator, please delete this entry.

Sorry, I thought I was responding to a thread I introduced in the alternate fuels forum and the NorCal forum. Ignore the rest of this. I was talking about my truck.

It is a '91 "Bounder" motorhome, which probably means a 1990 Truck. OBD I.

I'm been in contact with the California Air Resources Board which controls all this stuff. They have a specific requirement that I am struggling with. They require that any modification like this be warranted by the manufacturer like a new vehicle. There are no manufacturers CARB certifying product for a 1991 platform. Apparently, the market is too small to warrant the expense.

I'll check into your recommendations and I thank you for them. If they are not CARB certified, I am at a brick wall.

 

If you are going with single fuel natural gas, open that block up again and increase the compression ratio to about 16:1. The gas will burn more efficiently and you'll be happier with the performance. LP has higher octane, but has less energy than gasoline for an equivalent volume.

You will probably want to advance your timing as well.

 

Mr. Gasman, i DO have expirience with LPG systems.
I have more lincolns, and one has a 300A mixer, and the one i want to switch the engine from, had a 300A system as well, and i converted it about 2-3 months ago to a holley valveplate and a impco 425.
We are not allowed here to use the vacuuum-shutoff valves, and use the electrical ones.
The problem with the LP gas shops around here, is that they're not familiar with such engines, and directly scream: " can't do it" or "impco 425".
Here in the Netherlands, the average engine is the size of a milkbottle....
There's just simply not much expirience in systems for such engines, and besides they calculate enormous amounts for such systems, IF they want to install them.
Add the fact that i'm handy and curious, i really want to make it myself, and gather as much info from forums like these, and make my own system.
So, any info you can give me is very highly appreciated!

Thanks!.

AnOldDog:
There are KB 138 pistons in them now. They have a dish from 22cc's in them, so flattops would gain some. The highest CR i can make is 11.5:1 with the KB401 wich have -11CC dome's...
They cost quite a bit however, so my intention was to get the engine fully running and drive it, and then, when i want to, open it up again (what a work... easyer to do when it's in my barn...) and change pistons..

maybe there are others that know where to get them for a reasonable price, or better alternatives?
16:1 seems quite high though for LPG. In Netherlands LPG is a mix of butane and propane, and has a mixture of 40/60 and 60/40 depending in witer or summer.
Also it has some impurity's, wich lower the octane.
If i'm right, the octane of LPG here is 108Ron at it's best. So lets calculate with 103-105, then i think 16:1 is on the risky side (and not achievable with the hardware available, i guess...)
correct me all if i'm wrong. thanks!

 

It will run fine at 10:1. It just won't deliver the power. The octane rating where you are may be different so don't quote me for where you live, but the higher you can get it, the better your performance will be. Well, at least until you blow up your engine

NG is used a lot around here for agricultural utility purposes. This is a common conversion.

 

but, getting back into one of my hardest q's: how do you get the gas into the engine?
injection? (how, which parts, links, advice!...)
or with a 425?

 

http://franzh.home.texas.net/

This guy posts often on an alt fuel forum with others. he is the go to guy for anything and everything.


http://www.propaneguy.com/ Another cool link

 

http://www.dualcurve.com/

 

Any other info?
It's not that hard to throw a 300A or a 425 in front of it, but how do i trick/fool the computer? Do i simply disconnect the central power lead of the injectors, fooling the computer by thinking he's actuating the injectors?
Any info very helpful, as i just purchased a '82 lincoln markVI, which has a 5.0L injection also.
Thanks!!

 

The dual curve support unit will "fool" the computor into not setting a code and turning on the light and allow you to reset the timing. The Impco CA300 is a bit small for a 460 but will work fine on a 302. Impco makes adaptors so that you can splice them into the air intake ahead of the throttle body. I have work for LP equipment Distributors in the US since high school so I fall into the habit of saying "Contact your local LP dealer" due to liability, if you can find the equipment and feel comfortable installing it, Go for it

Good Luck

 

ok, so, i need a dualcurve unit for sure?
Does this also takes care of disconnecting the injectors and so forth?

Now, about the adaptors:
Do you mean that the mixer comes before, or after the throttlebody, seen in the direction of the airstream?
You also say "splice" ...? So, i can mechanically connect/disconnect the mixer, like the 300A does with the handle?
Do you have some more info on that, and maybe some good shops on where to buy such?

Thanks!!

edit: PS. I need the info for the 460-EFI, as well for the 302: i bought a Lincoln mark-VI also with a 302 injection

 

The Dual Curve doesn't disconnect the injectors. Depending on the engine you may not have to, However I know Autotronics (Dual Curve) has some support boxes to do it and most of them are "Plug and Play" using the factory connections. On the simplest installations you would cut the air intake tubes between the throttle body and the air box. You can put filters directly on the CA300 and or CA425 they also had at one time a shroud that you could put over either unit so you could tie back into the factory filter.
Depends on how much room you have. The CA425 would be the better choice for the 460 it will pass more air and fuel than the CA300 the numbers by the way are the cfm of the units. I have seen some applications where you would need 2-CA425's due to HP of the engine. The 425 unfortunitly doesn't open like the CA300 so while it will work on Bi-fuel systems it will degrad the gasoline mpg due to restricting the airflow. If you are running dedecated LP then it doesn't matter except for engine size.

PS I am at a loss as to where you can purchase equipment outside of the US but I can put you in touch with some US distributors