Power difference after FDC bypass

[Lax]

Okay. Once again I ask what can I burn with the FDC bypassed?? Is my truck still a USABLE AND TRUE MULTIFUEL or just a diesel??? If it is not a multifuel now that is fine. I will try to reverse the bypass. If it is a multifuel but with limited choices that is fine but I need to know what are my choices. That is all. I'm not trying to be short with anyone or a jerk but within about two or three answers we are way off topic with no answers but a million opinions. Thank you and sorry for sounding crabby.

 

[OPCOM]

short answer:
use diesel in your multifuel engine when the FDC is bypassed.

long answer:
Supposed to burn diesel according to the stickers on the Toole-rebuilt engine with FDC bypassed that says "diesel fuel only". That sticker came from the army after they did the work. Their work including recalibrating the injection pump. If you don't want any trouble and don't want to go on the opinions or reports of what people have done, just use diesel. Can't go wrong with diesel. The engine itself is still a multifuel and will try to burn what you put in it, but no longer has the capability with the FDC bypassed to adjust the fuel rate properly for burning other fuels and mixtures of fuels. Some people here have lots of $ and like to try all kinds of things and if they blow it up, oh well.. Others like myself do not wish to blow it up. Is the cost of having to replace the engine due to burning odds and ends in the thing worth the economies of doing so?

 

[cranetruck]

The FDC has nothing to do with the combustion of the fuel, burn bio, veggie, kero, engine oil, anything, there may be some power differences, but probably not noticable in average around town use. The multifuel uses a slow combustion process based on a patent owned by MAN in Germany (license notice on engine tag) and is a very efficient engine with more complete combustion.
The FDC was patented by Continental and is only an add-on device controlling the amount of fuel delivered to the IP. It makes adjustments according to the viscosity of the fuel and will only work for fuels that have a BTU heating value, which increases with its viscosity. True for fuels listed on the data tag, but not all, biodiesel is an exception, where the FDC works in the opposite, reducing amount delivered when it really should increase it. Still, no effect on the engine's ability to burn it.
Even if the IP was "recalibrated", it would not change the combustion process.
The FDC does not "protect" the engine in any way.

 

[cranetruck]

Got a request for these instructions, might as well show them to all (from MVM article).

 

[yorkgulch2]

performance differences on gas

So the bottom line is that performance will suffer on gas more if the FDC is bypassed than if it is not. Is that correct.
Also with the FDC bypassed and running diesel it will run better than without the FDC by passed ?? Some responses indicate little or no difference that maybe individual unit condition or fuel age and quality.
Craig

 

[67Beast]

Re: performance differences on gas

with the FDC bypassed and running diesel it will run better than without the FDC by passed ?? Some responses indicate little or no difference that maybe individual unit condition or fuel age and quality.
Craig

Mine runs great with the bypass and straight diesel. About the same it would be for turning up the IP pump.

 

[Djfreema]

RE: Re: performance differences on gas

I ran about 5 gallons gas mixed with about 42 gallons diesel and didnt notice any difference and that was with the FDC bypassed. I plan on throwing some WVO in the mix soon.

 

[WillWagner]

RE: Re: performance differences on gas

I run mine reguarly on diesel/gas mix. On the trip to Barstow, I purposly ran it out of fuel and filled it with all diesel and bypassed the FDC, had a leak at the little plate on top. The only thing I noticed was a little more smoke on acceleration. No power differences, not really that much MPG difference. The only thing I notice if I run more gas than diesel is a lope at hot idle. I had the heads off and the pistons and cylinders looked fine, but that was b-4 the bypass. It is still in bypass and I just put 40 gal of less than 50% diesel and gas mix and it seems to run fine. Guess it's just cleaning the carbon off of the nozzle tips!

 

[67Beast]

Well I drove 100 miles yesterday, all hiway and the truck ran great. I was able to hold a comfortable 55 mph @ 2400 rpm everywhere, even up the bigger hills I was on, and was able to push it to 60 mph @ 2650 rpm anytime I wanted. On straight diesel I burned just under a 1/4 tank to cover the 100 miles. I very happy with the bypass. And on a side note I got to meet the guy who wrote the article on how to bypass the FDC which is Pierre Jalving. I definately need to get down to his place and wander through some of the stuff he has.

 

[JDToumanian]

Why loop the fuel lines into one another when bypassing the FDC? Couldn't the tee pieces be unscrewed and plugs put in their place instead?...

I just think it would look cleaner to have the holes plugged than to see the fuel lines looped around like that.

Jon

 

[rdixiemiller]

Get a pyro and hook it up. Mine runs great with the FDC bypassed! It also is running the EGT's WAY too high! I can hit 1400 with no trouble at all. I don't really know the "burn down the engine" point, but the general consensus seems to be not to exceed 1150 to 1200 F on a long hill. I'm going to back my fuel rate off some until I get to that point on a hill. Yours may not be going too high, but I would definately check it. Don't get me wrong, I love the way mine runs right now! I just don't want to slag down the pistons and fry the turbo.
A pyro can be nothing more than a K thermocouple and a Fluke volt meter. I think my K thermocouple was 15 bux used, and I have 2 fluke meters.

 

[rdixiemiller]

Jon
The lines are looped like that so you can re-connect everything in an emergency (if needed). Keeps all necessary parts in place so they don't get lost.