Methanol in Diesels

[tdirs1]

I race a VW Golf Tdi and along with lots of diesel i also use methanol as a fuel not an anti detonant.At the rolling road i picked up 40hp at the flywheel up to 223hp and 204.5@ wheels.My question is what damage can the methanol do to the engine?The engine note changes alot when its on boost and the methanol is being injected and it sounds like the big ends are going to drop out!!

 

[Metalguy]

Add a little nitro to your methanol and those noises will get a lot louder-at least for a second or two.

What do your bearings look like? Have you pulled the head and looked? Oil analysis?

 

[tdirs1]

Well to be honest i bent all the rods and vapourized part of 1 of the pistons!!But the rods were std and the pistons were machined a little too much on the valve cut outs but the bearings are fine as is the rest of the motor so im having stronger rods made and new std unmachined pistons so i dont think ill have the problem return.As i part own a vw audi specialist repair garage i change the oil every 3k miles so i havnt really needed any oil analysis.Also the rest of the pistons are fine too.I am going to try a little bit of nitro when its back together but as its a daily driver i just need to be a bit careful as to ruducing reliability.

 

[Metalguy]

Uh, unless you're racing in a "bone-stock" class, IMO you can't win with a "daily driver"-the 2 term are mutually exclusive.

 

[tdirs1]

As i drag race in the uk and the class system im allowed to use any fuel i like as long as my car doesnt go any quicker than 11.99 and as im at 13.2 at moment ive a bit of work to do!!

 

[Metalguy]

How much boost? Do your pistons have forced-oil cooling from beneath? BTW, I was involved in a failure analysis of a *big* con rod that bent. It weighed about 250 lb. but the failure mechanism isn't possible in your engine.

 

[tdirs1]

I currently run 30 psi boost and the pistons are cooled by oil jets.Its as if the rods have been shortned as they've bent in both ways in direction of rotation and to the side too

 

[ShaunT]

Sometimes a lighter oil will help cool better because it circulates faster. Oil is not just a lubricant, but also a coolant, as we all know, but sometimes keep that knowledge in the back of our heads. If you haven't already, switch to a full synthetic(LIGHT weight)oil.

Have fun.

Shaun TiedeULTRADYNE/LUNATI Arl,TX(stiede@ev1.net)

 

[dgallup]

To start with the methanol will be very corrosive to your fuel injection system so expect it to wear out much faster than normal. I also expect that the cylinder pressure rise is much faster than on straight diesel. You probably need to retard your injection timing with this more volatile fuel mixture. You need a cylinder pressure transducer, an engine speed sensor and an oscilloscope to properly adjust the pump timing on the dyno. You want peak cylinder pressure to occur a few degrees ATDC. Try to keep the rate of pressure rise down as well if you want the bearings to live.

I hope your joking about this being a daily driver because you have already virtually destroyed the engine with 4 bent rods and a burnt piston!

 

[tdirs1]

No not joking it is a daily driver.The methanol has its own fuel supply stainless tank,pump,plastic fuel lines,filters and fuel rail.I found out that because i reduced the compression to run higher boost ive needed to run the injection timing quite advanced but now the pistons are std un machined but the rods are being made slightly shorter i will be able to retard the timing.

 

[Metalguy]

Many years ago I had a mild, NA SBC running with a methanol/oxygen combo for "extra power". I mounted a SS fire ext. in the trunk for the meth., and used a 12V tire inflator to pressurize it to ~30 psi. A small lightweight cyl. of oxygen lasted a long time, but it tended to detonate easily.

 

[SMOKEY44211]

Just a thought. It sounds like you're detonating the methanol. The pressure spike is occuring before TDC exposing the weakest link falure that you've experienced. Addmittedly you get some benifit from the latent heat of vaporazation on the intake conduit.My suggestion is to eliminate the methanol(btu value per volume is about 1/2 that of the diesel fuel), pull the cr ratio down to 17:1 kick the boost up, and/or increase the intercooler capacity and adjust the fuel curve to take advantage of the increase in air supply. This should keep the pressure spike about the same as before but the BMEP will be higher overall. See if you can get some info from one of the guys that race those diesel trucks. The guy I think is the most knowledgable in this area is Gale Banks. Wishing you the best of luck----Phil

 

[deanc]

After driving VWs and VW diesels for years,I only have one thing to say(which surprise some in this group).

WOW!