Running Methanol as a sole basis of fuel on an EFI car?

Floyd · Post by **Floyd** » Sun Apr 03, 2005 9:50 pm

I was wondering if anyone on here has done this yet? If so could you please point me to how you constructed your fuel system and what kind of engine management you are using?

I'm going to be running "Big Stuff 3" and it's capable of running up 16 injectors. I'm under the assumption that it would be best to run twice as many injectors with a Methanol system. Assumptions are the mother of you know what so hopefully someone here can educate me a little on this subject?

Thanks for the replies/advice

Floyd.

bill jones · Post by **bill jones** » Sun Apr 03, 2005 10:07 pm

-in the engine forum there's a guy "let er eat" who asked a question about helping him design a set of headers.
-When I quizzed him about the engine it came out that he's using individual stacks and individual throttle and EFI with methanol, for an off road type application.
-You might find that thread which is several days back and ask him what he's doing.

Floyd · Post by **Floyd** » Mon Apr 04, 2005 2:59 am

Found the thread. Thanks for the heads up.

autorace · Post by **autorace** » Mon Apr 04, 2005 1:30 pm

It very simple. The most important thing is that for every HP you need on lb/hr of fuel. If you were going to make 1500 HP you need 1500 lb/hr of fuel divided by number of injectors. If 8 injectors you would need 187.5 lb/hr injectors. The common injectors are 160 lb/hr which would be good for 1280 HP, so you can add injectors above that. It will slightly change on the engine BSFC requirements but this is a good rule of thumb. You also need a fuel pump that can handle that much fuel for that HP, best ones are the mechanicals.

airflowdevelop · Post by **airflowdevelop** » Mon Apr 04, 2005 1:56 pm

now their is also a limited production 220 lb and 250 lb injector. it has been rumored that hilborn is doing this conversion on a deka style injector. I have played with a couple sets, and work very well. mototron also has a large alky compatible injector.

biggest problem is coming up with a devisor for closed loop operation from gas to alky. most people will tell you you start by using 2. we have found that 2.07 - 2.11 works best on the newer boxes (bs3,dfi7,etc)

also, forget about using the bosch o2 with alky.....keep with the ntk.

Dennis

Floyd · Post by **Floyd** » Mon Apr 04, 2005 2:21 pm

Autorace what % duty cycle would you reccomend I run the injectors? I know most people reccomend keeping them at 80% but I'm not sure if the same rule of thumb applies to Methanol. If I'm shooting for 1200 HP with a power adder (I'm very conservative on the abilities of my build

) and have 8 injectors thats 150lb injectors. If I want to keep the injectors at the 80% level I would need enough fuel for 1440 HP or 180lb injectors. Someone correct me if my math is wrong.

biggest problem is coming up with a devisor for closed loop operation from gas to alky. most people will tell you you start by using 2. we have found that 2.07 - 2.11 works best on the newer boxes (bs3,dfi7,etc)

Dennis

how exactly are you guys setting up the fuel systems on these cars? 2 seperate fuel cells or using a sumped gas tank and a fuel cell?

Thanks for the advice/information guys I appreciate it.

Floyd.

airflowdevelop · Post by **airflowdevelop** » Mon Apr 04, 2005 5:05 pm

everything I have played with is a single fuel system, no gas. It will start fine on alcohol.

if you are running a good pintle injector, they will tolerate 70# of fuel pressure..this should get you out of the woods. If you carry 90% duty cycle on your richest possible tune...you will be fine. injector drivers have come a long way, so the primary concern these days is leaning the tune out.

Thanks
Dennis

Floyd · Post by **Floyd** » Mon Apr 04, 2005 5:24 pm

What is the coldest temp you have started a methanol only car?

Also are there any other drawbacks with running methanol? Will I have to keep all air out of the fuel system?

autorace · Post by **autorace** » Mon Apr 04, 2005 7:33 pm

The duty cyle you should stay below 85% although I have run the 160 lb/hr at 100% which just stay open at that and won't flow less. The smaller injectors above 80% will decrease flow. What power adder are you running? I have not run the bigger injectors than 160's mainly because of the price. I find it is cheaper to run 16 160's at $50 ea. than 8 200's at $200.00 ea. When running alcohol for a weekend race I put it in on Friday and drain it Monday morning. You will want to flush it with regualr gasoline on Monday and start the motor briefly. I leave the alcohol program in and build fuel pressure and then turn off the fuel pump, when the motor starts to die I click the fuel pump briefly to keep it running. I find this quicker than changing out the program and you don't need the laptop.

Grocerius Maximus · Post by **Grocerius Maximus** » Tue Apr 05, 2005 10:57 am

The only problem with the Bosch 160 lb/hr units is they can be pretty inconsistent. After all they are an OEM CNG injector. And there are two different ones- 5 ohm and .5 ohm. The .5 ohm will be capable of higher pressures and will be more consistent maintaining small differences in PW., but your ECU must have 8 amp capable peak/hold injector drivers to use them directly without a ballast resistor.
It pays to have someone test them (or any other low priced 'off the shelf' injector) at various duty cycles and RPM's, you'll be shocked at how far off a 'matched' set of injectors can be.
If your ECU allows individual injector trims by RPM by all means take advantage, your engine will like it. I've tested sets that while within 1% volume at static, were off by more than 6% at lower duty cycles and different RPM's.

If you need to run high (over 100 PSI differential) fuel pressures and run high RPM's, you really don't have much choice but to spend money on racing specific injectors. The real high-end stuff is 24v 20+ amp fast response very high pressure (up to 30 bar) that requires specific electronics.

autorace · Post by **autorace** » Thu Apr 07, 2005 10:18 am

Grocerius Maximus,

Do you have any information or links on those injectors and what electronics do you have to run? How do you get to the 24 volts?

Thanks

Floyd · Post by **Floyd** » Fri Apr 08, 2005 12:17 am

I'm interested too.... Really appreciate the help btw

How much power is ussually gained by switching over to methanol vs gasoline?

Floyd