OkinawaFD3S

iTrader: (14)

Hey y'all,


As a guy who loves cars, but loves investing and saving, I find myself in a unique predicament.

We can only get premium gas off base, which is like $8/gal, but on base low octane gas is like $3/gal. Even after my most recent tune I'm still getting lousy gas mileage, so I'm trying to find a solution.

I had the understanding that since water injection raises the overall octane rating of the mixture going into the motor that it could be used to compensate for using lower octane fuel. I spoke to my tuner over here and he wasent tracking on any of that.

Could I get some input from you smart gentlemen?

fendamonky

iTrader: (6)

Injecting water doesn't raise octane rating, however it will help decrease knock.

Guys in cali and the west only have 91 octane, proper tuning and water injection go a long way

fendamonky

iTrader: (6)

Also... you're driving a 400whp rx7, what exactly were you expecting for fuel economy?

(Octane rating and fuel economy aren't related, higher octane just means higher resistance yo predetonation/knock.)

Tem120

iTrader: (5)

theoretically you can , but you will need to retune . your whole timing map will need to get retarded and boost will need to go down as well , even with water injection to combat knock .

Tem120

iTrader: (5)

if you ran pure meth , with a 3d map you may be able ot run more advanced timing as the higher octane form the meth may help with that issue .. BUT then you need a VERY reliable meth system , that flows quite a bit of meth look at howard colemen's setup you will need something like that . and then retune for it .


This is a dark slippery slope you're going and you will not have the power you have now.

fendamonky

iTrader: (6)

Running pure methanol as an additional injectant is a horrible idea. Running meth as a fuel works, but you need to run LOTS of it (think e85 conversion).

Howard Coleman is an excellent example of pure methanols effectiveness as an additional injectant... he tried to make it work for years and his only real result was blown engine after blown engine...

Military aviation initiated using additional injectants WAAAYYYY back in they day and found that running pure alcohol flat out didn't work...

Straight water is fine, WM50 (50/50 water/meth, by weight) is fine, pure methanol is not.

Monkman33

iTrader: (28)

This.

OkinawaFD3S

iTrader: (14)

Thanks for the very insightful input ya'll. It being a weekend car only, I'll just bite the bullet and continue on. Seems like it's more work than it's worth.

dradon03

iTrader: (2)

What? They found that running Isopropyl achool had no beneficial effects.

Have you ever run 100% meth on the side? Because I have.

How can you say that Howard's failures had anything to do with running pure methanol rather than a more diluted mixture of it?

You should find that 80% or more of your time is spent in idle or cruising areas of your map. Your tuner should be able to lean out your idle until it looses smoothness and find the cliff. For some cars this can be 13 AFR for some 14's. If you are idling in 10-11 range then there is a clear area for improvement. Also in your cruising areas you can remove alot of fuel, if you cruise at 12.5-13 again more room for improvement.

50/50 and or methanol can be used to replace fuel, as has been documented from factory up to 10% of fuel is added for cooling purposes. My experience has been that removing these quantities of fuel can be had when injecting 50/50 with nominal affects on knock.

However, gas qualities vary from country to country I think you would have a hard time getting away with 87 even with AUX IN but 91-93 vs 98 is another story all depends on your testing with what you have available on hand. Anyways before getting into that look at the places mentioned above and compare and contrast.

As a disclaimer I run 16 psi spring, 18psi low boost and 20+ psi high boost on 50/50, the most I have hit on a tank of mixed driving (200kph+ pulls and cruising) is 630kms.