Forced Induction - Who knows how Meth injection affects AFR?




Fastdriver1992
04-19-2012, 09:50 PM
looking for some solid advice, i have a regular sbc with a d1sc procharger, i've been racing for the last month or so and car is running great no problems, AFR 11.5 right where it should be. my question is now that its getting hotter out i'm going to start to use my methenol injection system, how much does meth change my afr? i run an index and i relle have no time to re tune this thing so i'd like to get close so it doesnt blow up. i've read mixing 50/50 changes the afr more then if i diluted it with water. any help would be much appreciated,
(ik its not an ls or fuel injected but i know this forum has the best guys who can give me the answer i need)

Here's a pic of my setup
http://i807.photobucket.com/albums/yy351/fastdriver1992/jakdslfjalfa.jpg


a4ls2goat
04-19-2012, 10:05 PM
It makes it run richer

Fastdriver1992
04-19-2012, 10:16 PM
It makes it run richer

yes but by how much?


9sectruck
04-19-2012, 10:21 PM
how big are the nozzles?? pump pressure?

5w20
04-19-2012, 10:43 PM
yes but by how much?

Depends on number of nozzles, nozzle size, and mixture percentage. I've heard 100% meth is where its at.

Fastdriver1992
04-20-2012, 05:49 AM
how big are the nozzles?? pump pressure?

i will get that information for you shortly

Fastdriver1992
04-20-2012, 05:50 AM
Depends on number of nozzles, nozzle size, and mixture percentage. I've heard 100% meth is where its at.

i run 1 nozzle i'm not looking for anymore hp, i'm just looking to keep the car from detonation because i do not run an intercooler

Fastdriver1992
04-20-2012, 06:29 AM
This is the pump i am using, i will try and find out the nozzle size by the end of the day
http://i807.photobucket.com/albums/yy351/fastdriver1992/b7edd34b.jpg

9sectruck
04-20-2012, 08:04 AM
that pump will start to leak like crazy if you try to run straight meth over time.. but any way on my car 2 14gph nozzles moved my afr from 11.9 to 11.0ish so 1 full point. and that was way up stream from the TB so alot had already evaperated into the air stream.
if you go with a 12-14gph nozzle that close to the carb I would go down 2-3 jet sizes to start off

Fastdriver1992
04-20-2012, 12:30 PM
Thank u thats the answer i was looking for i have ghe nozzle about 4 inches from the carb

stevieturbo
04-20-2012, 04:45 PM
i run 1 nozzle i'm not looking for anymore hp, i'm just looking to keep the car from detonation because i do not run an intercooler

Then run water only. It will provide the best cooling, and it will provide the most detonation suppression and also have virtually no impact on AFR's/mixtures. But it will allow more timing, and it will allow you to run leaner. Both of which will see more power freed up as well as the safety it offers
It also wont need huge amounts to achieve it.

If you arent convinced by water alone, then go for the 50/50.

A good resource here

http://www.aquamist.co.uk/vbulletin/

The Alchemist
04-20-2012, 05:31 PM
Just to clarify a quick point, just because the meoh is fully evaporated doesn't mean it's not going to impact afr, quite the opposite. Most of the fuel injected by the injector is evaporated once it hits the back of the valve. Technically speaking, nothing burns until it's evaporated.

Remember, liquid doesn't burn, gasses do.

BigRich954RR
04-20-2012, 10:07 PM
100% gas.......................14.7
90% gas, 10% meth.......13.87
80% gas, 20% meth.......13.04
70% gas, 30% meth.......12.21
60% gas, 40% meth.......11.38
50% gas, 50% meth.......10.55
40% gas, 60% meth.......9.72
30% gas, 70% meth.......8.89
20% gas, 80% meth.......8.06
10% gas, 90% meth.......7.23
100% meth.....................6.4

bad6as
05-02-2012, 08:10 PM
when frost and i were tunning my last set up with pure meth 10 and 15 nozzles we looked for low 11s afr