[GTPM90]

Hi, I recently installed the water injection on my car and am wondering what would be the best way to find the correct nozzle size and mix of meth? Currently I have a 3.5 "with supporting mods" pulley using the 7gph nozzle and getting 2* of knock randomly and some times 0* but 70% of the time it is close to 2*. The car is running 21* timming at wot before knock.

[dvldoc]

GTP' have plenty of things that give false knock from the transmission, to upper engine mounts, They are a nightmare to rid of all knock and trust me nobody knows these cars better than us for alcohol injection since we actually owned them.

I think your running a bit to big of a nozzle, The M90 does not like alot of alcohol injection pushed thru it.

A D05 or DO4 work better with close to stock GTP's Remember the D07 is only 7gph at 100psi it flows more than that. To much alcohol injection induces knock on those vehicles.

[GTPM90]

Yea I did the calc and it said 5.86 I think so would it be better to go with a 5? sence they dont make a 6? Also under half boost if the meth is on it will bog so I agree with the smaller, but the only other smaller one is the 3 that came with the kit. Also I have the autotap and I know what perameters I should normaly watch but are there any in particular I should be watching with the alc? Thanks for all the help!

[dvldoc]

You can go with a DO5 for the nozzle size, it's 5gph @100psi so slightly higher since it flows well over 150psi.

Watch your 02s, If you can get them to around 920 with no knock your doing good. That's were I made the most power but then again it's a GTP, they tend to break all the tuning rules. The biggest thing is no knock and not running pig rich.

[GTPM90]

Yea, I think I'll be getting the DO5, if at half boost I can feel it bogging down. I also need to get a afc of some kind, or get the computer reprogrammed I am running about 10/1 a wot and I haven't checked it with running the meth. When I get he new nozzle and a day off work I think I'll start with water and slowly add meth to see were my car will work the best. thanks for the info.

[fst100]

to add i a bit, if you're tuning via the narrowband(NB) remember that it varies for every car. im running an M2 nozzle and although my car's an L67 my setup consist mainly 42.5# injectos, 3.3" pulley, 89octane, and commanding 21-22* of advanced timing. even though i have a PLX WBo2 it reads "RCH" or rich, but my NBo2s range ~960-970. now if i increase timing by another 2* i'll get more knock and if i add 3*+ then even more and etc. tune safe then add either more timing(no more than 24* on daily driving WOT IMO) or drop pulley until u see knock show up.
just my $0.02.