water injection

[91turbo2]

i got a question, i want to purchase a water injection system, but i am wondering if it will help. Can I really run 91 gas and run 17psi with water injection, i already have the greddy intercooler. I want to make sure that its safe so that i can buy it. Because I dont like purchasing a lot of race gas, it gets expensive. Thanks for the help guys.

[rezzle]

With forged pistons 17 psi possible.



About octane and engine mods
http://sdsefi.com/techocta.htm

http://sdsefi.com/meltdown.htm

Good How to.
http://www.avatar.com/~kory/h2o-injection.htm

[91turbo2]

no i mean with stock pistons...

[rezzle]

See the picture of the piston on the 'meltdown' page?

As a matter of fact I have one just like it, I used to know the guy that wrote that web when he raced at the track. When I blew my piston I took it in in to show it to him and he friggin laughed his ass of at me. 'Cuz he knew I new better.

you won't get much over (EDIT: 8psi INCREASE 5+8=12psi) without troubles on high compression stock pistons, even with a programmable ecu and water injection. If you do end up running over 8 it usually means something is fucke dup with your piping and you have a restriction, (usually a lousy intercooler or intake manifold setup)

[MRQtwinturbo]

i ran 16psi on my stock ct-26 (also have greddy ic)........on my current setup up..running 14psi for the street on 94 octane gas........

i'm not too sure about water injection setups...i'm sure JH will answer cuz he is using it.....

[rezzle]

You made a good point MRQTurbo.

I should have mentioned that factory turbo's and supercharged engines are exceptions because they already have semi forged pistons and most are also already running at reduced compression.

The original mod on the engine I blew was just the addition of a S/C on a stock 4age with some minor ignition changes.

[91turbo2]

so you guys dont think water injection will help me out that much, with 50/50 water alcohol. I just want to run 15 psi with no pinging or anything at all. 17psi just for race use... I mean if water injection supposidly helps that much then it should cool down the intake charge and lower temps. Well enough for me to not use race gas.

[rezzle]

Kinda hard to say the PSI without knowing the engine, but stock high compression pistons and turbos/superchargers on anything less than 95 octane is trouble.

Water injection does help, read those webs, I expect you'd gain 5-8 psi if everything is set up perfectly, and that is a considerable amount.

Water injection slows down and smooths out the burn so that there isn't as much detonation. Thus allowing you to run more psi while keeping the timing advanced. It only reduces preignition (aka auto-ignition or dieseling) by a small margin though; so once you reach that critical point of compression, you are in trouble. It wont matter how much you retard the timing the mixture is going to start burning early anyway, and starting with 10:1 (a standard normally aspirated compression ratio) doesn't give much room to work with *especially* with pump gas.

[JekylandHyde]

Not only am I on stock pistons, I am on the whole original engine with 195,500 miles - never opened.

I run 20-21 psi of boost at the track and have spiked during burnouts to 24 psi. Why is my engine together? Protection.

Water Injection is one of the many things I use.

The only way I ever run over 15 psi of boost is:
Upgraded Intercooler (I have the GReddy)
Water Injection (I have the aquamist)
base-idle fuel pressure upped to make sure I have fuel
race gas

I used that for many miles and only recently upgraded to 550s injectors/SAFC/VPC.

There are a number of people who run 17-18 psi on 91 octane with Water Injection with no problems. I personally would never chance it. I never run less than 94 octane in Hyde (but then again I do not live in Cali).

Water injection not only increases the affective octane of your fuel, it also steam cleans your engine and lowers your intake charge.

Prior to WI, my compression was 18X, 17X, 16X, 15X from cylinder 1 to 4. After 14,000 miles of hard driving with WI my compression is now 175 across the board ... dead even. WI cleaned up years of carbon biuld up.

Water Injection is INSURANCE for your engine and you only pay the premium once.

I run 60% distilled water and 40% methanol in my system. Methanol's octane is 113.

Hope that helps.

[JekylandHyde]

Originally posted by rezzle
Water injection slows down and smooths out the burn so that there isn't as much detonation.

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

Originally posted by rezzle
starting with 10:1 (a standard normally aspirated compression ratio)

Are we talking about a NA engine? I thought we were talking about a turbo MR2 (whose compression is MUCH lower than that).

[rezzle]

I have no idea what he is talking about ... that is why I keep adding disclaimers lol.

If it is already turbo, then he can add a good 5psi to those numbers I posted because of the better pistons and lower compression ratio..


But you post makes sense, and your precautions are also why the death pool is still going. heh.

[JekylandHyde]

Originally posted by rezzle
I have no idea what he is talking about ...

Well his screenname is 91turbo ... so I was assuming ....

Originally posted by rezzle
your precautions are also why the death pool is still going. heh.

[91turbo2]

well obviously i have a turbo since my user name is 91turbo2 like hyde mentioned, and also i'm talking about boosting 17psi with my "greddy intercooler", but aside from that, all turbo cars have low compression pistons, especially toyotas because these damn engineers are too smart, and yes they are semi forged, but all i wanted to know what, "will water injection help me run 17psi on pump gas?", and the answer i finally got was yes, but it would help on 94 octane...Thats all i wanted to know guys, thanks for the help.