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View Full Version : hello, im new too the forum with a couple of q's

thelevman
21-08-2007, 03:09 PM
hello everyone my name is Lev and im in sydney australia.
i found this forum through www.ausrotary.com and its very interesting, ive read through quite a few threads but havent found quite what i'm after regarding my situation.

ok i have a s3 rx7 with a 12a turbo engine, its reasonably modified with more injectors a fmic, aftermarket ecu, bigger turbo, ive purchased a pre turbo water injection kit brand name CAPA, now i dont like having a fmic for a few reasons, less air flow to the radiator, makes my car look modified i like the stock look, lots of piping which i assume means added lag.

my question is, if i get a small top mount intercooler like on later rx7's together with the pre-turbo water injection am i likely too see any improvement? im not so sure because i think the stock piping on those intercoolers is 2inch and my whole intercooler setup atm is 2.5 and also the intercooler is alot smaller however im not sure if thats a large factor because ive read on here that water injection can even be used without an intercooler. or would the engine heat just rewarm my air through the "cooling fins" due to it being top mounted lol.

any suggestions are much appreciated
thanks
raddy
22-08-2007, 08:19 AM
you will see benefit of pre comp injection also without ANY IC....Just choose right size of nozzle and you can get acceptable inlet charge temp without using any IC....
thelevman
22-08-2007, 01:11 PM
would pre turbo injection with no intercooler bring cooler inlet temps than a fmic?
keithmac
22-08-2007, 10:22 PM
You can`t inject a lot of water PRE turbo (a 0.3mm jet seems to be the best size from reading on here), so that will limit the cooling ability. You can inject quite a lot of water / methanol POST turbo and this will bring the charge temps down nicely.
thelevman
23-08-2007, 08:24 AM
sweet thanks for the replies guys, what about using pre and post turbo water/methanol injection, that would be super effective wouldnt it?
keithmac
23-08-2007, 10:47 PM
Some people see gains pre turbo and some don`t, only way to tell if it works or not in your application is to have a go!.
JohnA
30-08-2007, 09:42 AM
I use both pre and post-turbo injection and it works very well. :smile:

It is not clear what the 'maximum' flow pre-turbo can be though. I wouldn't be surpsised if one used a large nozzle and there was no problem with the compressor at all.
As all this water tends to boil early due to the pressure drop so steam would come out along with the compressed air.
All this steam will have absorbed quite a bit of heat, making the compressor discharge temps much lower that they might otherwise have been.

The downside is that this water has already absorbed all the heat it can, so there is no additional in-cylinder cooling to be had afterwards. That's why post-compressor injection is also needed.
thelevman
09-09-2007, 12:24 PM
heya guys, thanks for the replies, i received my little pre turbo kit and am a bit unsure how to hook it up, there isnt alot of parts but i have no experience with hobbs switches, if i took some pictures of the kit could some of you guys give me some pointers on how too hook it up?
thanks
maxc
14-09-2007, 01:10 PM
The downside is that this water has already absorbed all the heat it can, so there is no additional in-cylinder cooling to be had afterwards. That's why post-compressor injection is also needed.what's hotter the cly walls, valves, reverion gasses in cly or the "steam"?
JohnA
19-09-2007, 01:01 PM
Max,

Could you rephrase the question so it is clear what the options are?
maxc
20-09-2007, 11:03 PM
Max,

Could you rephrase the question so it is clear what the options are?

So if the total air, gasoline, steam, mixture is say 150F it will not absorb any more heat?
It takes time for the heat in the combustion chamber from the previous combustion cycle to make it to the cooling system. We should take this over to In Cylinder Effects, sorry.
JohnA
21-09-2007, 08:08 AM
Are we talking pre-compressor temps or post-compressor?

Pre-comp doesn't make much difference, it will all turn to steam anyway

Post-compressor temp does matter a lot, but in any case it is unlikely to be able to generate steam. Just some heat exchange between the water droplets and the air.

In-cylinder is another story, it will all turn to steam because of the pressure/temp conditions.



What I was saying is that if the water has already turned to steam pre-comp, it has nothing left to do afterwards. :wink: