changing the pressure and vacuum tank capacity on FD

marco · May 18, 2008, 10:45:50 AM

right, it looks like the plan for getting more power out of my engine is slowly taking shape, and as part of it i will be replacing the solenoids and relocating them. whilst i am doing it i may as well replace the pressure and vacuum tanks, and was thinking of using small catch tanks available for monkey bikes (see here for example) obviously i will have to block one of the holes off, but i was wondering if the larger capacity of the tanks would have any effect of the operation of the turbos? anyone got any ideas on this?

marco · May 21, 2008, 07:12:43 PM

ok, i have been doing a bit more looking at the system diagram, and as far as i can see the two tanks just act as accumulators. if this is the case then the size of the tanks does not matter, although the larger the tanks the longer it will take to initially charge them. so long as they are not overly large ,the increase in time will be minimal. as such i should be ok to use slightly larger tanks.
Anyone agree/disagree with this? the system does not use the discharge of either tank as some kind of timer does it?

marco

marco · May 22, 2008, 03:01:27 PM

ok, so this thread seems to only interest me! however in case someone in the future is wondering something similar, i thought i should add to it.
have spoken with a guy in the US via email, and he seems to be in agreement. going smaller than standard size is a no-no, as it may not have enough in reserve for correct operation. however going larger should be ok, so long as they aren\'t mahoosive (taking an age to charge) and you can fit them in the engine bay. once i get my new solenoids fitted i will have a go with different tanks and let you know how i get on.

Nik da Greek · May 22, 2008, 08:24:21 PM

I was interested, i just couldn\'t think of anything intelligent to say about it! I think replacing the tanks is a great idea, given how tired and frangible the stock ones get when cooked for 15 years. I\'ll be interested to see how this works out. Also, I love those little monkey bike tanks you found, bargain. You probably couldn\'t even buy the braided hose for Â£12.49 including postage anywhere else!

RemarkLima · July 26, 2008, 04:05:41 PM

Hey Marco, did you try this in the end?

I\'ve got the UIM off at the moment and redoing all the hoses under there, but also stripped out the AVC etc... I\'l like to put the pressure tank under the UIM where the new space has been created but I\'ve not been able to see how the standard one would fit under there!

marco · July 27, 2008, 09:34:38 PM

err, no. although i may well do so in the near future. whilst i think it is pretty easy to replace the pressure tank, i have a feeling that the vacuum tank has quite a large capacity so would need to find a large catch tank- considering how hidden the stock one is i would be tempted to keep it. people are selling cheap monkey bike catch tanks again so i might give it a go, got nothing to lose!
as for fitting the pressure tank, yes it can be hidden under the uim, but it needs the blanking plate for the air pump related thingy (whos name i cant remember at the moment)

shaunwil · July 27, 2008, 10:06:27 PM

One thing I learned later on was that the stock solenoids only really like running on 0.7bar. If you look at running higher boost it is a good idea to add a pressure regulator on the outlet to the tank of the tank behind the water pump. Can\'t remember which line but there was a couple of big threads on rx7club

Shaun

marco · July 27, 2008, 10:11:03 PM

i have an after market solenoid set, and after the first real test of it this weekend i have to say i am really impressed with it, awesome bit of kit! the only thing it could do with is a mounting bracket, i cowboyed myself one using some zipties and double sided tape, but could do with something a bit better...

RemarkLima · July 27, 2008, 11:09:13 PM

OK, cool. The vacuum tank I\'m happy with because as you say, it\'s hidden away. But if I could ditch the pressure tank, or hide it away.

I\'ve removed the air pump, ACV, Split air pipe etc, and have blanking plates on them now, but can\'t see if the pressure tank will "mount" of anything already there or if I\'ll have to make something up?

Or better would a smaller one that\'s easier to hide

marco · July 27, 2008, 11:16:35 PM

\'mounting\' is perhaps the wrong word. think more \'shoved under so it cant be seen\' it does fit and is restrained by the WG/pre control solenoids, the rats nest frame and the LIM/uim, so it wont move, even it is isn\'t bolted down. if you are going to fit a different one bear in mind that the tank acts as an accumulator, so you don\'t want to reduce the tank capacity too much, otherwise the rats nest wont work properly*

*i mean it wont work properly for a another reason...

RemarkLima · July 28, 2008, 07:26:54 AM

Heh heh, I see! Thought that may well be the case but thought surely not... But yeah, I don\'t think it\'ll be moving anywhere once it\'s in.

Quote*i mean it wont work properly for a another reason...

PMSL! I\'m so not looking forward to everything going back together and finding it just doesn\'t want to have it at all... Still, make driving fun when you don\'t know if you\'ll get full boost, no boost or something sputtering in between