7 BOUND

Hey All Just Got The 1.3 Bar Just Wanted To Know Witch One I Should Put It On Thanks

KaiFD3S

iTrader: (37)

It goes on the AST

DaveW

^^^^

Logic:

The cap with the spring allows coolant to enter the space between the sprung seal and the sealed top of the cap after the set pressure (0.9 or 1.2 bar) is exceeded. The AST has a hose nipple in this area for this coolant to flow to and from the overflow tank. The filler neck has no overflow port between the sprung seal and the cap top, so the coolant goes nowhere. While it shouldn't hurt to have a relief-type cap at the filler, it would perform no useful function, unless the AST has been eliminated and a filler neck with a nipple in this area (to the overflow tank) has been substituted.

7 BOUND

Thanks Guys And Note: Its Not Logic If You Dont Know Hmmmmmmmmm

DaveW

By using the word "Logic," I just meant that I was going to explain why which should be used where, no flames intended.

7 BOUND

hey dave its kool man i was just lost thats all thank you for helping me, its kool

sDylish

If I already have a Pettit AST......Should I still get a Biltz 1.2 or Greddy 1.3 rad-cap?? or they won't even fit with the Pettit AST? or should I still get them to replace the Filler cap?

scotty305

iTrader: (2)

Sorry to butt in, but I HATE hearing this mentally lazy sort of attitude. It's still logic, even if you can't figure it out on your own. Learn more and you might be able to solve your own problems in the future.


Being dumb is not cool, quit watching MTV!

-s-

7 BOUND

scotty please is all that nessasary, your popin off and wanting to be in the click and your wrong, last i check if you dont know something you ask, you were not allways knowlegable with the FD, so you had to learn or somebody told you so chill, we dont have a problem so why should you, in that GOD bless and keep the 7's alive

scotty305

iTrader: (2)

7 BOUND, God bless you too, I don't mean to single you out as being the only lazy, overly-dependent person on here. Still, I think that a mentally lazy attitude is a dangerous thing to have. The answer to your question is in the owner's manual, for crying out loud!


There is a saying, "Give a man a fish, and he'll eat for a day. Teach a man to fish, and he'll never go hungry again." You were asking for a fish, and then acted like DaveW was trying to insult you by teaching you how to fish.



Think of it like this: you had a problem that you didn't know how to solve. You have two choices:
a.) Figure it out yourself, by learning how the system works so that you can manipulate it to acheive your goals.
b.) Ask someone else, and hope they understand things well enough to help you. If they give you the wrong answer, you don't know any better, and you're screwed.


Are you really satisfied to take someone's word for it? What if someone told you the wrong answer? (I've seen it happen on these forums before.) What happens when you face a problem that nobody has solved before? Or what if nobody is around to spoon-feed the answer to you? Will you just give up?




All I'm trying to say is that you should make a good effort to understand your problems, and you will be able to solve them for yourself.

-s-

FDNewbie

iTrader: (10)

No, it goes in the garbage. Ditch that 1.3 bar (aka 19psi) cap. Mazda had a recall in 93/94, and changed all the caps from 1.3 bar (19 psi) to 0.9 bar (13 psi). If I may quote Scotty from a diff thread:

kuroi FD

Thats correct! You beat me to it.

FD_dave

as to the folks w/ the aluminum ast, like the pettit or something, what's the pressure of those caps? i think it's 16, am i right?

dubulup

if your coolant system can handle 19psi (brand new hoses, and eliminated a ton of smaller dia. hoses, steal braided lines, etc.) How much advantage could the 1.3 bar cap give?

airborne

The only thing more pressure does is raise the boiling point of the coolant/water right? I'm mentally and physically lazy at the moment so I'm not looking up just how much it raises it...

FD_dave

wait... i'm confused as to how the ast cap works and how the drawing back coolant from overflow tank when engine cools down works. if the ast cap is sprung, it basically acts as a one-way valve, right? meaning when the cooling system reaches the pressure the cap is rated, the lower valve lifts and expels enough of the hot expanded coolant to lower the pressure in the cooling system, and when the pressure is low enough (below the pressure the cap is rated at) the lower valve would seal against the ast again thus sealing the cooling system. since the valve on the ast cap is one way, how the heck does it draw coolant back into the system when the engine cools down and all the pressure lowers again? the cooling system at this point should be under some kind of vacuum and it'd pull the lower valve of the ast cap tight. the only other way i can work this out in my head is if there's another connecting from the overflow tank to the system with a one-way valve that works in the opposite direction. somebody please explain this to me!

KevinK2

BP's with 50% eg-water

261F 0.9 bar
267F 1.1 bar
273F 1.3 bar

If at the track running 220F, 1.3 bar caps increases the temperature gap, between bulk temp of coolant and ususal local boilng points, by 30%. a good thing.

Mazda retro's the .9 bar cap to protect heat weakened ast's, turbo coolant hoses, and mabe plastic rad end tanks.

FD dave .... look for the return "check valve" in the bottom center of the rad cap. These are prone to internal leaks and loss of pressure ... replace cap every 2 years.

dubulup

so, the car won't actually run cooler...?

Retserof

iTrader: (1)

It won't run any cooler, but the coolant will run hotter before it boils due to the higher system pressure . So, the car won't overheat as easily under heavy load or track conditions.

NuTbAgSaN

meh i have one on the t stat...i have a pettit ast, and i had the cap. it doesnt do anything but it looks shiny.

scotty305

iTrader: (2)

Exactly. Let's take the concept a bit further: running your coolant at a higher pressure will enable you to safely use less Ethylene Glycol and more water, since the extra pressure is preventing boiling. Water has better heat transfer properties than EG, so the cooling system will be more effective. The rotor housings will transfer more heat to the coolant, which will transfer more heat to the radiator, which will remove more heat from the system. Coolant temperature is only part of the equation. Your coolant temps might not decrease much, but if you measured the metal temperatures, you should see a decrease in temperatures.


One good way to measure the efficiency of your cooling system is to use two temperature sensors, and measure the temps going into the radiator (hot) and at the exit of the radiator (cold). In an ideal cooling system, the hot temps would be nearly boiling and the cold temps would be nearly the same temp as the air flowing through the radiator.



Don't forget that oil cooling is a major factor in rotary engines also. Upgraded oil coolers have been proven to decrease coolant temps.


-s-

7 BOUND

WOW! didnt know that this post was still going, Well i thank every every everybody for giving there input, does anybody know if RE-AMEMYIA makes a .9 bar cap i have there 1.3 im sure those guys knwo there struff.

scotty305

iTrader: (2)

I doubt RE-Amemiya makes the 1.3-bar cap that they sell. They probably put their name on a larger manufacturer's part, possibly Denso or Calsonic. If you want your radiator cap to say Amemiya, put a sticker on it.

FYI, the OEM radiator caps from many Japanese-made vehicles will fit our cars. I've seen the same cap on motorcycles and dirtbikes, as well as on an Infiniti SUV.


-s-

maxcooper

The cap is actually like two one-way valves. One opens at the rated pressure as you described. And there there is another one that opens under light vacuum (when the engine cools) to pull the coolant back into the engine. If you look at one of these caps, you will find a metal disc in the middle of the bottom of the cap, seated against some rubber. This is the valve that opens under vacuum. You can get a fingernail under the metal disc and gently pull on it to see how it opens.

Simple radiator caps are actually pretty neat little devices.

-Max

FDNewbie

iTrader: (10)

The funny thing is, none of these big name companies make the 0.9 bar (aka 13 psi) caps, OR no one here carries them. Check RX7Store, GothamRacing, RX7Trix, etc. Everyone sells Greddy, Blitz, etc radiator caps which are 1.3 bar (19psi) caps.

The ONLY place I've found that sells the 0.9 bar (13psi) caps so far is...you guessed it: Mazda lol. I had to get one of these caps for a friend overseas, and get this. The aftermarket (Greddy etc) high pressure caps usually run $22 - $28 or so. Ray @ Malloy hooked me up w/ the low pressure cap for $14.25 (list is $26.22). Price is good as of July.

So, moral of the story: more expensive and big fancy schmancy name isn't always better. Stick w/ Mazda on this one, and you'll have no worries

~Ramy