Most stock 8's in our summer weather conditions should stabilize at around 185F at cruise. I would like to see proof of an RX-8 cruising at 172F on 90+F weather. If the weather is cool yes, but not in the heat of the day during the summer. No way.

at highway cruise 90+ my temps are slightly below 180. mizu rad and hoses, mazmart wp and t stat

I don't think that it devalues the Mazmart thermostat. Just that with your thermostat fully open and temps still not dropping it means your radiator needs to improve it's ability to shed heat. If your radiator can't get the temp down to the thermostat open temperature, they yeah, lowering the thermostat won't produce a visible effect.


That doesn't mean that they "don't work".

What are you using to monitor coolant temps? OBD port?

prosport gauges and ap. my water temp sensor is where the pipe used to be between rad hose and block hose

Not sure if ambient temp is logged, but would a log of intake temp plus the other normal points suffice?

I'll get one next time it tops 90F here. It's been hovering high 80s pretty much non-stop so won't take much to get to the 90F you ask for.

Granted, I have the coolant issue, but I don't think that would impact this?



Another possibility is the humidity? Higher water content in the air could mean better heat shedding from the radiator. You have drier air than I do.

I'm using the OBDII port, I'll get readings on my way back through the VA mountains when its 63* outside :(.

See what my temps are at...

I don't have an issue, my temps are quite low considering the addition of the turbo and the intense heat we experience here in South Texas and I attribute that only to my more efficient fans and secondary rad. I'm just saying that before, when I installed the Mazmart pump and thermostat I saw no difference in coolant temps what so ever. I just don't think it's worth the money if your OEM coolant system is working as it should. I think people buy those items thinking it will lower coolant temps and from what I have seen that is just not the case.

It may help with cavitation, etc. but i'm not sure how you would know if that were the case.

People also say the under tray plays a very important role in cooling yet a few guys locally have run without it for some time under the same conditions and never see any higher temps than anyone else.

To counter that, I have personally seen several examples where better sealing of the undertray HAS dropped coolant temps.


If you can show examples where they don't work, then both sets are viable possibilities. There are just more factors / variables influencing the end result that aren't being considered.

What is the difference between the two usually? I know from testing that taking a reading from the heater hose usually varies as much as 10F from what the factory coolant sensor is seeing.

Intake temps at cruise are usually a non issue unless you are running a hot air intake or something. AMB is not logged. I dunno, humidity supposedly helps but it's pretty damn humid here :lol: it's not really dry at all.

Referencing intake temp as an indirect method of getting to ambient to show them both in a log.

I dont have an undertray and see the same temps everyone else does...

Just saying.

Thanks for clearing that up RIWWP, I'll add the thermostat to the list.

I do a lot of city driving so I don't think it would be worth getting the pump too.

I think my OEM thermostat was headed toward failure (104,000 miles), and would expect that a brand new OEM thermostat would have the correct 183F to 203F range.

That's fine, 203 is too hot for my Kool-Aid anyway. :)

9k, temps are usually pretty close between gauge and ap. oil temp is usually a couple deg cooler. i did open up the splash shields behind oil coolers too

Intake temps are a funny thing, I find they vary even on stock setups. But like you said, there are so many variables.

the mazmart pump will cavitate much less at higher rpm-the oem water pump will start cavitation at 6K.
Look at the design of the S2 water pump, look at what the track guys do. Now--yes --different operating conditions, different average rpm usage by the racing guys, but the impeller on the MM pump will still pump well in the lower rpms. Is it a must before you can have a good operating cooling system---no. but it is a good thing to have if you do canyon runs, track days etc.
In Ga , during cruise on the interstate, ambient temps less than 95F, with the a/c on--i will see approx 175-178F ect, oil is about 15-20F higher.
9 k those are good temps considering that you have that intercooler up front.

Yeah, remember though they upgraded the impeller on the S1 pump as well so if you have a reman you have the updated pump. I am really happy considering I have the inter-cooler up front and my second oil cooler up against the condenser as well. My system is forever changing, I will be going to dual oil coolers in the stock locations soon and so I will have to mount my secondary rad differently as well. My oil temps actually stay a bit under what water temps are unless I am really driving hard.

Thread revive. Going to be a Mizu owner right about now! my radiator top hat broke. So i'm ordering a new Radiator, Radiator Hoses and rest of the other hoses oem. here's some pics for you guys. :mdrmed:

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Texas weather killed my radiator but oh well new bling and cause


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How are the fans holding up? No more procrastinating for me, Fan #1 just took a dump, just in time for summer. :(

Looking at this one...

Flex A Lite 12 1 8" Dual Shrouded Pusher or Puller Universal Electric Fan | eBay

The fans are a larger factor in actual cooling then the after market rads.

That being said man that nipple is a B and I cant blame you for replacing it at all. Lets us all know how it turns out.

I'm thinking about running two of these... Amp draw of 7, CFM at 1150, full setup would be 14 amps, 2300 CFM's.


AFCO 80180 Electric Cooling Fan, 12 Inch S-Blade - Speedway Motors, America's Oldest Speed Shop

Are Yall capable of replacing the fans without removing the radiator? I only ask because my upper neck has a crack where the hose slides over it and I doubt it will survive me removing that hose again. Normally I would just go ahead a replace both but I'm being a penny pincher right now cause I'm trying to save up to get a house.

Shady, any reason why you prefer a fan set up without a shroud? From my understanding a shroud helps for low speed cooling which is what I need. Majority of my driving is city traffic.

I would get a custom shroud made...

Our alternator can barely supply the amperage needed as it is with factory equipment. People go and add more electronics, sound systems, etc and it stresses the system out even more.

Reducing that amperage while keeping CFM's the same would be an ideal situation that is essentially what those fans would do.