40 replies to this topic

[Duane Polsley]

Recently had some higher than expected temps while on track (225-230 w/ rad inlet sealed up very well),and wanted to know what other racers use. I've heard some use no t/stat and others use a drilled out 160 degree t/stat. Also what radiators are the best. I'm told some have quality problems.Any suggestions ?

Thanks

[Jamz14]

Hello Dewey,

Take my setup with a grain of salt. Only four races into it. However we have run in over 100 degree weather and we have had zero cooling issue ( with the possible exception of it taking a long time to build heat in the engine).

We use the top Mishimoto radiator and no thermostat. The radiator price was excellent, the quality of workmanship was good, and it came with a cap. We also use the Mishimoto radiator hoses. Nice hoses, a bit pricey, but nice. Engine is staying very cool.

[HoneyBadger - BrianW]

I live in Dallas and frequently have over 100deg temps. I have found the Koyo to not be enough radiator, if you are in any kind of draft. I switched to a SpringField dyne (as do most people in Texas), that along with a gutted thermostat seems to do the trick.

[Greg Kimble]

Running Springfield Dyno and no thermostat in FL heat, no issues and significantly cooler than the Mizu unit we were using previously.

Greg

[Dennis]

Hey Dewey,

Haven't seen you for awhile. Come run some NCRC, there were only 8 SM last weekend, we need you!

Where is your temp gauge sensor? Mine is in the heater hose where the water comes out of the back of the head, it reads 220 when the fan comes on at "207". In hot weather my gauge can read 220-230 I think that's fine. I use the big Koyo and have found the CX Racing to be equivalent, except for the price being 1/3. I have a 165 thermostat.

Dennis

[Alberto]

Dewey,

Darin is a fast mofo. In 90* heat running at his level, looks like you're be pushing the limits runing a Tstat and something like a Koyo, Mizu, Mishimoto, CX racing rad. They are all the same design, single pass and same dimensions. The math all works the same for those rads since they are all the same dimensions and fin count is close enough.

The Springfield dyno is a larger rad with more cooling capacity and it is a triple pass so the math and design favors that rad.

If you have the opportunity, I'd test running w/o the Tstat as that will improve flow a bit.
If you have more budget than time, get the SD rad and make sure there isn't any metal rubbing during install. Here are my notes installing in an NA chassis. May be similar in your NB chassis:
http://mazdaracers.c...dpost__p__29748

[Ron Alan]

Recently seen 2 SD radiators develop pin holes and not be repairable after 1 season. Seem to remember another thread about this subject with a lot of mixed reviews on the SD. Our aftermarket temp gauge is at the stat housing...never saw anything above 180(in draft, Godspeed)) this weekend. But Dennis has a point if your temps are being measured from the heater hose or the bottom hose.

[MazdaSteve]

When the B6 & BP engines were first designed they were used in front wheel drive cars with the engine mounted transversely. In this configuration coolant went in the front of the head from the radiator and out the back side of the head into the radiator. In the Miata, the only coolant getting through the engine to the rear of the head is what is running through the heater core and then up the side of the engine to the waterpump.

The reason to run the thermostat is to put sufficient restriction on the coolant flow so that it runs completely through the head and exits the rear. Otherwise with no thermostat, the coolant will follow the path of least resistance and circulate not through the head by back to the radiator. There is a better explanation on this on Miata.net and in Keith tanner's "High Performance Mazda Miata MX-5".

[davew]

I have said this a bunch of times, Take the stat out and throw it away you do not need it.

The hole in the head before getting to the thermostat neck (where the rubber o-ring goes) is small enough to create the restriction. Even a gutted thermostat allows more flow than the hole built into the head.

We ran both Koyos and SD rads at Gingerman this weekend. 100*+ and neither car ran above 205 in the draft, 190 in clean air.

dave

[Keith Andrews]

I've had good luck with C&R racing single pass. It is a bolt in replacement. If it matters it is built in the USA and quality is very good.

I've spent a lot of time in 100+ temps in a draft. I have run with and without a thermostat. Currently I'm running with a stock thermostat without issues. It was over 100 at my last race, Roebling Road, track temp was near 130.

A good exercise is to get a diagnostic tool that you can plug into your OBD2 port and verify the actual temp (the temp your ecu is seeing) your thermostat is cycling vs. your indicated temp.

http://www.crracing....arket-radiators

[FTodaro]

I Know we have had this discussion before and I apologize for not looking back, the location of where you take the temp is relevant for an apples to apples comparison. I have my temp gauge sensor located ant the back of the head as the hot water runs out of the head and into the heater core, so I assume this is the hottest point in the system and why i test it there.

I have the SD rad with no stat, in the draft I can get to 210 and unfortunately, I am in the draft more than the lead.

Dave W is that where you are measuring?

[LarryKing]

Take the stat out and throw it away you do not need it.

Several respected engine builders disagree.

[davew]

Several respected engine builders disagree.

I run 10 cars about 25 weekends and most run double classes. I would guess 350 to 400 races per year. I have almost every respected engine builders engine in one of the cars. I have ZERO thermostats. I have never had an overheating problem that was not caused by the driver going off track and packing the nose with debris.

Yet, I have removed dozens of thermostats to cure a hot running engine.

The purpose of a thermostat is to stop flow to the radiator. This aids in faster warmups and cold driveability. It helps emmisions and heaters. None of these items are important for our purposes. Once the thermostat opens, it serves no further purpose.

If you want 180 degree water temp (just to pick a number) a 160 stat would be fully open and doing nothing at 161 degrees. Your 195 stat would stay closed until it reaches 195. Once the stat is open, the rad is what controls temp. So if your car is running hot, the fault lies in a stat not opening 100% or a cooling system without adequate cooling capacity. Lack of a stat CAN NOT cause the car to run hot.

So the only thing a stat can do is fail in the closed position causing the car to overheat.

If you think a gutted stat acts as a restrictor, look at the inside diameter of the upper radiator hose nipple on the stat housing. That is a restriction.

Dave

[Chris Adams]

I have a koyo and gutted stat. Last Mid-Ohio event the ambient temps were in the mid/high 90s and I was seeing >200* water temps.

I'll remove the gutted stat before our August event, but I'm guessing its not going to make a huge difference.

[Duane Polsley]

Thanks everybody for the input.
I think the Rad. cap may have been playing a part in the high temps. Had a 21 psi cap that when tested only held 13 psi. We did remove the t/stat at one point and found the same temps 225-230 at heater hose. Just took a little longer to get there. Still going to get a larger three pass rad. Looking into the C&R three pass rad. hoping it's a direct replacement, using stock mounts.

Dewey

[Keith Andrews]

Still going to get a larger three pass rad. Looking into the C&R three pass rad. hoping it's a direct replacement, using stock mounts.

Dewey

The Radiator comes with mounting brackets that replace the factory brackets. Bolt off bolt on.

[Adam Molaver]

110% agree with davew. in my much smaller sampling (two SMs i've owned), tstat is just another potential failure item. i've had great luck with the CX radiators, one in the old car (96) and in the 99. i did have an SD that got crunched, and it does work better. its just too bad saferacer was of no help when the replacement brackets that i waited an extra week for, still didn't fit right. and the hoses don't come with the rad. and SD/saferacer refuse to say, 'x part number is the correct hose'. yes, they work, but for the price, its ridiculous that it doesn't fit. if a $130 ebay special can drop right in, why not a $600 SD? we've got VIR in a couple of weeks, and i'm expecting it to be very hot, but so far, my CX saw middle 90's with temps never getting over 190 (even drafting with a CRX) with the probe in the upper rad hose. using a scangauge (obd2 reader/display), i've never seen over 205 (while the upper rad hose probe shows ~190).

ahm

[FTodaro]

and the hoses don't come with the rad. and SD/saferacer refuse to say, 'x part number is the correct hose'.

ahm

NAPA makes an Upper hose that fits the SD rad perfect If anyone needs it i will look at mine and post it. I want to say 8815 but I better check it.

[Muda]

"Install a top hose extension tube or find a different upper hose. A trustworthy customer informed me that Gates part number 22133 is a perfect fit for a 1.8 application."
From Sam's 2007 installation guide.

[Armando Ramirez]

110% agree with davew. in my much smaller sampling (two SMs i've owned), tstat is just another potential failure item. i've had great luck with the CX radiators, one in the old car (96) and in the 99. i did have an SD that got crunched, and it does work better. its just too bad saferacer was of no help when the replacement brackets that i waited an extra week for, still didn't fit right. and the hoses don't come with the rad. and SD/saferacer refuse to say, 'x part number is the correct hose'. yes, they work, but for the price, its ridiculous that it doesn't fit. if a $130 ebay special can drop right in, why not a $600 SD? we've got VIR in a couple of weeks, and i'm expecting it to be very hot, but so far, my CX saw middle 90's with temps never getting over 190 (even drafting with a CRX) with the probe in the upper rad hose. using a scangauge (obd2 reader/display), i've never seen over 205 (while the upper rad hose probe shows ~190).

ahm

"its just too bad saferacer was of no help when the replacement brackets that i waited an extra week for, still didn't fit right. and the hoses don't come with the rad. and SD/saferacer refuse to say, 'x part number is the correct hose'. yes, they work, but for the price, its ridiculous that it doesn't fit. if a $130 ebay special can drop right in, why not a $600 SD?"

Not to thread jack, but 100% in agreement with you. Neither Saferacer or Springfield of any help at all!