Region: NNJ
Car #: 51
Year : 1991 Posts: 161
Status: Offline
posted
Let me start by explaining that the last two seasons have been killing me with coolant temps. Two years ago an i was running at 220-225* with drafting, and roughly 210-215 without.
This was with the stock radiator, nothing else.
Last year, i started by trying inexpensive solutions to fixing my problem. I installed a new thermostat and flushed my radiator because i had noticed that every time i drained it, the water was rather "muddy." first race of last season, i was running 220 the WHOLE time.
Now, i'm getting annoyed. i've heard that for maximum power you should be running ~180. now, i don't really expect to gain power by switching to a new radiator, but its always nice to hope :rolleyes:. i dyno'd at 109whp, which i don't think is Low, but isn't exactly where i want to be. i know power will make no difference compared to me upgrading the driver, but i've already got that part covered.
anywho, can you guys help me answer these questions?
1. what radiator are you running? 2. What are your average coolant temperatures? 3. where do you measure coolant temp from (i run mine where the heater core was)? 4. has anyone had any experience with csf radiators, if so, what temps? 5. if i were to go the koyo route, how big of a difference is the 3x vs. 5x mm radiator? 6. what is the optimum coolant temp? 7. at what temperature/when does the ecu retard the timing?
thanks guys for answering all of my questions ahead of time. :thumbsup:
Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991 Posts: 1111
Status: Offline
posted
Ah, I just went through this last summer. Here's the benefit of my experience.
First, my radiator was clogged. So I unclogged it, and, ultimately, replaced it with a 37mm Koyo. Filled it with distilled water and Water Wetter.
Didn't help! I wanted to scream. Then I removed the thermostat. All was well.
Turns out the stock Miata thermostat is a 192, not completely open until 212. You will ALWAYS run hot with this thermostat. I bought a 160 from the MiataCage guys. Now, I run at about 165+/-, measured at the back of the engine on my AiM system, and 173+/-, measured at the same place on my aftermarket gauge.
Now, I race in the Pacific northwest, where it rarely gets above 85. If I raced in California, I would get the fatter Koyo. But here, I'd rather do without the extra weight.
I have no idea what the "optimal" coolant temperature is, but my car runs fine with this coolant temperature. I don't know what temperature the ecu retards timing, but I never noticed a problem at 195, and started to notice power issues at above 200 (on the aftermarket gauge). Hope this helps.
Region: SFR
Car #: 70
Year : 1990 Posts: 768
Status: Offline
posted
I take the Thermostat and remove the center this creates enough restriction to slow the flow thru the engine. In the summer at Thunderhill I run 190-200 degrees with the big Koyo on very hot days and 180 on days that are below 95.
Region: SF
Car #: RIP #56
Year : -- Posts: 663
Status: Offline
posted
Andrew-
It sounds like you bypassed the heater core. Adding a large restriction in the bypass line (I have a large sender in a very small ID pipe) dropped my temps from 200's to 170's in identical conditions with no other changes, and before that I'd been chasing my tail for about a year. If your sender isn't too restrictive you could always try adding a bigger restriction in the same line for very low $$ while observing the result. FWIW, I run a 160 stat and thick Koyo. I know several others that were in the same situation and had a similar drop in temps by upgrading to the SD radiator, it just costs a whole bunch more. I can't advise you on power vs. temp other than to say that my car made noticeably more power once it ran cool.
Region: mid south
Car #: 2
Year : 1999 Posts: 4275
Status: Offline
posted
Buy a Springfield dyno radiator and gut the thermostat, if you run hot from there, I will pay for the radiator myself and you can keep it. It is the best, by far! Your car will run 160-180, I have to routinely tape up my grille to get to 180. I was routinely 210 in race conditions Jim
Region: chicago
Car #: 72 and ?
Year : 90 and 90 Posts: 1051
Status: Offline
posted
I've said it before and I'll say it again.
THROW THE STAT IN THE TRASH
Get a big radiator and you will have no more problems
Dave
-------------------- Advanced Autosports, The Midwests leader in Spec Miata Service, Parts and Rentals 608-313-1230 Authorised Spec Miata service center www.advanced-autosports.com
Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991 Posts: 1111
Status: Offline
posted
If he has a properly-functioning 160 thermostat, and he's still running hot, removing his thermostat will do not good. He has a cooling problem. Either his radiator is clogged, his cooling system outside his radiator is clogged, or his radiator is inadequate to the task.
I'd check the timing, to make sure you're not too far advanced. Assuming that isn't the problem, I would do, well, what I did--slice the Gordian knot, and just buy an aluminum racing radiator. You won't regret it regardless, and it may well solve the problem.
Region: CACC British Columbia
Car #: 34
Year : 1991 Posts: 115
Status: Offline
posted
I've read on these forums about the peculiar (to me) circuit of the cooling system. If I understand Mr Morris correctly, bypassing the heater core by looping the hoses, will cause the coolant to not fully circulate through the rad?
Would it be better to partially restrict the heater hoses, or to block them completely?
I typically run well below 200, but was getting up to 210-215 on the hot weekend in Spokane last summer. 10 or 20 degrees cooler for cheap sounds very appealing!
Region: Kansas City
Car #: 70
Year : 95 Posts: 477
Status: Offline
posted
I have to second Mr. Drago's recommendation to use the Springfield Dyno radiator. Runs cooler and it's lighter than a Koyo when filled. We've had other Midiv guys struggle with the exact problems you describe and have cured the problem with the SD radiator, designed specifically for Spec Miata.
Full disclosure: we sell this unit at SafeRacer.com, but we also race them in all of our cars, including in the Run-offs polesitter.
Region: NER
Car #: 7
Year : 1999 Posts: 636
Status: Offline
posted
Where do you guys typically tap your cooling systems for the temperature reading? Could various placement locations of the senders across a number of cars produce differing "race condition" readings?
-------------------- -Cy Supported by LTD Racing & Speed Shack - New England's Premier Auto Accessory Store Rt1 AutoMile - Norwood, MA http://www.speedshackonline.com
Region: Des Moines Valley
Car #: 59
Year : 1991 Posts: 1910
Status: Offline
posted
quote:Originally posted by CP: Where do you guys typically tap your cooling systems for the temperature reading? Could various placement locations of the senders across a number of cars produce differing "race condition" readings?
Absolutely!
As this discussion continues, it's important to keep in mind that this engine and the way the coolant flows in it were initially designed for a transverse mounting. What that means to us is that the water flows backwards from you would expect - it comes out of the back of the head, goes into the radiator through the bottom hose and flows from the top of the radiator into the engine.
At least that's how the 1.6 works; can anyone verify for the 1.8 and 99+?
The common places to tap that I'm aware of are:
1. In the thermostat housing 2. In the upper radiator hose 3. In the heater hoses 4. In the "cap" on the back of the head
Region: chicago
Car #: 72 and ?
Year : 90 and 90 Posts: 1051
Status: Offline
posted
Jarod, you have it backwards. The lower radiator hose is the INLET for the water pump.
If the upper hose was the intake for the pump, even a small air bubble would cause the pump to suck air only.
I typed a whole disertation on how the Miata cooling system works a few months ago. Somebody do a search.
I still do not understand why you guys insist on running a thermostat. If you can't get your water up to 160 degrees, you need to drive harder. The ONLY purpose of a thermostat is to get the car up to temp faster. It does not control how hot it gets. It only sets a minimum point.
I don't remember hearing of anybody running hot with a good radiator (Koyo or SD) and a gutted or removed stat.
Just the opinion of the guy who takes 10 or more cars to the track every weekend.
Dave
-------------------- Advanced Autosports, The Midwests leader in Spec Miata Service, Parts and Rentals 608-313-1230 Authorised Spec Miata service center www.advanced-autosports.com
Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991 Posts: 1111
Status: Offline
posted
quote:Originally posted by davew: I still do not understand why you guys insist on running a thermostat. If you can't get your water up to 160 degrees, you need to drive harder.
Dave, is this the explanation you were looking for? Your fine post is the third on the thread.
As to running with a thermostat, some of us drive our cars to the track. When I tried that without a thermostat, on a cool August morning in these parts, the car never got above about 130, and would get down to about 105 going down a long hill. Not good.
And I really don't feel like going through a couple of thermostat gaskets each weekend, taking the thermostat out and putting it back in.
Furthermore, I was out at the track on Saturday. Temperatures were close to freezing (frost all over the place). With a 160 thermostat, the temperature hovered around 160; without a thermostat, it would have been lower.
For those who live in the tropics, I agree that no thermostat is needed. For me, one is.
Thanks for the link. It saved me a bunch of typing again. These threads pop up every 3 months.
Andrew, muddy water is not good. Start with a thorough flush, check the thermostat on your stove with boiling water and meat thermometer and go from there. Do the basics first. Call if you need some help or suggestions. Faster than typing. Read the other thread too.
Region: SFR
Car #: 70
Year : 1990 Posts: 768
Status: Offline
posted
quote:Originally posted by Rye: Would it be better to partially restrict the heater hoses, or to block them completely?
Richard
Definitely do not block off completely. The rear water outlet is where your Coolant sensor for the ECU is located. In addition you would lose your cooling in the cylinder head.
Region: Houston
Car #: 91
Year : 1991 Posts: 2171
Status: Offline
posted
Dennis is right from what I've heard. I've been told that the flow of coolant is rather delicately balanced between the front and back of the head by the restrictions present in the thermostat and the heater core. Unfortunately, we don't really have a way of measuring the temperature of #4, which is supposedly the most sensitive to the issue. We just measure the average overall or a subset. I measure mine in the heater hoses, but I'm not sure that's the best either.
-------------------- Do I turn my 99 Hard S into a killerfast SM or seek a donor?
Region: Lone Star
Year : 1990 Posts: 4253
Status: Offline
posted
Kent the heater hose is a good place...just make sure you have the one going into the core not out. That's as close as you can get to the stock sensor location I think.
Has anyone seen decreased performance after adding a sensor in a hose (using a fitting of course)?
Dave, when do you guys stop racing up there? We race until late November here, and start again in January. Our off-season is during the summer. So we run in both extremes of the temperature range, from freezing to 100°F.
I've had overheating problems before...with a Koyo, thermostat, no thermostat, gutted thermostat, or restrictor plate. I did find that my radiator cap was a bit tired while I was at Mid Ohio (overflowed just idling on a cool morning) so that could have been an issue all along. Mr. Ed and Chris found a loose fitting on the thermostat housing, one of the little nipples where the IAC hose attaches, or maybe it's the oil cooler, can't recall. Ed had to replace that. I can't wait to race my car in the summer again...hopefully I'll have no problems anymore.
-------------------- "Your victory is tainted! Asterisk! Asterisk!!!"--Lisa Simpson
Region: Chicago
Car #: 30
Year : 1991 Posts: 62
Status: Offline
posted
Come to think of it. The only comment I have on the Koyo is that the filler neck seems a little flimsy. The cap does not seem to engage the neck with a lot of gripsion.
Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991 Posts: 1111
Status: Offline
posted
The only comment I have on the Koyo (other than that it works well) is how easy it is to strip the drain plug, which has plastic threads going into plastic threads.
Region: NWR, OR
Car #: 30
Year : 1992 Posts: 8523
Status: Offline
posted
Plastic into plastic? I guess I didn't look close enough, I thought mine was plastic into aluminum. BTW, anybody know where to get spare drain plugs for the Koyo?
quote:Originally posted by Jim Boemler: Plastic into plastic? I guess I didn't look close enough, I thought mine was plastic into aluminum. BTW, anybody know where to get spare drain plugs for the Koyo?
jim
The 37mm Koyo I have in my '99 is a plastic plug into aluminum. The OEM plug is identical to the Koyo,.. at least on mine.
-------------------- Chris
"Nothing can be simple. Everything's got to be a pain in the ass." - C. Adams
Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991 Posts: 1111
Status: Offline
posted
Plastic into aluminum would be nice, since the plastic plug didn't survive the engine swap in decent shape. I'll look into that, and into the OEM plug.
Region: Oregon
Car #: 80
Year : 93 Posts: 602
Status: Offline
posted
My Koyo radiator (50mm) plastic plug busted after four years of use too. I took the old plastic threaded plug down to the local hardware store and found a matching short stainless bolt in metric size that fits perfectly and cost about 50 cents. Works perfectly and you can get some real torque on it to seal it up too. And the hole in the radiator was definitely aluminum threads.
Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991 Posts: 1111
Status: Offline
posted
I called up Koyo (888-557-5696), to buy a supply of the plastic ones. They acknowledged the problem, said they now make them with metal plugs with rubber grommets, and offered to send me one, gratis. And, yes, the receiving end is metal, so this should solve the problem.
Region: NER
Car #: 7
Year : 1999 Posts: 636
Status: Offline
posted
I found a Ron Davis all aluminum radiator for half price ;^) I'm in the process of replacing the stock radiator and all the little coolant hoses, including the two to the heater core. I figure this is as good a time as any to add one of those inline temp sensor housings. Any suggestions on where to get it from (vendor)? Possibly one of these?
On a related note, what sort of coolant mixture do you guys use? My car will see freezing temps in late March/April in the northeast, so I'll need some coolant mixed in with the distilled water. I'm looking for a suggested ratio. I was planning to run straight distilled with Water Wetter once freezing becomes a non-issue in May, but someone just brought to my attention that MORE coolant than water may help with boil-over when the car gets really hot.
What pressure radiator cap do you guys use?
[ 01-29-2008, 12:31 PM: Message edited by: CP ]
-------------------- -Cy Supported by LTD Racing & Speed Shack - New England's Premier Auto Accessory Store Rt1 AutoMile - Norwood, MA http://www.speedshackonline.com
Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991 Posts: 1111
Status: Offline
posted
Cy,
FWIW, I run about 25% antifreeze here in the Pacific Northwest in the winter, where my car is garage-kept, and it rarely gets below 25. I'm in the market for a trailer, so next winter my car will live in the (unheated) trailer; I'll use 50-50 then.
Once freezing no longer is an issue, I'll take all the antifreeze out, and just run distilled water and Water Wetter. Antifreeze is bad stuff if you have a coolant leak on the track; it's really slippery, and dangerous to you and your fellow racers, so I try not to have any antifreeze in during races. Also, coolant doesn't cool as well as water, or water with Water Wetter.
quote:Originally posted by CP: On a related note, what sort of coolant mixture do you guys use? My car will see freezing temps in late March/April in the northeast, so I'll need some coolant mixed in with the distilled water. I'm looking for a suggested ratio. I was planning to run straight distilled with Water Wetter once freezing becomes a non-issue in May, but someone just brought to my attention that MORE coolant than water may help with boil-over when the car gets really hot.
What pressure radiator cap do you guys use?
If you're running in SM, no coolant is allowed on the track, just water and water wetter. When I store my car outside for the winter I use 100% antifreeze, I froze it last year so I am not taking any chances. I will run the first track day with the antifreeze and then flush it and replace it with water and water wetter before my first race in May. BTW, we still get snow and freezing temps in late April and early May up here in Vermont so I may end up flushing it at the track!!!!
Tony Senese SM #99
-------------------- Tony Senese SM#99 2008 NASA-NE SM Champion NASA-NE SM Director 2008 PRO-IT SM 3rd place http://www.nosenseyet.com/coppermine
Region: NC
Car #: 86
Year : 1990 Posts: 135
Status: Offline
posted
quote:Originally posted by CP:
On a related note, what sort of coolant mixture do you guys use? My car will see freezing temps in late March/April in the northeast, so I'll need some coolant mixed in with the distilled water. I'm looking for a suggested ratio. I was planning to run straight distilled with Water Wetter once freezing becomes a non-issue in May, but someone just brought to my attention that MORE coolant than water may help with boil-over when the car gets really hot.
What pressure radiator cap do you guys use?
It may help with boilover, but the heat transfer is not going to be as good as water + water wetter. Chances are you'll run higher temps with the anti-freeze in there.
Region: NER
Car #: 7
Year : 1999 Posts: 636
Status: Offline
posted
Thanks for the replies guys. Water and wetter it is come May.
I stopped by my shop tonight to ask about where to tap for the coolant temp gauge. He showed me a port on the rear of the head (the t-stat housing looking thing), facing the driver's side that will accept a NPT-threaded sender and will show the temp of the coolant at the back of the head.
Will a 16psi radiator cap be alright?
-------------------- -Cy Supported by LTD Racing & Speed Shack - New England's Premier Auto Accessory Store Rt1 AutoMile - Norwood, MA http://www.speedshackonline.com
Region: New England
Car #: 92 Posts: 1993
Status: Offline
posted
quote:Originally posted by tony senese: ]If you're running in SM, no coolant is allowed on the track, just water and water wetter.
This isn't 100% true. Some tracks or maybe some regions forbid the use of antifreeze (or anything other than water). But it's not a national SCCA rule.
Here in the NE Div we often have events where the ambient drops well below freezing at night. We NEED antifreeze in the early season.
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