14 replies to this topic

[Brandon]

2 questions:
#1. Running with or without a thermostat. I presumed (incorrectly) that my previously-owned car was running w/o one but low & behold, removing the housing reveals *queue fireworks* a thermostat!

I went ahead and reinstalled the housing without one but was curious about other's approach to this. FWIW, I'm in the NE area so I don't regularly see 100+* racing days and I do have an aluminum radiator.

#2. Doing a remote oil sender install and I noticed the original one didn't have the single-tab wire attached to it. The PO did have an oil pressure gage installed (but non-funcitonal) and there was a "self-installed" wire leading from it to the sender.

Does the PCM require a signal voltage from the sender? If so is it only to prevent the oil pressure idiot light from being lit? I don't recall any oil light illuminating but the PO may have removed the bulb from the gauge panel.

Summary:
T-stat or no t-stat?
Oil sender hookup to PCM required or not?

Thanks!
Brandon

[davew]

No stat
No need to install teh wire, it only runs the guage

Dave

[dmathias]

There has been some debate on the usefulness of keeping the thermostat. One particular engine builder insist that the Mazda OEM 195* thermostat is necessary to make peak HP. His theory is endorsed by at least one fast guy/engineer type. The thoery is that you want the motor temp as hot as possible, without overheating, so that the tolerances are loose. Conversely, the intake should be kept as cool as possible.

I know from personal experience that without a thermostat, my motor would not reach proper operating temperature at Spring and Autumn events in the Midwest when the weather was cool.

P.S. a properly functioning themostat will not contribute to overheating.

[FTodaro]

I installed a 170 degree stat The idea is that if the water is rushing past the rad to fast it reduces cooling efficiency. So the speed of the circulating water is an issue.

[Scottie]

+1. I also installed a 170, kind of happy medium between having one and not having one I guess.

[James York]

There are pros and cons to running a variety of temperatures depending on which car you have (Fuel maps, timing, etc). However, one fact is true for all models; hotter temperatures (not too hot though) produce better thermal efficiency in the engine. More BTUs can perform work versus being used to heat the block. Too hot though and the ecus start to adjust timing in a negative manner for power.

I used to run no thermostat but instead used a plate with an orifice (to provide some backpressure for the pump to prevent any cavitation). I have a monster radiator for the Texas heat. During the winter and fall, I would have to tape up the radiator opening to keep the car hot enough. I got tired I having to constantly tape/untape and went with a thermostat now vs. the restrictor.

[Brandon]

Okay, so you've convinced me my thermostat would be helpful but now what part number do I order?

Mazda Speed the place to get one of these 170* jobbers or will any parts store that stocks Stant suffice?

And I guess I'll return the sending unit for the thermostat.

Thanks!

[FTodaro]

Okay, so you've convinced me my thermostat would be helpful but now what part number do I order?

Mazda Speed the place to get one of these 170* jobbers or will any parts store that stocks Stant suffice?

And I guess I'll return the sending unit for the thermostat.

Thanks!

I would start with NAPA

[dstevens]

I installed a 170 degree stat The idea is that if the water is rushing past the rad to fast it reduces cooling efficiency. So the speed of the circulating water is an issue.

Many think that but that isn't the issue. Chris Paulsen of C&R Radiator for one disputes that reasoning. What is an issue though, like James says is back pressure. That's why some use a restrictor in some cases instead of wide open. One possible downside is that you have to manipulate the temps via tape on the radiator, like one would in a shifter kart.

[Ron Alan]

There has been some debate on the usefulness of keeping the thermostat. One particular engine builder insist that the Mazda OEM 195* thermostat is necessary to make peak HP. His theory is endorsed by at least one fast guy/engineer type. The thoery is that you want the motor temp as hot as possible, without overheating, so that the tolerances are loose. Conversely, the intake should be kept as cool as possible.

I know from personal experience that without a thermostat, my motor would not reach proper operating temperature at Spring and Autumn events in the Midwest when the weather was cool.

P.S. a properly functioning themostat will not contribute to overheating.

Interesting! So could someone chime in on what they feel an ideal motor temp would be for peak HP...give or take 5 degrees?? At what temp(hot) will the ECU begin to rob HP? And at what temp do you shut it down assuming you see it in time?

Sometimes we don't see 180 degress


Wheeler, Drago, Collins...Bueller???

[dmathias]

I reiterate - OEM, 195*

danke schoen

[davew]

I have 41 Miatas in the shop, only one has a thermostat. Ann's street car.

There is no need for a restrictor. Look at the size of the inner diameter of the upper radiator hose neck. It ain't very big! And, the hole in the cylinder head, where the water neck attaches behind the timing belt, is small aslo.

On a cold day, when you can not get the temp up into operating range of 180-200, put some tape on the radiator screen. You are running a radiator screen, aren't you????

I start my dyno runs at about 160*. I usually get 5 pulls in before the temp gets to 215* which is where I stop. I have found very little difference in 180-210 degrees.

I have removed dozens of thermostats at the track to cure running hot issues. Often drivers complain of the temp guage going up and down. As the stat opens and closes. You will never have an issue with a stuck thermostat if you do not have one!!! No REAL race car runs a stat, even the roundy round boys adjust with tape on the grill.

Works for me
Dave

[Ron Alan]

Thanks Dave. Anxious to get your FP gauge installed when it shows up!

[Dr.Dan]

save your money make plate with a 7/8th hole of thin alum. and put that in. Adj for cold temps by blocking the rad. been doing this for years.

[dstevens]

No REAL race car runs a stat, even the roundy round boys adjust with tape on the grill.

It's a combo of different size restrictors and tape. The volume is about 3 times that of the little four banger and if you don't restrict there can be issues with hot spots in the coolant flow and cavitation on the pump impeller. The amount of tape and the size of the restrictor is a tuning combination that must be learned for each car combination.

Thanks for the temp range info.