So I was reading the Datsun / Nissan Cherry race motor prep manual (the one on dastuncherry.ch) and it says to remove the thermostat. Anyone actually doing this? The manual also was water temp should be 175F.

Tom

bad idea i think. better to use blanking plate with a suitably sized bypass hole. you need to regulate the flow and pressure of the coolant.

This subject is covered in depth in the great technical reference book. 4-stroke performance tuning by A Graham Bell

There is a relationship with block pressure generated by the water pump and the operating temperature requirements. 30PSI seems to be the sweet spot for block pressure. Pump speed is the variable here.

175F degree water temp is ideal: hot enough for the oil to be optimal. Engine oil works best when heated to around 200F (engine oil runs about 20F hotter than the oil)

how to regulate water temp to 175 though is the question. In some kinds of racing removing the thermostat will allow erratic temp variations. What problem is solved by removing the thermostat? What is the advantage? For drag racing it doesn't matter if the oil works well, you can always rebuild the engine between races

Benny the thermostat has made itself a blanking plate; I pulled the thermostat out of the shagged head and it's stuck open.

Dave no clue what the intent is the manual just says "remove thermostat".

I agree with Benny if you remove a thermostat always use some form of flow limiting plate, I have experienced engines without the thermostat only circulating water through the front cylinders leading to overheating of the rear cylinders and if very high compression detonation carnage on the rear cylinders.

i know such plates are available for some chevrolet and ford motors, Heck I even used a Ford Windsor thermostat outlet for my L series FIA head when I got that as that part was missing, Fitted perefectly

Do not run without a thermostat, as the coolant will recycle through the engine and bypass the radiator. This has happened to me. Two options, IMO, one is to replace the thermostat with a washer that has a hole drilled in it, approx. 3/4" to slow the flow rate down (This an old Clive Trickey solution for BMC A-series race engines in the 60's). The other option is to test your thermostat in a pot of water on a stove to see when it ACTUALLY opens. Also critical - check your radiator for proper flow, especially if it'sen sitting for more than 6 months.
I went through several race motors from overheating, first from a plugged aluminum comp rad (didn't check it!), then from thermostats that didn't open properly. I now run a Chev. 160 degree stat that I checked to assure it opens properly, a new three core x 3/4" rad with electric fan and a shroud.
I run a long rod A12A (1237cc) with 13:1 compression and high lift Electromotive cam. Once I got it sorted it runs a 30 minute race with 8500 redline and I rarely see more than 190 degrees.
FWIW. thanks for listening.
Lorne

I don't have a thermostat (in the traditional sense) in my A15. I replaced the mechanical pump and thermostatic throttling valve with an electric pump, temperature sensor and controller. I've had no issues flogging it or driving interstate. Always sits on the middle of the gauge.

I can't think of any good reason to get rid of temperature control. If you're not getting enough flow and hence overheating drill a hole or two in the thermostat. It'll take a bit longer to warm up but maximum flow will increase.