Monitoring engine vitals (basic to advance)

Hi guys, I want to install a coolant pressure sensor on a drag Evo 2, where is the best location to install the sensor??? What's the best sensor to use???

The pressure in the coolant system will essentially be the same everywhere. In race cars we typically install the pressure sensor in the header tank. Best practice is to use a solid-state pressure sensor. 0-30 PSI is sufficient range normally. What is the rating on your pressure cap? You should probably have a sensor that covers that range.

Sometimes the choice of sensor comes down to what the logger / ECU can easily work with (ie, you have calibrations, or the ability to calibrate for the sensor).

Ok so just to clarify, the head tank is the radiator top tank ? I have to verify the radiator cap also, using a an AEM2 engine management system.

The car is not fitted with any air intake temperature sensor, I want to install one, I'm using water meth injection and the nozzle is in the intake pipe about 4-6 inches away for the throttle, how far back from the water meth nozzel should I install the air intake temp sensor???

The header tank is the highest point in the cooling system, typically that is where the pressure cap is. We often have bleed lines that terminate into this tank. You could put a bung on your radiator, or mount it to the coolant outlet fitting on the engine, or inline with any of the coolant hoses.

Sorry, I don't have any experience with how a water/meth injection would affect the air temp sensors and where you should mount it relative to the nozzle.

As David said, pressure 'should' be the same everywhere in a sealed system, as simple hydraulic theory. However, i assume you are using a water pump and they, especially mechanical ones, can cause the block to pressurise more than some other parts of the cooling system as the pump is both forcing coolant through the thermostat plate (you may still be using a thermostat but unlikely in your country, but some builders wil use a plate with a hole drilled in it to regulate flow through the system and the increased back pressure helps increase boiling point and reduce hot spots developing steam pockets) and pulling coolant from the radiator.

That may not be that relevant, though, as you are looking for a increase in the pressure and that increase 'should' be evident throughout the system. I would probably place the sender as close as practical to the cylinder head gasket area as it should be most evident there.

Air temp sensor location is a good question - don't use water/meth but I would probably mount it downstream of the injection point, where it has had a chance to cool the intake charge, as that is what the engine is going to be getting and if there is a problem with the W/M, like a blocked jet, faulty pump, etc, it will be registered by the ECU and your protective settings will take affect - if it was upstream it wouldn't and so you may run into problems.

In the drag engines we built we fitted the coolant pressure sensor to the header tank as David has mentioned. I used a 0-100 psi fluid pressure sensor from honeywell. Theoretically you shouldn't be seeing pressure higher than your radiator cap rating but the reality is that it may spike above this point before the cap has the ability to release pressure.

Personally I prefer to mount the IAT sensor before the WMI nozzle as if you spray water onto the IAT sensor it's going to affect the accuracy of the measurement. Some will counter that the WMI is cooling the charge air which is true, however I prefer to account for this with my comp tables. It's often overlooked that the fuel being injected into the inlet ports also cools the combustion charge but we don't want to fit the IAT after the fuel injectors.

thanks alot guys, just to let you in on the project, its a evo2 stock 4g63 motor at the moment, AEM2 1000cc id's, watwe meth.

i would like to build it to handel 500-600 street car and the drag strip on a weekend, im not sure if to stay 2L or do a stroke 2.3L

In front of would also have been my preference except I would be paranoid about a problem with the W/M injection failing and charge temperatures spiking - but they're not something I have played around with so better to take Andre's suggestion as he has a lot of experience with them.

However, does the pump you're intending to use have a speed signal wire (more familiar with PC pumps that do) as, if it does, you could have the ECU monitor that and if it failed you could drop the boost, or something?

BTW - for our road racing applications, the reason for coolant pressure is to detect leaks -- a hole in a radiator can leave the coolant temp sensor reading the air temp inside the coolant system, and the engine will overheat warping heads and ruining blocks. So we generally set an alarm at < 3 psi. There are also simple (preset or adjustable) pressure switches that can be used for this purpose as well.

If you're concerned with WM diagnostics/failsafes I'd just run some sort of TC expander and open tipped thermocouple elements. Currently I'm using RaceGrade TC-8s and have garnered some pretty useful information running ambient, post compressor, post intercooler, and post WMI as deltas.