MicroSquirt.com read only forum (Jan.15,2018)

Here's the standard shpeel -

MS-II v3 spark and fuel
4.6L DOHC aluminum Ford modular motor
multiport w/ roots type supercharger
street use, stock bottom end, low boost

OK,
It's rouighly running and driving, but thats ok, wb o2 on the way. It's good enough to test drive and work some bugs out.

Should I be alarmed at a 200 degree MAT at idle? I know the roots blower is a heat generator and as it is running dry, there is no fuel to cool the mixture until it reaches the injectors at the ports. I keep telling myself thats ok because it gets cooled at the intake valves anyway and running a stock 200 degree tstat, thats how warm it would be anyway. What MAT do other boosted motors running? (at idle or boost?)

Thanks for any input

I have zero experience with your setup, but wow, 200 degF sounds really hot to me... Did you do any calibration of the unit itself? What does the MAT indicate when the engine is cold, prior to startup? It should be very close to coolant temp after a night's cooldown.

Roger

yes, on cold startup, the sensor reads a reasonable ambiant temp. I wouldn't think an mat of close to engine temp is outside the norm, just want to know what others are getting.

Is your sensor actually sticking well into the airstream. Sounds like it may be heat-soaking from the manifold, and measuring manifold metal temp, rather than manifold air temp?

Well the sensor is at the bottom of the intake plenum and the blower discharges directly at it. I hadn't thought of heat soak, but it responds quickly to changes in map, so it would seem to be sensing the air temp properly.

Do you have a by-pass valve?

I have a setup with two twinscrew chargers on a 355" chevy and when I measured my discharge temperature at idle it was 75ºC (167F) with closed by-pass and dropped to 45ºC(113F) with the by-pass open.

There is more good info. here:http://www.msefi.com/viewtopic.php?p=78430#78430

Lars

Wow, I was worried about 50c temps! what ignition advance do you guys run under boost? (10 to 15 PSI).

do you have any intercooling? what kind of intake sensor do you have (open cage or solid metal type)
200 deg is pretty high for idle, i would think. i have an intercooled (very efficient self designed setup) turbo, and i see MAT of a few degrees above ambient on idle, and about 45 deg c under load.... what kind of intake temps are you seeing under load?
i would look into intercooling in the future... with air temps that high, your really losing a huge amount of power to retarded timing to combat knock. if you're limited by package constraints... an air to water intercooler might be a good option, they are much more compact inside the engine bay, and keep your piping short.

is the sensor before it enters the air to water intercooler, (assuming this is a 03/04 cobra)

no intercooler

still has stock 205 F thermostat. Thinking of trying a 180 F and that might bring temps down. Test drove the other night an I think it was pegged at 214.9 under boost, so that's not good. May have to do some reconfiguring to get it right.