Can you have ACTs that are too low?
Turbo Mini Forums

Own the day

Own the day

Yep You read Right, I Have the datalogs to prove think I have one that goes lower possibly! but we are talking rather large shots of nitrous.

Of cause with ECU control it is relatively easy to alter the mapping to take into acount the Cooler/denser air as in my situation, but of cause this is the only thing that will be cold all other temps will be correct normal operating etc, a carb/SU has very limited temperature compensation the only comp on a SU is in the fuel temperature either via the bimetalic strip within a HIff or a waxstat on the older style which is about as relable as a chocolate tea pot most of the time seeing it gets heated by the exhaust.

the cut off point for a carb would depend on at what temperature you set it up for and as long as you can prevent icing as you dont want the butterflies to stick open, take a methonal drag car, when you see them start up they are spraying deicer over the butter flies to stop the sticking as methonal is so cool burning

WEST

Edited by SidewaysGTM on 22nd May, 2009.

Got A GTM With A Honda In the Back, and huge Nitrous bottle where the passenger seat should be when racing!

The ecu will know just fine what temperature the engine is from the coolant temp sensor.

Charge air temperature sensors tell a very different thing.


On some methanol fuelled engines, the coloijng effect of evaporating methanol being injected, can even lead to ice forming on the external surfaces of the intakes.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Why the offensive Matt.. I answered the original question.

IME you are not going to get ACT too low in mini - partly as there is no perfect turbo to keep ACTs naturally low.

AlexF

fookin hell 5 degrees thats a whole 100 degrees cooler than some of the IAT's ive seen on mine!! that said mine appears to be shite! hahahaha

100degC is not good at all.


Anything above 40degC depending on ambient, and you should be looking to improve things.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

as above. my average inlet temp when on the moove is 30-40 degC. Once boost starts to build this drops to 25-30 degC and stays down to the red line. and thats with an intercooler sitting right above the turbo/manifold and a cylinder head right behind the intercooler blocking some flow.

it heat soacks badly when stationarry but just one pull on boost and the inlet temps are back in check.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I think Denis is saying that due to heat soak, the air temps increase. Due to poor air flow at slow speeds or being static the charge temps don't drop untill it has sufficient air flow.

Could be wrong though...

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1/4mile in 13.2sec @ 111 terminal on 15psi

rubber-isolated thermocouple in the inelt runner to cylinder No4.

when i was running a smaller turbo the inelt temps rose with boost perticularly higher up the revs, but with this unit, the inlet temps drop with boost, i assume because the compressor is operating very efficiently + the denser air can cool quicker in the intercooler. i got those figures by averageing 5 power runs in different datalogs . i know it goes against convention but the numbers are what they are. i mentioned the heat soak and head to show that my setup is far from optimum and still achieved sub 40degC inlet temps. in the winter the figures are obviously colder again. if i get time tonite i'll do an ambient temp reading and a power run and datalog :) not looking for an argument, just sayin the figures as they are!

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Not looking to start an arguement.

Just saying thats I find it impossible for normal, uncompressed ( unheated )air thats passing through the engine, also via the intercooler....so starting cooler, and getting cooled, can possibly be warmer than air that has been heated.

At cruise etc...every turbo car I have monitored temps, have always been in and around ambient off boost. ANd regardless of even the best intercoolers...temperatures on boost, always rise. It just makes sense.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I agree with Stevie...

AlexF

A bit off topic, but I was suprised how slow normal air temp sensors are compared to thermocouples

Team Racing

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

I had previously used the plasitc tipped Bosch sensor.,

Talk about slow...they have something like a 20s response time.


It's a total waste of time monitoring temps with anything slower than an open bulb type thermocuple

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

pulled from an old datalong, unfortunately its started raining so not been able to do a run! shows cruising on the motorway for a while then floring it. But after what you have said will check it with a thermocouple in the inlet piping, dont really want to be spouting shite on here :)

EDIT as its not so clear from top to bottom :
1st window:
RPM
MAP
IAT (or MAT in megasquirt)

2nd window:
TPS
AFR
Duty Cycle

Edited by evolotion on 25th May, 2009.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

When I sued a crap sensor like i described....temps appeared to stay cool on boost, then tended to rise shortly after, before falling again.

But when cruising they did reflect ambient, or around it. They were just incredibly slow to respond

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Interesting. I have been asked to modify and repair some temp probes at work and having asked the question they are quick enough to to take 20 data points a second, a little slower than the user would like but well within the tolerence band. And the temperature range you are all talking about is ok to.

I will do some more digging and get some more info but we get them from RS.

Edited by Mr Joshua on 26th May, 2009.

Own the day

i think i need to change my sesor.

Had a conversation with the guy I was doing these for and he confirmed that the elements being used were platinum resistance thermometers with a temperature range of -60 to +600 degrees running at 35hz. I initialy used some slower ones that cost about £5 each from Farnell. These new ones cost about £12 each.

Own the day

I think the main problem with the sensors is the mass of them, I think they can detect temp change quickly, but it takes a few seconds for the actually sensor to lose it's soaked heat

Team Racing

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Own the day