Hi all, I know inlet temp threads are all over the place and I have decided to buy an ACT gauge BUT... An ACT gauge will tell me the temp of the air going in to the engine, is it better to compare the ACT temp with ambient temp or the temp after the air filter or temp after the turbo but before the intercooler?

Depending on the answer to the above, is there a gauge available that can show more than one temp and maybe warn when there is a pre set difference that could be harnful?

Or is it a case of buying more than one gauge - 2 ACT gauges is starting to look expensive. Is there an ambiant air temp gauge?

Is a knock warning gauge a good addition to the above and if yes can anyone suggest a good one?

Thanks

 

Can't answer the first part of your question, but I've recently fitted an ambient air temperature gauge, bought from Darms on here. He bought three from China, I believe.

Dead easy to fit, I had to extend the probe wiring as it only comes with around a metre, which would put the gauge under the car or on top of the gearbox, not useful, or in the engine bay, equally not useful. Mine has been extended to sit under the o/s wing.

It cost me around £20 delivered.

I also have an act from Harvey and can compare the two. I don't think that any differential is important, surely just the act?

For a definitive answer, PM harvey Smith, he posts on here as harvey.

 

I'm sure harvey does a dual act gauge, comes with 2 probes and a switch to select which probe. one as the air charge temp and one as ambient.

 

i got one of the gauges that harvey sells, and have got one sensor in the pipe work where the filter is (inner wing) and one in the boost pipe just before the inlet manifold.

on normal driving i get between 6/7 deg difference between charge temp and air time at the filter

 

Depends what you want to know. Comparing the charge air at the throttle body with the "after turbo" temp will tell you how good your intercooler is at doing its job. If you really want to be a know-all, you can have sensors in all three locations, thereby showing you how much your turbo is heating the air, before the intercooler cools it back down.

However it's more useful, most of the time, to know what the charge and ambient air temperatures are. To be honest though of the three, the only one that really matters, from an engine safety point of view, is the charge temp. There's an argument for saying that festooning your cockpit with gauges you don't absolutely need is a waste of money and an unnecessary competitor for your attention.

It's more useful to be able to datalog things like this so you can examine them after a drive.

A knock monitor is probably more useful than a charge air temperature gauge, so if you are deciding what to buy, a good knock detector should be higher up the list. If you want a plug and go off the shelf unit, you will find it difficult to beat the Phormula KS3/KS4. Oil press/temp gauges are probably more important than charge air temp too.

 

The dash outside air temp display on newage cars is a good indicator of ambient temperature.
As for a dual temp gauge, the ultimate would be SPA fitted with K probes but would cost IRO £250.

If its just a passing interest in dual temp readings then for about £90 this http://www.novusautomation.co.uk/acatalog/myPCLab.html plus a couple of K probes slipped under hoses is a very good PC test kit with data logger to work out IC efficiencies.

 

Thanks for all the answers, my reason for asking is that there is a strong possibility I am moving to Spain and will probably take the scoob with me. Obviously the ambient temp out there is hotter than this country so I want to make sure my engine stays in one piece if I decide to use the power it has, hence trying to find out what to monitor and what not - I already have an oil pressure and temp gauge, I may need to fit an oil cooler but wont know until I get out there and see what the temp gauge says

Will a knock link give a better indication of impending doom, and a don't boot it message? than an ACT gauge??

So many questions......

 

In very hot climates, I'd fit both.

Mine was destroyed by heatsoak in 40 degree temperatures in France, let alone Spain.

 

Hmm, sort of following on from this, my car will have the polar performance chip fitted, when I get around to it so that will allow me to use 97RON as opposed to 99RON, but can the ECU compensate for hot thin air by increasing the fuel level? or is there no air temp input to the ECU (96WRX)

Thanks

 

If you don't need an oil cooler over here, in the sort of weather we're seeing at the moment, the chances of you needing one there are minimal. The stock modine setup deals well with a variety of ambient temps. You're likely to find the difference between Spain and the UK not as pronounced as you're expecting anyway. The main difference is that it's hotter more of the time.

A knock monitor (as opposed to a KnockLink), definitely. A charge temp gauge will (obviously enough) tell you what your charge temp is. This information isn't really that much use to you on its own given that you won't know what sort of temperature is "safe", and what isn't.

Bottom line is that if the temperature is sufficiently hot to cause the engine a problem - and the ECU hasn't (or isn't capable of) responding proactively to that, a genuinely good knock monitor will tell you what you need to know in time to do something about it. And, more to the point, if there are any other issues impinging on combustion - for example a compromised airflow meter or injector, a knock monitor will sweep those up too.

The KnockLink is very old tech nowadays, btw, and isn't anywhere near as accurate or discriminatory, at least in standard form, as some of the more modern digital instruments like the Phormula products.

 

Thanks splitpin, very informative answers , I will look up the Phormula Knock monitors with a definate view to getting one.