Intercooler Intake Temps

[GTR 400]

I am wanting to know what sort of intake temps should a turbo car be running roughly. Eg if ambient temperature outside is 25 degrees what sort of intake temps should i be seeing. I have a R32 GTR highly modified with 335Rwkw and with my Pfc hand controller when i am cruising along after driving for about 15mins i notice it is reading 45 degrees intake taken from the factory sensor tapped into the front of the intake manifold. Yet if i jump out and touch the intake side after the air has passed through the cooler it is really cool like as if ambient temp outside or slighty cooler than, so im thinking damn that doesnt make any sense its really cool but my controller says its not, i always assumed that the intercooler will match the air temp outside or a little lower than it at night.

I am running a Huge Trust tube and fin 149mm cooler which is in my opinion one of the best brands of cooler product coming out of Japan so if this PUPPY cant cool than nothing else will.

But still my temps displaying on the Pfc hand controller are usually 20 degrees above the given ambient temp outside, so i am asking people in the know is it maybe my intake sensor is probably not accurate, or is that really the best air temp ratio to outside temps a cooler will keep. Mind you i am not pushing the engine yet even though when i do it only goes up 1 or 2 degrees.

Is this right or is there more to it????????? I was actually having a joke about it with a close friend saying that maybe the sensor is faulty and reading the temps before its going into the intercooler hahaha.

But when i start the car the controller reads from the sensor the ambient temp outside and then it will gradually go up till it meets the required happy level.

I am puzzled and confused anybody that can expand on this dilema please.

[Guilt-Toy]

in my old datsun fj20 days i remember some guys reporting temps of -2 deg etc etc but this was late at night in winter, freezing cold, and they were using some dodgy truck chop coolers, I had a GTR cooler on my datto and it was the best one around at the time...

I want to get a air temp sensor for my rb25

[Fixxxer]

On my other car (rotary) it used to read about 2-5 degrees C above ambient when on the move (throttle open), and go up another 5 or so degrees more when you closed the throttle (e.g., coast to a set of lights). I did see it as low as 4 degrees on a cold night in Brisbane/Gold Coast.

I think it's just a case of where you get the reading from. I'm sure that massive cooler is doing it's job.

Fixxxer

[GTR 400]

Well i now have found out real time intercooler temps.

My R32 GTR has a air temp sensor that is in the inlet manifold, i took this of extended the wires, took of the aluminium intercooler piping and got a tap welded to it with the same thread as the sensor and bolted it into place.

I put a bolt in the inlet manifold with washer and PRESTO my PFC hand controller now reads real time intake temps.

I love it it works perfectly and i have a Trust 150mm tube and fin intercooler my intake temps are usually 2 to 4 degrees below ambient on a day of 27degrees. This massive cooler works SUPERBLY.

You can never have enough cooling i reckon well i have sold my problem when the sensor was tapped into the inlet manifold it was getting heat soak hence why my inlet temps where so high.

[wolverine]

how are you getting lower than ambient temperatures?

approaching ambient is possible but below ambient temp is breaking some laws of physics (unless there is some other cooling medium being used such as water spray).

it sounds like either the inlet (or ambient if you have one) sensor is not accurate.

Edited November 25, 2007 by wolverine

[BHDave]

I agree. I don't doubt that the big core is capable of dropping the temp considerably, but unfortunately the ambient air cannot cool something to less that it's own temperature.

[Dale FZ1]

  GTR 400 said:

Well i now have found out real time intercooler temps.

my problem when the sensor was tapped into the inlet manifold it was getting heat soak hence why my inlet temps where so high.

You've really identified the issue there. Yes, your cooler can work quite effectively, though Wolverine and Guilt Toy are correct. Unless there is something extra happening you won't get below ambient.

Heat soak definitely works against the intercooler. Basically the cooler sheds heat, and then the manifold takes in heat from the engine bay and reheats (to some extent) the post-cooler air before it is drawn into the engine. Air speed, mass flow, and flow type ie. laminar vs turbulent will play some part in just how much the air is reheated.

If you were running full noise, extended loading, and had reached saturation point for the cooler and achieved inlet temps 20 degrees above ambient then there is nothing wrong with that. Remember a cooler is a heat sink so it will initially accept a fair amount of heat before it begins to shed the heat.

If you're stressing about highish temps in stop start, light load, low speed cruising, then don't. Heat buildup is what happens. Take the thing for a reasonable run and in 5 minutes you will see temps tumbling.

[Dale FZ1]

Edit: double post.

Edited November 25, 2007 by Dale FZ1

[rev210]

If you have unshielded pods / turbo's etc. those 'around town' temps are going to be 20deg + over ambient.

I noticed a significant intake temp difference between pods and the stock airbox (after the intercooler). I also saw a few extra degress drop by removing the rubber strip at the windscreen side of the underbonnet, a mod similar to raising the rear of the bonnet (without the hassle).

[Guilt-Toy]

Wind chill might have something to do with it.... Bit like being out in the freezing cold... when the wind starts blowing at you it will feel much colder then it was without the wind.....

[Blue32]

Ah - the dreaded heat soak issue! I have had an issue with my PWR FC D-jetro RB26 on hot ambient days getting inlet manifold heat soak after shutoff (up to 80 deg after some time 10 or 15 mins) - and it makes it hard to start once it exceeds the 80 deg. I have to hold a bit of throttle on to allow it to continue running until the temp drops below 80 and it returns to running fine . I realise there are compensations built into the engine management to pull timing etc once the intake temps exceed 80, but it is obviously heat soak NOT actual inlet temps of 80+ deg. To combat this problem I have ordered a Gizzmo Phenolic inlet manifold gasket to try to prevent the heat transfer to the manifold / temp sensor, and I will be fitting it in Jan when I get back from overseas to see if it makes a difference - I'll post the results. If this doesn't work adequately, I will be moving the sensor into the intercooler output pipe as previously posted.

Anyone else had experience with these gizzmo gaskets? Real time results? I will datalog the results I see and post for all to see in January!

[Guilt-Toy]

how much was this gasket?

[rev210]

I doubt you are going to see much benifit, if any at all, from the phenolic gasket in the GTR application. Heat soak of all components underbonnet after shut down is a fact of life. The 80 degree temp reading on the inlet sensor is initially from static air inside the plenum that has been very slowly heated up, once the engine is started the air temp falls immediately and rapidly drops down to where it normally is when the engine is warm and the car stationary. The speed at which the temp drops is effected by the air temp the intake is sucking in so if you have unsheilded pods this will be slower than a sealed and cold air fed enclosure. This I checked again after reading Blue32's post today.

The heat transfer to rapidly moving air of the relatively small surface area in the plenum isn't significant.

However , phenolic gaskets work great on carby based applications where the fuel is carried in a fuel bowl and transfered heat can boil fuel causing vapour lock. Cooler fuel is a good thing.Unfortunately the liquid fuel transfers heat very well compared to air. It's up for debate as to whether insulating the fuel rail and lines in the engine bay would be of benifit, don't know about that one.

[kjb_r33]

I went and bought on of those $40 temp readouts from jaycar and fitted it into the rubber coupling at the throttle body. Its amazing how much temps vary. Mild cruise and it can climb, low air flow and heat soak gets it. Open it up abit and temps drop. Sitting in traffic it sky rockets. Highest ive seen it with heat soak engine off was around 80 c. Under full boost (15psi) it drops fairly quickly, usually to within 5 degrees or so of ambient (compared to skyline ambient temp sensor). Go back to cruise it starts to rise again.

EDIT: http://autospeed.com/cms/A_0807/article.html

Edited November 27, 2007 by kjb_r33

[GTR 400]

Wow how this thread has taken of now hardly any one bothered before well thats good, so getting back to the air temps that i stated before this i will update, on a normal 25 degree day my cooler will sit on Ambient depending on if its city driving or a slight highway bash on the F7 or M2/M5/M4, although i will add my cooler even in city driving will not go above ambient if i have been driving sensible. I have gone out and absolutely given my car the dick for a good 5mins all 335Rwkws worth and i will swear that i will not get more than 5 degrees above ambient, its incredible and no i have no water spray. the sensor works perfectly nothing wrong with it that for sure. I will retract my 2 to 4 degree below ambient even though on a cold night i do achieve those figures but in every day driving in the city i get ambient.

But this i noted in my TESTS that after i turned of the car for at least ten minutes, then started it up again to drive of somewhere the cooler heat soaked from the engine bay temps and it then was 4 degrees above ambient even just driving normal speed limit, and it would mot come down to ambient unless i went for a highway cruise and even then for a good ten minute uninterupted cruice the cooler could not shake of that heat soak better than 1 degree it would require alot longer drive for it to come back down as the cooler is so big that once the stationary heat had soaked into to it, it needed alot of time to entirely cool the whole core down.

My temps do not fluctuate like Kjb r33 do they are steady, and only more like i said before if i hit her real hard.

I do have the rubbers removed from the rear of the bonnet where the bonnet meets, and all at the front lights etc and i have a 15mm raised bonnet to help assist the heat disapating out of the engine bay which works a treat i will add.

My cooler can just cool down the hot air that my turbos are producing that efficient and well that ambient or a little above on any given temp day is not a problem for my big bulky cooler to achieve.

I guess garrett 2860r dash -7 flowing at the absolute maximum just dont delivery enough hot gas flow for my cooler to have a problem re cooling down.

This is my true testing and with this cooler i guarantee if you have all the right mods with fuel,injectors,exhaust etc this cooler size should do exactly the same to any other R32GTR.

Cheers,

Dave.

Edited November 27, 2007 by GTR 400

[GeeTR]

Wait up - the PFC clearly uses the temp sender in the plenum for correction. Wouldn't sticking it in the intercooler pipe (where its almost always going to be cooler then right up against the head) going to effect the correction amount? (ie, if there was a condition where the cooler was cold and the plenum was heat soaked and hot...?)

Fancy low heat transfer gaskets would do bugger all in a modern engine bay like a Skyline I reckon. Although I’m not discounting the huge transfer ability through solids, the whole engine bay is full of radiant 90o engine, radiator, oil lines, HICAS lines, brake lines, heaven forbid a high mount setup.

[GTR 400]

I always thought of it as the sensor was necessary for the original ecu when it ran in closed loop, but with the PFC that takes it all away as you are tuning the car to run a certain way at all different boost levels etc, etc, etc, you should in theory as an example if i am correct be able to pull out the exhaust sensor and it wouldnt make a difference to the car right? Hence why the dyno tune from scratch when you have so many mods added to the car, so re routing the sensor shouldnt be a problem that would affect the car. So i have used it for a better purpose of monitoring my intake temps.

Please correct me if i am wrong is the inlet temp sensor still needed once you have had a PFC installed and your car re tuned on the dyno for all the supporting mods???

[GeeTR]

  GTR 400 said:

Please correct me if i am wrong...

Your getting the zhaust O2 and intake sensor mixed up

O2 sensor feedback can be turned off in the PFC, but I'd keep it turned on, specially if it's a daily / often used car; helps with fuel consumption. (The fact a faulty sensor can take 200km's off the mileage [kilometre'age?] of a tank, shows this) It's a reason why people like to use the injector correction when using larger injectors, it allows the closed loop and target AFR to function properly. (VS those that say, install 700cc squirters, leave the correction to stock and tune from scratch)

The intake manifold temp sensor, for intake temp correction, is always on I believe, and plays a pivotal role in telling the ECU (be it stock, PFC or full AM) charge density. I don't know the specifics of the PFC setup, but you can bet when the intake temp goes up, ignition advance at least, is wound out.

  Quote

So i have used it for a better purpose of monitoring my intake temps.

Keep in mind, if the sensor was there to inform the user of benign temps, there'd be a dash gauge or something

[Blue32]

Guilt-toy: The gasket was $105 delivered from www.shopx.com.au

I am mildly skeptical as to the results I might see from this gasket - but can't hurt to try I guess! With the std intake air temp, I think something that really lets it down is the abililty to shed heat from the sensor itself. It really seems to slow to react to temp change. I know when I start the engine, after it has heat soaked, the sensor is reading quite high, but after a minute or so of running (especially driving) the temps of the air charge entering the engine should be much closer to ambient plus a little bit (depending on intercooler efficiency etc) and not linger around the ambient plus 40 or 50 that it does. At least by moving the sensor to the cooler outlet pipe, it won't be so susceptible to this, therefore running a more accurate intake temp vs ignition correction? Thoughts?

[GTR 400]

I cant claim to have the knowledge mechanically to respond to your last question but with the knowledge i have learnt in working with these cars it does make sense as to what you said that it should give a more accurate intake temp as it is now reading true intake temp versus engine heat soak temps.

I to used to have readings of 47 to 52 degrees intake temps depending on ambient temp and how hard i drove, and it makes sense that that is gravely in accurate for the ecu as intake temps would be nowhere near that hot.