HSRK Components?

[MeanGreenZ71]

I know there are a ton of HSRK threads floating around but I didnt find out the specific info I was looking for.

I am looking at purchasing the Casper kit #108165 http://www.casperselectronics.com/st...oducts_id=1137

Is the harness long enough to place the new IAT sensor in the partitioned area of a Spectre intake close to the filter? Also is that the correct part number that I need from Casper?

Second, what do you think about this IAT sensor on ebay? http://www.ebay.com/itm/TS10072-AX32...6f385f&vxp=mtr

It is significantly cheaper than the ones from local parts stores...which are closer to $18 plus tax. If the ebay one looks good enough im going to try it out. I figure they are all probably manufactured in the same factory in China and boxed up differently for different parts stores.

Is this all I will need besides a rubber grommet for mounting the new sensor? What size grommet will I need?

[STL_G8GT]

I don't know that I would cheap out on the sensor... they have various reaction times, and I would imagine the "Cheap" ones are going to be on the lower end of that scale...

As far as the grommet, I can't help you there, I'm sorry... I had an IAT relocate, but it came as a kit. Good luck!

[MAC the KNIFE]

that's the GM one alright. i was testing it's reaction time and i'm satisfied by how quick it responds. with a tune and CAI, i think you'll be fine with the regular sensor you're looking at.

[MeanGreenZ71]

OK. Im going to order the harness and ill figure out the sensor later. I may order the cheap one and try it out or just go get the brass one from Autozone SU-176 that has been recommended before. Thanks for the info.

[toedrag]

...or just go get the brass one from Autozone SU-176 that has been recommended before.

I've also been playing with this over the weekend...What I've found is that the SU176 may not be the best choice, depending on where you install it. Here's why I say that:

I have a Roto-fab, and I installed the SU176 in the common location w/Roto-fab, just after the filter and before the MAF housing (borrowing a picture from someone else, although this is NOT a picture of an SU176):


What I found is that the brass body of the SU176 conducts heat much worse than the plastic MAF housing of the stock sensor. I got home after a short drive, and compared IAT from the stock sensor and the SU176...the SU176 read 135F, which was 15F higher than the stock sensor, which shouldn't have been the case. Ambient was 98F. I took the sensor inside the house, along with the casper's break-out cable, a trusty multimeter, and another meter w/a temperature probe attached. I held the SU176 under a trickle of scalding hot water from the faucet. The water only touched the brass body, not the actual temperature probe. I watched the resistance of the sensor change from 2k ohms down to about 1.4k ohms (which is around 125F I think), then I stuck my other temperature probe right next to the probe portion of the SU176, and my temperature probe read 85F. If the air temperature was really 125F, my probe would have seen it. The fact that my probe only sees 85F suggests it's the heat from the brass body that's affecting the SU176's resistance.

I tried another experiment where I used a hair dryer to heat soak the brass body of the SU176. I placed my temperature probe so that it was nearly touching the SU176 probe. As I held the hair dryer, both probes got hot fairly quickly, up to 160F, and then I turned the hair dryer off. Over the next 2 minutes, the SU176 resistance didn't change at all, but my other temperature probe returned to room temp during that same time period. I then took an ice-cube and placed it on the brass body of the SU176, and only then did the resistance of the SU176 finally start increasing again.

My conclusion is that the brass body of the SU176 can heat up really easily and distort measurements. So, if you want to use it, just keep heat away from it. Or, find a plastic bodied IAT sensor like AC Delco 213-243 that has also been recommended before. I'll probably order one now.

But, there may be other options too, such as just wrapping the intake in some heat-reflecting material. It wouldn't be pretty, but heck, it might be all that's needed to keep the stock sensor from heat soaking, but I may also try bending the stock sensor up 45deg as has been suggested elsewhere. I have a feeling those two steps will be as good as this IAT relocation exercise. Sort of wish I tried this before drilling a hole in the Roto-fab neck...

Regarding the grommet, I used Duralast 42058, which I found from some other reference...can't remember where.

[jcmGT]

I did a much HSRK work also. My reason to preference the su176 was the thermistor itself. It's the same one as the "omega" that was said to have better response (not much if any in actual use) and the leads on it allow it to be readily removed from the brass body and extended into the airflow with minimal thermal mass to heat soak.

[toedrag]

How did you remove the brass body?

The whole sensitivity justification for the omega thermistor seems like a red-herring to me; I'm not surprised your data confirmed that there isn't much difference between the omega and the aftermarket IAT sensor you tested. I just finished bending the stock sensor in the MAF, and even me blowing on the stock sensor was enough to change the resistance value instantaneously, which suggests that it's plenty sensitive.

I feel like people, including me, have been duped in a way...what I'm just now realizing (5 years after the Aussie's figured it out) the primary flaw in the stock design is the recessed placement of the thermistor, resulting in near zero airflow, which allows the radiated heat from the plastic MAF housing hang around without being flushed out of the little pocket w/the thermistor. Fix the placement of the stock sensor, and it seems like the radiated heat problem isn't so much a problem anymore.

Then, add that I apparently made the situation worse with my choice of the SU176 as my new IAT, and I feel really dumb.

Bending the stock sensor is super easy, quick, and free. I wonder why more people haven't done it? Seems like it should be #1 on the 'Free performance mods' list.

[MeanGreenZ71]

Well I may order the cheap OEM style plastic sensor from Ebay then. It was $8.50 or so with free shipping. It looks identical to the OEM piece. How could I test if it is sensitive enough for my car? With a multimeter?

I also thought about just mounting the sensor inside of the heat shield instead of actually drilling a hole in my intake tube.....I have the lower panel mod where I sawed off the back of the honey comb to allow air to be forced into where the intake draws from. Will this be ok?

[MeanGreenZ71]

I ordered a AC Delco sensor the other day. I just have to wait for it to come in and then buy a grommet. Does the sensor have to be mounted in the direct air flow of the intake tube or can I mount it somewhere inside the heat shield of my Spectre intake (somewhere near my filter inside of the heat shield)?

[toedrag]

I ordered a AC Delco sensor the other day. I just have to wait for it to come in and then buy a grommet. Does the sensor have to be mounted in the direct air flow of the intake tube or can I mount it somewhere inside the heat shield of my Spectre intake (somewhere near my filter inside of the heat shield)?

I don't have an answer for you, sorry. It's an interesting question. I've been doing lots of testing and have more to go. Even my roto-fab plastic tube is being cooked enough to heat up the air several degrees between the filter & throttle body, in addition to letting the stock sensor & AC Declo sensor end up in thermal runaway, i.e. heat soak (at Idle). The Spectre intake, being aluminum, will likely conduct heat a little more than than the plastic. My thought is that you will definitely have lower readings inside the heat shield than if you put it in the tube, but that may not be a good thing if the air entering the throttle body is much hotter than what the ECM thinks it is.

Another consideration is your air temp prior to the filter...just idling in my garage on an 85F day with the AC on and after the car warmed up, the air temp under my Roto-Fab air filter was anywhere between 100 to 116, depending on when the fans turned on, and I think it would have kept going. It never leveled off, even after 10-15 min. This suggests that both the lower panel mod & block off plate might be required with the RF/Spectre style intake (not required, however, with something like Vararam where the intake isn't sucking in hot air all the time).

More to come later...