Raise your hand if you suffer from heat soak

I do. It sucks. Figured it was due to the intercooler getting heated up and then being the so-called interheater. So i extended my pettit coolcharge II's duct to this crazy thing you see and also sealed it to the IC.

https://www.rx7club.com/forum/attach...postid=1722114

Then i got an IC fan. The concept seemed reasonable but the results were (are) lacking. So I went to good old radio shack and got some temp sensors. These things have a box that displays temps, one readout for where the box is and one for where a wired sensor is. I have one sensor between the two big filters of my pettit intake

http://www.pettitracing.com/Images/P...IntakeCrop.jpg

and one on the other side of the heatshield. i found that yes the heatshield definitely is a good idea since any air coming out of the rad is in excess of 70C (the upper limit of the sensor).

Also i found that when idling at a standstill the temperature of the air around the intakes increases quickly. I saw an increase as much as 10C in only 30 seconds. Thats crazy. So ducting fresh air in and the conversion of the rear wiper spray into an IC spray is in the works.

So since the intake temps seem to increase accordingly with the ambient air around the intakes it would seem the IC is not to blame for heat soak. thoughts? suggestion?

anyone care to post about the location of the intake temp sensor and its general quality and responsiveness?


and has anyone done this procedure and can comment on it? using the rear wiper pump/resevoir as an IC spray, i found it here:

http://www.scuderiaciriani.com/rx7/i...olers.html#WAT

 

extending the duct....i am gonna do that....everylittle helps

 

when i extended the duct i did notice intake temps lowered faster while at speed. with an upgraded rad i don't think you have to worry about blocking air from it. my water temps are the same.

 

What did u use to extend the duct?

i think an ic spray is the answer...but what do i know...it just sounds logical.

 

intake temp sensor is located on the underside of the UIM

 

I used some "flashing" that i got at home depot in the roofing section. essentially its a roll of thin aluminum. i anchored the top by screwing into the bumper reinforcement ... the rest is duct tape incase i decide to change things around.

i have high hopes for the IC spray. wanted to ditch the rear wiper anyway...

 

search the power FC forum for : IAT sensor

lots of good stuff there

 

KevinK2 is right, this has been discussed in the PFC forum and Datalogit mailing list. Relocate your Intake Air Temp sensor from the UIM to the IC discharge piping or end tank. The sensor is very slow to react and takes forever to register lower temps in the UIM. In the IC end tank or discharge piping it won't get as hot.

Jack

 

The reason your car turns into a dog when the ait sensor heat soaks is cause you have timing and fuel correction factors that change your tuning to be more conservative when you temps get high.

Basically the sensor heatsoaks which kills your tuning cause your computer thinks its 150 degrees outside then it takes 10 minutes for the sensor to go back to normal eventhough your air temps are ok after about 1 minute or less of driving down the road.

STEPHEN

 

IC FANS PICS and RESULTS
I have a GReddy SMIC. Surface is 94 sq in.

I bought two SPAL 5.6" fans. 295CFM, 2.5 AMPS.
One pull-type and one push-type. They cover 53% of the IC surface.

I have 6 pics of the install showing it all but can't post them as they are 104-108K bytes. If anyone would like me to e-mail them to you, you can post them. My .JPG reducing program is not working so I can't reduce them.

Here was my first temp test. I gave up on the PFC intake temp numbers. I don't know where that probe is, but seems like when idling it just keeps going up from 23C to 53C not matter whether radiator fans are on or not and IC fans on or not.

It was 60F in my garage. Under hood temps where 110F. I was idling for about 40 minutes doing tests.
When the IC fans are off there is no air coming in the IC duct or coming out after the IC. When the fans are on I can feel air being sucked in and sucked out of the IC. I put a indoor thermometer taped in the intake duct above the radiator. Temps where 110F with fans off. The temps dropped to 70F with the IC fans on. So 70F degrees are being sucked through the IC compared to the 110F degrees with them off. I put me hand after the IC with the fans on and I can feel the air being sucked through is hotter, in other words drawing off some hot air. How much it really reduces the intake temps I do not know.
My install will show I cut up the ducting a little bit to improve air flow. I am using only 3 pins to hold down the two fans, so you don't need to order two install kits if you buy two fans.

I suppose I could use my 5 gallon fuel cell that is used for my water injection and jury rig something up to spray water on my IC. I wonder how much good that would do?

Ken

 

i did read a bunch of threads in the pfc forum, thanks for the direction all. so if you relocate the sensor do you need to change the correction values? it seems that this just lets the the maps work correctly by giving a more accurate temperature. my first issue i had with moving it is that if the sensor is heat soaked then so will the air moving through that area, thus making the sensor accurate. but saw a post that said due to surface area and the air's velocity that is not a significant factor. sound right?

also, you have to remove the UIM to get at the sensor right?

 

In my opinion, the only way to make any stock mount IC function acceptably is to make a bigger duct. The stock duct passageway is way too small. Here's what I did:

Relocate the relay box to where the battery is/was by splicing about 10 wires.

Drop the radiator along its stock axis about 1.5 inches by removing the stock mounting plates on the swaybar mounts and making some new ones (bolt the plates between the mounts and the swaybar bracket).

Drop the AC condenser to a flat position by making new brackets for this and the PS loop.

Make yourself a duct to utilize the new opening. I used sheet zinc which is easier to work with than Al.

I added a large puller fan to the IC.

You'll also need to remove the inner tray from the belly pan and seal around the rad. with AC foam. I relocated my stock air temp sensor to the IC outlet pipe (make and weld an Al bung, yes, the UIM must come off).

This has made a huge difference in water and air temps. My outlet pipe is never hot to the touch, I haven't seen intake temps greter than 5 degrees C above ambient, and the sensor does not get heat soaked (but it still reacts very slowly).

It was a lot of work but it's the only solution for a stock mout IC and radiator. These V-mounted setups may show some promise.

Below is an image. It's not shot low enough to really show the duct but it's about 3" wide on the pass side and 5" on the driver's, running the full length of the IC.

Alan

 

that is a ton of hardcore good work, my complements adax -one hell of a setup there.


for those of us with limited fabrication skill and budgets simply moving the sensor is still good stuff? and in one of the threads the intake temp sensor thread is said to be 10mm with a 1.25 pitch, when tapping the new spot are those the right numbers? also, what to plug up old hole with?

any comments on modifying maps/temp corrections after the move?

 

I think that's correct, but 10 mm seems kind of large. I just bought a bolt at Home Depot, cut it short enough that it wouldn't protrude into the UIM. I cut off a 10mm length of 3/4" Al rod, drilled and tapped it and had someone weld it to my IC pipe (after drilling a hole in it). Contrary to the opinions of others, I don't see much need to alter the maps, but I run a wide-band O2 sensor so I have pretty close eye on things. Really all you need to do this is a drill (drill press is nice), hacksaw and maybe a dremel tool.

Alan

 

I sent Dave at KDR an e-mail on moving the PFC air intake temp sensor.

This was his reply:

Hey Ken...think about this...the fact puts the airtemp sensor as close as possible to the engine becasue that is the temps the engine is getting...if you move it away from there you are getting the airtemps coming from the intercooler...not the intake itself...yes it heatsoaks..but so does the intake itself..so you need it there...I do agree the sensor itself may not be perfect but putting a different sensor in will not be accurate as the apexi is designed for the fact one...hope this helps...dave@KDR