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Water-to-air intercooler installation - 81 931
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chuck21401  



Joined: 20 Feb 2005
Posts: 402
Location: Annapolis, MD

PostPosted: Tue May 18, 2021 12:15 pm    Post subject: Reply with quote

Mike9311 wrote:

Edit: Chuck, I am at full swing redoing the programming for machining all weekend on and off. Should start making chips in the next day or so


Cool. Hopefully my crypto will bounce back by then
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chuck21401  



Joined: 20 Feb 2005
Posts: 402
Location: Annapolis, MD

PostPosted: Tue May 18, 2021 12:35 pm    Post subject: Reply with quote

lildude4life wrote:

Here is overall view of the drive. Steady increase of IC water temps the entire time, with an obvious spike during the onramp pull. Which kinda proves the point of the IC rad being too small, the IC water temp steadily increased even cruising under vacuum on the freeway for 2-3min.


Very interesting.

Have you decided which radiator to try next? Looks like Frozen boost has a wait list for the one you mentioned earlier.
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Tue May 18, 2021 1:31 pm    Post subject: Reply with quote

lildude4life wrote:
Fasteddie313 wrote:
Data is nice!!
Just beware the influence of your water temp on your other temps, as they correlate so perfectly, even your pre-ic..

I would like to see your data after/during a much longer drive making sure you are up to full operating temp..


Actual coolant temp leveled off at 176F about 8min into that drive. So in the data log photos above, the IC water temp climbed the entire time and never leveled out even at high speed on the freeway where one would think the massive airflow over the radiator would help to lower the IC water temp closer to atmospheric...

Fasteddie313 wrote:

If you are going to push to the limit of MAT, to be on the safe side, I would calculate the difference in tempature between your water and MAT reading, and then add that to your MAT data to get closer to an estimation of your actual MAT..

If water = 80 and MAT = 100 then true MAT is probably 120..
True MAT = MAT+(MAT-Water)
Somewhere around there I’d expect to be closer to accurate..

Looks like your MAT reading touched 85 while water was 75 so I’d say your true MAT probably reached around 95..

You’re probably in the safe zone, MAT wise, up to around 130-150 max, so you are well in the clear for now..


I get what you are saying, but at WOT I'm not sure the temperature of the air entering the cylinder is going to be much higher than the IAT reading with a fast sensor.. But what haltech allows for that is super neat, is a calculated IAT table. It takes your coolant temp (not the IC water temp shown above) and RPM, and allows you to set a percentage value for each RPM/coolant Temp cell. That percentage is a scale between your coolant temp (100%) and your IAT temp reading (0%). Why? At low RPM, high coolant temp, your value could be set to 100% of the coolant temp value. At high RPM values, your calculated IAT can be 0% of coolant (aka whatever the IAT sensor is reading). Its function is so when your throttle is closed and air movement is slow, the calculated IAT the ECU is using is much higher than the IAT reading your sensor sees. When you are at WOT high RPM and airflow is supper fast, your IAT reading is what your IAT will be entering your cylinder.

I'll let the tuner use his fancy witchcraft and magic to use the new IAT data from the faster sensor to find the boost limits for me and they are what they are.


By water temp I meant your IC water temp, and full operating temp as in the point where your IC water temp stopped increasing during cruising/normal driving..

Whatever the temp is of whatever you have the MAT sensor screwed into is what will need to be calculated against..
Seeing it correlate with your IC water temp to perfectly, I suspect that is it’s largest factor, especially now that you say it correlates with your IC water temp much more than your CLT temp..

What I mean, is that the temp of whatever your sensor is screwed into dampens the reading of the sensor to it, as if it were a capacitor..


I forgot you have a fancy haltech and are going to hire a fancy witchdoctor to tame its black magic..

If he is any good at his craft, and you let him have his way, I expect to see some incredibly nice numbers from you..

I hope when you go to upgrade your heat exchanger for your IC, you go to an absolutely massive one, as big as it will fit, so that is removed as an excuse as much as possible..
Get a hecking big one..


I forgot I was talking to the guy with the EFR and a haltech..
I surely hope that you become some camaraderie competition..







To the best of my recollection, we have only ever seen properly intercooled and fueled engines blow from overreving, and that was at well north of 400HP..

...knock sensitivity...

This is basically another dutchpug build but with a 931 head..
Should be able to reach dutchpug levels if this IC is any good..

Don’t rev it, boost it!!
Remember, it’s a diesel..
Increase cylinder pressures, not RPMs..

http://www.924board.org/viewtopic.php?t=38765&postdays=0&postorder=asc&start=0&sid=36c67ea673b1cc9bb1d23ad3a13d4800

DutchPug wrote:
Update; have been driving the car a lot last year, the engine didn't miss a beat .
...
The results; 352 rwhp @ 1.6 bar of boost pressure (around 400 engine hp)...

On an NA head..
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lildude4life  



Joined: 27 Apr 2015
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Location: Milwaukee WI

PostPosted: Wed May 19, 2021 9:40 am    Post subject: Reply with quote

We're going justttttt a bit bigger
(old core was 7.5" x 5.5", new is 18.5x5.5")



https://www.ebay.com/itm/324321625495?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

Should fit just fine, but gata figure out how to mount it. Routing hoses may be interesting too as I do still have the AC rad in there....
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Mike9311  



Joined: 14 Dec 2004
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Location: Chicago-ish

PostPosted: Wed May 19, 2021 10:38 am    Post subject: Reply with quote

Oh this is going to be some cool testing. At first I thought this looks like the same one going into the '82 right now but it isn't

This looks bigger. Need to check my dimensions
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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chuck21401  



Joined: 20 Feb 2005
Posts: 402
Location: Annapolis, MD

PostPosted: Tue Jun 22, 2021 11:22 am    Post subject: Reply with quote

chuck21401 wrote:
With the warmer temperatures the temps are increasing but street driving and occasional boost runs not sure if it's needed.


Now that the summer is here, I'm running into some issues with heat.

I have a lower temp thermostat and fan switch but just recently figured out that only the passenger side fan is coming on. My car previously had AC so I have two fans.

I signed up for an autocross with the local Porsche club two weeks ago. The first run went well (though I went off course). The second run was my best run...on course and no cones knocked over. But as I was waiting for the next run, my temperature gauge started climbing. Ambient air temps were in the high 80s/low 90s. In the picture below the temp is creeping up, after the third run the needle was close to orange box so I called it quits for the day. The intercooler temperature gauge was also going up and up and not cooling down until I was on the highway driving home.



When I returned home I read up on the operation of the two fans...and then figured out that the drivers side fan was not coming on. I connected 12V to the fan manually and it came to life.

I'm running a separate switch/relay for the intercooler pump and that draws around 3.5 amps from what I've read online. I decided to wire the drivers fan to that circuit figuring that there would be plenty of power and the wiring would be up to the task. That made a huge difference in the temperatures though not sure if the fan needs to be constantly running...it's pretty loud at idle.

I'm looking into a larger intercooler radiator. Frozen boost has a 10 X 13 model in stock...but it's blue...though will not be that visible. I don't have the AC condenser to worry about so there should be plenty of room.




http://www.frozenboost.com/water-to-air-heat-exchanger/water-to-air-radiator-cooler-p-1114.html

Here's a question....should I wrap hose running from the cool side of the intercooler radiator to the intercooler? I found this with google: https://www.heatshieldproducts.com/hp-hose-sleeve
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Tue Jun 22, 2021 11:46 pm    Post subject: Reply with quote

lildude4life wrote:
We're going justttttt a bit bigger
(old core was 7.5" x 5.5", new is 18.5x5.5")



https://www.ebay.com/itm/324321625495?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

Should fit just fine, but gata figure out how to mount it. Routing hoses may be interesting too as I do still have the AC rad in there....


Why not leave the small one plumbed in and run them both in series?
It’s already there, just add the other one too..

Could probably just zip tie the new core right to the front of your AC condenser, through the fins, in like 8-10 places across the top and bottom..
I see racers do it with their rad fans all the time and it seems to work..

I don’t really like the big gap between the AC condenser and radiator though..
I think it’s better if they are as close to eachother as they can get, maybe even with a ring of foam tape around the outer edges of the IC to seal the flow path between them..



Rad fans..
I like them best just wired to the same solid power source for both fans, and then grounded through rad thermo switch..
Don’t even need the slow speed operation with key off function..

My brown car had no cooling problems like that ever (power from back of alt), and just did the 941 up that way too (pass side was doing nothing) but through the original drivers side fan power circuit including the low speed circuit, because it works (for now)..

Brown car I eventually replaced the rad thermo switch with a relay to ground them controlled by my computer based on water temp at the thermostat housing at the back of the head.. Works even better..
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lildude4life  



Joined: 27 Apr 2015
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Location: Milwaukee WI

PostPosted: Fri Jul 02, 2021 5:55 am    Post subject: Reply with quote

Fasteddie313 wrote:


Why not leave the small one plumbed in and run them both in series?
It’s already there, just add the other one too..



I thought of using both and I may still do that depending on results.

Fasteddie313 wrote:


Could probably just zip tie the new core right to the front of your AC condenser, through the fins, in like 8-10 places across the top and bottom..
I see racers do it with their rad fans all the time and it seems to work..

I don’t really like the big gap between the AC condenser and radiator though..
I think it’s better if they are as close to eachother as they can get, maybe even with a ring of foam tape around the outer edges of the IC to seal the flow path between them..




Never would have throught of using zip ties to hold it to the AC rad... Its got M8 threaded holes so I just got some threaded rod and mounted it to the top flange where the hood latch is mounted. There were already holes there.

I don't like the gap between the two rads either... Makes it way harder to fit this specific new rad in there as there is less "depth" to fit it in. I may try to remake the 4x mounts that connect the AC rad to the coolant rad.
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Mike9311  



Joined: 14 Dec 2004
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PostPosted: Fri Jul 02, 2021 11:10 pm    Post subject: Reply with quote

I had zip ties on the temporary rad strapped up front on the 82 simply because nothing else worked (too wide) and I knew it was temporary. I also realized the air conditioner rad was pulled from the 82

The new one is similar to yours but one side has a larger end tank I have been thinking of cutting down and re-welding. Yours has nice and tidy end tanks. I would leave in series too.
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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chuck21401  



Joined: 20 Feb 2005
Posts: 402
Location: Annapolis, MD

PostPosted: Sun Jul 18, 2021 5:49 am    Post subject: Reply with quote

chuck21401 wrote:
When I returned home I read up on the operation of the two fans...and then figured out that the drivers side fan was not coming on. I connected 12V to the fan manually and it came to life.

I'm running a separate switch/relay for the intercooler pump and that draws around 3.5 amps from what I've read online. I decided to wire the drivers fan to that circuit figuring that there would be plenty of power and the wiring would be up to the task. That made a huge difference in the temperatures though not sure if the fan needs to be constantly running...it's pretty loud at idle.


The driver's side radiator fan worked well...until it didn't. It started making a bad sounding noise and seized up. I removed the fan assembly today. When I turned the fan by hand it sounds like there is a box of rocks in the motor.

I'm wondering if it was mounted upside down. The small fan (which works fine) was on the passenger side and the larger fan on the driver's side.

This thread was helpful: http://www.924board.org/viewtopic.php?t=13861&postdays=0&postorder=asc&highlight=anyway+fan+bearing&start=0&sid=e5010645b19bad51457dc3622607bf3c

From what I've read, the larger fan is the engine cooling fan and the smaller one is for the A/C. My car no longer has A/C.

I'm going to order a new fan rather than buying used; looks like Vertex Auto has them. https://www.vertexauto.com/porsche-924-auxiliary-fan-assembly-p-9912.aspx




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chuck21401  



Joined: 20 Feb 2005
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Location: Annapolis, MD

PostPosted: Sun Jul 18, 2021 12:32 pm    Post subject: Reply with quote

In other news, I've decided to wrap the water hoses from the heat exchanger to the intercooler and back in "thermal heat sleeving." One hose wrapped so far.



Not sure if it will make a difference but I was inspired by the picture below.


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Last edited by chuck21401 on Sun Jul 18, 2021 12:56 pm; edited 2 times in total
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chuck21401  



Joined: 20 Feb 2005
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PostPosted: Sun Jul 18, 2021 12:49 pm    Post subject: Reply with quote

The larger heat exchanger arrived yesterday. I'm not crazy about the color but they were sold out of black and silver.



Here's the new one compared to the original. I will need to modify the mounting bracket to deal with the extra weight.



Test fit



Not sure if the water lines will fit using the 90 degree NPT to hose barb fittings. Well the lines will probably fit...but the plastic grill might not fit over top of them. I'm wondering if I could use banjo fittings instead.


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Cedric  



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PostPosted: Sun Jul 18, 2021 9:33 pm    Post subject: Reply with quote

Can't you flip it around 180 degree so more of the radiator sit lower, down where most likely most of the airflow is? Banjos work but they to have larger internal pressure drop, but if you have a steady pump it maybe isn't a problem in this case. The rad looks much better then the old, not just size but also the tube density looks more suitable for the job.
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chuck21401  



Joined: 20 Feb 2005
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Location: Annapolis, MD

PostPosted: Sun Jul 18, 2021 10:04 pm    Post subject: Reply with quote

Cedric wrote:
Can't you flip it around 180 degree so more of the radiator sit lower, down where most likely most of the airflow is?


Now there's an idea. I'll try that.

Cedric wrote:
The rad looks much better then the old, not just size but also the tube density looks more suitable for the job.


I'm hopeful!


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chuck21401  



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PostPosted: Wed Jul 21, 2021 12:06 pm    Post subject: Reply with quote

I flipped the radiator 180 degrees and adapted the mounting bracket.



It turns out there are two holes in the top of valance...and coincidentally they lined up with the bottom bracket of the radiator. I may need to notch the black plastic grill in two places to make it fit. I'm going to put everything back together to try it out, then clean up the installation. Those threaded rods can be cut down quite a bit.




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