How's yer BobG Radiator working?

geekdaddy

geekdaddy

X1/9 Learner's Permit...
I installed my shiny new BobG radiator this past Spring. I've now put about 150 miles on the X since installing it. Here are my observations thus far:

1. Installation was easy-peasy. Went right-in. Much lighter.
2. "Feels" like it's working more efficiently than my prior OEM unit.
3. I only installed one fan at this point. Allows for better airflow when car is moving and will stay with one-only if it is adequate in stop-and-go hot weather. If not, the 2nd will go in.

It's not very warm here yet. A few days in the 80's. But I can idle my X in the driveway and wait for the temp to rise. Once the thermostat opens it stabilizes. On my old setup, the same occurred but at some point the radiator couldn't "keep-up" without more air circulation and the OEM fan (as loud as hovercraft) would kick-in.

I've tested my new radiator fan to ensure the circuit works, but I've only been able to get it to turn-on once -- the system runs so efficiently in 75-85 degree weather that the circuit doesn't turn on very often.

How's yours working???
 
Worked fine on 10 autoX runs

I installed one of my BobG rads in the 85 I take to the autoX events. Last season the car would spike up above 190 into "scary range" between runs. It made me very nervous as we continued piling up runs.... and heat soak.

This past Sunday we made 10 runs (5 per driver) in hot (89F), humid (~70%) conditions. We always popped the engine cover between runs last year, so we kept that pattern this year. I noticed in my 3rd run that the temp was still a notch or more below 190. I also made the 10th run of the day and the temp was barely below 190. :)

The only issue I have is that I think I installed the lower rad bracket backwards. I didn't realize it, but it isn't straight, it has a shape to it. I will try to get it reversed and see if it clears up my issue with some interference from the sheet metal above the rad. I am pretty sure this issue is an installer (me :() related error. I am really happy with the rad.
 
Mine is still overheating between autocross runs. I an going to raise the engine idle a bit to speed up the movement of the coolant and add the second fan with an on/off toggle over the summer. Hopefully that will help. The factory thermistor turns the circuit on way too late.
 
I've been evaluating mine with one fan and have had a similar experience. Don't have much traffic in rural NH so I've been letting the X idle in the driveway after a long drive to let the engine temp run-up. Seems like the thermistor is activating the fan too late. In my case, the needle is pushing 3/4 of the way up the gauge when the fan kicks in and it's definitely moving a lot of heat (I can feel it with my hand held behind the rad) but the temp doesn't drop very quickly.

I think I'm going to add the 2nd fan, but wondering why the fan is coming on "late" with the new radiator and why the recovery time to cool off is so long??? Should be the SAME OEM themistor in both rads although I installed a newer one in the new radiator.

So compared with the OEM radiator and ran, the new aluminum one requires the fan less often, but when it does the fan comes on later and the recovery period to cool-down the engine is much longer.

I'm going to install a 2nd fan to see if the recovery occurs significantly faster...

AZDrifter said:
Mine is still overheating between autocross runs. I an going to raise the engine idle a bit to speed up the movement of the coolant and add the second fan with an on/off toggle over the summer. Hopefully that will help. The factory thermistor turns the circuit on way too late.
Click to expand...
 
JimD -- I think you nailed it...

Upon closer examination the P.O. of my X installed the radiator fan switch for an early X (74-78). I installed the OEM-spec for an 81 when I installed the new BobG aluminum radiator. This explains why my fans cut-in later now.

So I'm going to install the older style switch. Time to drain the coolant again...

Question for all you dual-fan folks... I noticed the BobG-supplied fans are rated at 80w for 12v applications. Two fans = 160 watts or ~13-15 amps? On my 81x, there is only one fan connector and one circuit to feed it. The electrical diagrams show 12ga wiring from the panel/relay to the fan and I'd estimate the length of the feed is ~7-8 feet max. The Fan to ground is 2-3 feet to the left-side headlight pod. Sounds like the wiring can adequately support the fan current but I'm pushing it a bit with a 16a fuse. Are any of you with the "old" fuse panel configuration running dual fans and how are they working???
 
Fan fuse...

FWIW, my Scorpion and my former car, the '87 X1/9 Corsa both had 2 fans running in tandem on the same 16A fuse. While the Corsa used the late model blade fuses, my Scorpion uses the early style bullet fuse panel.

About different radiator fan switches, keep in mind your radiator fan only comes into play when the radiator gets too hot for the radiator to shed the heat. If you start cooling the fluid in the radiator before it's fully hot or fully open, then the thermostat might not fully open.

So rather than a lower temp fan switch, a lower temp thermostat might be better. But then, the engine may not get up to operating temp except under competition conditions, which will affect mileage etc.

IMHO, there's nothing wrong with the system getting extra hot, especially when pushed hard. As long as you don't actually overheat (steaming coolant, coolant expulsion from tank) it's doing it's job.
 
Greg -- thanks much for the insight. I can see when my engine thermostat opens. When my temp gauge hits the mid point, the thermostat opens and it stays there. I can also hear/feel coolant running thru the radiator hoses.

However, when sitting in traffic etc the fan doesn't kick-in until the temp gauge swings a full quarter (up to 3/4) with my current fan switch. Just guessing, but I think my prior fan switch kicked-in when the gauge was just under 5/8 of the way up.

Are you suggesting it's ok for the engine to run in the "3/4" range for periods of time (say stop and go traffic)? Just don't want to blow the ol' head gasket...
 
Yes...

geekdaddy said:
However, when sitting in traffic etc the fan doesn't kick-in until the temp gauge swings a full quarter (up to 3/4) with my current fan switch. Just guessing, but I think my prior fan switch kicked-in when the gauge was just under 5/8 of the way up.

Are you suggesting it's ok for the engine to run in the "3/4" range for periods of time (say stop and go traffic)? Just don't want to blow the ol' head gasket...
Click to expand...

Yes, I'm suggesting that. This is how mine works on track days in 100ºF weather. If you think the switch is opening late (measure with I.R. thermometer) try a new one, yours may be tired. After a long pull on the freeway, if I hit stop-and-go traffic, mine will do the same, rise to say 3/4 gauge and then settle back down after the fan runs a few times.

Mostly I wanted to explain the relationship between the thermostat and the fan switch. A cooler fan switch won't help unless you use a cooler thermostat.

Also the cap has to be good. One thing though, if you can hear the fluid running through the pipes under the car, you probably have air in the system. Without bubble gurgling and rushing around the cooling system is generally pretty quiet.
 
geekdaddy said:
So I'm going to install the older style switch. Time to drain the coolant again...
Click to expand...
You don't need to drain the coolant for this. If you work quickly and have the tools and replacement switch within easy reach you can do the swap with minimal coolant loss. After the old switch is out, I plug the port with my thumb while I fumble for the new switch.
 
Efficiency

We've installed several here, the fit and finish is pretty good.

We did a unit in a customer car, a regular member of the forum here and had an interesting observation.

After the install the car came up to temp just fine, up to 190, then the longer you drove, the temps would fall. Banging 45 minutes on the freeway at 75MPH, the temps would eventually bottom out around 140-145 degrees (right around the first hash mark on the gauge) and stay there.

Come to find out the car also had a thermostat that was stuck open.

So, bottom line, these units have some serious efficiency.

-Matt
 
Greg... the stock wiring appears to handle the...

current well on my TANDEM fan operation. I do not know what the fuse amperage is but I do know when I added the second fan, I did not increase it. I had expected it to blow, but hasn't now in the last 10 years or so. Did the same with Mike Busman's car... same success.

BUT... I'm not saying that the fuse rating is stock! Judging from YOUR math, a 20 or 25 amp fuse would seem appropriate.

(BTW... I have twin fans in my Vette that can draw up to 20 amps apiece. Not the ones I originally wanted but they work well. My point being, I believe they are using 12 gauge wire as well!)

SECONDLY... STOP guessing about the temp! Get Mama's Turkey Thermometer when she's out shopping and stick it in your reservoir! (I bet you thought I was gonna say something else...)

I used two... one digital and one dial... Our turkeys have never tasted exactly the same but I now know EXACTLY what temps the engine sees near the gauge sender. You can then make a MENTAL note of what the needle is ACTUALLY pointing at and at what temp. I found my factory gauge to be fairly accurate too!!!

OH... I forgot all about my $29.00 HF temperature gun... These work great all over the car, radiator inlets and outlets and on and on. You can also take you own temperature... on your forehead or... well, I'll leave the rest up to YOUR imagination...

LASTLY... make sure the radiator is CENTERED in its TOP mount... as it will go up on either side of it. If it does, airflow is NOT as efficient going through it. (Guess how I know?) Additionally ensure the front spoiler is mounted correctly and not sagging. Add addition support underneath it with flat bar straps if needed. This also has an effect on the correct flow. THEN, if you still have a front license plate mounted in the center of your front bumper... it does a GREAT job of deflecting air down-and-around the radiator at speeds over 65 mph. Prove it to yourself if you doubt me... If convinced, move it to the RH side with another fabricated bracket or zip-tied to the grille... like Bob Brown might do... (HA!)
 
OK so I did some testing... When my temp gauge sits in the midpoint, my coolant overflow tank is ~190 degrees.

If I let the engine idle while the car is sitting, the temp slowly rises past the midpoint. With the cap off, I had to stop the engine because it was exceeding 220 (222? 223?) and was gurgling and spilling coolant out the top. At that point the temp gauge was just shy of 3/4 and the coolant fans had not kicked in yet. They typically start at ~3/4 which I'm guessing is at a point where the engine temp is ~225 (maybe a little higher). With one fan it and the vehicle not moving (or crawling in traffic) the engine temp doesn't fall very quickly.

So I will install the 2nd fan, but thinking I want a lower point for the radiator fan to kick-in. I may install the 82'c version. Is there anything about the aluminum radiator which could cause the stock fan switch to "see" a lower temp and therefore start later than with the OEM radiator???



Black-Tooth said:
current well on my TANDEM fan operation. I do not know what the fuse amperage is but I do know when I added the second fan, I did not increase it. I had expected it to blow, but hasn't now in the last 10 years or so. Did the same with Mike Busman's car... same success.

BUT... I'm not saying that the fuse rating is stock! Judging from YOUR math, a 20 or 25 amp fuse would seem appropriate.

(BTW... I have twin fans in my Vette that can draw up to 20 amps apiece. Not the ones I originally wanted but they work well. My point being, I believe they are using 12 gauge wire as well!)

SECONDLY... STOP guessing about the temp! Get Mama's Turkey Thermometer when she's out shopping and stick it in your reservoir! (I bet you thought I was gonna say something else...)

I used two... one digital and one dial... Our turkeys have never tasted exactly the same but I now know EXACTLY what temps the engine sees near the gauge sender. You can then make a MENTAL note of what the needle is ACTUALLY pointing at and at what temp. I found my factory gauge to be fairly accurate too!!!

OH... I forgot all about my $29.00 HF temperature gun... These work great all over the car, radiator inlets and outlets and on and on. You can also take you own temperature... on your forehead or... well, I'll leave the rest up to YOUR imagination...

LASTLY... make sure the radiator is CENTERED in its TOP mount... as it will go up on either side of it. If it does, airflow is NOT as efficient going through it. (Guess how I know?) Additionally ensure the front spoiler is mounted correctly and not sagging. Add addition support underneath it with flat bar straps if needed. This also has an effect on the correct flow. THEN, if you still have a front license plate mounted in the center of your front bumper... it does a GREAT job of deflecting air down-and-around the radiator at speeds over 65 mph. Prove it to yourself if you doubt me... If convinced, move it to the RH side with another fabricated bracket or zip-tied to the grille... like Bob Brown might do... (HA!)
Click to expand...
 
The gurgling was caused by the cap being off, not by the temperature. If the fan wasn't on, it's because all that hot coolant wasn't in the radiator yet. You need to measure the temps at the radiator hoses to see what is getting to/through the radiator. Could be low idle (I've raised mine to 1K) could be the thermostat not opening soon enough or far enough.

Having the fans turn on sooner won't help if the coolant in the radiator isn't moving.

To your question, the aluminum radiator might shed heat better than the stock one and so the fan switch wouldn't turn on as soon, guessing.

geekdaddy said:
OK so I did some testing... When my temp gauge sits in the midpoint, my coolant overflow tank is ~190 degrees.

If I let the engine idle while the car is sitting, the temp slowly rises past the midpoint. With the cap off, I had to stop the engine because it was exceeding 220 (222? 223?) and was gurgling and spilling coolant out the top. At that point the temp gauge was just shy of 3/4 and the coolant fans had not kicked in yet. They typically start at ~3/4 which I'm guessing is at a point where the engine temp is ~225 (maybe a little higher). With one fan it and the vehicle not moving (or crawling in traffic) the engine temp doesn't fall very quickly.

So I will install the 2nd fan, but thinking I want a lower point for the radiator fan to kick-in. I may install the 82'c version. Is there anything about the aluminum radiator which could cause the stock fan switch to "see" a lower temp and therefore start later than with the OEM radiator???
Click to expand...
 
geekdaddy said:
Is there anything about the aluminum radiator which could cause the stock fan switch to "see" a lower temp and therefore start later than with the OEM radiator???
Click to expand...

Yes since the radiator is more efficient the core may be bringing the temp down fast enough that the fan doesn't need to run.

Taking the cap off dropped the boiling point down from 220 to its natural 212, thus why the coolant boiled up. Pressure is a wonderful thing.

(whoops, what he said \|/ )
 
Uh, yup, I'm a doofus... Greg was correct and I had air in my system. I thought I had burped all the air out but apparently hadn't. After removing considerable air from the system, the stock thermo switch activates when the engine temp needle is just a few ticks over the mid point. And it was rather cool this evening, but I had to let the engine idle for a long time before the engine temp exceeded normal.



I also installed a 2nd fan and when they turned-on, they only had to run for about 20-30 seconds before the temp reached normal. All good now.



Although I purchased two fans from Bob, I had already acquired two good quality aftermarket fans and fabricated my own brackets for the OEM radiator. I decided to use my fans and brackets because they mount closer to the radiator and block less air when the car is moving. Working very good so far although others have reported the BobG fans/shrouds work well too and are finished a bit nicer than mine.



Some photos of my homemade fans/brackets compared to the BobG ones:





 
Good thing you figured it out. :thumbsup:

Air in the cooling system is always a PITA. It seems like sometimes it bleeds out super fast and easily, other times you can get a stubborn bubble that won't leave until after you think you're done bleeding, like days later.

Due to the arrangement on the Scorpions, this can mean the thermostat won't open until you think the engine will overheat and then suddenly it opens and you have to deal with a nearly-overheating engine and adding coolant all at the same time. :mad4:

I added a flush tee tee to the top most heater hose on my car, it doubles as a fill port that seems to help a great deal.
 
Indeed, BUT...

"Taking the cap off dropped the boiling point down from 220 to its natural 212, thus why the coolant boiled up. Pressure is a wonderful thing."

My math says * 13 pounds pressure the coolant will not boil until 239 degrees!You should not be operating at anywhere near 212 degrees... so leaving the cap off is really not a problem or contributor to the high temps you are experiencing.

If you don't have a Laser Temp gun... feel the hoses with your hands up front to see if the coolant is reaching the radiator.

You still have not mentioned the t-stat... and that is what I would be changing out at this stage.

OH... and THANKS for using a thermometer so far... it really helps KNOWING and not GUESSING...
 
Ah... I see you found the problem...

I just figured the system was purged...

As far as YOUR fan and BobG's fans go... each has their good and not so good points.

YOUR fan mounts allow air to more freely pass through the radiator with little restriction... but with LESS efficiency when the fans operate.

BBOG's shrouded fans tend to restrict air from flowing through the radiator but offers MORE efficiency when they do operate.

I have a "staggered" set of fans on my Vette that are shrouded as well, but have additional rubber FLAPS that are forced open when the car is moving, and are sucked shut when the fans are on and drawing air through the radiator. I doubt there is room or that they would be that efficient on our rather small radiators... and I also doubt that the differences I mentioned concerning your homemade fan mounts versus the shrouded mounts would be that noticeable as well...

They look something like this:

http://www.summitracing.com/parts/der-16927

Kinda like the best of both worlds... I also found some "big & little" fans that probably are not a consideration for our X1/9s, but interesting for some other projects. Lastly, the fans operating for 20 -30 seconds is something we experience here in LA-LA-LAND as well. It either means the thermoswitch is faulty or they are actually WORKING well! Since the temp drops drastically and fast, I lean towards the latter!

Good work!
 
Fans are more effective with a shroud vs. open bracket. I made a shroud for my aluminum rad after running them without & not being happy with their performance. Slightly tapered to allow air to feed toward fan opening is better - OEM shrouds are designed that way

IMG_2820_zpsf034b4d9.jpg
 
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