TF running hotter on highway than in-town.

[roger55]

It's a 1991 7730 speed density version. EGR programmed out.

[1project2many]

Thanks. GM actually released many different calibrations for that year and engine. They usually use a four letter code on the chip to identify which calibration is programmed in.


Not a big deal... you've got bigger fish to fry there.

[roger55]

Another guy told me he thought 36 to 38 degrees total advance sounded low but then thought it might be right since it was only at 2,000 rpm.
Anyway you are right, it's probably not in any kind of range that would cause a heat problem. Someone did say I should check the advance with a timing light to make sure I'm actually getting the amount of advance the ECU is commanding as it doesn't get feedback of any kind to tell me this in the readout.
I will do that but based on the fact the engine runs like a top, I don't expect it to be off.

Btw, I sent that chip to Larry's Electric and they programmed it to take the EGR out and disable the VATS. Not sure what else they usually do for swaps. I bought my harness from them too. I can get the chip number if you think it will be of help at all.

I wouldn't mind getting the gear it takes to program these. I also have a 83 El Camino SS with a 96 LT1 engine running controlled by a 94 ODB1 ECU. Both these vehicles are long-term holds for me and it would be nice to have programming capabilities for both.

[roger55]

Take my shroud off and cut the entire rear section off leaving a 1/2" perimeter so I can attach a new sheet of aluminum too it with rivets.

Then make cut-outs to accommodate 2 - 11" fans in the upper left and and lower right corners. Also cut holes for vents in the other to corners.

Here is rough sketch:



I would use Spal Extreme Performance fans. I wouldn't need a slim design for these like I am using for my 16" electric. These Spals have a high cfm output and combined would give me 2926 cfm.
I can see a lot of advantages to this over the the 16" fan I have now. Thats 35% more air flow than I have now and it's spread across the core better. I should have better cooling in stop and go city driving as well as highway especially with the vents. I am confident I can come up with an inexpensive solution for flaps or shutters for those too.

A huge advantage to me is that I can set it up for 2 speed operation. I'd get the Dakota Digital controller to make the easier. Electric fans are noisy full-speed but when run at half-speed the are incredibly quiet. We can put up with noise no problem with them going to high-speed as that's probably only going to be when the A/C is running in the summer and the windows will be rolled up. I would bet that in 3 of 4 seasons of the year, the fans would only run on low speed.

There's still somewhat of an investment with this new idea but way, way less than the $2K+ AutoRad system. A whole bunch less work too. The Spal fans run $120 a piece and the Dakota controller is $115.
By the time I got the little stuff like the aluminum sheet, relays, wire, fuses and whatever I do for the vents, I think it would be in the $500 ballpark.

[ChuckDriver]

That should do it!

Before you remove the single fan shroud, how about trying it with a couple vent holes cut in it since you plan to remove it anyway?

[dwcsr]

I used 4, 9" 1200 cfm fans, it cooled a 600hp 468 in Houston on a 105 day idling in traffic, never got past 195F. The radiator was a stock 6 cylinder brass/copper.

[tmoble]

$500?? chump change for a man of your stature.

[roger55]

Originally Posted by tmoble

$500?? chump change for a man of your stature.

It's comin' out my ears so I got to find some place to put it!

Seriously, it will only be $400 out of pocket tops since I have all the relays and little stuff lying around.
Happy I don't have to spring for another radiator and all the work involved. Doing this will be a snap.

I'm pretty confident it will take care of all my concerns and give me the 2-speed capability to quiet it down for all but hot summer with the A/C on when the noise doesn't make much difference anyway.

[ETraugott]

Sounds like yall are on the right track with the air flow. Another thing i would add but may be completely irrelevant is how the heater is plumbed. Is it connected like the factory? Could it be possible its letting water bypass the radiator. Like i said just throwing it out there.

Another idea would be if you had a go pro camera to mount it under hood with some tassels to actually see how much air is moving in there.

[roger55]

So now that it is starting to get warm here, I decided to get back on this issue and finish with the plans I made last year.

In case you may have forgotten, my plans were to install dual 11" high-output Spal fans and also install flap valves to get more air flow at highway speeds.

I got started on it this week and completed the job today. I decided to go with a Dakota Digital controller and set it up for 2-speed operation using 3 relays. So it took a lot of time to get all the wiring done.

Here's how my new shroud design came out:







I mounted the 3 relays on the driver side inner fender:



I really like these Dakota controllers but I wish the unit didn't have the wires connections on the bottom of it like that. Looks a little tacky but I wanted to put it in a convenient location. I made it as neat looking as I could.



I got it programmed using my electric Autometer temperature gauge sending unit. Works well. The readings from the controller readout are right on the money with the Autometer gauge. I adjusted the controller to 195/190 on/off for the half-speed and 205/200 for full-speed.

I did a preliminary test drive on the highway. It was 89 degrees ambient outside.
I drove it 25 miles at 65 mph with the A/C on full blast and the windows open. The water temperature topped out at 188 degrees.
This is a lot better than it was however my tests last year were done at 95 degrees ambient.
I did drive it around town in stop-and-go some but when doing that the A/C trinary switch caused the fans to run on high (as it should). That made the water temperature drop down to 174 which is even lower than the 180 thermostat temperature. This must mean that the thermostat starts to open lower than it's 180 rating.

I sure like these Spal fans. On high they move a bunch of air. Yet they are noticeably more quiet than the old 16" single fan was. I've got a total of 3210 cfm now and with the 16" it was 2170. Almost 50% more flow now.

The forecast has it getting warmer here after the weekend and up near 100 by Wednesday. So, I will be doing another test very soon.

Anyway, I'll update again here after that next test but so far it's looking pretty good.

[roger55]

I took the truck out for the same drive this afternoon. Ambient was 96 degrees and A/C going full blast. On the highway part of the test It didn't run any hotter than the last test at 89 degrees ambient. In fact, it ran 2 degrees cooler. Topped out at 186. Since I just re-filled the radiator before the first test, I'm guessing there were probably air pockets or some foaming going on.

For stop and go in-town, it ran 182 to 190. Sitting at a stoplight for an extended time cooled it down to the 182. I don't have the fans cut onto low until 195 but when the truck is sitting still and A/C on, the trinary switch will turn them onto high. This explains the variation in in-town driving temps.

In case you've forgotten, this same test done with my old fan and shroud setup was 210 highway and 192-196 around town.

Bottom line is that it's absolutely fine. I'm convinced it will still be fine in the hottest part of the summer. It can get to 110 but not often. We do usually get a pretty good stretch where it's 100 to 105 though.

I'm calling it success!!!

Thanks to all for your help!

[ChuckDriver]

Nice work, congrats!!