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Tedor
05-28-2013, 06:56 PM
Hi I just brought a DIS unit that came from a 1990 SC and I have a 1991 SC, I replaced it with the one from the 1990 SC and the car runs normal. There are different numbers on them, I dont have them in front of me right now. Have yet to drive the car only idled for 5 minutes.

But my question is, what will happend over time, nothing?

Thanks

J dot Miller
05-28-2013, 07:54 PM
It should last a bit as long as you used heat sink compound. I prefer to be cautious. Fast Freddie made me a heat sink to place under mine to keep it cooler than stock. :)

Tedor
05-29-2013, 06:12 AM
Why will it not last as long as the right DIS? If it works now it will work as long as the right one? If i make it cooler of course

J dot Miller
05-29-2013, 07:18 AM
I can not predict the future and tell you how long a DIS will last. All I can tell you is that in the 90 they are exposed to heat that shortens their life. Some add heat sinks under the DIS. Others relocate it to the fender-well.
:)

David Neibert
05-29-2013, 08:16 AM
Why will it not last as long as the right DIS? If it works now it will work as long as the right one? If i make it cooler of course

Same DIS module will work on 89-93.

David

HwyStar
05-29-2013, 03:57 PM
Where may i get one of these heat sinks you speak of? Anyone have a pic?

bowez
05-29-2013, 05:16 PM
I figure the heat sinks are CPU ones Zalman come to mind for me.

As for the part number difference I bet its just a revision number.

Tedor
05-29-2013, 06:58 PM
Thanks for the help guys!

I'm going to raise my DIS an inch so that it have less contact and in that way runs cooler, seems like a good idea

bowez
05-29-2013, 07:01 PM
The base of the module need to be in direct contact to the chassis for ground and disperse the heat created by the ~30A form the module.

J dot Miller
05-29-2013, 08:22 PM
The heat sink I have is extruded aluminum. Aluminum is a good conductor/ ground. I currently do not plan to do it because I was told 1-2 screws ground the DIS but, you could add a grounding wire jumper from the bottom of the DIS to below the sink on the engine side.

The heat sink Fast Freddie made for me is extruded aluminum that is approximately 70mm wide x 100mm long x 17mm high. Cost $10 (2-3 years ago). Who knows, he may have some more lying around... It has four holes drilled in it to match the DIS mounting screw holes. The fifth hole was a oops. ;) Flat side will face the DIS and get a whole tube of heat sink compound.

The stock 5.5mm hex head screws with washer are not long enough. The stock 1990 XR7 DIS screws are M4 x .7 x 20mm long (5.5mm socket). 17 + 20 = 37 so 40 mm long should work. I ordered Ford PN N808155-S434, N808155S434, M4 X 0.7 X 40mm long. Cost $8.50. Expect to get them tomorrow. Wish me luck. :confused:

I will caution that I used an M6 x 45 mm long screw for my 90 Thunderbird. So confirm the diameter before committing.

Attached are pictures.

slick59
05-29-2013, 09:47 PM
don't raise it up and let it "float" on spacers it will burn up faster. the accessories bracket actually acts as a heat sink. it needs to be mounted. heat sinks are readily available of many varieties. use heat sink compound,use heat sink compound,use heat sink compound.

HwyStar
05-29-2013, 10:38 PM
Kind of how I imagined it would be. Same sort of deal with the PMDs on the Chevy 6.5. Used to be under the intake behind the injector pump, and it would burn up due to heat. The fix was a heat sink similar to that located elsewhere. That, and the new style Stanadyne PMD.

Would you be interested in selling one of your spares? Dont mean to hyjack the thread....

J dot Miller
05-30-2013, 07:07 AM
Kind of how I imagined it would be. Same sort of deal with the PMDs on the Chevy 6.5. Used to be under the intake behind the injector pump, and it would burn up due to heat. The fix was a heat sink similar to that located elsewhere. That, and the new style Stanadyne PMD.

Would you be interested in selling one of your spares? Dont mean to hyjack the thread....

Fast Freddie made it and he is "ThunderRoad" here. He used to make raised tops and other things... Now he is a retired layabout. Send him a PM.

S_Mazza
05-30-2013, 12:11 PM
In the stock mounting location, I don't see how you can improve much upon the stock arrangement. The air there is hot anyway, so you can't cool the module much below the temperature of the engine (200-220?). If you extended the wires from each side of the harness, you could move the DIS somewhere else and mount it with a heat sink in some airflow. But then you would have issues such as water intrusion to deal with.

The stock piece seems to last 15 years in the stock location, so I think I will keep it as is. If aftermarket pieces prove to fail sooner, maybe I will reconsider.

bowez
05-30-2013, 05:01 PM
IMO the aftermarket units are fine just get one with a lifetime warranty. I believe a lot of DIS claimed issues is either ECT or Balancer.

J dot Miller
05-30-2013, 06:30 PM
I have it so I will use it. In summer heat and stalled traffic a 180-200F temperature can be seen under the hood.

For a quickie... Assuming no air flow, DIS at air temperatures and using Fourier's Law:

ALUMINUM
Area 0.007 m2
Thermal cond 210 @ 220 F ALUMINUM (dart throw)
Temp eng 104 C @ 220 F
Temp air 93.3 C @ 200 F
delta T 10.7 C
Wall thick 0.02 m

q = k A dT / s = 925 Watts

STEEL
Area 0.007 m2
Thermal cond 43 @ 220 F STEEL
Temp eng 104 C @ 220 F
Temp air 93.3 C @ 200 F
delta T 10.7 C
Wall thick 0.02 m

q = k A dT / s = 189 Watts

DELTA ALUMINUM VS STEEL 736 Watts

Not much. But my DIS is old and I am too cheap to get a new one. :cool:

KMT
05-30-2013, 07:13 PM
As you can see in this thermal image of my '90, the DIS is cooler than the pedestal, which seems to be similar in heat to the pulleys.

The DIS is actually similar in temp to the fender.
http://lh4.ggpht.com/KentidCN/R_QM4WXGd0I/AAAAAAAAC3U/R-I0_RyplOs/s800/D07.jpg

If you're looking to mod things, perhaps the plan should be to shield it from heat from the pedestal, and move away whatever heat it happens to generate on it's own...better airflow, maybe, but I'm not convinced it is a source of heat on it's own so much so that it needs help, etc.

I've seen aluminum heat fins stuck to the the top of a DIS, but I have no idea if they supplied any added benefit.

J dot Miller
05-30-2013, 08:56 PM
Cool stuff... :cool:

HwyStar
05-30-2013, 09:41 PM
Tried to leave Fast Freddie a messege, but his box is full. Honestly havent ever had one fail on me, but i will be turning this engine a bit higher from time to time.

S_Mazza
05-31-2013, 12:36 PM
I have it so I will use it. In summer heat and stalled traffic a 180-200F temperature can be seen under the hood.

For a quickie... Assuming no air flow, DIS at air temperatures and using Fourier's Law:

ALUMINUM
Area 0.007 m2
Thermal cond 210 @ 220 F ALUMINUM (dart throw)
Temp eng 104 C @ 220 F
Temp air 93.3 C @ 200 F
delta T 10.7 C
Wall thick 0.02 m

q = k A dT / s = 925 Watts

STEEL
Area 0.007 m2
Thermal cond 43 @ 220 F STEEL
Temp eng 104 C @ 220 F
Temp air 93.3 C @ 200 F
delta T 10.7 C
Wall thick 0.02 m

q = k A dT / s = 189 Watts

DELTA ALUMINUM VS STEEL 736 Watts

Not much. But my DIS is old and I am too cheap to get a new one. :cool:

Where's the steel come in? I am pretty sure that both accessory brackets are aluminum.

bowez
05-31-2013, 05:02 PM
I would think steel as in the fender

HwyStar
05-31-2013, 10:35 PM
I havent seen those equations in a while! Since i left the boat three years ago...

boogeyman
06-01-2013, 11:48 PM
i run a 92 sho dis i had laying around and ran a relay to the keyed power side of the dis to supply full battery voltage to it at all times when running, i was able to open the plug gaps back up to.38 from .32 after doing the rewire

HwyStar
06-02-2013, 01:52 AM
Hmm, sounds like a great idea. Didnt know you could interchange. What kind of plug wires you running? I just looked at my old set of Jacobs wires and they were ~1kohm/ft. Ordered a set of Taylor ThunderVolt wires, they are 50 ohm/ft. Should try a set of those. Should be able to open the gap a little more.

bowez
06-02-2013, 08:42 AM
Yeah the module is also used on 3.2 SHO and 3.0.

J dot Miller
06-02-2013, 12:19 PM
Finally installed the heat sink. The 40mm long screws I found were the correct size. But they were not the same as the picture. They had phillips heads and were silver so I painted the tops black.

Now the DIS is above the wire harness that runs in front of it. Did not take a picture because I have too much work to do. Besides the view of the heat sink is blocked by the harness. Not much to see.
:eek:

Tedor
06-03-2013, 07:50 AM
The base of the module need to be in direct contact to the chassis for ground and disperse the heat created by the ~30A form the module.

You mean so the heat from the DIS can spread to the bracket instead of itself? Is the DIS being hotter than the bracket?

bowez
06-03-2013, 05:32 PM
I believe the base would be hotter during operation but I have no proof.