DeWitt Radiators
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DeWitt Radiators
Hi!
Has anyone done a direct comparison of the difference in operating temperature a DeWitt radiator makes? By "direct" I mean a before and after comparison where only the radiator was changed (not also the thermostat, etc etc). Also, the DeWitt radiator is advertised as a direct replacement, but I have learned that this often still means that some modifications are necessary to make an aftermarket part fit. Is this the case with the DeWitt? The DeWitts seem to be good units, but at $500 bucks you can get an original GM radiator, new Air conditioning evaporator and still have lots of change left over.
Thanks,
/s/ Chris Kennedy
Has anyone done a direct comparison of the difference in operating temperature a DeWitt radiator makes? By "direct" I mean a before and after comparison where only the radiator was changed (not also the thermostat, etc etc). Also, the DeWitt radiator is advertised as a direct replacement, but I have learned that this often still means that some modifications are necessary to make an aftermarket part fit. Is this the case with the DeWitt? The DeWitts seem to be good units, but at $500 bucks you can get an original GM radiator, new Air conditioning evaporator and still have lots of change left over.
Thanks,
/s/ Chris Kennedy
Le Mans Master
Joined: Apr 2000
Posts: 5,713
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From: Manassas VA
I looked at them at Carlisle this year. Started to get it but hauling it was going to be a bear.
The problem with your comparison will be this. If you change it out and it does run cooler, then the question is going to be was the GM radiator up to new specs. ie. dirty, bent, etc.
The problem with your comparison will be this. If you change it out and it does run cooler, then the question is going to be was the GM radiator up to new specs. ie. dirty, bent, etc.
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Originally Posted by 93 ragtop
I looked at them at Carlisle this year. Started to get it but hauling it was going to be a bear.
The problem with your comparison will be this. If you change it out and it does run cooler, then the question is going to be was the GM radiator up to new specs. ie. dirty, bent, etc.
The problem with your comparison will be this. If you change it out and it does run cooler, then the question is going to be was the GM radiator up to new specs. ie. dirty, bent, etc.
Thanks, again, for your reply!
/s/ Chris
Former Vendor
Joined: Jan 2000
Posts: 5,593
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From: Brighton
If the GM radiator was brand new and you replaced it with the dual core radiator, you'd probably see no change at all. That's because the ECM "tells" the system to run hot. I think they kick the fans on at 228. If you want it to run cooler, you'd have to run the fans earlier.
I often get asked about the stock single row capabilties and I sum it up like this. First of all, there is nothing wrong with running 220-230 with these cars. GM made them that way. Is the radiator big enough? Well barely....They built no extra cooling into these radiators. When the radiator builds up with bugs and/or crude inside, the temps go higher. If you add performance items and/or push the car to the limits, it goes higher. I think "marginal" is a good word to use.
I often get asked about the stock single row capabilties and I sum it up like this. First of all, there is nothing wrong with running 220-230 with these cars. GM made them that way. Is the radiator big enough? Well barely....They built no extra cooling into these radiators. When the radiator builds up with bugs and/or crude inside, the temps go higher. If you add performance items and/or push the car to the limits, it goes higher. I think "marginal" is a good word to use.
Instructor
Joined: Jan 2004
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From: Katy TX
Originally Posted by Tom DeWitt
If the GM radiator was brand new and you replaced it with the dual core radiator, you'd probably see no change at all. That's because the ECM "tells" the system to run hot. I think they kick the fans on at 228. If you want it to run cooler, you'd have to run the fans earlier.
I often get asked about the stock single row capabilties and I sum it up like this. First of all, there is nothing wrong with running 220-230 with these cars. GM made them that way. Is the radiator big enough? Well barely....They built no extra cooling into these radiators. When the radiator builds up with bugs and/or crude inside, the temps go higher. If you add performance items and/or push the car to the limits, it goes higher. I think "marginal" is a good word to use.
I often get asked about the stock single row capabilties and I sum it up like this. First of all, there is nothing wrong with running 220-230 with these cars. GM made them that way. Is the radiator big enough? Well barely....They built no extra cooling into these radiators. When the radiator builds up with bugs and/or crude inside, the temps go higher. If you add performance items and/or push the car to the limits, it goes higher. I think "marginal" is a good word to use.
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Thanks, everyone, for the replies. I have the switch that turns both fans on earlier than usual, and do not have cooling problems. The temperature goes up a bit more than I would like when I have the air on and am puttering about or stopped, but nothing alarming. At some point I probably will replace the radiator and evaporator (the car has 134,000 miles and a "checkered" past, I suspect), which is why I asked.
I appreciate your detailed reply, Mr. DeWitt, and think your characterization of "marginal" is right on---are there any modifications needed to fit your radiators to an '89 manual?
Cheers,
/s/ Chris Kennedy
I appreciate your detailed reply, Mr. DeWitt, and think your characterization of "marginal" is right on---are there any modifications needed to fit your radiators to an '89 manual?
Cheers,
/s/ Chris Kennedy
Team Owner
Joined: Sep 2001
Posts: 62,143
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
There were no fitting modifcations needed in my 86. Aside from a small issue that corrected itself I have nothing to complain about.
The average cruising temps tend to run 10F cooler with the new radiator than before. Hwy cruise temps can run 20-30F cooler than the oil (mine ran 200F oil and 170-175F coolant at 75). At a stoplight, the engine will still get hot, so if you are having idle overheating issues, you have no need for this radiator because it will not cure them. However, once you start moving then the temps immediately drop 5-10F.
All my experience is in Louisiana summer heat.
The average cruising temps tend to run 10F cooler with the new radiator than before. Hwy cruise temps can run 20-30F cooler than the oil (mine ran 200F oil and 170-175F coolant at 75). At a stoplight, the engine will still get hot, so if you are having idle overheating issues, you have no need for this radiator because it will not cure them. However, once you start moving then the temps immediately drop 5-10F.
All my experience is in Louisiana summer heat.
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Le Mans Master
Joined: Dec 2002
Posts: 5,270
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From: Seattle Area WA
I think Dewitts is called a Direct Fit, because it is supposed to fit so well. I believe they even supply new rubber grommet/dampner pads that the rad sits on with the correct shape for the new rad so you don't have to mod the old ones.
I don't have one though so ....
I don't have one though so ....
Safety Car
Joined: Sep 2003
Posts: 3,692
Likes: 5
From: Hayward CA
I can't do a direct comparison because I also replaced the water pump with an HD electric pump but......
Before:
Outside temp 90+ degrees
Idle (sitting in traffic) water temp = 220-230 degrees
Crusing water temp = 200-210 degrees
After:
Outside temp 90+ degrees
Idle (sitting in traffic) water temp = 195-205 degrees
Crusing water temp = 185 degrees
Before:
Outside temp 90+ degrees
Idle (sitting in traffic) water temp = 220-230 degrees
Crusing water temp = 200-210 degrees
After:
Outside temp 90+ degrees
Idle (sitting in traffic) water temp = 195-205 degrees
Crusing water temp = 185 degrees
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Thanks, again, everyone---this is all very interesting. My '89 Ebay rat (manual-134K miles) has the standard 195 stat, radiator etc., with the only change being that I added a kit to switch both the main and auxiliary cooling fans on at 180 (yeah, I know--the fan/stat may be fighting each other a bit, but I don't want to fiddle with stat now and I don't think a lower stat would result in much lower temps, for all the reasons we've discussed on the Forum). What all this does do is eliminate the big cycling fluctuations in temperature. Temps run about 188-195 around town without air on (the "town" is Houston), and the only time it goes much over 200-210 is idling with the air on in traffic. Driving on freeways (air off) is about 187-190, and about 190-192 with air on. So.....what I am thinking from all this is that Mr. Dewitt is basically correct, and that the Dewitt may add is reserve cooling under adverse conditions (idling with air on in traffic), and resistance to plugging.
Cheers,
/s/ Chris
Cheers,
/s/ Chris
Former Vendor
Joined: Jan 2000
Posts: 5,593
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From: Brighton
Originally Posted by BillSF49
I hate to disagree with the vendor, BUT, I bought a Dewitt about a year ago, and I had instantly cooler temps while driving. It seemed like it cooled faster, and stayed cooler longer. Maybe my imagination, but I love it. I replaced the fans at the same time, and my temps rarely go over 200 deg, I still have the stock thermostat. Just my .02
Former Vendor
Joined: Jan 2000
Posts: 5,593
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From: Brighton
Originally Posted by Corvette for life
so the real question is, is it worth the price???
I'll be buying one eventually.
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Originally Posted by Tom DeWitt
If you want a robust cooling system then a double row radiator is the only way to get it. You can buy one from several different manufacturers but ours fit the best and typically run about $50-100 cheaper than the others. Worth it? Only you can decide.
1. I think I know the difference between the standard radiator and a double row radiator, but could you explain it?
2. Are there any modifications that need to be made to fit the Dewitt radiator?
Again, I want to thank everyone for taking the time to respond. I, for one, have learned many things I didn't know previously on this topic.
Thanks,
/s/ Chris
Pro
Joined: Jun 2001
Posts: 656
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From: Fort Worth TX
Well i have a brand new factory original radiator still in the box if anyone needs one , i went ahead and bought a Dewitt from Tom. Well let me tell you Tom's radiator is a work of art and works very well never put the new original in even though i bought it so i could not compare but i sure do like Tom's radiator.
Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
Originally Posted by Chris Kennedy
I have a couple of follow-up questions for Mr. Dewitt:
1. I think I know the difference between the standard radiator and a double row radiator, but could you explain it?
2. Are there any modifications that need to be made to fit the Dewitt radiator?
Again, I want to thank everyone for taking the time to respond. I, for one, have learned many things I didn't know previously on this topic.
Thanks,
/s/ Chris
1. I think I know the difference between the standard radiator and a double row radiator, but could you explain it?
2. Are there any modifications that need to be made to fit the Dewitt radiator?
Again, I want to thank everyone for taking the time to respond. I, for one, have learned many things I didn't know previously on this topic.
Thanks,
/s/ Chris
2. We include a sheet of paper in the box with the C5 radiators. This instruction shows trimming both upper corners of the shroud about 1/4" x 1" piece. I know several people that skipped this step and it still works but I found that the top panel fits on better when you do this. Other than that, it's a perfect fit.
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Instructor
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Originally Posted by Tom DeWitt
1. The stock radiator feature one row (1" tubes) aluminum core with plastic end tanks. The end tanks are crimped on and sealed with gaskets. Over time the gaskets and/or plastic tanks will fail. Our radiator is a double row (1" tubes) with press formed end tanks. The end tanks are hand TIG welded on and they will never fail.
2. We include a sheet of paper in the box with the C5 radiators. This instruction shows trimming both upper corners of the shroud about 1/4" x 1" piece. I know several people that skipped this step and it still works but I found that the top panel fits on better when you do this. Other than that, it's a perfect fit.
2. We include a sheet of paper in the box with the C5 radiators. This instruction shows trimming both upper corners of the shroud about 1/4" x 1" piece. I know several people that skipped this step and it still works but I found that the top panel fits on better when you do this. Other than that, it's a perfect fit.
/s/ Chris
Instructor
Joined: Jun 2005
Posts: 231
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From: Waterbury Connecticut
Originally Posted by Chris Kennedy
Hi!
Has anyone done a direct comparison of the difference in operating temperature a DeWitt radiator makes? By "direct" I mean a before and after comparison where only the radiator was changed (not also the thermostat, etc etc). Also, the DeWitt radiator is advertised as a direct replacement, but I have learned that this often still means that some modifications are necessary to make an aftermarket part fit. Is this the case with the DeWitt? The DeWitts seem to be good units, but at $500 bucks you can get an original GM radiator, new Air conditioning evaporator and still have lots of change left over.
Thanks,
/s/ Chris Kennedy
Has anyone done a direct comparison of the difference in operating temperature a DeWitt radiator makes? By "direct" I mean a before and after comparison where only the radiator was changed (not also the thermostat, etc etc). Also, the DeWitt radiator is advertised as a direct replacement, but I have learned that this often still means that some modifications are necessary to make an aftermarket part fit. Is this the case with the DeWitt? The DeWitts seem to be good units, but at $500 bucks you can get an original GM radiator, new Air conditioning evaporator and still have lots of change left over.
Thanks,
/s/ Chris Kennedy
I have a brand new still in the box AC Delco GM Radiator that I'll let you have for 100 bucks plus shipping which is probably going to be between 10 & 15 bucks. I was going to put it in my vette but the one it had was like new so I just flushed it out and cleaned out the debris between the Rad & AC Condensor. These OEM Rads work just fine as long as everthing else in the cooling sytem is functioning correctly. In fact I read on this forum that the OEM's are designed like a Nascar Radiator to be small, lightweight and efficient as long as they are maintained properly and kept clean of debris. Going for $500 bucks is probably a $400 waste of money because you're probably still going to get hot in traffic and that's how the darn car was designed to run. My take is will it cool quickly when moving and my experience was that the OEM Rad properly maintained cools just fine when moving. I've also learned that you rarely get back what you put into these cars, so a 500 radiator won't make your car worth 500 more. If you or anyone else is interested in the OEM for 100 bucks just drop me a line. 
Last edited by papidos; Oct 19, 2006 at 11:44 AM.