Aftermarket radiator and the necessity of a shroud

[minigts]

I know it will seem as though I have my answer based on what I'm going to post, but how necessary is a shroud for the radiator?

Originally I had a fan that was like 16" in diameter when my radiator is only like 14" tall. I'm running an aftermarket radiator, btw. The car ran very cool with just water in it and no shroud. It would definitely cycle from hot to cold frequently, but that was with water only in the radiator. When it was driving down the interstate, it ran like 2-3 bars at the bottom of the stock gauge.

I break the car down and in the process move to a smaller fan that fits correctly and I add a shroud and swapped out the T-stat for a new one and drilled the 1/16" bleed hole. The hole couldn't be any bigger and it would either hit the edge of the t-stat at the top or bottom. The smaller fan doesn't seem to move as much air as the other one, but I have the shroud in place that will be pull air across all the channels instead of JUST where the fan is when at idle. When I'm moving, air obviously was moving across the entire radiator. Now with this setup, my car runs much warmer all the time, but never over heats, that I can tell. I am going by the stock gauge, but RELATIVE to that it's running warmer. Please don't post about how inaccurate the stock gauge is. I haven't seen any evidence that mine is wrong or way off, so again I'm going by what it was showing before and what it is showing now. Currently I have about a 3/4 container of coolant in the system, the rest is distilled water.

So I guess my question would be, should I remove the shroud or is it better on the radiator to have it?

[GLHNSLHT2]

Make the hole in the t-stat smaller, the coolant needs to sit in the radiator to cool off. Did you change any other shrouding? The guage is on one side of the head and the tstat and ECU sensor are on the other, they read different and the gauge tends to jump around more.

[contraption22]

A shroud is nessescary to effectively force air to be pulled by the fan through the radiator. Without a shoud, the fan can pull air from any direction that offers less resistance than through the radiator core.

However, at higher speeds, when a fan isn't needed at all.... the fan shroud can actually become a restriction of flow. So if your shroud is restricting airflow through the radiator your temp at cruising speed could rise.

For example, the L88 Corvettes with the "425hp" 427 were all-but street legal road race cars. Because of this, they were delivered form the factory without fan shrouds, at it had been proven that they cooled better on the track without the fan shrouds. However when Joe Schmoe bought one and drove it on the street, they would easily overheat, because at low-speeds, the fan wasn't pulling enough air through the radiator.

I'm not going to say anyting about the accuracy of the factory gauge. But at least it would be easier to recognize and resolve a problem using real numbers.

[minigts]

Make the hole in the t-stat smaller, the coolant needs to sit in the radiator to cool off. Did you change any other shrouding? The guage is on one side of the head and the tstat and ECU sensor are on the other, they read different and the gauge tends to jump around more.

Well I don't think I could do smaller than 1/16". :) I mean, I'm sure there are bits out there, but that's pretty small. :p And things changed:


shroud added
smaller fan
new T-stat
added coolant instead of just water
went to 2 piece intake
radiator was epoxied at the top and bottom corners


I guess I'm just concerned about the reading and how it sits close to middle or slightly above that in traffic versus before where it would sit just under the 1/4 mark from the bottom. I guess as long as it's cycling the coolant from the engine that's a good thing, but cooler is always better and I'm just thinking the shroud is causing an issue with air flow at higher speeds.



A shroud is nessescary to effectively force air to be pulled by the fan through the radiator. Without a shoud, the fan can pull air from any direction that offers less resistance than through the radiator core.

However, at higher speeds, when a fan isn't needed at all.... the fan shroud can actually become a restriction of flow. So if your shroud is restricting airflow through the radiator your temp at cruising speed could rise.

For example, the L88 Corvettes with the "425hp" 427 were all-but street legal road race cars. Because of this, they were delivered form the factory without fan shrouds, at it had been proven that they cooled better on the track without the fan shrouds. However when Joe Schmoe bought one and drove it on the street, they would easily overheat, because at low-speeds, the fan wasn't pulling enough air through the radiator.

I'm not going to say anyting about the accuracy of the factory gauge. But at least it would be easier to recognize and resolve a problem using real numbers.

I plan on removing the shroud to see how it cools, but that's the reason I'm asking about whether or not to keep it off. I'm worried that not cooling certain areas will cause or could cause damage to the channels that really don't get the air flow when cruising through town.

And I understand about the gauge and I do plan to get my AutoMeter one installed. However going by what was happening before and what is happening now, the factory gauge is showing an increase in temps after the change. I still think mine is reliable in the sense that I can see a difference between the two setups, I'm just wondering if it's worth having the shroud on if overall temps are going to stay high in the long run. I'm planning on getting an oil cooler, which hopefully will help the overall temps of the car.

BTW, thanks for the info guys and the time you're taking to respond. :thumb:

[contraption22]

I'll give you another example... I have this factory fan and shroud... I think it's from a LH body, but I am not sure. It has rubber flaps on it. Basically these flaps are closed at low/no vehicle speed forcing the the air to be pulled by the fan through the radiator... however at higher speeds these flaps open up, allowing air to pass through the shrould, offering less restriction for air to flow through the radiator.

[minigts]

Yeah I thought about cutting some vents or slits in the shroud to allow air to flow though, but wasn't sure the impact to the effect of the shroud at lower speeds.

[contraption22]

Yeah I thought about cutting some vents or slits in the shroud to allow air to flow though, but wasn't sure the impact to the effect of the shroud at lower speeds.

The flappers would be the only way to do it effectively, otherwise the slits you cut in would remain the easiest path for the air to be pulled in by the fan.

[rbryant]

Last year in Phoenix my 4.0 Cherokee would overheat if sitting and I ordered a new radiator. When I started to change it I noticed that the bottom of the fan shroud was gone. I put in a new shroud and returned the radiator. All of the cooling problems are solved.

I doubt the hole in the t-stat is really that relevant. If you want to reduce the size of it drill it out and but a hollow center brass rivet in it.

-Rich

[minigts]

I get mixed signals on the hole. Some say have it to let the air bubbles out, other say not necessary. I have the t-stat that I replaced. Should I just put that one back in and see?

[rbryant]

I get mixed signals on the hole. Some say have it to let the air bubbles out, other say not necessary. I have the t-stat that I replaced. Should I just put that one back in and see?

If you bleed the air out of the system until you get water coming out of the top of the waterbox then you shouldn't need the hole but it can't really hurt anything. If it was really needed then it would be there on all of them.

Many of our cars have the plugs totally rusted/corroded in the waterbox so they are very hard to bleed and in that case the hole helps.

I actually recommend putting a 3/8 to 1/8 brass bushing in the waterbox top hole and using a 1/8 plug in it instead of the 3/8 plug. That way you can bleed the system via the 1/8 plug which is always easy to unscrew!

-Rich

[minigts]

Here is a picture of the shroud. The edges of it hit JUST at the inner edges of the tanks. Today driving home, it stayed at 3/4 of the factory gauge, well about 2 marks below where it gets hot. It would move a little to about mid a couple of times, but if I were to speed up it would climb and stay there. I mean, it was under 90 today with an index in the mid to high 90's and it was cloudy. I can only imagine how it will run when it actually gets 90 or better.

Would this little bit that is covered cause it to run hot like it is?

I am going to get a sensor for my Auto Meter so I can get some specific readings, but compared to how it was running previously, I'm a little worried. Maybe I need a better fan. :(

[crazymadbastard]

Is that shroud tapered? I can't tell from the pic, if it is not you need to make tapered or make a box for it.

[cordes]

Here is a picture of the shroud. The edges of it hit JUST at the inner edges of the tanks. Today driving home, it stayed at 3/4 of the factory gauge, well about 2 marks below where it gets hot. It would move a little to about mid a couple of times, but if I were to speed up it would climb and stay there. I mean, it was under 90 today with an index in the mid to high 90's and it was cloudy. I can only imagine how it will run when it actually gets 90 or better.

Would this little bit that is covered cause it to run hot like it is?

I am going to get a sensor for my Auto Meter so I can get some specific readings, but compared to how it was running previously, I'm a little worried. Maybe I need a better fan. :(

My ride will run at 180* all day in the 90's. That's with a crappy old TII rad also.

http://www.omniglht.com/fan.html

[minigts]

Is that shroud tapered? I can't tell from the pic, if it is not you need to make tapered or make a box for it.

It's not, but the fan sits about 1/2" or 3/4" off the channels. Should it be more and would that help?


My ride will run at 180* all day in the 90's. That's with a crappy old TII rad also.

http://www.omniglht.com/fan.html

Please don't rub it in. :( Maybe the radiator is too small. That would REALLY suck if that was the issue, but since it was running cooler before, I'm thinking it's either the fan not pulling enough or the shroud. But I'm thinking it may be the fan.

[BadAssPerformance]

My fluidyne radiator worked great with the old Spearco IC... when I upgraded to the big Spearco IC and switched the fan to a blower instead of a sucker the cooling went to hell. I ducted a box between the IC and radiator to force all the air to go thru.. much better now.

[black86glhs]

Fan shrouds(that work) are perfectly flat, they are rounded at the edges. If the shroud is flat(even if it is 1/2"-3/4" away from the radiator), it is probably blocking some of the air flow.

[minigts]

My fluidyne radiator worked great with the old Spearco IC... when I upgraded to the big Spearco IC and switched the fan to a blower instead of a sucker the cooling went to hell. I ducted a box between the IC and radiator to force all the air to go thru.. much better now.

I thought about getting a second fan to push and one to pull, but I'm thinking it really shouldn't be that complicated.


Fan shrouds(that work) are perfectly flat, they are rounded at the edges. If the shroud is flat(even if it is 1/2"-3/4" away from the radiator), it is probably blocking some of the air flow.

Yeah, I started thinking about it after I looked at mine and I can see where the air (when leaving) would hit that "wall" and cause some turbulence or issues with the air leaving. I may have to get another piece of aluminum and build a box like I was going to do.

For right now or tomorrow really, I'm going to leave just the fan on without the shroud and see how it does. If it does significantly better I MAY still try to build an effective shroud, but if it cools, not sure if I should worry at that point. The only issue I can see is possibly with the corners not getting cooled properly at low speeds and causing stress there. I did have some leaks at the top channels on the corners and I'm wondering if it had to do with improper cooling at those points. I'm REALLY hoping it wasn't due to shoty workmanship. I'll report back tomorrow with my results.

[contraption22]

By the looks of it, that fan should work fine without a "shroud" other than it's own. Thats what I am using.

[butchsuppe]

The factory doesn't use a shroud, so why even put one on ? While working at a hot rod shop we used alot of electric fans without shrouds and had no problems.:nod:

[minigts]

Well the fan is 14" in diameter and the radiator is like 13.5". The width is 16", so there is some area that isn't getting the cooling of the fan, but maybe with less restriction that area will get the proper cooling it needs once I'm moving.

[contraption22]

But your area of concern is when the car is moving, not when the car is idle, correct?

[minigts]

But your area of concern is when the car is moving, not when the car is idle, correct?

Yes, you are correct. I guess I don't want to over look the low speed potential issues to correct the high speed issues. But yes, right now I want to find out why I'm having cooling issues cruising at 70 mph on the highway.

[contraption22]

It's the shroud. Ditch it and attatch the fan directly to the radiator core. The fan itself has a built in shroud that will keep the fan from sucking air from around the radiator. It should work fine.

[minigts]

It's the shroud. Ditch it and attatch the fan directly to the radiator core. The fan itself has a built in shroud that will keep the fan from sucking air from around the radiator. It should work fine.

I think I will end up, assuming it cools ok tomorrow. It really should as I'm running coolant/water mix and so far no leaks in the system that I can tell. I'm going to get the engine block testing kit out if it still runs hot tomorrow. It's some device that sucks some coolant out into a container and mixes it with some fluid. If the fluid turns a certain color, it means there is combustible gas getting into the cooling system. I'm sure a lot on here know about this, but I hadn't heard about this until I drove my car across country with a lifting head. :p I think this will do the trick though.

[minigts]

Ok, so this wasn't the best test as the overall temps this morning were like 20 degrees cooler than yesterday. However, the gauge stayed at about the 3rd small bar from the Cold values on the factory gauge all the way into the city which is about 20 miles. It didn't move past the second bar until I got into some traffic and then it started to climb up a tad. Worst it got when going about 55 mph in traffic was just over the 4th bar, but once I got moving to about 60 it went back down.

It's not conclusive, but it's definitely running more consistently and closer to what it was before. I may still run a box/shroud with a fan that pulls more CFM, but for now it will be just the fan. I'll provide numbers for the end of the day today, although it seems like it will be cooler so it may not be conclusive until we have a 90 degree day again.

[Darkapollo]

Well the fan is 14" in diameter and the radiator is like 13.5". The width is 16", so there is some area that isn't getting the cooling of the fan, but maybe with less restriction that area will get the proper cooling it needs once I'm moving.

if the fan is 14'' and the rad is 13.5'' you are cooling the whole core. you have 1'' on either side of the rad BEFORE and AFTER the fan but those areas still run through the area covered by the fan.
On my Shadow, I had a 16'' fan on a stock T2 rad and it over lapped the top and the bottom but not the sides so there was a gap of about 1/8'' between the core and fan. I never had a problem with over heating.

[chilort]

The factory doesn't use a shroud, so why even put one on ? While working at a hot rod shop we used alot of electric fans without shrouds and had no problems.:nod:

The factory did use a shroud on some cars. It was integral to the fan itself.
http://farm3.static.flickr.com/2213/2091626501_b0e7e4db50_o.jpg

I run the above setup plus a small pusher. This is mostly to assist my AC in the hot Atlanta summer traffic.

I run an 1/8 hole in my t-stat as well since I cannot bleed my system because the bleeder deal is stuck. Many vehicles come with a captured bb in the t-stat. My 440 is like this. I believe Neon has one as well. I wish someone would make one like that for our cars.

My car stays cool until I start pulling major grades (i.e. Smokey Mtns) and then it wants to creep up, but never overheats.

I don't run a shroud on the Swepty mostly because I can't find one that fits right. It gets a little warm on the interstate at 70mph when the outside temp is above 90*. I don't drive it much when it is above 90 though because it doesn't have working AC and I don't like sticking to the hot black seat.

http://farm2.static.flickr.com/1377/1308095894_816e25e98c.jpg

[cordes]

Ok, so this wasn't the best test as the overall temps this morning were like 20 degrees cooler than yesterday. However, the gauge stayed at about the 3rd small bar from the Cold values on the factory gauge all the way into the city which is about 20 miles. It didn't move past the second bar until I got into some traffic and then it started to climb up a tad. Worst it got when going about 55 mph in traffic was just over the 4th bar, but once I got moving to about 60 it went back down.

It's not conclusive, but it's definitely running more consistently and closer to what it was before. I may still run a box/shroud with a fan that pulls more CFM, but for now it will be just the fan. I'll provide numbers for the end of the day today, although it seems like it will be cooler so it may not be conclusive until we have a 90 degree day again.

From personal experience in testing my fan when I didn't know what was wrong with it, I can say that there is a huge cooling difference in those 20*s. Hopefully you have it working well though.

[minigts]

Well we will see how it runs on the way home. That ride is always hot and I may just book it home once I get out of the city and force it to get hot. The other day I was driving it at 70-80+ MPH and it just kept getting hotter and really didn't cool down until I got to 55 mph once off the interstate. I guess time will tell. :)

[minigts]

I think I can safely say it's not the shroud that was the problem. Drove all the way home, same route and it got just as hot an never cooled down until I got to my exit.

Going to do an engine block test. If that's negative, going to replace the t-stat with the one I had in it originally. If THAT doesn't work, guess I need to check..... timing? Maybe I'm off a tooth. It's at 12 degrees on the gun, but maybe the cam is off or something. Seems to idle just fine and rev just fine, so not sure.

I'll report back in a little bit after the engine has had time to cool down to where I can pull the rad. cap off to do the block test. I think that's what it's called.

[cordes]

You might recall that my car was running really hot last year at SDAC. I thought the rad or fan just wasn't up to the task, but as it turned out there was an internment fault in my fan. You may want to try some vigorous wire giggling while you are under the hood too.

[minigts]

Well it shouldn't be running 3/4 of the gauge or worse at 70 mph at low to mid 80 degree weather. The fan is definitely working and cooling down when driving at low speeds. Something is going on at high speeds, flow or something in the system. I did the block test and it came up negative. Going to pull the t-stat and check that or replace it.

[rbryant]

I think I can safely say it's not the shroud that was the problem. Drove all the way home, same route and it got just as hot an never cooled down until I got to my exit.

Going to do an engine block test. If that's negative, going to replace the t-stat with the one I had in it originally. If THAT doesn't work, guess I need to check..... timing? Maybe I'm off a tooth. It's at 12 degrees on the gun, but maybe the cam is off or something. Seems to idle just fine and rev just fine, so not sure.

I'll report back in a little bit after the engine has had time to cool down to where I can pull the rad. cap off to do the block test. I think that's what it's called.

If you were off a tooth you would have either no high end or no low end power. I drove a car accross the country with it retarded a tooth and it was hell to get it up and going but once I hit 70mph it was fine and I just couldn't understand why...

-Rich

[minigts]

Hmm, I have both. That really stinks. I hope the t-stat is jacked up or something. I'm running out of potential problems. :(

Block test proved negative. :( That's good though, I guess. :)

[minigts]

Hmm, I have both. That really stinks. I hope the t-stat is jacked up or something. I'm running out of potential problems. :(

Block test proved negative. :( That's good though, I guess. :)

[contraption22]

Is the radiator flowing evenly? DO you have an infared gun to check temps across the radiator?

[moparman76_69]

just water instead of coolant/water could explain some of it. Coolant cuts down on some of the heat transfer abilities of the mix. Should make that big of a difference but could compound some of the other issues.

[minigts]

Is the radiator flowing evenly? DO you have an infared gun to check temps across the radiator?

Actually, I do. I should check that.



just water instead of coolant/water could explain some of it. Coolant cuts down on some of the heat transfer abilities of the mix. Should make that big of a difference but could compound some of the other issues.

Yeah I may change the mix and have more water, possibly try that Wetter's stuff as well. I don't know how well it did before because the radiator was leaking. Maybe it will help.

[moparman76_69]

I just realized I said Should instead of Shouldn't but seems you got the right idea.

[jake]

Are you running a cat? If so take a look at as soon as you get out after a dive when it got hotter, maybe it is getting clogged. Also if you have a way I would check your air/fuel and EGT you may be running lean (more air from your two piece intake?) and over heating or to rich and burning off the extra fuel in the turbo. Might want to try bumping the timing just a few degrees and see if it cools down or heats up more. You may have just inadvertently got a higher temp thermostat; there are several different choices, as low as 180. If all else fails and you are sure there are no clogs in the radiator you can try running a cooler set of plugs. Good Luck.

[rbryant]

Is the aftermarket radiator in the same place as stock?

When I had my silver car and put in a T2 daytona radiator it shifted it a little to the passenger side.

Because of that the stock radiator air deflector covered a large portion of the radiator and it didn't cool so well until I trimmed it back. It seems like it would be obvious but it really wasn't because it is on the front side of the radiator and behind the AC condenser where you can't see.

-Rich

[minigts]

Are you running a cat? If so take a look at as soon as you get out after a dive when it got hotter, maybe it is getting clogged. Also if you have a way I would check your air/fuel and EGT you may be running lean (more air from your two piece intake?) and over heating or to rich and burning off the extra fuel in the turbo. Might want to try bumping the timing just a few degrees and see if it cools down or heats up more. You may have just inadvertently got a higher temp thermostat; there are several different choices, as low as 180. If all else fails and you are sure there are no clogs in the radiator you can try running a cooler set of plugs. Good Luck.

Actually, the cat. converter has something loose in it and rattling, I just never thought anything about it. I'll have to check that out. I have a narrowband I can and should hook up, so I'll do that as well. Ordered the Autometer temp sender for my gauge and will have some actual numbers next week.

And I'll try moving the distributor to see if that changes anything. Last night driving home it was fine and never got hot, but that was with rain at about 1am. It didn't get hot so I'm thinking that most things are good like the timing and the cat. not being clogged, but I will be double checking. I did pull the T-stat out and check it. It's a 180 (says on the actual piece) and I poured some 200+ temp water into a cup with it and it works fine.

What are cooler plugs? I can check the gap on them, but they were the same ones as before.



Is the aftermarket radiator in the same place as stock?

When I had my silver car and put in a T2 daytona radiator it shifted it a little to the passenger side.

Because of that the stock radiator air deflector covered a large portion of the radiator and it didn't cool so well until I trimmed it back. It seems like it would be obvious but it really wasn't because it is on the front side of the radiator and behind the AC condenser where you can't see.

-Rich

Yeah it's in the stock position, just under the radiator support where the condenser should go. No A/C in the car though. The only thing in front of it is the IC, which was there before.

I'm beginning to wonder if the gauge was reading correctly, but with the leaky radiator, wasn't getting proper temp readings due to the lack of water in the system. I mean, it seems to stay in a general area when driving, but it just doesn't stay in the middle after a while driving during the day. I'm going to check out some things today and see if the gap is good, adjust the timing a couple of degrees and do some infrared temp readings on the radiator to ensure it's cooling evenly or at least reading even temps. The lower hose is hot so I know there is flow. I may also remove some of the coolant and run more water. I put 3/4 of a container in the car with whatever water was in it. Maybe there is too much coolant.

The other thing I think I will do is get some metal and create a couple of air deflectors to divert air to the radiator. Maybe that will help a bit.

Thanks again guys for the input!

[badandy]

Jon,

I too have an aftermarket radiator in my car which was installed by the previous owner. Mine is of the Scirocco variety and I believe is a 4 core...so it's huge. When moving my fan doesn't even kick on...and it takes forever at idle before it will. When I beat on the car for awile I do know that my slimline fan has a hard time cooling things down. I've known for a good long time now that I really need to get a good flexalite fan (or equivalent). I need something that moves more CFM's...especially accross a core that is much thincker than stock. The fan I have just isn't up to the task of shedding the heat of the larger radiator just due to it's sheer mass (my guess).

...so, my point is your fan is simply too small/not strong enough. I bet if you reinstall the large fan your issues will be resolved.

[minigts]

Well I kinda sold it, so I'd have to get another one. I don't know what CFM it was pushing, but this one seems to pull significantly less. I can't even hear it run with the hood down. The other one, oh man, you could hear that thing 5 cars away.

There are a couple of 2300-2700 CFM 14" fans out there I may get. The best 16" fan I saw pulled around 3000 CFM, but I don't know how accurate the numbers are. The Flex-lite ones pull just at 2000 for a 16" and like 1800 for a 14". Wish I could see some true examples of what 2000 CFM sounds like and the effect when running. But I think I'm going to get a new fan anyways, this one doesn't seem to cut the mustard.

[cordes]

Well I kinda sold it, so I'd have to get another one. I don't know what CFM it was pushing, but this one seems to pull significantly less. I can't even hear it run with the hood down. The other one, oh man, you could hear that thing 5 cars away.

There are a couple of 2300-2700 CFM 14" fans out there I may get. The best 16" fan I saw pulled around 3000 CFM, but I don't know how accurate the numbers are. The Flex-lite ones pull just at 2000 for a 16" and like 1800 for a 14". Wish I could see some true examples of what 2000 CFM sounds like and the effect when running. But I think I'm going to get a new fan anyways, this one doesn't seem to cut the mustard.

The needle on my temp gauge drops like a rock when my new fan kicks on, and it's not that loud. It is also much slimmer than a lot of the other offerings out there. That might not be a bid deal due to the way you have your rad mounted, but it made all the difference to me.

[minigts]

Well I adjusted the timing to 10 degrees and it seems to idle and run the same. Again, this morning isn't going to be the best test, but this afternoon assuming it doesn't rain is going to be pretty hot or close to 90. With traffic and the high temp, I should be able to tell if THIS makes a difference. Now, with the timing retarded 2 degrees and the apparent lack of change in idle and driving, is the computer adjusting for the change or is it that negligible?

And Brian, I'm going to order another fan that can push some CFM, hopefully one that will move 2000 CFM or better.

[cordes]

Well I adjusted the timing to 10 degrees and it seems to idle and run the same. Again, this morning isn't going to be the best test, but this afternoon assuming it doesn't rain is going to be pretty hot or close to 90. With traffic and the high temp, I should be able to tell if THIS makes a difference. Now, with the timing retarded 2 degrees and the apparent lack of change in idle and driving, is the computer adjusting for the change or is it that negligible?

And Brian, I'm going to order another fan that can push some CFM, hopefully one that will move 2000 CFM or better.

2* of base timing isn't a huge difference I would think. The computer won't compensate for it though.

[minigts]

http://www.accuweather.com/us/tn/mason/38049/city-weather-forecast.asp?partner=accuweather&u=1&traveler=1

Weather for today, very similar to last week. So what the heck does 10 degrees vs 12 degrees DO?!

[jake]

If it were me I would look further into that cat. Cats should not rattle. If you can look at is as soon as you get out (in a safe location of course) and see if it is glowing red. Better yet if you can pull it and check to see if you can see light through it. I would also check that I wired the fan right, some aftermarket fans can be both pushers or pullers depending on wiring. If it is pushing back on the radiator it might work fine at low speeds but not at high speeds. Try putting a piece of paper in front of the radiator with the fan on. If the fan is pulling I doubt another fan or bigger fan would help much because you should have plenty of flow at 70 mph and the fan should not even be on. 2 degrees in timing should not do too much, but hopefully you will see if you are going in the right direction or making things worse. Plugs come in heat ranges, do a search there is a lot of info out there on them. I usually run one stage colder than stock with a 180 degree thermostat. I think the really big boost guys usually run a even colder plugs. One stage colder plugs will not drop your engine temp 100 degrees but it might help a little.

[minigts]

If it were me I would look further into that cat. Cats should not rattle. If you can look at is as soon as you get out (in a safe location of course) and see if it is glowing red. Better yet if you can pull it and check to see if you can see light through it. I would also check that I wired the fan right, some aftermarket fans can be both pushers or pullers depending on wiring. If it is pushing back on the radiator it might work fine at low speeds but not at high speeds. Try putting a piece of paper in front of the radiator with the fan on. If the fan is pulling I doubt another fan or bigger fan would help much because you should have plenty of flow at 70 mph and the fan should not even be on. 2 degrees in timing should not do too much, but hopefully you will see if you are going in the right direction or making things worse. Plugs come in heat ranges, do a search there is a lot of info out there on them. I usually run one stage colder than stock with a 180 degree thermostat. I think the really big boost guys usually run a even colder plugs. One stage colder plugs will not drop your engine temp 100 degrees but it might help a little.

I'm with you on the cat, but unless I cut it off it will be next to impossible to check it. I'm trying to get away from my previous/current logic about previous temps and how it ran, as before the radiator was leaking, now it's not. So I really can't confirm it was running as cool as it was before, although it did cycle the fan off and on. With the cat ratting being the same before, it still could be an issue just now really noticeable with my current setup. Right now I'm going to assume it's not the main problem, but definitely will keep that as a potential issue.

And the fan is definitely moving air correctly. I checked it immediately after installing it when I timed the car, so I know it's ok. Today will be the best test as to whether or not the timing makes a difference. My only concern is when I'm running boost above the current 11 psi. Will retarding 2 degrees hurt or help or be indifferent? Should there be any difference in timing when running a one-piece vs a two-piece? The information I provided for the FWDP cal I have in the car was related to a 2 piece.

[cordes]

The two degrees of base timing you pulled out shouldn't hurt anything. You probably won't notice anything at all really.

[black86glhs]

The two degrees of base timing you pulled out shouldn't hurt anything. You probably won't notice anything at all really.It will be a couple degrees away from detonation too. It is probably better at 10* anyway over the 11 psi. No worries.:D

[minigts]

I got my IR temp sensor and did some measuring.

Before Cat - 260-280
Cat - 310-315
After Cat - 260-270

These numbers are pretty close to what I read, but nothing was written down it's only what I remember. The bottom line is, it gets hotter at the cat, but that makes some sense (to me) because there is some restriction there.

Also, the radiator showed about 190-200 on the hot side and roughly around 160-170 after the fan. Probably needs some more cooling there, but overall it was pretty even across the radiator top to bottom.

After talking to my friend, he strongly recommended I re-time the car...AGAIN because he felt everything that I was describing was point to timing. It did seem to run a little cooler on the way home, but it's really hard to tell as there was yet another storm that came in close to when I was heading home. It didn't get worse than it has before where it was hot in town and there was lots of traffic. So it didn't get worse, but it didn't run significantly cooler. Going to re-time it and see if that helps.

[minigts]

Well I re-timed the car (12 degrees) and it seems to be cooling better. Not what it used to be, but it didn't continually creep up on a day hotter than the one when I first began the thread. Got about half way up and hovered there most of the time in the city. It began to settle just below the half the rest of the way and pretty much stayed there or lower at the lower speeds on the back roads. That must have been the real issue, but the fan is going and I'm getting a higher CFM fan. Still going to dilute the coolant/water mix with more water and plan to add some Wetters as well.

[fishcleaner]

The other day I was driving it at 70-80+ MPH and it just kept getting hotter and really didn't cool down until I got to 55 mph once off the interstate. I guess time will tell. :)
Try installing a rubber air dam under the radiator support (like the Buick Grand National) to create a better low pressure area under the car, that should help at high speeds, but I think its something else, your fan covers the radiator, that should do it. I'm thinking the water pump vanes are worn out and not pushing enough water thru as the engine gets hotter under load.