Callaway ZR-1 Overheating Hi Temp

mangusta1969 · Nov 14, 2003

Header Wrapping

Wrapping the headers will definitely improve performance (faster exhaust gas flow) and reduce heat in the engine compartment. See this url:
http://thermotec.com/technology/how/how.html

On the same web site, Themotec says that header pipe heat will be reduced from approximately 1300 degrees to 750 degress at the surface. That is a big reduction in a hot engine compartment.

However, I have read multiple sources that state the the exhaust wrap will eventually cause header pipe cracking -- not a good thing with high dollar ZR1 headers.

I have never used this stuff on any of my cars. Hopefully someone with actual/long term header wrapping experience will add to this thread...

rkreigh · Nov 14, 2003

be very careful wrapping the headers, I don't recommend it for the following reasons.

the wrap holds the heat into the headers so well that the steel becomes brittle and cracks. Unless you have 321 stainless, you will shorten the life quite a bit.

the stuff loves to suck up oil and catch on fire, don't ask me how I know!!

I ruined a set of headers with this stuff, and advise you proceed with caution.

it does help minimize heat transfer, but honesly, increasing the fan flow is the real solution to evacuate the heat rather than ruining the headers and having engine fires.

mangusta1969 · Nov 14, 2003

Thanks for your first hand report on header wrap. That's what we need instead of more science and speculation.

Do you remember what brand of header covering material you used? Was it the wrap type or the clamp around the tubes type of material? How long did your headers last with this before cracking?

Engine fires are something I hadn't even thought about. There is certainly no mention of that on the advertising web sites. Imagine that.

Since your car is running cool, have you removed the rear of hood/center plenum rubber gasket?

*89x2* · Nov 14, 2003

mangusta1969 said:
Do you remember what brand of header covering material you used? Was it the wrap type or the clamp around the tubes type of material? How long did your headers last with this before cracking?

Mangusta - I know the Thermo tec brand was on an LPE 406 car (Ron, remember that teal one??

) and it didn't last much mor ethan a year before blowing out - It used the band clamps around it and was wrapped VERY nice - Effective, yes - Cost, high (in the long run)

Good for a last resort as the holes I saw blow into it were not exactly small :eek

...did you find your digital pyrometer yet?????? :beer

EricVonHa · Nov 14, 2003

Hearye, hearye on the negative effects of exhaust wrap. I had a buddy that all but burned his car to the ground from a power steering fluid explosion! I've only ever wrapped the collectors on one of my cars and that was only to keep excess heat off of the floor board area. -E

rkreigh · Nov 18, 2003

the thermal coating is a much safer and better way to go and yes if coated on the inside of the headers does a pretty good job of limiting the underhood heat.

yes I used the thermotec stuff and it's ok to use it where it can't pick up ANY oil and far enough from the exh ports.

if you have the headers coated inside out you can also use the wrap but I would save it for "down stream" on the exh by the collectors.

anything you can do to retain heat in the exh is a good thing as it adds to velocity and helps scavanging.

to us turbo guys it's even MORE essential as heat is the energy the spools the turbo.

anyway, coating the header WON'T cure the overheating problem which is why Aaron @ SGC said to save your $$$

bigger fans are the answer. spal makes a 3800 cfm dual fan setup that covers more of the rad core.

look at the factory fans, even with both running with a switch, they just don't have the zots to cool off a high hp engine with a "bottom breather"

the zr1 guys all mentioned that removal of the A/C evaporator core will cure the heating problem. the fans just don't have enough "pull" to get the airflow through the entire cooling stack and you also have that hot oil cooler to contend with too.

the nice fluidyne racing radiator puts the oil cooler "stacked" instead of in front of the rad which helps, but even then you still need the big fan flow especially with the wider core which is tougher to pull the air.

I'll talk to aaron about this, some fabrication to mount the fans will definitely be needed but it won't be too big a deal.

on my turbo buick, I just use a "low tech" thermal switch tapped into the coolant to turn the fans on @ 170 and off @ 160 (running a 160 thermostat). I have a front mount intercooler which give the exact same problem, not enough airflow with the a/c on in hot stop and go. that way I can set the temps any way I want without messing with switches or the chip!! it also runs the fans for just a minute or two after the car shuts down to prevent the hot soak problems which is great.

the turbo buick guys also use the dual fan setup and it cures the issue of running hot in traffic with the a/c on. keeping the turbo cars with the front mount intercoolers is tough too!!

give the BIG spal dual fans a shot!! overheating the LT5 is a sure path to a blown head gasket, once temps reach over 240, turn the a/c off, if the check guages light comes on pull over and sit it out until you can avoid the stop and go!!

my LSV runs up around 235 even with all the tricks with the A/C on in heavy traffic above 90. the car is OK at this temp, but it's still too hot for me and I don't like the big "temp swings" once I start driving. between 180-190 is just fine IMHO, I like to keep it there!!!

mangusta1969 · Nov 18, 2003

Ron,

Thanks for the informative post and keep us informed on you SPAL fan findings.

I found my digital pyrometer and will take some measurements in the next 4-5 days of my 91 L98 stock motor, a 90 L98 motor with in/out coated headers, and my 92 CR1 with in/out coated headers. Subjectively, both of the coated header motors seem to feel much cooler in the engine compartment.

*89x2* · Nov 18, 2003

Mangusta - That is an envious duty - driving the heck out of cars to get them hot for comparison sake :cool

Enjoy!!! Looking forward to hearing the results~

mangusta1969 · Nov 19, 2003

Digital Pyrometer Readings

Here are some preliminary digital pyrometer readings from the DRM 368 c.i. motor in my 92 CR1. This car has in/out JetHot coated headers on it. The headers are made by Watson and connect to a dual 3 inch exhaust system with Borla XR1 mufflers on it. It does have two Random Tech catalytic converters on it, mounts just aft of the Watson collectors.

Test conditions:
Air temp 76F
Car had just been driven fairly hard on the street and was idling for about 2 minutes in my garage in San Diego (so probably about 30%-50% humidity)
Coolant temp on car's digital gauge 186F
Oil temp on car's digital gauge 192F
Both radiator fans were on (aftermarket DRM chip)
Radiator upper housing left and right sides: 140F
Right Cylinder Head cam cover (didn't measure left yet): 130F
Black cam cover bolts on right cylinder head: 170F
Fluidyne/KryderRacing race radiator

Right side of engine
Header pipe from cylinder number 1: 298F (measurement from above motor as close to cylinder head as possible (about 6-8 inches from head, I would say)
Easy to measure Watson collector pipes under car (not sure which right side cylinders these go to; will have to get under car to verify)
Top collector pipe about 8 inches ahead of Watson collector: 291F
Bottom collector pipe: 270F
Watson collector: 293F

Left side of engine
Header pipe from cylinder number 5: 285F (measurement from above motor as close to cylinder head as possible (about 6-8 inches from head, I would say)
Easy to measure Watson collector pipes under car (not sure which left side cylinders these go to; will have to get under car to verify)
Top collector pipe about 8 inches ahead of Watson collector: 301F
Bottom collector pipe: 274F
Watson collector: 305F

Rear of car
Internal area of double D center exhaust
Left side D: 205F
Right side D: 204F

The above measurements are not super scientific and are probably variable due to the reflectivity of the surfaces that I pointed at with my laser beam/digital pyrometer. I will get some boiling water and pan measurements with the same device and report back on results. When I measured the shiny stainless steel surface of the exterior of the Double D exhaust openings, I only measured about 135F on both of these pipes. Note above that the interior measurement was 204/205F, so there may be big differences due to reflectivity. I saw much the same thing with the black cam cover bolts which were 170F vs. the polished cam cover temp of 130F.

Bottom line is to wait for some more data on other cars with the same measurement device, some boiling water calibration measurements, and I will see what I can find out about the big differences between black surfaces and shiny surfaces. For now, I would think that the exhaust header measurements should probably be increased about 70F, since all of these pipes were still somewhat "shiny" due to the external JetHot coating.

*89x2* · Nov 24, 2003

Mangusta - those sound reasonably cool - How has the rest of your research come along??
Looking forward to hearing more

Fun!!!!!!! :upthumbs

mangusta1969 · Nov 24, 2003

I will see if I can get off my butt tomorrow and take some comparable measurements with the same pyrometer on a fairly stock 91 L98 motor with stock exhaust manifolds and cats on it.

Measurements on the L98 with JetHot coated headers will take me about 10 days or so, as other projects are in the way of that one.

At least I haven't re-lost the pyrometer yet.

*89x2* · Dec 27, 2003

mangusta1969 said:
At least I haven't re-lost the pyrometer yet.

Any more on this Steve?? :beer

stuckatcuse · Dec 27, 2003

Update

Hi guys thanks for all the great suggestions.

My dad is pretty busy right now so the new parts are just sitting. One thing I didn't consider (didn't know) was that apparently the cats are integrated to the callaway headers. This may prevent a ceramic coating all together...

Has anyone coated the callaway headers with integrated cats???

Thanks again...

mangusta1969 · Dec 28, 2003

Chris,

Okay, okay.

I am getting off my Christmas egg-nog butt, re-locating my pyrometer and going to fire up and measure the 91 L98 motor's exhaust manifolds and exhaust pipes -- today!

From a heat standpoint, I wouldn't think the powder coating ovens would hurt the catalytic converter, but the powder coating guys might not want to put the integrated units into their ovens. Give Jet-Hot a call and see what they say.

Steve

stuckatcuse · Jul 2, 2004

Problem solved. We think. We're keeping our fingers crossed. I am sure my dad will take forever to update this post so I'll do it.

Here's what my dad did: Updated higher pitch fan blades, new thermo with 1/8" holes drilled in it, new clutch stuff (slave cylinder?), with some sort of super high temp fluid. I also know that a flexible rubber clutch hose was replaced with a braided stainless hose. Aparrently there were dead grass clippings and leaves/pine needles obstructing over half the radiator stuck between the ac condenser or something. We think this was the primary cause. He also removed the hood seal except for around the electronics at the back of the plenum. One of the shocks in the rear blew so he ordered a new one from callaway and had that put on as well. When my dad got the car back it was running fine but was sluggish like the power key wasn't turned. He took it back and they found a vacuum line knocked off that controlled the secondaries. All is well so far, but no parades for this one yet. The shop let it idle for two hours in 90 degree heat at a standstill and the engine was nice and cool. So far so good. Stupid dead grass.

I'm going to go home one of these weekends with one of my cables, run datamaster, and creep around for a while parade style while keeping an eye on everything. I'll let everyone know how it goes. Maybe I'll even post the datamaster file if we get some 0-60 runs in and they're respectable.

Enjoy your vehicles, whatever they may be....

Sean

500HPCR1 · Jul 2, 2004

Hi to all!

Well, Sean has beaten me to the punch again with the good news- 500HPCR1 isnow performing more awesomely that ever- very smooth, very quick, very COOL, true 500 hp.

I'm still very inexperienced at navigating and operating this type of site, I need help! I'd like to post some pics of my car to that thread, plus I have a digital album of the entire convrsion process of my car from reb/black 1990 ZR-1 to Viper Blue SuperNatural Aerobody CR-1, done over winters 1996/7 at Old Lyme.
I'm sure the membership would be interested, but I don't know how to post pics or albums to this site.

Please call me at 518-877-7629 if you think you can help walk me through the process.

Later I'll post all the things we did to restore and improve 500HPCR1's awesome performance.

Keep the Revs Up!

Steve D.

*89x2* · Jul 2, 2004

Guy's, that is great that you have the car all set to go now, no more overheating!

The C4's are "bottom breathers" and pick up a lot of debris, that may be the single biggest factor in the problem you were having, so simple yet always overlooked :eek

Steve, regarding posting pictures, you can add some pics to your posts as an attachment - I will walk you through the process :beer

- After typing your text, look below and you will see a box titled Additional Options Within that box, look under Attach Files and you will see a tab marked Manage Attachments, click that.

- once that is clicked, another box opens up...

- under File to Upload, click Browse to look through files stored on your computer.
- Select where you are "pulling" the attachment from, hard drive, cd drive, floppy, etc...
- Once you do that, it will show all your files in that drive, select the one you want to upload by clicking the image itself. It will list the location in that box previously blank, all you do then is click the "upload tab" to the right and in a moment it will be done.

Once you are finished (general upload size is 85kb), simply hit Submit reply as you would normally do, and the thumbnail size pic is avail. for everyone to see :cool

Steve, I hope this helps - I also sent you an e-mail about "plan B" for getting those neat images online for all to see, let me know

Chris