I have a 1986 Camaro IROC Z. No longer a daily driver. Want to basically turn it into a mild street & strip/drag n drive/bracket car. For now the nearest drag strip to me is almost 90 minutes away and my daily driver isn't a truck. Not sure how often I will go. But a factor to consider, for now I have to drive to the strip to get there. The area I live in, is very suburban with lots of sprawl and tons of gated communities. Speed limits are basically around 45 MPH with lots of traffic lights. I have a Mr. Gasket 180 thermo in the car. I know Mr. Gasket's thermos have a mixed rep and often seem to open later with age. Car seems to run around 200 on the highway with the AC off but in lots of "city" or suburb driving it's usually around 220 with the fan on. I doubt it's anything with the car itself. Not overheating. Just the thermo is opening later.

I did buy an ACDelco 170* thermo and was planning on installing it. However, one of the bracket racers I know gave me an unopened Edelbrock 160 thermo meant for a SBC. He recommend 160 for a street and strip car that sees lot's of street driving. Which do you think I should use? Engine is the LB9 with less restrictive air box and HVAC piping and a full Hooker exhaust system with Headers, Y-Pipe and muffler. Engine has long since been de-smoged. It's a mild motor for now.

All of the older threads about this topic were from 15 to 25 years ago and people were often concerned about winter time driving and the heater working with too low of a thermostat. This car will never be driven in winter or snow. Plus I wanted some drag racers perspectives.

 

I run 160 in all my 3rdgens. Also have fans set to work with the cooler temperatures.

 

i dont know what a mild drag car is to you, but, most of the guys around me run 1000+ on the street and use off the shelf autozone parts for things like thermostats.

I'd fix your cooling issue first. And by doing that, youll need to verify if those temps youre seeing are true.

 

Quote:

200 on the highway with the AC off but in lots of "city" or suburb driving it's usually around 220 with the fan on

...isn't a cooling system problem. That's driving in low or no air flow conditions, and the fan coming on to limit the upper range of the temps, to ~220. I agree however, with verifying that the temp gauge is correct or at least close.


OP, run whatever thermostat strokes your psychology. Choosing a stat is more a personal decision (meeting criteria that YOU want to meet), than one that matters to the engine. The engine is fine at 180. The engine is fine at 230. Since engines make more power at colder operating temps, and your car is not a DD and you likely want good numbers at the strip? I'd probably bias my personal choice to a colder stat, and change the oil at lower mile intervals or sample it.

I wrote a small essay about the subject, you can read it HERE.

 

If you put a 180* thermostat but did not retune, the fans will still start high. If dual fans, the ecm triggers the first one around 225* and the second fan is trigger mechanically around 235*, IIRC. The mechanical fan switch is on engine head, passenger side, just over the knock sensor. It can be changed to match your new thermostat.

With your set up, at idle and low speed, you will see higher temp, no matter the thermostat. Stock LB9 calibration can run 215-230* at idle. Having said that, on the highway, you should see lower temperature with airflow since you have a 180* thermo. Is the thermo defective? Could be. Is the temp gauge accurate? Don't know! More accurate way to measure engine temp is by monitoring the ECM data. The CT sensor for ecm is located near thermostat housing on intake manifold. The dash CT gauge sensor is located on engine head, driver side.

You can do a test by monitoring the ECM CT value vs an infrared reading of ECM CT sensor and thermostat housing (using infrared temp gun). You start with cold engine and let it run, no HVAC, until fan kicks in. You compare data from infra red and ECM. Dash gauge is only accurate once near 200*, very hard to extrapolate as the scale is not linear, IMO.

On the first slide, it shows a stock LB9 with 195* thermo from cold start to operating temperature. Red is speed, Green is CT. Notice the dip on the green line around 203*? That's when the thermostat opens. It will dip then start fluctuating once fan kicks on and off. In this case, the fan had been tuned to on 203* / off 204* but later retuned to on 200* / off 201* which worked better. I also swapped a mechanical fan switch, GM# 3053190, on 209* / off 199*. The combo worked perfectly and kepth the CT very stable compared to GM's original tuning.



This second slide shows a defective thermostat on a stock LB9 with stock tune. It was an idle warm-up test in garage. One can observed the green line flattening around 146*, which indicated an early thermostat opening. However, there was no effect on cooling. The green line starts going down at around 228* after the first fan kicked in.



This last slide shows a 383 stroker TPI with LB9 stock radiator, dual fan and 180* thermo. Both fans are controlled by '7730 ECM. First fan on 187* / off 186*, Second fan on 190* / off 186*. Engine temp is very stable. Red is speed, green is CT in Celsius. As one can see there is a peak at 195* (90.5*) when car is stationary. It's the delay for both fan to start their cooling effect at idle. CT varied from 181* to 186* once we started rolling. Ambiant air temperature was 63*.



This following post shows the cooling effect of highway speed on a stock LB9 with defective thermostat opening at 150*. That should give you an idea of what a 160* would do without retuning the fans. It did go up eventually because the fans were set at 225*+. So a thermostat alone is not enough, you need to retune fans. https://www.thirdgen.org/forums/diy-...ml#post6511314


Here's an interesting post on thermostat testing:
https://www.thirdgen.org/forums/cool...tested-ok.html

This post took about an hour to write, including digging into my archives!

Peace

 

Thank you for this post. My car running at 200 or 220 isn't a cooling system issue. It's often 90+ degrees out and the area I live in is all subdivisions and busy suburbs. I often have 5 to 10 minute long stop lights that my car sits at and my temp often rises fast from 180 to 220. Trust me I verified via temp gun in my driveway after a long drive. It's a lack of air flow because on a day to day basis my car just sits at stop lights. Even late night a lot of the lights are still a good 5 minutes. By time I get to the highway (which takes a good 20 to 30 minutes driving across town) my car does cool down to about 200 at highway speeds.

I'm enjoying your post on Corvette Forum. Thank you for this. It's why I am leaning towards just trying the 160. I know most NHRA Stock Elminator guys either run 160 or even lower such as 140 or no thermo at all. But as you said in your post on the Corvette Forum, they often have really advanced timing (I've been told some guys in the 20s and 30s) and aren't street cars. But even with 6* BTC some head cooling should help.
I would like to get an Oil Temp gauge wired in. I'm not an expert but I am going to bet that even at 160* on the highway, my Oil Temp is probably going to be closer to 180* or 200*? Is that what you have seen?

Thank you for this.

 

I have verified via temp gun. There really isn't a cooling issue. It's just the area I live in is very suburban with a lot of subdivisions and gated communities. On the main roads, many of the lights are very long (often 5 to 10 minutes) some times it takes 2 or 3 lights to get though a light (even on Sundays) that my car quickly warms up to 220 sitting in traffic. However, by the time I get highway and start highway driving it cools down to 200. It use to cool down to 180. So that's why I think the thermo is opening later. It often takes me 20 to 30 minutes from my house to get to the highway. It's all low speed suburban driving with long lights. So my car heats up fast.
When I drive the car late at night/early in the morning, when it gets up to temp. It gets up to 200 now rather than 180. Verified with heat gun.

 

Thank you for this post! I've used both my Temp Gauge (which is fairly new, a good 7 years old) and TurnerPro as well as a temp gun to verify temps. It used to open at 180, now it clearly opens later.

Part of the problem with my fan. Is I have the 85-86 year TPI with single fan. This forum insisted my car had to have a fan switch (years ago when my fan wasn't coming on) and that I must have aftermarket heads and that's why no fan switch. No they are the stock 58cc heads. The 85-86 TPI cars simply don't have a place for a fan switch (or they do but you have to remove the Cylinder head to remove the plug). I believe the fan only originally came on via stock ECM. When I replaced the ECM (after it died) is when I started having issues with my fan. I got it to come on via Fan Controller and it comes on at about 220. (Maybe 215).

Before anyone says anything, even the 1986 GM Service Manual shows that the 86 TPI cars do not have a fan switch. The fan is supposed to come on just via ECM.I think originally it came on at 230.

That being said, I'm removing my fan controller and just going to install a manual toggle switch so I can turn the fan on as needed. It's what a lot guys I know who drag race do. Too many variables and headaches other wise. Just a simple switch and it turns on at will.
I appreciate this post. Very well thought and I like the data you put into it.

I know another thing I am going to do, is get one of Tuned Performances' Custom Proms for the car. I did get a chip from PNC of NC but I have never been fully happy with it. It seems like it just makes my 700R4 shift harder. I'm going to tell him of what thermo I use for the tune.

 

You're welcome

No worries
The 383 stroker TPI mentioned in early post also had a manual switch to bypass ECM. I mostly used it at the track after hard acceleration. It only controlled 2nd fan. The '7730 with $8D & S_AUJP was modified to controlled both fans. Worked flawlessly. The '7165 with upgraded $6E and CSI delete would work great IMO.

I also figured you probably had single fan. The whole point of my post was to point out the importance of matching fan on/off setting and thermostat so CT stay within the range you want.

Yes to @Tuned Performance

 

Interesting you mentioned that. I use to put my 3rd Gens to "spring datalogging rides" every year with TunerPro. You would not believe the amount of stuff I would find just analysing the graphs, but barely showed symptoms. Failing alternator, bad MAF, bad 02 sensor, bad VSS, bad gas, bad thermostat, failing knock sensor, DTC codes without SES light on, etc..

It was like an annual visit to the doctor!!!

Peace

 

It's the one thing I wish I know 13 years ago when I brought this car, that this forum thought me a few years ago. I got one of those adapter cables for my Laptop and learned to use. It's been a huge headache relief and has made working on my car so much easier.

 

So true! TPIs are not very advanced technology but they are sensitive and any little glitch can cause bad symptoms. Then you get the usual parts cannon crowd cheering!

 

I haven't run a car with a 160 stat...that also had an oil temp gauge. I DID have an F-bod that I ran a 160 stat in (and NO stat, for a while) and I sold that car w/200k on it, still ran like new -to speak to longevity.
My current car (a '92 'Vette) and my previous car ('06 'Vette) both have oil temp gauges, both eventually get to higher oil temps than water temps. The oil takes longer to heat up, but given time and a load, it gets hotter than water. The 06 had an (stock) oil cooler so wouldn't get more than 10-15 degrees higher than water temps in typical highway driving....the '92 does not have an oil cooler and oil can get as high as 220 hwy, while coolant is at ~190-195 or so. Variations on that depend on conditions. At the road track, both cars would drive oil temps up to ~270-280 or so, in minutes and temps don't climb any higher than that. At the same time, coolant would be 200? 205? Ish?
This^ would be Max effort driving on 90+ degree days. One track day was 105 and numbers were about the same.

I would confidently predict that if I had a 160 stat in my current car and did the same driving routine, I'd see ~170-180 coolant temps combined with oil temps seen above, in similar conditions.
HTH.

 

Thank you for this! I think my oil pressure sender is on it's way out (I'm 99% sure it's the original and it's jumping all over the place until it's warm) so I was going to replace it anyway. Might as well install an oil temp gauge in there while there is room. Get two birds stoned at once.
There isn't a ton of info on classracer or Yellowbullet about thermostats. But a guy on Yellowbullet on a thread from 15 or so years ago, did comment that he liked to enter the waterbox around 150 or so. Stage at 160 and cross the finish in the 1/4 mile around 180*. Sounds like a 160 or so thermo to me. Don't know what car he had or what ETs/MPH he is running.
It's why I am leaning towards using that Edelbrock 160* I got for free. The guy that gave it too me said he ran 160* in his old street and strip 2nd Gen F-body. He was going to build it again and but sold it. Now he just has two dedicated drag cars with no thermo and chiller lines to cool them down between runs. (One dedicated bracket car and one stock eliminator car).

I don't think I'm super worried about Oil and condensation. As you mentioned in your thread on Corvetteforum, modern oils are so much better than they were in the 60s-80s. I run Mobil 1 0w-40 European Formula, both for the slightly higher zinc and I like the bearings getting oil instantly. I've ran this oil for a good 5 or 6 years now in the car. I change it every 3 months like clockwork.

 

No truer words have been said. They are very sensitive. I love the TPI, I hope a bigger aftermarket for it returns one day. But they are very sensitive to every little change or adjustment.

 

While we are talking about track and temps

Here's log from a road circuit track I did with a 2018 Camaro SS M6 1LE. It has engine, transmission and rear end coolers. It's the LT1 not LS. No clue what the thermostat specs are has it is probably ECM controlled anyway. That was early summer so around 70* ambient air. During hot summer sessions I get some CT highs in 230s but engine oil is always the same, around 250* max. It's a short track with lots of corner so we only reach 116-118 mph on back stretch. The fun part was the front tires at 265* temperature coming off a 30 minute chase style session with a Mustang Shelby GT350R... He had to box before me, his tires were just shredding lol.

Note: It's a wet sum system. We do run Mobil1 0W40 Supercar with extra quart for track session. We could also run 0W50. Car reaches 1.4G in certain corners. Just to keep in mind if you ever take it to road circuit, running thicker oil and adding some oil helps, but there is also the dry sump system options.

 

Just got back from a Salt Lake City; a 30 minute drive at 80 mph....

 

I have a 195f thermostat. Tried to stage the car at 170f, was about 205f at the end of the 1/4 mile and got up to 230f on the return road waiting for some lady to finish driving up it backwards in her giant Audi suv. My second fan never came on, I plan on installing a manual override for it for situations like that but at no point did I ever actually need it.

 

This is why I am planning on installing a toggle switch. Just turn it on as soon as I cross the finish. Last time I made a 1/4 mile pass a long time ago, mine had similar numbers to you. That was with the stock 195.

 

Man, the Corvettes are spoiled with the built in oil temp sensors. What thermo are you running, 180?

 

Yep. 180 is stock for the LT1.

Yep, the stock gauge is nice. Corvettes are my first car with that feature and it's been interesting seeing and playing with the conditions to affect oil temps. Based on those observations, I'd like to (someday) build an oil cooling system with a water-to-oil exchanger (like the one on the L98 between the filter and block), but rather than sharing that heated water with the cooling loop, I'd run that water through it's own radiator. That would require an electric circulating pump, and that is what makes this whole idea totally wicked; The electric pump could/would be controlled by an oil temp switch. You'd essentially have thermostatically controlled oil temp, w/o the complex plumbing required to port pressurized oil to various places to manage the temps. The thing electric water pump would likely never run in the winter....in the summer you could feasibly hold the oil temps down to whatever. Whatever you want to, I'd think.