Running hot.. restrictive exhaust?

[VincentVega]

I'm trying to track down a hot running issue with my 3.6 SC. On the street the temp never gets past 210. On track I reach ~240 after 10-12 minutes.

I have a front mount B&B cooler, with room behind for airflow, and just added a Modine in series in the fender. This helped a little, but I still had to cut my sessions short at the last DE.

Last event I checked temps at the cooler with an IR thermometer. At the fender cooler the inlet was ~240, outlet 235. I expected a bigger delta from inlet to outlet as the I removed the turn signal for airflow.

I checked the surface of the front mount, ~235 on the left and only ~150 on the right side. Inlet and outlet are on the left. Could the cooler be clogged?

I just added a shroud around the fender cooler and cut out some of the headlight bucket, but still need to test.

The above tells me the thermostat is working, as the lines and the coolers get hot. Air/fuel was checked on a dyno and is fine. Could timing be off?

Last thing I can think of is the exhaust. I have stock early 911 heat exchangers and a 2 in 1 out muffler. I am grasping here, but as this system is restrictive, is it causing my hot running condition? I dont want to throw $$ at the problem and hope a new exhaust will fix it, any data on this?

Thanks for any ideas

[fintstone]

Maybe a bit too lean.

[Bill Verburg]

With that much cooling you should be running ~180&degF almost all of the time on the street.

If you are running closer to 210 then something is wrong, rear fender well P/T valve, restriction in the lines or some such.

Yes, the early exhaust is far to restrictive and yes, it does need attention. It' probably not the issue here though.

[VincentVega]

Thanks guys.

The oil lines look fine, at least from the outside. I'll look into testing the thermostat.

Frustrating.

[ael911]

Check out what I went through with my thermostats.
Maybe it will help you out. The problem was the lower
oil pressure would not push enough oil through the
cooler up front.

oil temp question...

[bigchillcar]

does any part of the exhaust begin to glow at these temps?
ryan

[VincentVega]

Good question. Problem is the car only gets hot on the track, it's hard to test otherwise. I'll try.

[stlrj]

Too rich will not only make your exhaust manifolds glow but cause elevated head and oil temps. Bad news for valve guides and life of engine.

[bigchillcar]

you're not meaning 'too lean'..??

[jaydubya]

If you want to measure accurate inlet and outlet temps on your cooler(s), you need to do it while the car is at speed and under load. I did this in the past using a two-channel thermocouple wired back into the cockpit.

If your car is sitting still the coolers aren't getting any air and the inlet/outlet temps you record won't reflect the actual reduction that you are getting when moving.

[stlrj]

you're not meaning 'too lean'..??

Nope, too rich. Found out first hand about the glowing manifolds when I accidentally got my ignition cables crossed and the resulting rich mix made my cat glow red orange in no time.

Never had that happen running lean or 02 sensor lean.

You can Google what happens when running an air cooled general aviation engine rich of peak and what it does to head temps. I'm certain the same must happen to our air cooled wonders too.

Joe

[bigchillcar]

odd..i've been a pilot for many years..spent a decade flying professionally, but those were in learjets, so it's been a while since i spent much seat time in piston equipment. won't dispute your findings though if that's what you found.
ryan

[Steve Marshall]

Could be a kink in a cooling line? The 150 vs 235 on the front cooler doesn't add up.