160-degree thermostat too cold?

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MOPARoldtimer

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My 408 has a 10.5:1 C.R. with ported "J" heads and has been detonating pretty badly on 91 octane, so I thought I'd try a cooler thermostat. I bought a 160-degree t-stat, and when I removed the old one I noticed that the engine builder had installed a 195-degree unit. What will be the effect of installing the 160-degree unit? Is it too cold? If so, what is the minimum temperature t-state you would consider using?
 
What temp does the engine run at now? A 160 degree stat won't necessarily make it run cooler. A 195 stat is what most cars came with from the factory.

What do you have your timing set at?
 
Thermostats only make sure an engine doesn't run colder than whatever value it is.

If your cooling system is strained it will run at whatever temperature it can.
 
Changing your thermostat will do absolutely nothing to solve your problem. Put the 195 back in.

Your answer will be found with timing, tuning or better gas.
 
You could try a cold can, or water injection, but I think you need better gas, try a different station.
 
10.5 with J heads and no quench. What were you thinking when you built that? You been readin too many forum genius threads. You cannot run that much compression with iron heads and no quench. You're going to have to either limit the timing curve so badly that it runs like sheeot or run race gas. Take your pick.
 
RustyRatRod said:
10.5 with J heads and no quench. What were you thinking when you built that? You been readin too many forum genius threads. You cannot run that much compression with iron heads and no quench. You're going to have to either limit the timing curve so badly that it runs like sheeot or run race gas. Take your pick.
Click to expand...
this....I agree with
 
1968FormulaS340 said:
Changing your thermostat will do absolutely nothing to solve your problem. Put the 195 back in.

Your answer will be found with timing, tuning or better gas.
Click to expand...

RustyRatRod said:
You're going to have to either limit the timing curve so badly that it runs like sheeot or run race gas. Take your pick.
Click to expand...

To the OP,

What is your current timing curve?

Are you using vaccum advance?

What is your base and total timing?

Is 91 premium by you?

=====

i've always run a 180 which is also what Be Cool Recommends in all of their systems.
 
RustyRatRod said:
10.5 with J heads and no quench. What were you thinking when you built that? You been readin too many forum genius threads. You cannot run that much compression with iron heads and no quench. You're going to have to either limit the timing curve so badly that it runs like sheeot or run race gas. Take your pick.
Click to expand...

X3 on above. On the 160 degree thermostat, I used to run them all the time for decades. Your heater will not put out air as warm as a 195 degree thermostat. And no, a 160 degree thermostat will not fix detonation or a marginal cooling system.
 
i think it is Snow Performace that does the water methanol injection. they have a plate that will fit right under your carb. then you can put on of there tanks in the trunk and mount the pump between or use you windsheild washer tank and mount the pump between that and the motor. the water will keep the EGT's down and the methanol will boots your octane level. and what is really cool you can use the blue windsheild wiper fulid from the store. along with a little tuning and it should run really good.
 
66fs said:
X3 on above. On the 160 degree thermostat, I used to run them all the time for decades. Your heater will not put out air as warm as a 195 degree thermostat. And no, a 160 degree thermostat will not fix detonation or a marginal cooling system.
Click to expand...

What's a heater??:happy3:

Snow Performance is one manufaturer making water/meth injection.

Let's find out the timing and carb situation first. I have a feeling we have a too much timeing and/or WAY too fast of a curve issue here.
 
rlevs said:
i think it is Snow Performace that does the water methanol injection. they have a plate that will fit right under your carb. then you can put on of there tanks in the trunk and mount the pump between or use you windsheild washer tank and mount the pump between that and the motor. the water will keep the EGT's down and the methanol will boots your octane level. and what is really cool you can use the blue windsheild wiper fulid from the store. along with a little tuning and it should run really good.
Click to expand...

There are a lot of Meth Injection kits out there. From my understanding, not some sales pitch, injecting Meth does basically nothing unless the air charge is heated up via pressurizing by forced induction. What the Meth/water/windshield washer fluid is doing is cooling the condensed air/fuel charge off. The cooler the charge, less likely you are to detonate. Spoke to a local fellow a while back that believed the sales hype.....bought a Meth Injection kit, only to have the death rattle continue. If you have to much cylinder pressure it is going to rattle unless you soften the tune a lot. Meth injection, for forced induction guys is used as a replacement/or to supplement an inter-cooler...

http://www.alkycontrol.com/
http://www.alcoholinjectionsystems.com/
http://www.snowperformance.net/

Are just a few. Google DIY water injection and you will find low buck ways to do it. Perhaps I should back off on the above statement a bit....I just have a very hard time buying that by attempting to cool off an ambient air charge it will be like increasing the octane 10 points or what ever the claim is. Would definitely not be the first time I am wrong....won't be the last....
 
Seems like I remember hearing that companies that re-flash auto ECMs for more performance, recommend a cooler thermostat, probably because of the more aggressive advance curve. This might be considered a "crutch" but I think it may help, if only a little......and like was stated, only if the cooling system if stout enough to bring down the coolant temp to 160, which is a bit doubtful actually, since it's a small block cooling system trying to cool big cubic inches.

I think it's worth a try, if only to help a little bit, plus it's interesting to see if it does.
 
MOPARoldtimer said:
My 408 has a 10.5:1 C.R. with ported "J" heads and has been detonating pretty badly on 91 octane, so I thought I'd try a cooler thermostat. I bought a 160-degree t-stat, and when I removed the old one I noticed that the engine builder had installed a 195-degree unit. What will be the effect of installing the 160-degree unit? Is it too cold? If so, what is the minimum temperature t-state you would consider using?
Click to expand...

A cooler thermostat may only mask an underlying overheating problem, and may lead to less efficient combustion as too much energy is being expelled via the radiator rather than the rear wheels. The purpose of an internal combustion engine, after all, is to turn heat into motion.

I had a similar problem with my slant-6 (compression 10.3:1) but found a solution in an aluminium radiator, engine-oil radiator and, most of all, a distributor from Hemi Performance (Australia) with an optimal ignition curve. The fact that I have easy access to 100 octane petrol from just across the border also helps. Now I have no pre-ignition, the engine runs cooler and the fuel economy is slightly better as well ; a consideration when a liter of 100 cost 203 centimes (about $ 8.50 a US gallon).
 
roccodart440 said:
To the OP,

What is your current timing curve?

Are you using vaccum advance?

What is your base and total timing?

Is 91 premium by you?
Click to expand...

^This.

If you're getting pinging at part throttle under a heavy load, you'll probably be able to tune it out.

We're going to need more information. When does it ping? Is it at WOT? Part throttle? Be as specific as you can.
 
You should be able to run 10.5 on 91, 93 would be better. Whats more important is what your Cranking PSI is, I run 11.25cr on a 360 with J's at 205 cranking psi, i run 20 initial with 30 total, a lot of little things will make it work like a Blocked heat crossover in the intake don't just use the paper felpros they will burn through you will need to add metal over the crossover with these gaskets, valley baffle will also help a bit. also a two or 3 step colder plug than the regular 340 hp plug. 180 t-stat with a good cooling system, no electric fan a good clutch fan. phenolic spacer under carb, electric pump (mechanical adds heat to fuel), insulated fuel lines. fresh air to carb will do a lot. Also its obvious but a lighter car with a hi stall and deep gears will make life easier in my case the demon weights a heavy 3,475 with me in it, 4,400 9.5" stall converter, 3.55. So its possible to run hi compression on 93 but you have to plan for it from the start, take your cranking psi and let us know what it is, if its up around 200 your cam is small and the easiest thing to make it live if the things i mentioned above don't work is to slide in a bigger cam. 408's can take a very big cam and still be completely streetable i wouldn't be afraid of running something like a 570 580 lift with 254 to 258 @.050 intake size cam.
 

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