Matt, one interesting way would be noting the oil temps on like runs (I would do at leat 15 minutes). As we know, our oil is cooled via the coolant... so the t-stat's impact might be seen here... It might be a neat and cheap way to keep oil temps down, as compared to an aftermkt oil cooler (all of which don't have t-stats, unfortunately).

 

The only way that I know of to empirically test the hypothesis (of 180 degree thermostats reducing octane requirement) is to do back-to-back tests with control and 180 degree cars. You would need exact duplicates to eliminate extraneous factors polluting your data set. The general consensus in the Corvette world is that the 180 degree thermostat is worth ~1 octane level (e.g. 93 octane requirement without the 180 degree thermostat equals 92 octane requirement with the 180 degree thermostat). I personally don't think that if Dr. O were to add a 180 degree thermostat to his present rig, he would be able to run the 91 octane pisswater and avoid timing retard.

 

but I'm hoping that a combination of things will keep the chemistry set at bay....

The IK24s (two ranges cooler than stock)
About a 75% water/25% Coolant with Water Wetter
180 Degree thermostat

Next step would be an oil cooler... Water injections... Bigger radiator (But I haven't seen one in the US, any one have a source?)

Matt

 

I am beginning to wonder if you are starting to wander into a cost-benefit consideration (cost of running higher octane fuel for the remaining life of your car versus the cost of the mods you would have to make to be able to run California's superior gasoline)?

 

$4.70 for 100 octane, <$3 for 91 octane. (right now about $2.75)

The plugs were about $42, and I just sold the relativly new IK22s, the thermostat is less than $40, and mine is an 02, and the Bently manual says change the coolant every 4 years... So I'm up! I do water wetter anyway....

I beat the crap out of my cars, and already did a Griffin radiator for my Mustang. So going above and beyond for cooling is just a good bit of insurance, and keeping the oil cool is the best way to keep a motor happy!

But really, I'm curious as to what it takes. How far can you go with power adders before you're chained to race gas!

I've already got a ported SC that I have to get off my a$$ to install, and I don't think it will give much more boost, but if it cuts down on air turbulence, it should keep air charge down a bit more.

But you're right, I'm almost at the end of the real cheap changes... Damn!

Matt

 

The real question will be if you can run your mods on say, 95 octane before the timing retard sets in - then the cost-benefit starts to become even more of a consideration because you are not at the $4.70/gal (it is really $2.00/gal ($4.70/gal - 2.70/gal of the pisswater you were going to buy anyway) decision point, but maybe $1.50 additional with blending.... Decisions, decisions, decisions....

 

and you then can only buy from a station that has the high grade to blend. I'm occationally really lazy, but I want my power!

Matt

 

The 76 station that you get your 100 octane at has a 91 octane pump right next to it - I was just there today with my Corvette doing a 95 blend. But I want the high detergent as well, so I have to go down the street to the Chevron station.... The things we do with our toys....

 

how does a 180 thermostat reduce the long term steady state temperature? won't it just open sooner? won't the coolant temperature settle to something higher than 180 anyway?

 

I know the stocker opens and closes to hoover around 190. This one should stay open more, circulating to maintain 180, or thereabouts... I haven't yet installed mine, and with temps in the 20's a few times this Winter, I'm not sure I ever will...

 

Much of that depends on cooling efficiency.
I went from 180 to 160º in my trucks years back. Operating temps with the vehicle in motion dropped in parallel with the thermostat drop. The important factor though was this:
In one of my trucks idle temps were different but both were lower than they were with the 180º.
The engines were very similar but unfortunately not identical. The thing I feel made the difference was that the cooler running motor ran an aftermarket radiator. Dimensionally the same as stock. Tube and fin count were even the same.

So really until there's data to support any theory we're all just bench racing.

 

we need a new buzzword: keyboard racing

it's been a long time since i took my engine class, but i remember that you need to get the engine oil hot enough to vaporize some bad things suspended in the oil (water?). so running the engine cooler than this all the time is bad news.

ideally you'd like to heat the oil up asap to this vaporization temperature, THEN if you want it cooler, ok. a variable temperature oil thermostat as part of a remote oil cooler system would be theoretically good, but i guess it has some practical/potential problems.

but don't race engines run much hotter than 180 anyway, so what's the point of the 180 for them?

 

Dr Obnxs,
Would there be a problem if i used the Denso iridiums with it's original gaps? What's the benefit in gapping them to .045"?

John

 

This is one of the reasons why I haven't gone with an aftmkt oil cooler. As I shared above, with none yet employing a control mechanism such as a t-stat, temps could get lower than desired...

Our stock heat exchanger works off of the coolant, so the t-stat is a factor... how much, I'm not sure. But, as Matt said earlier, a little here, and a little there can make a difference.

If all goes according to Hoyle, I'll remove my A/C after this upcoming Summer, and I feel that should help also with cooling... if a lower temp t-stat is being used.

 

On that note I'm remembering that ideal oil temps are in the 210º- 220º range.

 

On the Densos, The IK22s came at about 0.065 gap, and when I bought them, they came with a note saying I should re-gap them to stock, 0.45 or so, using wire gapping tools. I'd run the last set at 0.065 (what they came at) and it seemed fine..

But the IK24s came in at 0.025", and that just seemed too small. In reading some threads from 2003, I saw gaps listed from 0.035" to 0.080". I pretty much arbitrarily chose 0.045.... And it seems better, but not perfect.

With a 180 degree coolant thermostat, oil temps will be higher than that. (Oil temps are pretty much always higher than water temps). JLM made a cooler with a thermostat, and pretty much anyone that gets put on a car should have one... Unless it's a race car, and it's always run hard, hard, hard, and you're pretty much hot all the time.

Anyway, that's about it....

Matt

 

does this mean you still have detonation with the IK24s?

 

and I sent out my BiM-COM so someone could test a GTT IC, so I can't really look for timing retard.

Butt dyno says things are much better, but a couple times I thought I heard something, but it was so brief I couldn't really tell.

I'll wait until I get the real numbers to post a conclusion...

Otherwise, it's just keyboard racing!

Matt

 

Or, butt dynoing; or, opinions being expressed on NAM....

 

My M7 Thermostat has seen sub 30 degree 4am trips to sk00l with nary a fault code. That's about as cold as it gets in north-central Florida.

 

This thread is full of good information - thanks to the good doctor as the OP for providing excellent fodder for discussion.

If I may pose a hypothetical question:
All things held equal, which would have a greater effect in prevent timing retard?

1. Colder air entering the combustion chamber after going through the intercooler, or
2. More heat transferred away by the coolant system

I suppose what I'm wondering is, which will have a bigger impact in reducing timing retard: having a larger/more efficient intercooler, or the use of Water Wetter or Evans NPG+ coolant?

 

depends on what's causing the knock...
if it's just from things being too warm, any of the above will help.
if it's from a hot spot from carbon build up, probably none of the above will help.

One note on the Evens, I've been thinking about this one for a while, and it was encouraging to read of other successful use of it in other thread (admittedly on other cars). But to do it right, you really need to up the capacity of the radiator, as it has less "thermal mass". But I think it does a better job of taking heat away from the heads....

Matt

 

my guess is that changing the water temperature has much more of an effect because it has much greater thermal mass than the air entering the cylinder.

i'd also guess that cooling the intake air has more of an effect on power, since it increases the density of the air, rather than an effect on cooling.

 

Any 274°C the volume of air doubles -> with plus 27,4°C increase in intake temperature you loose 10% power.
With a reduction of 27,4°C you win 10% power.
It´s that simple ;-)

 

I decarbonized my combustion chambers and things got much, much better. With 100 degree temps, the ping wasn't totally removed, but it really is reduced by a couple orders of magnatude.... All my logging stuff is on loan to help with MSFITs troubleshooting, but it should be back tomorrow. Don't know when I'll get to measure timing under load, but this definantly helped me.

My car has 73000 miles on it, and I've been chasing this issue for quite a while. I think now that a lot of MCSs are getting up in miles, more and more of us could benefit from this.

Matt

ps, I started a thread about the decarbonization here: https://www.northamericanmotoring.co...ad.php?t=74535