adam c

iTrader: (2)

I have not started a new thread here for a while, so I thought I would stir things up a little and see what peoples thoughts are on a "new?? " issue.

If I am out on the open road, my car runs at 180 degrees. Unless it is a very hot day, or I am in slow traffic, 180 is where it's at.

But, at 180, it doesn't perform as well as it does at 190 or more. I like that the car runs cool, but I also like the peformance that I get at 190. So, do I change to a 190 t-stat, or live with it as is, or do something else?

I'm curious to hear what the opinions are on this one.

Thanks, Adam

COsborne

Im pretty sure it just "feels" faster at that temp. That goes against physics and stuff. Go to a dragstrip and see how it does.

ijneb

Mine feels the same way, but I think it has something to do with limp mode or something.
In your case maybe being at 190+ makes it burn more fuel or something?

adam c

iTrader: (2)

I'm thinking that the ecu is "warm up/protect mode", and won't allow the car to use full power at 180 degrees. Seems like I get full power at 190 or more.

spurvo

Uh-uh. I recall dyno charts somewhere that showed measurable power gains at 190F, enough to warrant investigation. If the intake charge were that hot, of course performance would suffer HUGELY, but combustion chamber temp might be more optimal, and moreso I'd bet intake runners and the ports themselves likely like a little better temp, as this should help to reduce the layer of unburned, non-moving intake charge along the walls (unless 'yall have ported it, and even then, laminar flow and all...).

I've kinda thought about a 190F T-stat, especially as I keep all over the temp gauge and don't let the engine heat up past 200F or so. But I'm not a performance crazed kinda guy, and I figure the lower the temp, the better for the water seals. And I'll take longevity over a little performance gain. Others will most likely differ...

Gonna get the po-man's cold intake in there one of these days, adam. I swear it. Lovin' the van though! Only 22 vacuum connection, all silicone now! HAHAHAHAHA!!!

Kento

Need a little more explanation of your driving at those temps.

If you're just cruising on the open road, and then getting on the throttle to drive up the temps to 190, then the reason your performance is better is because you've heated up the exhaust side of the turbo to its optimum operating range. Up to a certain point, the hotter the exhaust area of the turbo assembly gets, the more effficient it is, because the exhaust gases aren't losing so much of their heat to the metals in the exhaust tract (exhaust ports, manifold, exhaust turbine, etc.). Less heat loss = more energy to drive the turbine. If you're cruising on the highway, then suddenly decide to dip into the boost, the turbos won't respond as well, because a lot of that exhaust heat energy is lost.

If you're just saying that your car runs better at 190 regardless, then that I can't explain. Perhaps some mechanical tolerance somewhere that's a bit too tight.

adam c

iTrader: (2)

Spurvo, I also pay very close attention to the temp gauge. Anything over 200 isn't allowed. I wonder if Mazda makes a 185-190 thermostat that would fit this car. By the way, that's the "Cheap Bastard Intake". Try it, you'll like it!!

Kento, If I am at 180 on the highway, a few "boosts" won't increase the temp. My cooling system seems to work very well. Seems like I have to get it up to 190 before getting on the highway. Then it screams.

Kento

I'm not talking about a "few boosts". I'm talking about some continuous time on boost under heavy throttle to get the turbo's exhaust assembly up to optimum operating temperature. This is probably why spurvo saw some dyno charts that showed power gains at 190 instead of 180-- it takes multiple runs to get the turbos fully heated up.

ttb

200 F ? that's only 93 C. your car doesn't get over 93 C???!!! tell me your secret.

adam c

iTrader: (2)

ttb, I have the "fan Mod" on my car. If I know I am going to be stuck in traffic, I just flip it on. It brings the temps down to 180 pretty quickly....unless its 110 degrees outside.

http://www.scuderiaciriani.com/rx7/fan_mod.html

Kento, It seems that my car runs well when the coolant temp is 190 or more. Of course, that means the exhaust temp will be higher too. I will do a test to see if the engine runs better after some extended boost, with water temps still at 180.

The engine operates in "protect" mode up to a certain point. Does anyone know what that point is? Is it a sensor that measures coolant temps? Exhaust temps? Something else?