Making Power with engine temp?
 

Ive heard all kinds of reasons to run your engine cold. Same goes for running a t-stat and running at 160 degrees, people say building heat, makes power. Some people run no t-stat, some people swear you need one. Dyno shop told me to run 140 t-stat. Some say its bad for the engine to run cold ALL the time........ WHAT PROS AND CONS ARE THERE RUNNING ENGINE COLD COMPARED TO RUNNING IT AT 140 DEGREES ??? Lets see if we can get a final answer on all this. Does it depend on your specific set up?

Blower motors, no stat. Keeps them running cooler, for detonation purposes.

More important than water temp, is oil temp in my opinion. Problem with no stats is sometimes you cant get oil temp, because the block being cold, combined with the oil cooler, wont let the oil get up to temp. Thats where oil t-stats come into play.

If it were mine, a N/A engine, 140* water temps, and good oil temps is what i'd shoot for. Water psi relief valves in the system also to keep water psi under control...

Im sure the experts will be of more help..

Final answer....yes

One of the biggest problems with running cold water temps is condensation building in the oil. That is why an oil thermostat is so important. I run an open crossover and never see anything over 110º water temp, but always run 215º oil temps. I am a touch over 10:1 compression N/A so controlling detonation is a big factor in my decision to not run a thermostat.

I dont know if it will make more power running colder, but it will allow a bit more timing and compression/boost, so that will boost power a little.

Well, just put stats in to get alittle engine temp.( Havent run them yet though, too cold out still) When I run them and the water pressure is above 25 lbs at WOT, I will put pressure relief valves in. Now, where do I plumb them in? I will post an engine pic if it helps. There will also be a 1.5 inch aluminum spacer under the water neck with 3 threaded port holes that I can use if needed.

Reading Philm's post, these are 10:1 comp 572 CI engines. would 140 be too hot? There also no oil temp gauges. Could I use one of those temp guns to check oil temp at the oil filter?

I am currently in this exact position. Fresh rebuilt 454 Mag with a Procharger, crossover, no thermostat, engine temp does not get above 100*.......oil temp is obviously not getting high enough because I am getting condensation in the oil.............it was suggested I take the oil cooler out of the equation....??? Anybody see a problem with that?

I run cold west coast Pacific Ocean water.....:coolcowboy:

PS. I use a temp gun to shoot water and oil temps, works well, take readings from oil filter as well as pan.....

Kreed:

Looking at your Avatar I will assume those are your engines?
If they have aluminum heads and you are running in salt water, corrosion will be your biggest problem without freshwater cooling.
I would suggest for longevity and durability, add freshwater cooling on the engine ( you can use nice remote stringer mount coolers)and put in a 143 degree stat and some antifreeze and your cooling temperatures will not be a problem. Your water temps will run at about 160-170 degrees which is perfect for combustion efficiency and getting rid of condensation in the oil and engine. Properly cool your oil and keep those temps between 180 -230 degrees and your engines should love you for many hours.

Best Regards,
Ray @ Raylar

Fog,
The oil theromsat is best way to build oil temp. It restricts the oil flow to allow the oil temp to build to the 215-220 degree level that cooks off the water. There are numerous boaters including myself that show 100 degree or no water temp...no issues.
Ben

Besides removing water from the oil, are there any other benifits to running a hotter(180 to 220) oil temp?

Thanks Ray. It does live in fresh water, but will go in salt on occasion. Im concerned that now that it has t-stats, water pressure will be to high, and Ive never installed relief valves. So Im wondering what is the easiest way to plumb them.

Thanks for the info.... I have been looking at oil thermostats, for the cost and time to install I wondered if just by-passing the oil cooler might do the trick?

Sorry about the thread hijack Kreed, it was just that your initial question was foremost in my mind right now......I am trying to answer similar questions to yours...:D

No problem!

[QUOTE=FogduckerIII;3361839]Thanks for the info.... I have been looking at oil thermostats, for the cost and time to install I wondered if just by-passing the oil cooler might do the trick?

If you can size the oil cooler accurately, you should be able to eliminate the oil cooler. I would say that if you can hold your typical WOT run to under 240 degrees (short period), you are good. It sounds like your current oil cooler may to be big. Big is good only if you have a oil thermostat.

[QUOTE=BenPerfected;3361976]Stock Mercruiser oil cooler......I think I will try with it by-passed, I will not remove it, just the lines, if the temps are not right I can always hook it back up and go the oil thermostat route.......friggin boats......:coolcowboy:

I'm slowly working up to trying to get my engines to run at a stable 180F water temp, a little bit at a time.

Even though as some say here oil temp is most important, seems to me that aiming for 210 - 220 oil temp but running at 160 or less water temp is a contrast in efficiency. One is trying to fight the other.

The closer you can get them both to where they really want to be, that being closer to each other but still running in an efficient temp zone for cooling and lubrication, the happier the engine will be. And, its easier to control each temp if closer to the other.

I can't help but cringe a bit seeing my engines running at over 5000rpm with only 140F water temp. Cylinder wall temps surely aren't as warm as they need to be when surrounded by a waterjacket to promote good long term piston ring wear. Not to mention valve guides, or hot valves closing on super cooled valve seats etc.

Hence my personal goal to see a stable 170 to 180F with 140F thermostats and a few 1/8" bypass holes in them.

Maybe I'm talking out my azz. But its what makes logical sense to me based on experience outside the marine world. Only time will tell if I'm really an idiot or not :D

I have 540s with alu heads,no t stat water temp 120 max oil temp 190 after a hard run,oil temp is key for wear cool water temp helps with detionation when running high comp,cool air will make more power but that is hard in a boat seeing we boat in warm weather,4 seasons no problems want to add motor is closed cooled my 2 cents

Rookie,
You are not likely an idiot, but you might be missing the point on oil temp's. I am from the school that says in a HP marine application that parts like the valve train are going to wear out well before the rings. Many believe the water temp isn't a big deal at anywhere between 100 -160. To remove the water from condensation and maybe small internal leaks out of the oil, you need a way to get the oil temp to 212+ on a regular basis. IMO, how you are you going to manage the oil temp is more important that the water temp. Even Mercury used a oil temp thermostat on the 500HP.

Actually no benefit quite the opposite in fact . On my truck I feel safe at oil temps at 180 but getting to 220 I start to ease up on the throttle If I just can high temps just kills the additives first. But keeping the engine otherwise hot as possible (water) makes more power if you can control it.
Smokey Yunick tried all his life to control high temps and run on the brink of detonation.. his Hot Vapor Engines was something to think about...
http://www.legendarycollectorcars.co...clusive-video/

Well, I'll throw in my .02. Living in the land of NASCAR, I talk to engine guys all the time, and some of the best know names are here. They run (IMO) pretty much like we do - at or near full load for hours - on high compression, carbed engines.

None of the guys I've asked run coolant temps under190 or so, and several things I've read or beeen told indicate they make best power at 210. They of course want oil temps at about the same. These are small blocks turning out 850hp for hours at a time.

So, I agree with Rookie: if you are not using forced induction and low temps for detonation control, you should be in the 160+ range. I run 170 at sustained WOT, oil temps peak ~220 (slightly high IMO). No issues, and I've noticed a bonus of decreased fuel burn.

I've heard Merc used the 143 stats to decrease salt damage in salt/brackish water, so perhaps that is where the 140 came from.

+1
As a sidenote;
Well try to heat/boil saltwater and look at the sides of the kettle after that.. you don´t need to be much of a genius to figure out why raw water cooled engines has low T-stats...

Maybe apollard and I run in the same circles :)

Since apparently today I'm throwing my opinions out there, I don't think controlling detonation with lower water temps is the greatest idea either.

Shouldn't detonation be controlled by effective ignition timing / air-fuel ratio (AFR) and compression (combustion pressure)? In rarer instances perhaps, also air intake temp and fuel burn rate (octane) too of course.

If a lower engine temp is needed to control detonation, seems to me it has too much or not enough of one of the above.

Ok, I'll sneak outta here now in case I just started a load of trouble. Just my opinion guys, don't let me pizz any of you off :D

ALL helpful info, so now, will running an engine at 150 water temp and a 180 to 210 oil temp as opposed to having no t-stat change carb jetting? Another words, will an engine run rich or lean depending on engine temp? Depends on air temp of coarse, but will engine temp affect it?

Maybe - Mooresville is full of us know-it-alls :drink:

FWIW, I'm with you on the detonation issue, but have zero experience with blown motors, and don't know any builders of blown moters, so it might be different. Engines don't always appear logical, at least until we figure them out.:popcorn:

Yes, it should - more of the fuel will be in vapor form and therefore burned. Vapor burns, liquid gas drops do not (or at least burn poorly). If jetted to run at say 100F, and you increase temp to 160F, you should go rich. Whether it would be enough to cause an issue depends on how bad your fuel distribution was at the lower temp. I had to drop one jet size on my secondaries when I started running 170F - but my jetting was slightly fat before (but not a full jet IMO)

Theres alot of theories here. Some good ones. However, sometimes theories, do not give real world results.

The beauty of this day and age, with the internet, is that one can save himself lots of time and aggravation, by not trying to re-invent the wheel here. It has been done, by people like merc, and many other successful offshore engine builders.

Controlling detonation can be done alot of ways. Its all about finding that happy median. Every application is different. The key to keeping a marine engine alive, is not only controlling detonation under most circumstances, but yet almost all circumstances. You want a good margin of safety, whether it be lower compression, less timing, aluminum heads, rich jetting, cooler water temps, etc. Car guys can get away with being close to that edge sometimes. Us however, put tremendous loads on our engines, get crappy gas at marina's, etc. One hard run while thinking you got 93 octane, when you really got 89-90, can cost you your engine.

One guy stated that he feels controlling detonation by means of water temp doesnt sound right to him. To me, trying to make HP by increasing water temps, doesnt sound right to me. If horsepower is what you seek, theres better ways to do it.

Bottom line, my thoughts are to stick with what works. Think about this, you got some stainless headers. You are out running hard, t-stat's wide open, sending 190-200* water to your headers. You shut it down to get gas. Your headers have 200* water cooking in them. Now, you fire it back up, and t-stats are closed, trying to build engine heat. In the meantime you are bypassing and sending 65* cold lakewater into your piping hot headers. That cant be good. You can put your hand on my headers after a hard run. 200* water temps, and those headers are gonna be HOT, along with the rest of the block. :party-smiley-004:

For me personally, its about engine health and longevity and not horsepower being the reason I'd like to see my engines run warmer.

I think someone earlier brought up a good point though. If Merc lowered the engine water temp by using 140 thermostats due to the salt remnants for those running in brackish or ocean water, that may explain why Merc wanted the water temp down.

Perhaps my little experiment with warmer water temps is only relative because I only run in fresh water on Lake Norman.

The older I get, the more I find out I know less... Maybe one day I'll learn to stop trying to reinvent the wheel, but it sure can be fun. And sometimes, you even discover something new :D

The key to engine longevity in a marine performance motor, is more in the valvetrain than anything. For example, a stock 310HP 454 may go 1000 hours, before needing a top end job. Where as a 450HP 454, might go 300-350 hours before it needs a top end job. Mainly because of the larger cam, stiffer valvesprings, lifter wear, etc in the higher power engine. The bottom ends, pistons, rings, bearings, etc rarely wear out prematurely.

Remember the old days, before cars had all this computer stuff.....Those hot 90 degree summer days when the temp would creep up on you, pinging was always a issue, even on a low compression smog V8 with a very conservative timing advance. It was the heat retained in the cylinder heads and pistons. Therefore guys were running bigger radiators, fans, cooler thermostats, etc. Hotter the engine got, more likelyhood of pinging. Cool it down, it was good to go.

The reason you can run a little more boost in a blower motor with aluminum heads over iron heads, given the same compression, timing, and boost psi. Because the aluminum head dissapates the combustion chamber heat better than the cast iron does. Same goes for water. Cooler water flowing thru the heads, around the cylinders, will help keep them from lighting that fire when you dont want it too..

I am no engine builder by any means. Just going off information i have collected from others over the years....Great topic though...Would love to hear some of the pro's insight on this...

It would be interesting to hear what Eddie Young or Ray, or other pros had to say- always up for learning something.

Yea, I agree, everyone has a different theory. I guess I need to figure out what works best for my combo. At the end of all this, I guess Im going with a 140 stat. Gonna start the engines, check water pressure, and then watch oil temp once the boat goes in the water. Is 25-30 Lbs water pressure pretty much max at WOT before I install pressure relief valves?

Well talk about running in the same circles. I worked for NASCAR during the good times. During motor development you try to make the motor last just as long as its needed. Its Like drag raing. If it blows up the last foot of the 1/4 mile thats fine. Everything is right on the edge. They fill thier blocks with concrete. Everything gets torn down and redone down the road or with drag racing at the track. Plus the things thier in house dynos are seeing daily and what we can see on our motors is not even close.
So play it on the safe side. Run as cool as you can but run an oil t stat to burn off the milkshake and keep your oil flowing. Most oil stats are 140 degree if I remember correctly.

No doubt you all could be right. Normally I try to play down my past experience in motorsport and race engines, especially here on the OSO forum. 25+ years of doing it for a living in other circles doesn't mean I know anything about the marine side, and I'm fully aware of that.

I guess I'm just struggling with how different it really is with water temps compared to other high performance engines. Based on this thread topic, apparently I'm not the only one. Its something that struck me as very odd from the first moment I started playing with higher performance boats. And to be fair, that was very recently.

Please don't think I believe what I'm saying is correct, or that I'm right and others are wrong. I'm looking at it like this is a topic I'm playing with personally on my own boat engines. Time will tell if past experience in other arena's makes sense in my boat, or if I learn WHY these engines are being built to run so cold.

I'm struggling to see why good engine builders want these engines running so cold is all, unless its purely as a safety margin for potentially idiot customers.

BTW, I really enjoy the ability to be able to come on here and discuss differing viewpoints as respcting adults. It makes me keep coming back here almost every day.

I just couldn't keep my big mouth shut in this thread, because its a personal project of mine right now. Treat me like the new guy asking the stupid questions :D

When I first started boating back in 99 I tried to apply all the things I was learning in racing to my boat and shiyat kept coming apart and not having expected results. I met a guy who does motors for the Navy and got to know him. A lot of it was so diff I had to change my thinking. The cleareances etc. were not what I expected.
I use him and him only to this day.
This place is great for knowledge and the people on here are extremely helpful