I noticed that my car looses quite a bit of power during the afternoon track sessions, and it occurs within the latter end of a 20 minute session. I'm assuming it's due to the heat (it was about 100 degrees yesterday). My temperature gauge looked fine, so I'm assuming I'm not in danger of overheating my car.

The loss in power is only temporary, as I regain full power after 45 minutes of cooling down. What is this telling me? Do I need a larger radiator?

My engine is stock.

 

What I'm going to write is pure speculation without being able to witness what is happening first hand,, but here goes.

It sounds like this could be heat related detonation which the car is fighting by reducing timing advance. Your gauge staying in normal range is no guarranty that your temps are normal. I believe (going from memory to a time, far, far away) that my gauge would not move until water temps were WELL into the 240's.

If this is the case, I'm going to recommend an external oil cooler before a radiator. Then I'd make ducting to go from the opening in the nose of the car to the radiator perimeter, to make sure that air can't escape and go around the radiator to other places. Make the air that enters the nose go through the radiator.

If none of this works, then go for a radiator, but make a wise choice here.

We've done an awful lot of work to get our turbo 350Z race car's temps in line here in Florida for the longer duration runs, and it all comes down to oil cooling and air flow management.

Nick R.
See my car here:
http://www.ntechengineering.com/inde...ction=datemenu

 

Thanks for the input. Since I only do 20 minute DE sessions, I imagine that there would be many more people experiencing the loss in power at higher temps. Perhaps there's a lot more going on here...

In any case, I checked out a few oil coolers, and the Nismo, Stillen, and the one sold at ntech Engr come to mind. Prices are $615, $355, and $575 respectively. IIRC, the Nismo used to be around $1200, which I think was completely nuts. I've heard enough about Stillen customer service to steer clear. Jeez, the "must buy" list just gets longer and longer...

 

Your ambient temp was higher than most track day temps, and it will depend on what type of RPM you are keeping up, as well as the grade of oil used, and perhaps the fuel quality that you were using. Too bad you didn't go top off with 100 octane when it started, to see if that helped. But if it did, that would just be a temporary fix to your bigger problem, as I see it.

It could certainly be something else, but that is my best first idea.

 

After doing some research, I found that both the Stillen engine oil cooler and the Nismo package do not come with thermostats. If my car was a track-only car, I wouldn't care about the lack of thermostat as temperatures are going to be high no matter what. But, since this car is 95% daily driver, and driven on the freeways in the winter, I would imaging that I could run into problems if there wasn't a thermostat.

The Ntech Engineering unit comes with a thermostat. Does this mean that there is an oil bypass line? A bypass line would also allow the oil to heat up quicker in the winter, which is a nice advantage.

I used to ride an air cooled ducati that had a oil cooler. I had to cover the oil cooler when I rode in the winter, otherwise, my engine would run really rough...sometimes even shuting down on me at stoplights.

 

search for my posts on oil coolers. i haven't done it yet, but you can put the pieces together for much less than any of the kits, especially if you know someone who can make up the hoses. All you really need is the sandwich plate (with thermostat), the cooler (radiator, whatever), and the lines.

as nick said, the temp gauge (and this is every new car I know of) is a basically an idiot light in a the form of a gauge. the needle movement is damped so it shows 'normal' for a huge swing of temperatures. since i'm going FI and adding gauges anyway, i'm going to use the defi 'display' to show oil and water temps. there must be a cheaper way to get this info, but i don't of one that doesn't look, well, too rough for this car.

i'm just trying to find the right place to mount the oil radiator now - have to have room for the FMIC too

ahm

 

Wouldn't be easier to route a separate water line to the existing oil cooler ?

While in the pits, do you open your hood to help the cooling ?

 

yes, I open the hood to help cool the engine. If this wasn't my daily driver, I would have already cut out openings on top of the hood to allow air to pass through the engine bay. Dealing with engine cooling, thermostats, and the sorts is sort of over my head. Even as an engineer, I'm not comfortable with just slapping on a oil radiator and fittings without finding out what thermostat to use that allows oil to flow through the oil cooler when it's necessary. Ideally, if optimal temperatures aren't reached, the thermostat should not allow oil to be cooled, otherwise, I'd end up in a worse condition.

Last year, I saw the Corvette C6-R with the radiator setup allowing air to pass from the lower-front portion of the car to the top of the hood. Looks cool (and mighty costly...)

Kolia, didn't you used to drive a WRX on the track? Did you ever run into an overheating problem since it's turbo charged? How do you know if you're running too hot? Did the gauge needle climb on you suddently, or did you experience some loss in power?

My old Nissan Sentra had a water pump go out once while driving on the freeway. The first thing I noticed was the sudden loss in power. When I peered at my gauges, and noticed that the oil temp needle was climbing quite rapidly. I pulled over, and only then did I notice steam and oil coolant start spilling out. That's why I think that my slight loss in power in the Z is due to overheating.

Now, I don't want to claim "Best Motoring" as a completely reliable reference on road racing and car setup, but in the comparo test they did a few years ago against the Boxter, M3, S2000, GT-R, etc... they mentioned that they outfitted the Z with the $1200 Nismo engine oil cooler for the track competition. Every other car was stock. Also, the rules in SCCA T2 allow the Z to run the same Nismo engine oil cooler sold by Performance Nissan (a less expensive version of the $1200 JDM one). It leads me to believe that the Z needs an engine oil cooler for the kind of abuse it sees on a road course.

 

I drove an Impreza RS (2.5l - 165hp). So the cooling level aren't as high as with a turbo engine.

The car has both oil pressure and oil temperature gauges. the oil temp gage is in the oil drain plug. In normal operation, the temp is around 140-160F On the track, it would go up to 210F. Cooling under the engine is not great because I have a large stainless steel skidplate covering the engine bay.

One time, at Monza (super fast track) on a hot day, the oil temp climbed above 240F. The only other indication I had was the oil pressure dropping 10 psi. I was using Mobil 1 10W30 and running Shell 99 Vpower fuel (equivalent to 95 octane here). So this might have helped.

My point is, check your oil pressure down the straights. Is it doesn't drop from lap to lap, oil is not in trouble yet.

Multiple options are possible to reduce intake charge temps. Better engine cooling via ducting to the radiator might help. The hood cutout certainly will.

One other, less dramatic, would be to put a spacer between the plenum and the block to reduce heat transfer to the charge. Wrapping the induction line will aslo help.

 

what existing oil cooler?

ahm

 

The water cooled one sandwiched between the oil filter and the engine block.

If you look at the technical drawings of the oil system, you'll see it. (Ref: LU-10 in the 2004 manual)

I have it on my '05 Track.

 

Not to ask a silly question but what kind of oil are you running? I'm assuming a good synthetic?

 

Me?

I run Mobil 1 5W30. Fresh oil before all track event (regardless of oil change schedual, wich I keep at 3750 miles)

 

Not a silly ? at all. Not sure who this one's aimed at, but I'm running Castrol GTX...10w30. Are all you guys running full synthetic? I got a bit scared off by all the claims of high oil pressures with some members who are running Mobil 1 5w30...though I haven't confirmed any truths to these claims. If you track guys have had no problems going synthetic, I think I'll switch over to Mobil 1 or something similar. I know some of you run on the track way more than I do, and are a more credible resource than the some of the folks posting in the other sections of this forum.

As for monitoring oil pressure, it seems to go up with the engine revs. I haven't seen my oil pressure needle drop on the straights, but then again, I'm more focused on the water temp gauge (which doesn't move at all). I do notice, however, that when the engine is cold, oil pressures are around 90-100psi, and it will climb to 120 psi quickly if I rev it past 3500rpm. That's why I drive very conservatively until the oil pressures reach "normal" operating pressure (meaning it doesn't fluctuate much relative to engine rpm). Once the car is up to temp, I can flog it all I want, and it doesn't move appreciably. Due to this behavior, I haven't determined how correlate oil temperature with oil pressure.

Is there a reasonable way to meaure oil temps gauge on this car?

 

We use Royal Purple 20W50 in the race car, and have found it to be more stable at higher temps than Mobil 1, 15W50.

 

Dnguyent, in my opinion your using too light of an oil for tracking your car in 100 degree weather. Last year I ran an event with a 100+ degree temps using 10w40 full synthetic and my oil pressure went very close to 0 at idle because it was too thin. I also experienced an extreme loss of power and had metal shavings in the oil. Funny thing was the temperature guage never read high. My engine power never came back either. I now use 20-50 for track events and I haven't had any problems.

 

huh. I didn't think there was one, but i'll be under my car this weekend and have a look. interesting... i have an '03 enthusiast - has the cooler been on the cars since production started?

ahm

 

i'd have to agree. 5w-30 is what i run in the winter. in the summer, i always run 10w-40. if i have a two day event coming, i'll switch to mobil1 15w50. if its a 1 day event, it depends on temps if i'll bother. even with 10w-40, i see oil pressure lower than i'd like after a session if its >85 degrees ambient.

i would also highly recommend a quality full synthetic. they are *MUCH* more stable at high temps - less evaporative loss, and less coking in hotspots. i used to use gtx, then read some of the oil test results that have come out (Motorcycle Consumer News did a big one a year or two ago), and GTX fared very badly. i've stayed away since then. if you insist on using non-synthetic, i'd look into shell's rotella T. there is both a synth and non-synth version i believe.

ahm

ahm

 

Sentry65 posted a schematic of the OEM oil cooler from the service manual.
https://my350z.com/forum/engine-and-drivetrain/134600-oil-cooler-vs-oil-pan-spacer-vs-nothing.html

OK, I'm going to try a heavier duty synthetic oil before my next event, and see how it fares. It seems that Royal Purple Racing 51 (20W50) runs what around $9 to $10/qt...$50 of "cheap" insurance for 100 degree days.

 

doesn't coolant loses it's properties after some time?

If you track the car, I'd flush coolant atleast once a year.

Also, I'd use a 40 weight synth oil. Lot of people even use use 50 weight oil on the track (might be a little thick for everyday driving though).

In anycase, some extra heat is normal from hard use. Race oil cooler, Bigger Radiator, Bigger oil pans, lower thermostats are all built for the purpose of reducing heat from hard use.(and ultimately protect the engine longer)...

A frequent habit is putting the heater at full blast, don't know if it changes anything. Haven't really run into heat issues yet