TunerMax

iTrader: (2)

I have been toying with the idea of installing cooling fans near the back of the head to keep the rear cylinders at a more even temperature, has anyone messed with this?

I was thinking simple like computer fans, maybe one or two on each side pointed toward the firewall, triggered on once operating temp is reached and just stay on.

I can think of things wrong with the concept, but seems there's more benefit than negatives. Basically I just want to equalize the cylinder temperatures, flow to the back of the engine is aweful in this chassis.

str8dum1

iTrader: (11)

so those huge fans they use to cool cars on the dyno still cause heatsoak, and you think 1cfm a minute computer fans are goin to have any effect on 200* heads?

get out your touchless thermometer and you'll see that the he heads already run at equal temps. Tiny fans wont do anything.

TunerMax

iTrader: (2)

Wow dude, chills. It was an idea, that's all.

It's well known that the back cylinders run hotter, that's simple fact. They're the first to wear out, and the EGR is right there too. Not to mention the exhaust flow past them from the front 4 cylinders.

I was just trying to brainstorm an idea to combat this, that's all.

P&K350Z

iTrader: (2)

I understand, what's odd about my situation is that I run cooler at idle or even bumper to bumper traffic than I do at a steady but relatively low load. Example: at 71 mph and 3000 rpm (I have a 3.90 final drive thus the higher rpms than stock) I climb to 220* and it holds there. On a hot Houston day it will climb to 225*. As soon as I come to a stop or hit traffic, it will relatively quickly drop to 200*. So the cooling system seems to be doing a fine job of removing heat.

Anyway, not really a big issue since I don't overheat and it takes several laps (8 to 10) at the track to get me over 260* but always found it odd how hot my car ran compared to others. Based on most of what I have read here over the last couple of years 210* seems to be the high average with 180 to 190* being what most report.

Thanks for the help

str8dum1

iTrader: (11)

can you please quote source of well known rear cylinders running hot as i have never seen a tech bulletin about it. not have ever measured it during my own data collection.

plus we dont have a EGR.

binder

iTrader: (8)

that is strange. It should cause temps to go down.

260*?! that's really high. well, i guess not extremely high but right on the boarder. 2 hours of back to back WOT pulls on the dyno at 600+ hp my oil temps never went over 220* oil temps. It was mid 80's ambient temps that day in the shop. hmm, if your motor has lasted this long i'm sure it's ok but still strange. I would change the oil frequently with those temps though.

Rich (str8) is right about the fans. The heads are no designed to release heat into the environment by air cooling. They are designed for water cooling so blowing air directly on them won't help the combustion temps a single bit. They are surrounded (and therefore buffered) by coolant.

TunerMax

iTrader: (2)

It's no big secret that cylinders closest to the firewall in almost any engine configuration are prone to more heat. This is more evident in RWD application because coolant flow is almost always from front to rear. So is oil flow normally.

Combine that with less airflow to assist in cooling and you have higher temps.

It's not a complicated scenario, look at where these engines fail rings first, it's almost ALWAYS the rear 2 holes. And if you monitor your cylinder temps (not head temps) I would lay money down that they will be higher as you move rearward. if you want proof of this you simply have to search around.

IJS, not trying to argue with you mah man, just saying. Take it for whatever you will.

Thanks for the response dude. I get what you guys are saying here. I really do. But Convection works, it's a real thing

It's not the primary method of cooling obviously, but it IS relevant, and it IS functional.

Now my computer fan idea might not be worth a crap, but the concept isn't failed. Anyways this is OT to this thread, so let's just drop it.

I will drop a couple pics pertaining to the recent talks about oil and coolant flow and temps. Gives a better idea of where you want sensors.
Also gives a better idea of what will naturally be hotter/colder in the engine.

OIL FLOW:



COOLANT FLOW:

P&K350Z

iTrader: (2)

Yep, I've scratched my head about this one for two years. I've resigned myself to just having an engine that likes to run hot. Over time I've modified the size and location of the oil cooler, added the fan to the cooler radiator, tried an aftermarket coolant radiator (that was a bad idea BTW, had to rip it out a month later) but the pattern has always been the same. The only thing it affects is how quickly the heat is pulled off at idle. Currently it is quite fast in doing so which is a positive. If I get to 260 when on the track, that's just a sign to pull off for a while and cool off. I do change oil at 2000 miles, oil sampling has been perfect even after almost 40k miles supercharged on a stock revup block. Luck may well run out though, I am under no illusions. Not a DD so at least some peace of mind there.

Anyway, thanks again for the feedback. I may try to run some refrigerant lines through the back of the cylinder heads next. Freon FTW.

Joking about that last part

-Pedro

binder

iTrader: (8)

yes, but the coolant around the cylinders would act like a buffer. At most you might pull 1* out of the metal then from the coolant but not measurable enough to warrant the work to do it. Also with the fans it would only be circulating hot engine bay air so the temperature gradient wouldn't be high enough to push a lot of heat out. Could you log 1* difference from a complex fan system, yes. 1* coolant temp difference isn't going to yield a bit of power difference so not really worth the efforts.

If you had heads with fins on it for a heat sink effect then it would have the surface area to transfer an amount of heat to actually make a change. Until then, surface area is low and heat gradient is low so I think the degree of temperature it can transfer would be tiny.

str8dum1

iTrader: (11)

I am saying it is a big secret because there are no documented cases of this. just because you think something to be true, in no ways means you should promote it as truth.

Cylinder 1 and 2 are just as close to the shock towers as 3 is to fire wall.

I have measured many times with my IR thermometer with no difference. Engine bay is heat soaked. Back cylinders dont run hotter than front.

We just dont need more BS myths on this forum..

TunerMax

iTrader: (2)

TY sir this is the type of intellegent construtive advice I was hoping to get.
You're right, especially about the ambient engine bay air being high temp thus not doing efficient cooling anyways.

Guess I'll can the idea, and I'm sure Str8dum1 is right at least to some degree about there not being a huge difference if you have a good working waterpump, etc.

I will do some testing on temps just out of curiousity.
But I'll have to take your word for the difference simply not existing, Str8dum1. Thanks for the imput on it man.

binder

iTrader: (8)

welcome.

there are a lot of things that seem like good ideas but after further investigation they just don't hold up. My brain thinks of things all the time that seem awesome until i start looking into it and the change is either not significant enough to warrant the time or it just won't work. Doesn't mean the idea was bad. It just means the idea was impractical in the real world.

EliteZ

iTrader: (1)

Wider Cog Belt

I was curious if we could use a 25 or 30MM wide cog belt instead? Seems like the idler pulley that comes with the vortech (Rev-Up) is about 30 mm wide.

binder

iTrader: (8)

shouldn't be any problem as long as it fits in the groves of the tensioner pulley.

why do you need a wider one? properly adjusted (1/4" play when hot) shows that the stock one is strong enough. It's when people set the tension while it's cold that it heats and puts too much tension on the belt causing it to break. Random failures wo'nt really be prevented by going to a wider belt since they would have about the same accidental failure rate as all other belts (due to manufacturing problems or defects)

4SHIZZIL

iTrader: (10)

You have to custom order them.

I am thinking about it. but keep in mind on my rev up ive got bracket flex and had to mount my SC to the driver side frame to keep it stable.

so if you run super high hp, you would just shred the belt once the bracket moved. I eat cog belts for breakfast now. lol.

mvthree50

iTrader: (3)

Realizing that this being my first post makes me look like quite a noob, but im much more involved on the other 350z forum lol. Im researching into buying a vortech kit for my car and had a few questions after reading through this thread. (yes, i read all 93 pages lol)

my goal is 400-420whp.

list as follows:
vortech v3 SCi tuner kit
3.12 pulley
koyo radiator
DW 600cc injectors
Walbro 255 fuel pump
Oil Cooler
Boost, A/F, Oil Temp Gauges
JWT clutch/flywheel
Berk HFC
Motordyne 5/16" Spacer
Tuning (see question)
(anything that should be added, let me know)
I already have:
Borla Headers
HKS Rep. Exhaust

So my questions...

1. UTEC vs Osiris Uprev
Tuning is totally beyond me, and I've already contacted my tuning shop and they said either way could be done. Any personal experience I'd like to know, I was leaning towards UTEC

2. Aftermarket MAF? Will I need one? I read that some people max'd out the stock ones and was wondering if my goal of 400-420whp would max it out and what a good aftermarket one would be to choose

I know I'll have more questions, just wanted to post up my very preliminary list and hopefully get some early questions answered. Like i said i did read the 93 pages and am really hoping everything goes well. Thanks in advance!

TunerMax

iTrader: (2)

I can say a couple things but cant help with a lot there:

You will probably need a smaller pulley to get in that WHP range with that tuning software.

You will need wideband sensors and a controller (not on the list)

You probably don't need an aux/bigger oil cooler but that never hurts things.

mvthree50

iTrader: (3)

Thanks! Yeah the oil cooler was more of a safety. Do you have an example of a wideband sensor/controller I can buy?

TunerMax

iTrader: (2)

Compatibility is the name of the game with Widebands from what I know.
You need to get a wideband that is compatable with the gauge you get, and if applicable, the Engine management you have.

in your case the Engine management part shouldn't matter because you're not running software based programs.

binder

iTrader: (8)

I would choose osiris over utec. Utec has been known to blow out ignition coils and cause other weird things. Osiris is pretty solid but might require a larger maf for 400hp+. Mine ran out just before 400hp.

I would still put the oil cooler on. With added horsepower the engine will produce more heat so it never hurts to have more cooling verses having less cooling.