Help Me Solve My Overheating Woes

[MBS206]

Yeah I have a vented bonnet. So frustrating!!

Do a test and ditch the vented bonnet.

Cars are designed so that when moving, you end up with a high pressure point ABOVE the bonnet, and a low pressure point under the car. This helps in aerodynamics, but also has a MAJOR contributing factor to air flow through the engine bay.

Cars with lifted bonnets at the rear often come across an issue where they over heat, especially when being worked, purely because there is a MASSIVE high pressure zone at the back of the bonnet and air enters through here, and escapes under the car meaning not as much air actually flows through the IC and/or Radiator.

Try boxing as much of your air intakes at the front direct to the radiator/FMIC, as well as changing the bonnet, and throw a BRAND NEW fan and hub on.

[badhairdave]

I'd say the problem's 2 fold.

You're over revving the water pump and it's causing cavitation rather than moving water, get an under drive pulley on there, or consider an electric water pump.

You put an rb in a silvia Tight engine bay and all the cooling issues that come with it.

The factory oil cooler/water heater mentioned above is a fair point but i didn't think that was carried over onto the neo rb25, just the r33 rb25's.

[D_Stirls]

Hey Simon Do you have an oil cooler and what are your oil temps like?

[lilcrash]

^ yes he does and 100-110 degrees

[mii11x]

perhaps a blockage or something to do with with your heater core??? dont know if this would affect it but maybe disconnect the heater hoses from back of block to firewall and join them together and test it.

[Simon-S14]

some good suggestions and theorys here thats for sure.. i have an event this weekend so not much time for major changes but after that it will be stripped down and im redoing the following

-ditching the 180sx front and going back to s14 front

-cutting off the rad support and tube framing it. mounting a larger radiator + shroud with new clutch and fan

-moving the intercooler and going back to a larger 300x600x76 core.. i dropped down to a smaller core to fit it between headlights in front of the rad... half the issue is it doesnt sit in the path of the air intake from the front bar.

-ditching the stock oil warmer/cooler (neo's do have this. but stagea versions do not)

-mounting a CPU fan or two behind my oil cooler and hooked up to an RPM window stitch so it comes on between 900-2000 rpm IE idle/low speed

-redoing a intercooler water spray unit that does the radiator also.

-N1 water pump (not sure if needed.. the theory about over reving them i dont believe is valid due to the fact there are so many other Rb;s out there doing same rpms and not overheating.. my motor is limited to 7000)

[kitto]

Hmmm, you say N1 waterpump.

The factory pump could be causing issues.

The N1 pump design is to stop water cavitation at higher revs.

Considered a Nismo low temp thermostat?

[Simon-S14]

i already have a lower then normal rated thermostat in there. although its a trident and not a nismo.. it didnt make diddy squat difference.

im not convinced that the n1 pump will help either

[STATUS]

Calsonic meaning factory GTR one?

Need bigger alloy one! 2-3 pass style for max effect

bingo... if a near std gtr struggles to do a track day then your never gonna keep it cool, if its a r34 gtr radiator your really in trouble as they fair the worst.

forget n1 pump, will make it worse.

not ragging on the tune but what timing has it got it in it along the top end and what af? (pm if you prefer)

[Bond]

Can anyone recommend a basic/cheap radiator upgrade for a S2 R33 that gets hot. Standard rad doesn't seem to cope when it's 30+ outside.

[STATUS]

Can anyone recommend a basic/cheap radiator upgrade for a S2 R33 that gets hot. Standard rad doesn't seem to cope when it's 30+ outside.

ebay asi.

[Bond]

ebay asi.

Any particular size/model

[Simon-S14]

i had an ebay ASI and the problems were worse then when i had a calsonic gtr rad lol

[R31Nismoid]

You should try and move your I/C at least another 15-20mm further away from your radiator. With it only 10mm gap how it is airflow can't get in from each side of the radiator, you'll just be forcing air that would usually direct into the radiator through the head light holes and off into the wheel wells.

I really don't think its that.

Reason I say this is because that's how a factory GTS-R is setup. Mine runs cool as and the I/C sits close to the Rad, and is virtually the same size. I get temps of around 70 on a 25 degree day, driving it hard its lucky to get to 85 so nowhere near 100. I run no extra ducting or anything.

It wasn't a triple pass like a PWR @ over 800+, it was from Race Radiators here in Melb and was around 650.

[Simon-S14]

yeah might be time to bite the bullet and get a decent radiator thats for sure

[STATUS]

i had an ebay ASI and the problems were worse then when i had a calsonic gtr rad lol

yeah but your far from std, i know of about 3 SAU r33's running quick times on ASI rads.

[N1GTR]

RacePace sell the same thing for $550 (Multiple pass etc). Works for Targa cars, cheaper than PWR.

[koe]

My cooling set up:

Billion thermostat z32

Fluidyne 27x4 radiator 37degrees up

Tube and fin type fmic

Swirl pod(bleeder tank)

Flex-a-lite dual slim pull fans with Thermo controller

Expansion tank(overflow tank)

Return water manifold

Bang 18lbs radiator cap and 18lbs swirl pod pressure cap

Hood ducts to extract the hot air away from the motor and twin 100mm ducts from front facia to the block

Lower front splitter covers front to the tranny bell house to insulate heat from the pavement .

13raw oil cooler -10 an to a grex set up(oem oil cooler deleted)using a s30 or Datsun 510 oil filter stud.

This oil cooler has a t type fitting with a -4 an hose that goes straight to the turbo oil feed with a -3an restrictor.

All parts that are heat sources are Thermo insulated.

I run 165f on dd and 175f max on track

Egt showing bellow 12 on 9.5 Rpms

With is candy

[discopotato03]

I think most will tell you that a 6 cyl engine in a four cylinder bay makes life difficult because hot post rad air has to find its way through the bay and out underneath . The very best radiators in the world do jack if the air through them has restricted flow downstream . It could be worth sticking this car on a hoist and having a look from under and behind the engine at where the air flows through - and removing anything thats not essential in the flowpath . Note that includes in the gearbox tunnel as well because if you have the large 25T box in there it takes up more room than the Ss one did .

Back to basics , you make more power you make more heat though rough rule of thumb is that only 33% goes down the cylinders and the other 66 is split between liquid cooling and exhaust heat . Any exhaust restriction won't help and if the tuning is iffy that could show up as elevated EGTs and coolant temps .

I don't know what oil cooler packaging works on S series cars but I do remember some Mazda Rotaries having reasonably effective oil coolers and they may have been long and not very tall , something to look into maybe .

I only ever had one GTR rad and that was a Koyo in a Bluebird . It has all single tubes as in the full thickness of the core and worked really well . I think multi row radiator cores are a bean counters decision not an engineers one because the gap between each layer does SFA for cooling . A real radiator has alloy vanes inside its tubes to break up laminer flow and make the coolant reject its heat properly . My personal opinion of multi pass rads is small cores in series and you have to hope each one can flow enough water to work properly .

I'm pretty sure most/all Skyline radiators have vertical flow because more tubes is better for flow and cooling than fewer longer tubes , its the same with intercoolers but packaging and costing means most are not .

Anyway as mentioned that viscous fan hub needs to be fully functional and a new genuine Jap one is probably the way to be sure .

I'd be running a real good group 4 synthetic oil as well if you have high heat issues and a high poundage rad cap to make sure the coolant doesn't actually boil .

The real danger isn't 120 degrees coolant temperature , its the coolant boiling and steam bubbles forming in the head and localisaed head temps cracking/warping things . I don't think its real well known that water boils at higher temps with higher cooling system pressure and its the rad cap that sets the MINIMUM pressure once warmed up . You have to make sure that all pipes hoses everything is fact is in good order so elevated pressures don't blow anything .

Just back to oil again I'd be watching oil temps and if its getting high enough to be a worry you may need a higher viscosity one to keep the film strength up . One that comes to mind is the highest of the three Mobil 1 Racing 4T bike oils , its a 25W50 and called "V Twin" and intended for Harlry Davidson V Twin tractors and the like . I know everyone has their favourite brand and theories on performance engine oils , mine is that real performance 4 stroke sport bike engines beat the christ out of the oil far more so than any car engine . BTW I realise that Hardlys are not sport bike engines (IMO) but this oil is in the same group of 10W40 15W50 25W50 so its good gear . 4T Racing has high concentrations of ZDDP or Zinc Di Alkyl Dithiophosphate which is the gun anti wear additives taken out of most of todays oils for Green Socialist Psycopath reasons - it poisons cat converters over time .

Hope this helps cheers A .

Edited November 7, 2011 by discopotato03

[GTScotT]

Not sure if this has been covered or not..

Nissan Exa's are notorious for overheating, caused by missing splash trays.

The splash trays play a massive part in keeping air that flowed through the front into the engine bay and out underneathe the way Disco described.

I myself have had a similar problem that continued to worsen the more bandaids I threw at it (bigger and better coolers and ratiators, thermostats etc).

Make sure atleast up to the cross member is covered from the front bar and between the rails.

My 2c.