Jump to content
SAU Community

Recommended Posts

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.

  • Replies 52
  • Created
  • Last Reply

Top Posters In This Topic

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.

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.

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)

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)

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.

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.

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

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 by discopotato03

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.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • See if you can thermal epoxy a heatsink or two onto it?
    • The other problem was one of those "oh shit we are going to die moments". Basically the high spec Q50s have a full electric steering rack, and the povo ones had a regular hydraulic rack with an electric pump.  So couple of laps into session 5 as I came into turn 2 (big run off now, happily), the dash turned into a christmas tree and the steering became super heavy and I went well off. I assumed it was a tyre failure so limped to the pits, but everything was OK. But....the master warning light was still on so I checked the DTCs and saw – C13E6 “Heat Protection”. Yes, that bloody steering rack computer sitting where the oil cooler should be has its own sensors and error logic, and decided I was using the steering wheel too much. I really appreciated the helpful information in the manual (my bold) POSSIBLE CAUSE • Continuing the overloading steering (Sports driving in the circuit etc,) “DATA MONITOR” >> “C/M TEMPERATURE”. The rise of steering force motor internal temperature caused the protection function to operate. This is not a system malfunction. INSPECTION END So, basically the electric motor in the steering rack got to 150c, and it decided to shut down without warning for my safety. Didn't feel safe. Short term I'll see if I can duct some air to that motor (the engine bay is sealed pretty tight). Long term, depending on how often this happens, I'll look into swapping the povo spec electric/hydraulic rack in. While the rack should be fine the power supply to the pump will be a pain and might be best to deal with it when I add a PDM.
    • And finally, 2 problems I really need to sort.  Firstly as Matt said the auto trans is not happy as it gets hot - I couldn't log the temps but the gauge showed 90o. On the first day I took it out back in Feb, because the coolant was getting hot I never got to any auto trans issues; but on this day by late session 3 and then really clearly in 4 and 5 as it got hotter it just would not shift up. You can hear the issue really clearly at 12:55 and 16:20 on the vid. So the good news is, literally this week Ecutek finally released tuning for the jatco 7 speed. I'll have a chat to Racebox and see what they can do electrically to keep it cooler and to get the gears, if anything. That will likely take some R&D and can only really happen on track as it never gets even warm with road use. I've also picked up some eye wateringly expensive Redline D6 ATF to try, it had the highest viscosity I could find at 100o so we will see if that helps (just waiting for some oil pan gaskets so I can change it properly). If neither of those work I need to remove the coolant/trans interwarmer and the radiator cooler and go to an external cooler....somewhere.....(goodbye washer reservoir?), and if that fails give up on this mad idea and wait for Nissan to release the manual 400R
    • So, what else.... Power. I don't know what it is making because I haven't done a post tune dyno run yet; I will when I get a chance. It was 240rwkw dead stock. Conclusion from the day....it does not need a single kw more until I sort some other stuff. It comes on so hard that I could hear the twin N1 turbos on the R32 crying, and I just can't use what it has around a tight track with the current setup. Brakes. They are perfect. Hit them hard all day and they never felt like having an issue; you can see in the video we were making ground on much lighter cars on better tyres under brakes. They are standard (red sport) calipers, standard size discs in DBA5000 2 piece, Winmax pads and Motul RBF600 fluid, all from Matty at Racebrakes Sydney. Keeping in mind the car is more powerful than my R32 and weighs 1780, he clearly knows his shit. Suspension. This is one of the first areas I need to change. It has electronically controlled dampers from factory, but everything is just way too soft for track work even on the hardest setting (it is nice when hustling on country roads though). In particular it rolls into oversteer mid corner and pitches too much under hard braking so it becomes unstable eg in the turn 1 kink I need to brake early, turn through the kink then brake again so I don't pirouette like an AE86. I need to get some decent shocks with matched springs and sway bars ASAP, even if it is just a v1 setup until I work out a proper race/rally setup later. Tyres. I am running Yoko A052 in 235/45/18 all round, because that was what I could get in approximately the right height on wheels I had in the shed (Rays/Nismo 18x8 off the old Leaf actually!). As track tyres they are pretty poor; I note GTSBoy recently posted a porker comparo video including them where they were about the same as AD09.....that is nothing like a top line track tyre. I'll start getting that sorted but realistically I should get proper sized wheels first (likely 9.5 +38 front and 11 +55 at the rear, so a custom order, and I can't rotate them like the R32), then work out what the best tyre option is. BTW on that, Targa Tas had gone to road tyres instead of semi slicks now so that is a whole other world of choices to sort. Diff. This is the other thing that urgently needs to be addressed. It left massive 1s out of the fish hook all day, even when I was trying not too (you can also hear it reving on the video, and see the RPM rising too fast compared to speed in the data). It has an open diff that Infiniti optimistically called a B-LSD for "Brake Limited Slip Diff". It does good straight line standing start 11s but it is woeful on the track. Nismo seem to make a 2 way for it.
    • Also, I logged some data from the ECU for each session (mostly oil pressures and various temps, but also speed, revs etc, can't believe I forgot accelerator position). The Ecutek data loads nicely to datazap, I got good data from sessions 2, 3 and 4: https://datazap.me/u/duncanhandleyhgeconsultingcomau/250813-wakefield-session-2?log=0&data=7 https://datazap.me/u/duncanhandleyhgeconsultingcomau/250813-wakefield-session-3?log=0&data=6 https://datazap.me/u/duncanhandleyhgeconsultingcomau/250813-wakefield-session-4?log=0&data=6 Each session is cut into 3 files but loaded together, you can change between them in the top left. As the test sessions are mostly about the car, not me, I basically start by checking the oil pressure (good, or at least consistent all day). These have an electrically controlled oil pump which targets 25psi(!) at low load and 50 at high. I'm running a much thicker oil than recommended by nissan (they said 0w20, I'm running 10w40) so its a little higher. The main thing is that it doesn't drop too far, eg in the long left hand fish hook, or under brakes so I know I'm not getting oil surge. Good start. Then Oil and Coolant temp, plus intercooler and intake temps, like this: Keeping in mind ambient was about 5o at session 2, I'd say the oil temp is good. The coolant temp as OK but a big worry for hot days (it was getting to 110 back in Feb when it was 35o) so I need to keep addressing that. The water to air intercooler is working totally backwards where we get 5o air in the intake, squish/warm it in the turbos (unknown temp) then run it through the intercoolers which are say 65o max in this case, then the result is 20o air into the engine......the day was too atypical to draw a conclusion on that I think, in the united states of freedom they do a lot of upsizing the intercooler and heat exchanger cores to get those temps down but they were OK this time. The other interesting (but not concerning) part for me was the turbo speed vs boost graph: I circled an example from the main straight. With the tune boost peaks at around 18psi but it deliberately drops to about 14psi at redline because the turbos are tiny - they choke at high revs and just create more heat than power if you run them hard all the way. But you can also see the turbo speed at the same time; it raises from about 180,000rpm to 210,000rpm which the boost falls....imagine the turbine speed if they held 18psi to redline. The wastegates are electrically controlled so there is a heap of logic about boost target, actual boost, delta etc etc but it all seems to work well
×
×
  • Create New...