Ideal Temperature

[Hunky]

just finished putting an rb30det into my skyline and have a couple of questions.

1. What is ideal running temp ? Mine seems to want to sit at the 100 degree mark it has a large alloy radiator and twin thermos and Nissan thermostat, 100 just seems a bit hot to me,

2. Does the hose for the aacv have to be run in between throttle body and air flow meter ? Or can it run from atmosphere ( with a filter) ?

3. I found I have a leaky welch plug, just a slow leak a drop every now and again, it is in an awkward spot behind an engine mount, will this get worse and worse over time ? Or can I use a sealant to fix this issue ?

4. I have read a lot about bov, and am a it confused some people say it is a must have item and other say it is not needed. Will it harm my turbo if I am not running a Bov if it is only running low boost pressure ?

[iruvyouskyrine]

1. Standard RB30 thermostat is 82.6deg if I remember correctly. Should sit around that happily. I suggest doing a proper bleed of the coolant system before anything else.

2. AACV hose goes anywhere between before the throttle body and air filter. Most people run it immediately before the TB.

4. There is no requirement to run a BOV. Personally I have never run one in my 5 years of ownership and none of my mates have ever run them.

[Kinks]

1. 100 is much too hot. It should sit arounc 85C operating temp.

2. if you run an airflow meter then you must have the AACV taking air after the airflow meter (so the air usage gets measured... otherwise the car won't idle). if you run a MAP based ECU (ie aftermarket) then you could atmosphere + filter it.. but then you need an extra filter etc.. I don't see the point personally.

3. pretty unlikely it'll get better on its own. you may be able to tack it up with some sealant. I once sealed the turbo water line behind the block by dripping some superglue on it. that held until I had time to get in there and replace the hose properly.

4. nobody has ever had a turbo die from not running a BOV. I ran a bovless skyline for several years pushing 14psi no problems.

[Hunky]

Thanks, what is best way to bleed cooling system ? I don't have bleed valve as I have a Freddiy plenum, I read that you can just raise the front of the car so that the radiator is highest point of cooling system and just run it with the cap off ?

[Ben C34]

Yep.

Not bleeding the cooling system is a good way to ruin an engine.

[niZmO_Man]

Bottle on the radiator

[Kinks]

sugestions as above are good. Also there is often a fitting with a warning label that says "do not open when hot" near the front of the inlet manifold (ie at the top of the inlet manifold, closest to the radiator). This is the highest point in the cooling system and can also be used for bleeding. To bleed it you need the top half of a 2L coke bottle jammed in the radiator neck with a bit of gaffa tape around it to provide a seal of sorts. you need an inch or two of water above the radiator cap level to effectively bleed the system.

[MrStabby]

sugestions as above are good. Also there is often a fitting with a warning label that says "do not open when hot" near the front of the inlet manifold (ie at the top of the inlet manifold, closest to the radiator). This is the highest point in the cooling system and can also be used for bleeding. To bleed it you need the top half of a 2L coke bottle jammed in the radiator neck with a bit of gaffa tape around it to provide a seal of sorts. you need an inch or two of water above the radiator cap level to effectively bleed the system.

In the 32 GTR i get full coolant out the bleeder by just topping up the radiator.

BOVs are designed to vent off the air that would otherwise slow the turbo down after the throttles shut. So if you have one you should produce boost more quickly after gear changes.

[Kinks]

BOVs are designed to vent off the air that would otherwise slow the turbo down after the throttles shut. So if you have one you should produce boost more quickly after gear changes.

Yes, if you have a correctly set up plumb-back on a MAF-based engine then it may help throttle response as opposed to BOVless. (remove plumb-back requirement for MAP-based). And if you are running REALLY high boost pressure then BOVless may accelerate turbo bearing wear.

There is also some thought towards keeping pressure inside the intercooler + piping. The rotating assembly in a turbo is quite light, and rather than worrying about slowing it down you can rely on maintaining a bank of pressurised air so that when the throttle opens you have a volume of pressurised air available that can go straight into the engine, produce power, and produce a lot of exhaust gas to spin the turbo up again. With a BOV that is venting all pressurised air, you may have a faster turbine speed but when the throttle opens you have no pressure and the turbo has to build pressure in the intercooler + piping all over again.

It would probably be fairly straightforward to measure the result by logging TPS and MAP, come to think of it.. I may play with it sometime in the future to see what works better