JZA70 Time Attack Track and Street

[spiller]

yeah my D1RS that i had on there were becoming a little chipped here and there and the widths will work better with the slicks I have for now than these.

im running KU36 in 235/40 on the front with a bit of stretch and 265/35 on the back. those sizes were just because that's what i already had but its worked out pretty well fitment wise. i think once i put the camber in there i could easily run the 265 on the front too. there is still tonnes of inner clearance up the front.

 

[leezymk3]

wow cool build man i like to get my supra ready time attack some day

 

[spiller]

thanks man.

I took the car through the twisty roads in the Adelaide Hills today just to make sure it would hold up to a bit of a push. Water temps seemed to be up around 105 and got as high as 110 but id expect them to go higher at the track as I wasnt on the limit the whole time today. The valve stem seals seem to be seeping a lot of oil particularly if I take the revs higher and then back off (vacuum sucking oil back through the open valves). there is also a major issue with the steering. It feels very detached to the point where the car simply wont go were I want to put it, and aggressive turns of the wheels produce a knocking sound. I need to have this checked out ASAP but I feel its an issue in the steering column somewhere.

 

[leezymk3]

Man I want to get my car running,I can't wait

 

[josbeat]

check the universal joints on the columm but maybe is the torrets on the top of the chocks.

temp. try to reroute the turbo cooling system throw the radiator but take the water from the back of the head.

 

[spiller]

yeah I think it may be an issue with either the universal joint or something loose somewhere. it has been like it for some time and hasnt gotten any worse but i need to fix it!! With the turbo cooling, I still have the stock turbos which have hard water lines, probably not worth messing around with because ill throw it all in the garbage when I eventually go to a single turbo haha. What do you mean by taking the water from the back of the head though? From what i've read/heard, JZ motors tend to run fairly hot without any problems. The temps came back down as soon as I slowed down

 

[josbeat]

ahh! forgot what type of engine are you using, sorry I was thinking that you are using the 7M

a cooling plate where the intecooler is , help a lot, is a must with aftermarket hoods and good thing with the original one

 

[spiller]

I do have a cooling plate here, I will install it I think. I'm also going to make up a temporary under tray to help direct air too because the factory one is long gone. I want to eventually do a front splitter but prefer to get the mechanical set up right before adding aero.

 

[1jz-Rolla]

Are you talking about a "cooling plate" around the bonnet catch by any chance?

 

[spiller]

yep, have had one here for a few years but never fitted it. I think the under tray would be more functional though so will make that a priority. out of curiosity phil, what sort of temps does yours see at the track? As I say, some people tell me JZs just run hot and 100-110 coolant temps arent unheard of but by comparison it is pretty high.

 

[1jz-Rolla]

Yep, you'd be wise to focus on the undertray instead Those upper cooling panels to two-tenths of fark all. Check out the underside of your bonnet, its designed to do exactly the same thing, so you're unlikely to see any efficiency from that panel, other than to hide your radiator recovery tank so that you can't check the level!

Haven't had a dry day to test the VVTi JZ in my Supra on the circuit, but my 1JZ in the Corolla sat at 105 deg throughout track sessions without a drama. Even on a 32 degree ambient day it would stay at that point and not get hotter. I ran a 0.9 bar radiator cap, since higher pressure = higher boiling point also, so cooling efficiency is not lost.

 

[mytmk3]

100-110 sounds pretty high to me I was backing off on mine at the track when it hit 100 maybe im a pussy? mine is a 7m I didn't push further after that so don't know if it was going to peak at that but a little distracting when my link display is flashing "DANGER WATER TEMP!!!" is hard to ignore

Been having this discussion alot recently with mk4 guys in the kiwi section on the au forums they say I should be aiming for about 85 degrees on the track I get that cruising but beating on it I doubt it IJ reckoned he would be about 90-92 degrees beating on it.

What temp do you start to worry? do you have an oil temp gauge? and what coolant % do you run?

 

[spiller]

Yep, you'd be wise to focus on the undertray instead Those upper cooling panels to two-tenths of fark all. Check out the underside of your bonnet, its designed to do exactly the same thing, so you're unlikely to see any efficiency from that panel, other than to hide your radiator recovery tank so that you can't check the level!

Haven't had a dry day to test the VVTi JZ in my Supra on the circuit, but my 1JZ in the Corolla sat at 105 deg throughout track sessions without a drama. Even on a 32 degree ambient day it would stay at that point and not get hotter. I ran a 0.9 bar radiator cap, since higher pressure = higher boiling point also, so cooling efficiency is not lost.

I should note that I dont have the rubber seal at the frontal edge of my bonnet (went missing previous owner) so perhaps some air is escaping from the top there also). Should I be running a higher pressure radiator cap? Isnt 0.9 bar about the norm? I remember last time I went to the track the factory temp gauge soared after only a few hot laps but the car had a huge spark issue that day and was probably running hot as a result. Id be happy with 105 at the track if it were steady tho!

100-110 sounds pretty high to me I was backing off on mine at the track when it hit 100 maybe im a pussy? mine is a 7m I didn't push further after that so don't know if it was going to peak at that but a little distracting when my link display is flashing "DANGER WATER TEMP!!!" is hard to ignore

Been having this discussion alot recently with mk4 guys in the kiwi section on the au forums they say I should be aiming for about 85 degrees on the track I get that cruising but beating on it I doubt it IJ reckoned he would be about 90-92 degrees beating on it.

What temp do you start to worry? do you have an oil temp gauge? and what coolant % do you run?

From what ive read, 7Ms run a little cooler than JZ motors. At the track you wouldnt want your water temp going much higher than 115 (i.e. slow down if you see this) and oil shouldnt be higher than max 120 degrees. This is what the guy who tuned my car advised - he races a 2JZ 180SX with 700hp.

 

[1jz-Rolla]

Should I be running a higher pressure radiator cap? Isnt 0.9 bar about the norm?

yep, sorry, 1.4 bar was my upgraded "TRD" rad cap.

and oil shouldnt be higher than max 120 degrees. This is what the guy who tuned my car advised - he races a 2JZ 180SX with 700hp.

Agreed, most oils start to break down/lose their shear strength at this temp, so i'd start watching it once it heads north of 110 degrees centigrade.

 

[spiller]

so whats the point of a higher pressure cap? google will tell me but im lazy today!

 

[1jz-Rolla]

The extra pressure helps to find potential leaks in your cooling system ha. No seriously though, its mostly about raising the boiling point of the water i.e: more of a margin before the cooling system becomes completely inefficient.


There are commercially available additives that "can" aid in making your cooling system more efficient by reducing the surface tension of the water. Redline's "Water Wetter" is one of them, i've run it in the past.

I would say though, that if you are still running that big thick JAR barn-door radiator, that you consider sending it to scrap metal once trying the other fixes, as its likely to be quite inefficient at shedding heat. Larger radiators generally only delay the onset of overheating problems through having extra coolant capacity - they won't help you in a constant thermal loading situation like on the circuit, where the focus should be on shedding heat from the coolant - i.e: efficiently passing as much air as possible over the core. A double core radiator will actually do this better than a triple core, through being less of a restriction for the airflow. Notice how most modern cars run only a single core, but large surface area? There's a good reason

Anyways mate, i'm sure you'll get to the bottom of it, but your steering is probably more of a priority right now hey!

 

[spiller]

Yeah needless to say I wouldnt have fitted that JAR thing if it were my car at the time . I had planned on adding some water wetter when I give it a coolant flush in a few weeks but as you say, one thing at a time. I've booked it in at a local suspension joint tomorrow so hopefully they will get to the bottom of it. The valve stem seal thing is really pissing me off most of all though, I find it hard to believe they could fuck out that easily from sitting around for 12 months given that they were replaced 3 years ago. The workshop got rid of my charcoal canister when they had the car, im wondering if they've rerouted something incorrectly, although the canister just soaks up left over fumes doesnt it? Not really related to oil blow by.

 

[1jz-Rolla]

Yeah that's right, the charcoal canister is isolated to the fuel system only, so shouldn't affect any oil usage/burning issue.

How many km have you driven since restarting the motor now? As you say, a bit odd for a valve stem leak with them being quite fresh. Have you pulled the spark plugs to see if any particular cylinders are more oily than others?

Also, are you still running the factory PCV valve from the valve covers to the inlet manifold, or a separate catch-tank?

 

[josbeat]

uhmm be sure that I never will say anything without be tested by me
If I say the cooing plate is a must with carbon hood or with the stock with out the rubber you can be sure that it is a must.

look! the other day going to the track and with the new cooling desing on my 7M the temp was dancing from 78 to 74º celsius so I was thinking what I can do to rise up the temp, what I did is to remove that cooling plate and the temp was stable at 79º .
The other evidence is that if I dont put some tape to hold the plate on place , after some laps it appears pushed up because my custom cooling plate is very thin of 1 mm only and the air pressure get it bended.
of course the undertray cover is a must aswell but .... spiller the temperature of your engine is normal.... it dont have nothing to cooling it!! jajajaja

 

[1jz-Rolla]

Yes correct josbeat, but the assumption for general owners is not that they run a CF hood or have the OEM seal missing Was not having a dig at you in the first place, just that the cooling plates don't have much benefit for the masses that buy them, having stock setups with the OEM seal in place

There are so many more places for the air to divert around the radiator core, to get serious about track cooling, diverter plates on all sides of the front face of the core would be the best way forward.