JZA70 Time Attack Track and Street

[spiller]

Phil, AFAIK still running the stock PCV on the intake, but I will check when I get home.

I took the car to a local suspension shop today to try and diagnose the knock and sloppyness in the steering. Car was put over the pit and the following was discovered:

1) All four bolts holding the steering rack to the subframe were 2-3 turns loose
2) All front cross member bolts were loose
3) Both engine mounts were completely loose causing the engine to move about an inch each side (this was causing the knock).

So, the previous owner must have gone to lunch half way through doing the engine conversion and forgot to tighten up all of the bolts!

My solid engine mounts now feel like solid engine mounts. The steering is a lot sharper and there are no knocks. Im quite happy but annoyed at myself for not finding these issues, then again I dont have a hoist and havent looked under the car for the best part of 2 years with it being off the road. There is still play in the wheel but the suspension guy checked the uni joint and the couplings and there was nothing unsual. Perhaps with the A70 being a 20+ year old car originally designed for Grand Touring and not track work, this is just how the car is?

 

[1jz-Rolla]

Good result! Especially since you didn't crash in the meantime

 

[spiller]

lol can you just imagine punting round the track and suddenly your front end falls out of the car?

 

[josbeat]

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.

but you say double core radiatyors , how we will know if is real a double core or only they say double core trying to sale it??
because looks like the stores say double core when the radiator core is double of the original but not when it is made with two cores welded....
can you help me trying to find a real one???


and yes if the rubber is in place no need the plate

I been playing with the sides with out really a noticiable different but... in my car , my radiators have a special positions

 

[josbeat]

spiller another day more runnign and you will be loosing part on the road jejeje
like on the loney toons jajajaja
basic to check the big bolts under the car !! and must if you whant to go to the circuits mate!

 

[1jz-Rolla]

Koyo make quality radiators for our cars.

There are two main options, though most seem to go for the 2nd one automatically cause its the "race" version

1.

#CO196
OEM style plastic top & bottom tanks
Aluminium 2 row slimline core
32mm core thickness
33mm hose fittings


2.
#RO171
All aluminium construction "Racing" version
53mm core thickness - 2 wide cores from memory
35mm hose fittings


There is possibly a third option, Koyo radiators prefixed with a "V" part number have a 36mm 2 core setup - i've not seen one listed for the MK3 Supra though.





*Spiller, let me know if you want this taken across to josbeat's thread...... don't wanna get too OT from your build here. CHeers

 

[spiller]

spiller another day more runnign and you will be loosing part on the road jejeje
like on the loney toons jajajaja
basic to check the big bolts under the car !! and must if you whant to go to the circuits mate!

Haha I know hey! The stupid thing is I was under the car a couple of years ago doing all of the lower ball joints and control arm bushes etc but was too fixed on that to noticed the other stuff. I think it has very much worsened over the past 3 years since ive had the car though. The scary thing is I have had the car on the track before but it felt fine!

Koyo make quality radiators for our cars.

There are two main options, though most seem to go for the 2nd one automatically cause its the "race" version

1.

#CO196
OEM style plastic top & bottom tanks
Aluminium 2 row slimline core
32mm core thickness
33mm hose fittings


2.
#RO171
All aluminium construction "Racing" version
53mm core thickness - 2 wide cores from memory
35mm hose fittings


There is possibly a third option, Koyo radiators prefixed with a "V" part number have a 36mm 2 core setup - i've not seen one listed for the MK3 Supra though.





*Spiller, let me know if you want this taken across to josbeat's thread...... don't wanna get too OT from your build here. CHeers

No dramas, its on topic so im happy for it to stay here. What are the OEM outlet sizes for our cars, must be 33mm? I think if I was going to upgrade the radiator I would go with the Koyo option 2 above but I may enquire about a PWR too. HKS_TRD has one on his car, from memory it was around the $800 mark but that was quite a few years ago.

 

[1jz-Rolla]

Just a hint: Don't waste all that extra cash on a PWR.......... the price does not necessarily reflect the design/quality.

Are you running a hydro, clutch, or thermo fan spiller? Both the PWR and the Koyo 53mm rads are quite a bit thicker than stock.

 

[spiller]

PWR are up there as far as quality goes, they were making radiators for a few F1 teams in the 2000s, not sure if they still have any F1 contracts though. Im running twin 12inch electric davies craig thermos. I wish it was a clutch fan or even hydro as they pull far more air but alas, they were deleted when the waterpump was replaced with the original engine conversion. I'm not sure how thick my "barn door" lol JAR is but its probably close to 53mm.

 

[1jz-Rolla]

What they do for F1 teams and what they do for us on the street are a bit different i'd say They sure are a nice piece of kit, but do they do twice as good (or even 10% better) a job as a reputable Koyo at half of the price?

I've had PWR radiators, and apart from the core itself (which are excellent), I can't be sure that they do much R&D with regards to end tank flow & fitment design parameters for the retail street car market.

I'm not sure i'll be able to squeeze my 2J clutch fan behind a thicker radiator - so still hung on that point as I don't want to go to thermos if I can avoid it.

 

[spiller]

yeah you raise a good point . i think core construction and quality control in that regard is more important than end tank design though. I mean its pretty hard to fuck up a tank, im no expert on the matter though. Are you still running OEM rad? I too was skeptical of the thermos and my skepticism has been confirmed by their function. I never had heat issues with my last JZA70 which still had the hydro fan. However I do like that electric thermos are maintenance free and are simple to fit/change as you please.

 

[1jz-Rolla]

Yep, OEM rad in this car for now, its doing the job well (has been re-cored a few years ago), the only thing that worries me slightly about it is the potential for old plastic end tanks to crack with thermal fatigue.

 

[HKS_TRD]

I've got the PWR rad on my car, and it still lets you keep the stock clutch fan. It also lets you bolt up the stock fan shroud and even the two stock thermos on the side, it was basically a direct replacement for the stock MA-70 radiator that still had all the holes for the factory shroud etc.

I got a good deal on the radiator from a friend who ran a business at the time, but that withstanding back when I bought mine there weren't that many other choices or if there were, shipping was going to make it a nightmare.

I would probably give a Koyo a try if I had to buy a radiator now as its so much cheaper. One thing to note about the PWR is the top tank holds alot more coolant than the Koyo, not sure of the implications but you can see what I mean in the most recent pics in my build thread.

I haven't had any overheating issues but I have stuck with the clutch fan, even with all the mods I am doing I have zero intention of going to thermos, you may want to go to a 2JZ clutch fan Simon with a stock MA-70 shroud, thats what Grant Warne went to in his Soarer after having overheating issues

 

[spiller]

Thats idea I would certainly entertain, might be hard to find the MA70 fan shroud though. I remember selling one years ago but ive never seen a good condition once since. I dont run a shroud at the moment at all but the clutch fan should still be effective even without the shroud there?

Does anyone know whats involved with using a 2JZ clutch fan on a 1JZ?

Im going to do a radiator flush tomorrow and fit my samco radiator hoses while im at it. If im motivated enough I might get started on a template for an under tray also. Dan does the factory under tray sit above the height of the lip? Surely the lip must dip below? Id like to run a tray from the bottom of the lip back to the sump essentially creating a flat bottom under the car but it might be difficult fastening the tray at the front as id need to create some sort of rigid structure to bolt it to.

I saw this under a GT-R at a workshop once and really liked the idea...

 

[HKS_TRD]

I think the shroud is still available new from Toyota. I'm not sure how well theclutch fan would work without a shroud. The lip does hang lower than the factory plastic under cover. There is a metal strap that runs along the lower edge of the bumper which it bolts to, I'm not sure if its the same one the lip bolts to but I have a feeling its not

 

[1jz-Rolla]

Thats idea I would certainly entertain, might be hard to find the MA70 fan shroud though. I remember selling one years ago but ive never seen a good condition once since. I dont run a shroud at the moment at all but the clutch fan should still be effective even without the shroud there?

Yep, as Dan said, you can buy the shroud new from Toyota, that's what I did when throwing the hydro fan in the bin Be aware though it is in two parts, as i'm sure you remember from your old one. Definitely a must even with the clutch fan, you don't want the fan pulling air from inside the engine bay and just circulating it around.

Does anyone know whats involved with using a 2JZ clutch fan on a 1JZ?

Depends which 2JZ it came from......... there are two bolt PCD's for the 4 studs on the water pump, varying in different chassis and across the NA, Turbo, and VVTi models.
On my motor, I wanted to replace the water pump anyway, so purchased an OEM 2JZGTE water pump, and then selected a 2JZ clutch hub & fan from the wreckers (chose the one that sat the fan closest to the motor - they have different offsets), as some fans (including the VVTi 1JZ) were hard up against the radiator.

Everything lines up perfectly with the 7MGTE shroud, however I did note on mine that one of the two lower bolts that holds the shroud to the JZA70 radiator was off by about 20mm, so had to make a small bracket. Of course on a generic aftermarket radiator, this won't be a problem.

Im going to do a radiator flush tomorrow and fit my samco radiator hoses while im at it. If im motivated enough I might get started on a template for an under tray also. Dan does the factory under tray sit above the height of the lip? Surely the lip must dip below? Id like to run a tray from the bottom of the lip back to the sump essentially creating a flat bottom under the car but it might be difficult fastening the tray at the front as id need to create some sort of rigid structure to bolt it to.

I'm a really big fan of this idea, and plan to do the same to mine..... once I finally find a lip

 

[spiller]

Right, well I have no idea what water pump is on my motor. I want to say its to suit a JZZ30 soarer but I can't be sure. In that case I'd need a clutch fan from a soarer I guess? I'm getting a bit ahead of myself as I am going to try other stuff first but it's nice to know what you're options are!

 

[1jz-Rolla]

Simon, have you seen these CF "hoods"?

http://www.advancarbon.com/#/item/1986-1992_toyota_supra_mkiii_intruder_carbon_hood/

For constant track work in higher ambient temps, having the vent behind the radiator could be beneficial for scavenging hot air from the engine bay. First one i've seen designed that way for our cars.

 

[spiller]

^^ have not seen that site before, look like some decent products. One thing im weary of with that design though, it looks like its just a hole with mesh over the top. I would prefer to see a raised section in front of the vent to create a low pressure area for the hot air to vent into. Agree? Otherwise, much more functional than most other bonnets out there ive seen. I wish they offered it in FRP though as im not a fan of the CF look and that's even more cop magnet.

I drained the coolant today, ran through a couple cycles of tap water until it looked clean then added a 50/50 (or close enough) mix of toyota red and distilled water. cooling system took on about 9.5L including radiator overflow. I also took the chance to fit samco radiator hoses i'd had laying around for a while. I went with black and eventually would like to change all of my visible joiners from blue to black.

Went for a quick drive to the hills again and temps didnt go higher than 105 but were much more stable around the 98 mark when I was driving hard at a decent pace. It seems to be the hill climb itself that makes the temps rise then they level off as the gradient levels off. I fitted my top radiator cooling panel afterwards (had to bore out a couple of the holes to accommodate the headlight adjusters and bonnet bump stops). Took some pics which I will post up when I get a chance.

I also spent a bit of time under the car (whilst flushing coolant) checking out where I could possibly mount an under tray. There are three very convenient threaded points on the subframe which must be for the factory tray. I will also use the bottom intercooler mounts as anchor points and will probably need to fab up a couple of angled brackets with welded nuts to secure it in the "winged" sections in front of the wheels. That would give me about 7 or 8 anchor points which should be plenty!

 

[1jz-Rolla]

Shouldn't matter without the lip - it could be better, sure, but the vent is already in the low-pressure zone of the bonnet already. Agreed on the FG vs CF though.


Looking forward to seeing the undertray

Cheers