Jump to content
The mkiv Supra Owners Club

Coolant bypass restriction to aid overheating on track


halllon

Recommended Posts

Hi guys,

 

We are a bunch of guys drifting our Supras. Some have single kits, some have Koyo radiators or higher capacity rads and all of us have different oil cooler setups. However, all of us are struggling with the 2JZ building excessive coolant heat when compared to the cooling setups on turbocharged BMW S50s and M50s and Nissan RB engines.

 

What is causing the excessive heat buildup of 2JZ engines?

 

An engine tuner I know found out that some 2JZ engines are running a restrictor plate in the coolant bypass found on top of the water pump. Have any of you guys tried the same measure to aid cooling capacity?

 

Looking forward to hearing your thoughts on the matter.

 

Cheers in advance.

Link to comment
Share on other sites

Stock rad, stock fan, stock fan shroud, and stock bumper with stock air duct into rad? Fiddle with these at your peril. In my opinion, and those professionally involved with radiator design and manufacture, the Koyo rads are LESS efficient than stock. Remove the standard duct to the rad to fit a FMIC and cooling goes to hell. Air will just bypass the rad core. Electric fans DO NOT move anything like as much air as a standard engine driven one. Do you want aggressive looks and a boiling engine, or stock (boring? :) looks) and a cooled engine? IMHO these "drift cars" are often built on looks and with scant regard to sound engineering from a cooling point of view ;) Revise the cooling back to a more standard set up and see what happens. You have low air speed from forward motion and high engine thermal loadings, not a good combination. At worst I'd say locking the stock viscous hub up should sort a stock system for your usage. YOU MUST RUN A `STAT!

Link to comment
Share on other sites

I would have thought using a V mount IC which will take the restriction off the rad, so long as the bumper and bonnet design allows enough airflow, although i agree with CW as to the std fan etc, i'm sure there are electric fans that can shift as much or more air, however it might be a good idea to actually find a accurate figure for the std fan air flow, and go from there.

 

Just another thought, i would hazard a guess that the std fan and rad core design are closely related, so a different rad core design and matched electric fan may give the advantages needed.

Link to comment
Share on other sites

You'd need a 3 or 4 hp 12 volt electric motor to drive a fan with with same same airflow capabilities as the stock one. Just look at the size and pitch of the stock fan's blades. Such a motor would be huge and heavy, with a current draw like a truck starter motor. I remember Andy Middlehurst used to race the R32 Skyline endurance cars with stock rads, stock fans, but a "seized up" viscous clutch. Even in hot climates they did 24 hour races with no water cooling issues. People would be better divorcing the oil cooling from the water system and adding a good air to oil lubricant cooler. This would unload the water rad significantly. Too much ill considered fiddling goes on :)

Link to comment
Share on other sites

People would be better divorcing the oil cooling from the water system and adding a good air to oil lubricant cooler. This would unload the water rad significantly. Too much ill considered fiddling goes on :)

 

Name a good oil cooler kit that does this :D I noticed my oil temps climb when hooning and take a while to come down, so I've always wondered about this move.

 

-Ian

Link to comment
Share on other sites

On my GTS-t I use a 32 row cooler, but it's a serious track day car now. For fast road, occasional track usage an 18 row cooler on dash 12 hoses and fittings, with the stock oil to water set up removed, with cooler in good air flow should be more than adequate. Use a thermostatically valved adaptor plate (I keep them). Serck, Think, Raceparts, Demon Tweeks all sell good oil coolers. Use proper braided hose and fittings, no Jubilee clips on oil systems! Given the plethora of front bumpers around a single fit all kit is a none starter, you need to adapt to what you have. Remember air has to exit as well as enter the thing, so a GOOD pressure differential across the core is vital.

Link to comment
Share on other sites

Are there any figures for the stock fan system Chris? be interesting to find out, i agree it should shift a fair bit of air, in theory, but could it be an over designed unit in response to the rad core design, bit like trying to suck water through a cigarette filter maybe? it is pretty fine.

 

As for oil coolers i run a 19 row with -12 hoses and thermo take off plate, the cooler is sitting just below the washer tank, with good airflow in front and hopefully good enough at the wheel well (low pressure) to give reasonable cooling, brings my oil temps down from around the 120c mark to just over the 100c mark on full boost runs.

 

But i do have an oil cooled turbo, and i'm thinking that having a water cooled turbo may be one reason for high coolant temps, and show up a tired or bad designed non standard system.

Link to comment
Share on other sites

Thanks a lot for your input Chris, it seems we are much better off taking the K.I.S.S. approach. :D

 

We've now removed the SPAL double fan & shroud and mounted up the stock rad shroud and a locked stock visco fan. There's a remarkable difference even at idle and we are looking forward to testing the new setup. We have made a custom duct to the upper half of the radiator which made quite a difference to cooling capacity back when we first made it. We think that the next step better be getting a slimmer FMIC core and then make a new rad duct from beneath the FMIC to the lower half of the rad.

 

Looking forward to testing the setup now, cheers again. :)

Edited by halllon (see edit history)
Link to comment
Share on other sites

i know electric fans are one of Chris's pet hates and obviously the devils work ;), but from memory the stock viscous is around the 3200 cfm mark, this is easily within the range of 2 decent quality electric fans and i am sure the more powerfull ones could easily surpass this figure :blink: could someone care to explain or are the electric fan manufacturers telling porkys

Link to comment
Share on other sites

3200 cfm:blink: are you sure? seems a hell of a lot, but i agree that there are fans that could equal or better the stock, provided the ducting is taken care of, and as i said V mounting the FMIC will make a big difference, its not just to avoid damage.

I don't think Chris takes drifting seriously, but there is some pretty clever stuff involved in keeping things cool and working right, whilst going sideway's at 100MPH

Link to comment
Share on other sites

3200 cfm:blink: are you sure? seems a hell of a lot,

I don't think Chris takes drifting seriously, but there is some pretty clever stuff involved in keeping things cool and working right, whilst going sideway's at 100MPH

 

i have a set of electric fans (un-fitted) so did quite a bit of research and the 3000 + sticks in my mind, cant remember where i saw it, it may even have been on supra forums (US), and yes your right the drift cars have to have top notch cooling due to the high rev, low speed (airflow) issues

Link to comment
Share on other sites

I run the Koyo rad and AAP electric twin fans on 3 cars , the fan shroud surrounds the rad very well and i havent seen anything more then 95 degrees on a very hot day round and circuit yet. I have ducting on my front mount . I have also placed a 14 inch spal fan on behind the greddy 4 row , this comes on if the temps ever exceed 95 degrees. I also run a TRD thermostat, i believe it opens at 79 degrees.

Link to comment
Share on other sites

If the stock fan is rated at 3200 CFM, this figure is probably based on the viscous unit working as intended... Surely the fan pulls a lot more air when the viscous unit is locked up.

 

I would suspect that that figure is for the viscous fully locked, if you are still having trouble, i would also look into V mounting the FMIC, have a look at Ryan's track car project thread, that has a semi V mount FMIC, this configuration can also free up some space to use electric fans on the IC.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.