2G parallel dual oil coolers - Tstats needed?
 

For my ITS race car. I've fabbed up a parallel dual oil cooler setup.
Do I need to retain the thermostat/bypass valves in each of the coolers?
And I do know if I remove them I have to plug the hole. I'm just wondering if I even need them at all. My gut instinct tells me no.

Any opinions?

TIA
Crispy

In our shop we have an EP car that has two coolers in parallel with the t-stats removed from both coolers. The oil gets to 210F and stays there. The driver/owner figures that no t-stats is two less things to screw up a race when one fails. I'm an doing a similar system on my car with t-stats at first to see if they help that much with warm-up, I'll probably end up with no t-stats and cover part of the opening in the grill to control temps.

if you remove the thermostat without blocking the bypass, isn't a lot of the oil bypassing the cooler?

i'd leave the thermostats in there. they ARE there for a reason!

Just like Crispy said,"And I do know if I remove them I have to plug the hole"

In a race car it can be a .50 part that takes you out first place when it fails. Two fewer moving parts on the car is good. I can control the cooling without the moving parts, it just takes some research and testing. Yes, the t-stats do something, and I would never remove them on a street car, but racing is a whole different game. I even run a blanking plate with a 7/8" hole instead of a water t-stat. That is better than nothing at all because it slows down the water flow in the engine. Covering up part of the grill to keep the engine warm also helps aero.

Hey Crispy,

Could you go into a little more detail on how you mounted and plumbed the second cooler? Was it similar to how Paul set up his rig, except parallel instead of series (and not cutting a hole in the nose of the car :) )? I'm going to eventually have to replumb the oil feed line in order to reinstall the front headlight assembly, so I was considering going parallel instead of series at that point.

Any good URLs or references would be appreciated.

-bill

What he said. I remove the t-stats and plug the hole with a bolt and lock nut. Trust that much more than a t-stat.

Carl still never posted his write up on his dual setup!

Bill, et al,
I never had a chance to see Paul's setup up close...only through the BIG holes lin his fornt bumper - which are not legal for ITS.

I'm mounting mine low and kinda in front of the OEM location. I made some broakctes with big hose clamps to kinda hang it *rigidly* from the front Xtube. I'm using two AN "T"s to slip the flow - yeah I spent freakin' $250 on fittings for this setup so it had better damn well work! I was seeing 250+ oil temps last summer.

Thanks for all the help guys. I'm thinking since this is a parrallel setup to perhaps run one cooler WITH the Tstat and one without. That way even if one Tstat fails I have one cooler I KNOW will work and I don't have to wait 45 minutes for it to
warm up. I may later remove the second Tstat.

Regards,
Crispy

I'm curious.

I've heard that oil coolers should be mounted in series instead of parallel, because one will inevitably run cooler than the other, and the hot one will see most of the flow because the oil is hotter and therefore thinner and easier flowing.

Old wives' tale?

I'm considering running "more than one" oil cooler (two or three, depends on how much room I can make) and parallel would be easier to plumb in such a way as to bypass a holed one than series would be.

Crispy, what was causing you to run 250+ temps?

Do not mean to thread jack, but do you think it is critical to have dual oil coolers
for an occasional track car?
John

Depends on how hard and how long your occasional use is. I don't think I'd put an RX-7 on the track without an oil temp gauge. If your oil temp doesn't go above 220 I wouldn't worrry about it.

Fubawu, if you have done anything that makes your engine create more power the answer is yes to dual or at least upgraded cooler. You can get your oil pretty hot under track conditions in about 8 laps. We had 280F on the race car once before the dual set-up.

Peejay, I had to go and learn something AGAIN because of your thoughts. :D I have always run coolers parallel because of ambiant to fluid temp differences. The second cooler won't be working as efficiently for you because of the lower temp difference from ambiant to the fluid if they are series. I found some info on measuring viscosity the temps they usually measure at are 40C and 100C. I don't know how much difference there would be say between 100C and 125C in flow but it doesn't look like much. If both coolers are seeing similar air flow I wouldn't think there would be much problem. It could be left over from single viscosity oils.

So, this myth..... Plausible or Busted? :dunno:

Ah, but you're supposed to use straight-weight oils because they have no huge viscosity-modifier additive package, so they foam less. At least that's what I've always been told... haven't had a pressure problem yet with good ol' 5W20. Then again I'm only revving to 8k, making maybe 130hp on a really good air day, when the planets are properly aligned (the trick is to set up Mars with extra toe-out)

Arg, I hadn't even *considered* the efficiency factor. I guess the proper thing to do would be to instrument oil temps coming out of each cooler and duct air as necessary. (But that sounds like *work*...)

In free air it wasn't an issue but when you run nose to tail behind someone you significantly reduce the amount of foreced airflow into the nose of the car. It is under these conditions that all temps rise. Water temp not so much as there is the fan to mechanically draw aire flow through but the static oil coolers aren't so lucky.

I've found the same thing on my FD at HPDE's. Even with bigger dual coolers if I get bogged by someone not watching thier mirrors I can see an increase in oil temps if i don't bob out into some clean air when I get a chance.

FWIW I'm trying to work separate ducts for each cooler even though one is behind the other - the front getting air from the nose and the cooler to the rear getting air from the lower opening under the nose from the lip/splitter. I haven't actually done it yet but it looks entirely feasible.

Crispy

If you are going to be at VIR for Mazda Drivers next month, you are more than welcome to take a look. But if I show you mine you have to show me yours! ;)

Paul mounted the second oil cooler in front of the radiator, right behind the nose and (as you mentioned) cut holes in the bumber cover to provide air.

Front view:
http://www.ee.duke.edu/~wrankin/rx7/...es/Image5.html

He then fabricated a divider so that air passing through this cooler gets ducted over the top of the radiator.

Top view:
http://www.ee.duke.edu/~wrankin/rx7/...es/Image3.html

From looking at things, it appears possible to rework some of the ducting so that the cooler draws air from the standard openings and then I could close the holes up. I would like to run this car in ITS eventually, so I figured that I would take a season or so and get things sorted in that regards.

I hate to keep saying stuff like this but...Speedsource says to run them in parallel and that's been good enough for me. I'm quite sure they've done the research to justify the setup.

Crispy, what you plan to do sounds a lot like the way I mounted mine. Only word of caution I have to mounting the 2nd cooler is to be very careful to not cut flow to the radiator. The 2nd cooler should be moved well down from the stock position. I made tabs from aluminum to mount the 2nd cooler from the same tabs that the stock position cooler hangs from. The 2nd cooler being as low as it is means the stock plastic undertray won't work anymore. This required the switch to some kind of undertray/splitter. I chose the ISC piece after having one other piece prove to be too fragile. The ISC piece is highly recommened as it's been use to cut grass on several occasions and has never had to be repaired. It sits low enough to provide proper clearance for the 2nd cooler.

Here are some crude pics of my coolers. It's hard to see how they are mounted or height relationships between the two but it's very hard to get a good photo inside the nose of the car.

Again, IMO pull both thermostats. Why is it EVERYONE pulls the thermal pellet out of the e-shaft when building an engine because they are failure prone but when a guy says they pull a t-stat those same people jump their shit? You really won't have any problems with warm up. We'll start the car the morning of an event and let it idle for 5-10 minutes to get the fluids warm and that's it for the day unless it's very cold. If it were a street car where you wanted to jump into and go on a 20* winter morning then, yes!, it needs a t-stat.

http://www.ludwigmotorsports.com/rx7/cooler.jpg

http://www.ludwigmotorsports.com/rx7/cooler2.jpg

http://www.ludwigmotorsports.com/rx7/cooler3.jpg


With this setup and proper ducting we see temps in the 190* range on most days. When ambient temps are 85*+ and we're racing in traffic temps have climbed to no more than 210*. Before the dual coolers 250* was normal. Only ran the car that way for two events and it was enough to torch the oil control seals.

Proper ducting is key. So many people say that for good reason. Speedsource takes a novel approach to mounting the 2nd cooler. It gets layed flat on the bottom of splitter over a hole that is used to exhaust the air under the car. There is a seperate duct to draw air and funnel it over and through the 2nd cooler. The benefits of this setup are nice but I'm happy with my temps so I've never thought about changing the setup. If you run in the SE or SW where ambient temps are consistently very high it might be worth it to look at this setup.

Carl,
This is pretty much exactly how I have mine mounted. Thanks for the pics. My second cooler doesn't sit quite as low but it essentially sits right on the stock plastic under tray.
As for torching the oil control seals I'm sorry to have to admit I just did that. Car ran the last event like a champ and at the end of the weekend (*after a proper cooldown*) I rolled it up onthe trailer and left happy. Fast forward to the following weekend when I go to move the car off the trailer and into the garage and it had magically become the worlds most effective mosquito fogger with liquid oil dripping out of the tailpipe. Crap! So I'm in the midst of an engine swap right now :(

Thanks for all the great advice all. Carl I may be pinging you for more advice ;)

Regards,
Crispy

Thanks info guys, this has been a great discussion!

Crispy - good luck on the motor swap.

-b

Bill,
Shoot me an email offline...I'd like to chat.
Regards,
Crispy

Cool. But I ain't Carl. ;)


Chris

in paralel doesnt it mean that the oil can go through one or the other oil cooler? and in series means it goes through both? so wouldnt the series be ideal, or would it be too cool in certain situations?

jgrewe where in florida do you live. im in orlando and am trying to get into road racing.

C. Ludwig whats the book speedsource? sounds like something i should be investing in

Chris...Carl...alls I know is you gots the answers I'm after Mr. C. Ludwig. :)

Queue thread hyjack...

Next question: I'm going to run a straight premix and ditch the OMP (block off plate installed). What can be done to trick the ECU into thinking the OMP is still there so it won't go into limp mode when the OMP is disconnected?

Humblest apologies,
Crispy

Well, my motor is out(cracked rear iron at the dowel land) after running 25psi of boost in heavy traffic (race track) on a ~90* ambient day. My coolers are in series, but I am changing them to parallel. The theory you are refering to is refered to as the Delta T, or difference in temperature between ambient and the oil in this case. I will post up some pics this week of my set-up, just sub parallel for series. I also use a deflector to divert airflow, but it is over the FMIC, and into the oil coolers, and radiator. The radiator is a dual pass Griffin with an AST system. All this, and I still overheat in traffic... I am rejecting heat from ~480rwhp, so it is a bit challenging. I also have the "holes" in the front bumper. Carl

There is no way to fool it. You either run with the OMP plugged up and no actually pumping oil or use it as it's designed. Only way around limp mode at this point is a standalone. PM Henrik and ask him where our S5 NA Rtek is with the limp mode "feature" deleted. I'm tired of asking. :)

BTW, I cannot exactly tell from the pictures, but if you have mounted one cooler in front of the other you are completely defeating the parallel set-up benefit as the air is heated by the first cooler, thus decreasing the difference as in an "in series" set-up. I'd like to see the Speed Source set-up, it sounds interesting. Ideally the coolers would be outboard, but cost of two correct size coolers as good as the TII coolers is over 500.00 IIRC, not to mention I have brake ducts there. Carl

I'll get pics of my mock-up. I welded some angle iron tabs/brackets to the round frame tube that runs between the frame rails. I have two going straight down and two going up and angling forward to make the cooler follow the radiator angle. I use the stock isolator rubber mounts and have the top cooler flipped so the holes are on the pass side. The lower cooler dumps air below the rad with a little shrouding to guide things along. The upper cooler is flat up against the radiator under the core support. I split the oil coming from the engine using a huge Moroso remote oil filter mount that has two in/two out. I just used one in/two out. All of this is custom shrouded with aluminum to make sure all the air that comes in the nose goes through coolers to get out. There is also some deflectors in the shrouded area to create higher pressure in front of the oil coolers to keep the air from taking the easy way out through the rad only.

I'm sure Carl and C.Ludwig will second that sealed shrouding is very important for a good cooling system.

Well crap. Guess I'll leave it hanging there then. Thanks
Crispy

For my setup each cooler will get it's own fresh cool air supply even though one is placed behind the other. From what Chris said this is also what Speedsource is doing albeit slightly differently than me
Crispy

wrankin, my setup is basically the same on my T2. I however put my oil cooler alittle further up, and made my holes alittle bigger for less restricted airflow. Im thinking of doing the dual setup, but Im not a dedicated track king like carl. If I can find another cooler for cheap, I will try the dual system since I need to order my AN stuff anyways.

I am in the exact position. I am hitting 250°F in like two laps at only 5psi of boost. Mind you I have a greddy VSPL FMIC installed and that takes alot of air flow out. (My car is running haltech e6k To4b60-1 etc)

I was looking at the parrallel oil cooler setup but wondering if I have to make up new lines and fittings would it not be better to purchase a bigger better oil cooler?

What about reverse hoods?


http://www.bakerprecision.com/setrab.htm

You're really not going to beat the quality or BTU potential of the stock cooler. Plan on spending well over $500 for anything close. In your situation the lack of airflow means you can have the uber cooler and it wouldn't be enough.

IAN,
Your issue is not the size of the cooler but it's location (relative to the FMIC) and the lack of airflow. Fix the airflow and your problem will go away.

Consider also that the FMIC is also reducing airflow to your radiator. It's the radiator and oil cooler combined to keep temps down. Get the water temps down as well and the oil temps will come down also...similarly get oil temps down and down will come coolant temps.
Sounds like your oil temps are getting so high so quickly you haven't had the time to overheat the coolant also.

FMIC's are the scourge of road racing ;)

Crispy

Im going to ditch the stock oil cooler and go to this much larger unit. Its an inch and a half thick and is about the size of the stock radiator. Its also a double pass and will add a lot more oil capacity. I have the mounting almost figured out. Im going to make a special aluminum frame with scoop so that it can mount flat (parallel to the road) infront/beneth the radiator. It will scop air throught it up into the engine bay.

CJG

More airflow eh. I will have to look into this. Not sure how to introduce more air flow.

You are right thought. Seems like my oil temps increase so fast the coolant has not had time to catch up since it still appeared normal. I was going to install a lip but not many front bumper lips for the s4:)


thanks for the input. I will post pictures/description if I do get this solved.

And herein lies the problem with FMIC's. They are air hogs.

The radiator at least has the ability to *pull* air through it by using the fan as temps increase whereas the poor oil coolers have to rely on natural airflow.
Add to this the radiator is a larger heat sink and will thus be able to absorb more heat energy before saturating. The smaller oil cooler will saturate quicker and thus oil temps will rise faster. This among other reasons.

I have an S5 aftermarket lip on my S4 bumper. It's not a perfect fit but it does fit.

Good luck, you've got a tough problem to solve.
Crispy

kinda digging it back up, but as for the T-stats, what Ive come to gather is you dont need them, if you drive street, just let yout car warm up, if you dont like it, keep the thermostats. NOW my question, shouldnt you really only need 1 stat? For the first cooler receivning oil? That way when temps reach limits, and the stat opens, it will alow oil to run in the first cooler, then pass to the 2 cooler,which the T stat has been blocked off. Im sure once I mount my 2nd one, and begin plumbling everything, it will make better sense.

The oil cooler stat acts as a bypass. When the oil is cool, it flows from the inlet straight to the outlet. When it's warm the bypass is blocked off, and the oil is forced to flow through the cooling fins.

Yes, well I kinda answered my own question there, once I read over it. I forgot you could block off the one, and force oil through it at all times, which I would assume to be more fail safe, and a over all Idea. Espically since I would assume most people who do go with a dual setup wont be driving the car everyday.

It is key to note that the t'stat is a bypass valve and if you do remove it you MUST plug the hole with a bolt and nut or else oil will bypass the cooler ALL THE TIME.

As for only needing one t'stat, with the coolers in **PARALLEL** each cooler gets it's own oil feed so *if* you wanted temp control two t'stats would be needed.

Crispy

And, as I think our earlier poster realized, if the coolers are in series then you still need to be running both thermostats if you want them to actually function correctly.

Just restating the not-so-obvious. :)

-b

Bill and Crispy, My oil cooler set up was patterned after Dave Lemons setup. He doesn't have the hole in the front bumper but he feeds air through the headlight opening with a duct. He said being in series causes less of an oil pressure drop than running them in parallel. He has pictures on the Mazdatrix websight.. P.

Hey Paul, thanks for the pointer. I went and found Dan's pictures.

( for those who are interested: http://www.mazdatrix.com/faq/epconv.htm )

-b

Funny. These two pics show Lemon's car setup in parallel.

http://www.mazdatrix.com/faqpics/roadrace/ep01123jb.jpg

http://www.mazdatrix.com/faqpics/roadrace/ep01063ab.jpg