Im going to be building a PP motor this year, tossing the turbo. I see alot of large dual setups, however Im thinking of running one very large oil cooler. It would be mounted parallel to the ground just in front of the radiator (if you have seen the 1st gen mazda comp manual, you know what Im talking about) This way I would still be getting maximum flow to each item, while freeing up the outer openings for brake ducts. My reasoning for this is also to save money, having to run extra AN oil cooler lines get very expensive quickly, this would cut down on cost.

 

Well the few coolers that are bigger than the stocker are quite expensive ($600+), and especially if you've already got AN lines on the stock single cooler, then it's really not going to be very expensive to plumb in another one, just a couple tee's, some metric thread adapters, maybe some hose ends and some hose.

 

If you have to ask.......

-J

 

Well this is why Im asking, Im not going to run the stock cooler. I know its a great oil cooler, but I feel for a 13b PP it would really have to work hard to keep my oil temps down. Most race cars I see run dual coolers, I was just wondering if one larger unit would be able to do the job of 2.

 

You want as many oil coolers as you can fit

 

be wary of adding multiple aftermarket coolers in series
aftermarket units may not necessarily flow the same pressure drops as the stock unit

adding two inline and making excessive serial pressure drops can make your oil pump work hard
( and failure of those not so cheap coolers under those conditions has been noted here )

while the rear plate may see normal pressure ( that's where the reg is )
the oil pressure coming out of the front timing cover may be pushing in excess of 20 psi more
( and potentially lifting the front oil overpressure relief reg , NOT good )

i am all for the twin coolers and the superior thermodynamics they bring
- but only if used as a pair hooked a parallel

 

Good advice.

Here is a great alternative to dual stock cooler setups.
Part numbers, prices and pics are included.
https://www.rx7club.com/forum/showth...44#post6290444
This worked better and fits in the stock location fairly easily.

 

Didnt ever think of using my two stock ones in paralel (sp?)...I was just going to put them in series. I think now, I will do this instead. Just need to get the thermostat, and the AN fittings...

 

The stock coolers have internal thermostats, so there's no need to add an external one.

 

The stock coolers are also a dual pass, crossflow design, which creates a substantial pressure drop across the cooler. For high rpm engines where high oil pressure is essential, the stock cooler can definitely be improved upon.

 

If you run 2 coolers in parallel you'll drastically reduce the pressure drop. It'll be something like 1/4 the pressure drop of one cooler (half the fluid going half as fast through each).

 

I was advised against coolers in parallel by a road racer, who pointed out that if (when) one runs cooler, the oil will be harder to pump through *that* cooler, or rather the oil will be easier to pump through the hot one, so the cool one doesn't see as much oil flow as the hot one... and it's a positive feedback loop until it finds its equilibrium.

 

IIRC at least one person has tested series and parallel and found that the parallel coolers ran cooler than the series ones.

 

I originally ran 2 stock coolers in series years ago and then switched them to parallel when I learned more from others. The setup in parallel ran significantly cooler though I do not remember by how much. I did not notice a change in pressure though iirc.

Even better than that setup was one upgraded cooler. In case you missed the link earlier:

https://www.rx7club.com/forum/showth...44#post6290444

 

You shouldn't notice any change in pressure, since you're measuring the regulated pressure downstream of the coolers. You'd only notice if they're so restrictive that the pump can't keep up. You would notice a difference if you measured the pump output pressure before the coolers.

 

Hey bro, do both. When I put them on my car, the drop in temps were crazy. As you know I just went road racing for the first time. After a session of laying into it my temps never went over 160 and thats even with a FMIC which everyone says is bad for road racing.

 

same difference. if you want to free up space for brake ducts then do one. it's actually a pretty good idea - a v-mount with a rad and an oil cooler.