Interesting /6 cooler set-up, RX-7 cooler in the lid. Options

[dion9146]

Oil cooler on a /6 should always be in the front.

Always.

I respectfully totally disagree. I've built at least two conversions with external oil coolers that were not in the front. Neither one runs too hot, both are still going strong one is 15 years on the conversion, and one is 8 yrs.

What is your basis for "always"?

I've got to agree with Perry on this one. My 3.2 never got above 210 this year even during the hot-ass Kentucky Summer we had. I regularly drove it at 80+ mph on the highway, and my aux oil cooler is tucked up under the right rear fender. If I were tracking it, than it would probably be a different story.



Ok, that's enough. One post per year is all I'm allowed at this point....

Dion

[IronHillRestorations]

Hey Dion! That's right where I put the oil cooler on my very 1st 6 conversion.

Works very well there without 20 feet of hose and cutting access holes. It also preserves one of the best things about a 914, the front trunk is totally intact.

[andrewb]

Nice clean install! Whatever works is the perfect solution. Sorry all you armchair engineers

(IMG:style_emoticons/default/agree.gif)

Everyone seems to be assuming that air will be flowing downwards through the cooler - which it will be with the car at a standstill (ref JP Steins test with a towel) - but when the car is travelling forwards the area behind the rear window will be at low pressure and will therefore draw air up through the grill and oil cooler from the engine bay. As long as the cooler is hotter than the air from the engine bay - which at 200 degs it will be - the cooler will have an effect.
Looks like a tidy, effective and elegant solution to me.

[jaybird840]

Henry,
Good to see you here! I l like the install. For those of you that don't know Henry, he is a highly respected member on the bird board, and is a top-notch P-car mechanic. He does an oil-pump modification for sixes that is the schnitz. I just put one of his modded pumps in my 2.7RS build. Let's all hope he hangs out here more... There's tons of info in that brain, especially for us six guys...

[J P Stein]

Per Anderson's 911 book, the 911 fan delivers between 1390 and 1500 liters of air
*per second* (I'll assume that's at wide guts) depending on which ratio fan pully is used. Since the engine is sealed off pretty well from all other sources by the engine tin, just where do you think that air is coming from?

Any rational answer is acceptable to we armchair engineers. We ain't near as smart as professional hammer mechanics.

[JmuRiz]

Henry,
Good to see you here! I l like the install. For those of you that don't know Henry, he is a highly respected member on the bird board, and is a top-notch P-car mechanic. He does an oil-pump modification for sixes that is the schnitz. I just put one of his modded pumps in my 2.7RS build. Let's all hope he hangs out here more... There's tons of info in that brain, especially for us six guys...

Cool, I may need to find out the specifics of this mod. I'm just starting to accumulate parts for my 6 conversion.

[ArtechnikA]

...when the car is travelling forwards the area behind the rear window will be at low pressure and will therefore draw air up through the grill and oil cooler from the engine bay.

Will this myth never die ?

Why do you think the '73+ cars got deflector flaps _under_ the car ? What is the purpose of the airseals around the engine? There is a reason the intakes and cooling fans (/4 or /6) are above the airseals...

The area behind the window has "lower" pressure than some places but it is not lower than the air pressure _under_ the car.

Air does not flow up.

(Some folks with water conversions have forced bottom-up airflow with scoops and modded (i.e. removed) airseals. We're not talking about them...)

[andrewb]

...when the car is travelling forwards the area behind the rear window will be at low pressure and will therefore draw air up through the grill and oil cooler from the engine bay.

Will this myth never die ?

Why do you think the '73+ cars got deflector flaps _under_ the car ? What is the purpose of the airseals around the engine? There is a reason the intakes and cooling fans (/4 or /6) are above the airseals...

The area behind the window has "lower" pressure than some places but it is not lower than the air pressure _under_ the car.

Air does not flow up.

(Some folks with water conversions have forced bottom-up airflow with scoops and modded (i.e. removed) airseals. We're not talking about them...)

I stand corrected - I forgot about the tinware and seals.
Thanks for the friendly explanation.

[brer]

a 200 degree surface can put out about 320 btu's an hour per sq/ft.

figure the surface area of the cooler, calculate the cubic ft. per hour going through that fan, figure the heat transfer/delta T equation taking into account the pressure and water content of the air and you will likely find that the amount of btu's transferred per second won't even be enough to get you 1 degree of air tempertaure increase.


i've sized a few heating systems in the past year, meh

[sean_v8_914]

speculation is fun. well thought out theories based on what we think is happening based on more speculation is also fun
I had alot of thoughts similar to those presented here but the data pointed out reality.
lid mounted coolers in 2.0, 2056, 2270 type 4 lowered oil temps on extended freeway runs, AX, DE and time trials. average reduction was about 20 deg. no fan
Lid mounted cooler on a 2.7 six was less dramatic but prevented temps from running away while up at willow running 30 min run groups.
head temps did not care a bit. I saw NO difference.
there are other racer-members here who had similar rusults.

[IronHillRestorations]

The only problem I can see with a lid mounted cooler, is pre-heating your cooling air.

Part of the oil cooling is just running the oil through the "radiator" of the oil cooler. Just like the brass trombone coolers and the 21 row brass coolers, it's the heat transfer running through the tubing that cools the oil.

You get into a problem when you get to the extreme thermal efficiency of the oil cooler, and that's where you need the extra air flow over the cooler. I was able to direct mount a 7" spal fan right on the oil cooler, similar to the set up that Dion shows in his post.

[J P Stein]

Here's a pic of my front cooler. Feeds at the bottom and expells at the top, all lines are well below the normal running full line of the tank, all 90 deg fittings are of the radiused type..no hard 90s here...there are 5 of them in the system I feel the is a sound reason for doing all this detail stuff but won't bore you with any armchair engineering. The thermostat was also the best available.....a pic of that also. This is no place to skimp said the CSOB. (IMG:style_emoticons/default/biggrin.gif)

BTW, all this stuff including a stock oil tank with fittings is now for sale.

[JmuRiz]

Did you sell the motor only? PM me the details if the conversion bits only are for sale (since I already have a motor but nothing else).