Fitting B&B cooler with RSR bumper...

[Moses]

I am getting a GT-racing RSR bumper for my narrow body SC. The cooler opening dimensions are slightly bigger than the outside dimensions of the B&B 20" cooler.

Many people on this board who have installed these coolers remark on the limited space behind the cooler for air flow. I do not want to cut into the trunk. The B&B cooler is only 2 1/4" thick. If I mount the cooler up inside the valance cooler opening I figure I should have plenty of room in back for air flow. Am I wrong?

I am also installing a Carerra cooler in the fender. After reading about this task in "101 projects" I am not looking forward to this adventure. Oh well, here I go!

[Tyson Schmidt]

It'll be very tight. You'll have to get it right up against the front valance so that practically touches it. Not the safest of positions in the event of an off-track experience

Don't forget about oil line clearance. There still may not be enough room for the oil lines and fittings to clear the front pan, even with the cooler as far forward as possible. You'll just have to wait for the bumper to get there, and do some trial fitting.

TRE has the steel piece to weld into the front pan which is a copy of the RSR Factory piece, if it turns out that you need the room with your particular bumper. Check out: www.tremotorsports.com and here's the exact page: http://www.tremotorsports.com/prods_02.html

[911pcars]

I would suggest installing it first w/o cutting any sheet metal and see how it goes.

Sherwood Lee
http://members.rennlist.org/911pcars

[Moses]

Originally posted by Tyson Schmidt
It'll be very tight. You'll have to get it right up against the front valance so that practically touches it.

What about a bracket that allows the front of the cooler to actually sit inside the valance cooler opening? (Mounted to the tub, not the bumper, of course.)

[cary]

You have to fabricate a frame to stand the oil cooler out from the tub. And it can't be a rinky dink deal.
That's been my hold up.
It has to be fairly solid to keep the vibration to a minimum.

Mark, I've been wanting to shoot some JPEG’s for you. To show the cavity, but went to Spokane for the weekend.

Maybe tonight if I get home early enough.

[Bill Verburg]

You want to stand the cooler as far forward as the bumper cap will allow. I used a nerf bar under the f/g cap which also serves as the cooler mount. On mine there is not much room behind the cooler but it is enough.


Get the cooler w/ straight ends, mine has an ~18&deg sweep back which is tough to fit at the corner of the tub.

To make fitment easier and since you will have the Carrera cooler in the fender a smaller spoiler mount would be all thats necessary.

The B&B spoiler mount is all the cooler you will ever need except in stopped traffic on a really hot day where a fan would be useful. Temps stay at or barely above thermostat opening temp of 80&degC at all times.

[ted]

I agree with Sherwood, try it first without cutting your car. Related issues…….

Mount your front spoiler as far forward as possible to allow more room behind your cooler for the heated air to exit. A large cooler may be wider sometimes than the cooler opening on the spoiler. Due to the curve of the spoiler it may require the cooler to be set slightly back from the front opening.

With some spoilers and with the B&B oil cooler mounted as far forward as possible you may have less than an inch of clearance between the rear of the cooler and the metal front of the trunk. It will help cool the oil though the cooler may not operate at full efficiency.
It may be enough for your car, outside air temps and driving style.

With the cooler in the far forward position it is more vulnerable to damage. Another plus for mounting it back in the car. The B&B would be expensive to replace.

If you decide to cut your car (mine’s a T so I did) you will need a simple sheet metal plenum to deflect the heated air out of the trunk. Most deflect the air down right after the cooler. This works fine though it may lift the car slightly at high speed. Race cars normally duct the air up through the hood to compliment the front spoiler/splitter.

Here’s a theory I tried. I talked with Dave at TRE (I think Tyson works there?) and he suggested exiting the heated air into one of the front inner fender wells. So I had a 20x7 tin plenum made and attached it to the inside and front of the trunk behind the cooler. On the drivers side a 4 inch duct now goes from the plenum to the driver’s inner fender well. This duct enters the fender well in front of the front brake (another body cut). My front batteries have already been relocated and the stock boxes filled.

*At least my cooler ducting should not be responsible for any lift at speed.

*The front brake may receive a little more air for cooling though they are ducted already.

*The 4 inch plenum duct may slow the air flow slightly helping the cooler’s efficiency.

*The cooler is mounted deeper in the car for more protection during off track adventures.

*Since the cooler is now back 3 inches from the spoiler opening I plan to make a simple front cowling from Delron plastic to direct the air into the cooler.

*Since I track my car in the summer I kept the Carrera fender mounted cooler plumbed in series with the B&B front cooler.

Dave at TRE offered to do the installation for a very reasonable price. If you are close to the LA/OC area you might get an estimate from TRE.

[pbs911]

Are the fittings on the B&B 12 or 16AN? I heard that when you run a front cooler in series with a fender mounted unit that the 16 AN provides too big of pressure drop, whereas the 12AN size at the front cooler keeps the oil pressure at a steady level. Of course this is not the case when you run ONLY the front mounted cooler.

As for cutting the front, I will not be cutting mine. I have 3.5 inches between the RUF bumper cap and the body, allowing about .5 to .75 inches from the rear of the cooler to the body when using an oil cooler that is 2.5 inches in width. I imagine you would have about the same. How much space do you need behind the front mounted cooler to get effective oil cooling?

[Chuck Moreland]

Paul

The -16 fittings are larger than -12. It is the -12 fittings that are restrictive, and the problem is compounded when two coolers are placed in series.

The -XX refers to the number of 1/16 inch of diameter. Hence -16 is 1 inch, -12 is 3/4 inch. This is the hose size, not the fitting size which is smaller.

[pbs911]

The -16 fittings are larger than -12. It is the -12 fittings that are restrictive

Chuck, that's exactly what I am refering too and completely agree the -12AN fittings are too restrictive if used on a single oil cooler (e.g. single fender mounted unit or front mounted unit).

However, when running both of these coolers in series does using the larger 16AN lines / fittings on both the fender and front mounted cooler cause the oil pressure to drop below factory specs? And if the pressure does drop with the extra cooler, would it not be better to maintain the higher oil pressure by using the 12AN fittings at the front mounted cooler and the 16AN fittings in the fender mounted unit? From the conversations with racers, it seems like this is the recommended set up?

[74911s]

i originally had a narrow body rsr front bumper on my 77 with the a fender mounted 28 tube cooler and a nose cooler mounted as far forward as possible. it worked good on the street but on the track i could still get the temps to 240. temps dropped fast on a cool down lap.

here is a picture of this setup with the bumper removed.




i then started my backdate project on the car and the early bumpers do not sit out nearly as far. the back of the cooler really needs to sit flush with the nose panel.


i had a air duct fabricated, ala rsr type, out of aluminum and rivited it in. clean, simple and great air flow. after this modification my temps on the track never got over 215


i think it is really worth the modification although as mentioned above in extended stopped traffic i do not get any air flow so those temps can rise but as soon as i get moving down they go.

[911pcars]

Using hose that is too small is like using thinner wire in an electrical circuit. As in an electrical circuit, if the wire is too thin there is more resistance to current flow. In the cooling section of the lubrication system, flow is more important than ultimate pressure otherwise we could make do with -6 hose. If you have a choice, use the larger hose.

Sherwood Lee
http://members.rennlist.org/911pcars

[911pcars]

BTW, to keep rocks and other projectiles off of the $$$ B&B or equivalent cooler, use stainless wire mesh in front of the cooler. The hardware store screen looks okay, but the galvanized steel is not strong enough to ward off solid objects at 70+ mph. The SS screen is available from places like Pegasus Racing and ??

Sherwood

[Chuck Moreland]

Originally posted by pbs911


would it not be better to maintain the higher oil pressure by using the 12AN fittings at the front mounted cooler and the 16AN fittings in the fender mounted unit?

I think I understand. The confusion is that there are two parts of the 911 oil system; pressure side and scavenge side.

The pressure side draws oil from the tank, sends it through the internal cooler then distributes it under pressure through the engine. Pressure side orifices need to be the right size to maintain pressure and correct oil distribution. Open one up too much and you may starve other parts of the system.

The scavenge side is a seperate system whose job is to remove oil from the sump, send it through the external cooler if so equipped, the oil filter, then into the tank. That is all it does. On the scavenge side, back pressure is the enemy. You want a free-flowing high volume of oil passing.

The scavenge side has zero affect on engine oil pressure.

External oil coolers and related lines should be non-restrictive. Remember that some cars come with no external cooler, hence zero restriction due to cooler.

[widebody911]

Just thought I'd throw in my 2 cents worth: http://vintagebus.com/howto/bumper-cooler/

[pbs911]

Thom,
Your front Setrab oil cooler is the very reason I ask the question regarding the -12AN fittings. Have you noticed any problems, or did any investigation, into the "more restrictive" 12AN fittings when running the front oil cooler in series with the Carrera fender mounted unit?

Also, can someone confirm whether or not the B&B cooler has -12 or -16AN fittings?

[TimT]

ok Ill throw in what I did.....

its a bit unorthodox perhaps? Im making my car a GT-5 car and figured eliminating as much air under the car might be a good thing

[Bill Verburg]

Tim, that is the best way to do it. But most of us don't want to give up our trunks Nice work!

[Bill Verburg]

Here's a similar setup in an RSR

[A Quiet Boom]

This is great, having just mounted a Fluidyne cooler in my RSR narrowbody spoiler and facing the same challenges. I had an idea for a winter project in which I would build a duct similar to what Tim did but instead duct it through hose and into the wheelwells like ted was suggesting, has anyone tried this yet so see how well it works? Another thought I have is for my new project, I've got a '78 targa widebody project car that the PO never finished, I was thinking RSR spoiler and those fenders that are "kicked out" in front of the doors and dump the air out there, is this perhaps the way the factory race teams did it? Anyway interesting thread this one.