Radiator fans and shroud upgrade

[lotus4s]

My current project is a 95 S4s that overall is in very good shape but in need of a lot of maintenance that had been neglected by the previous owner for the last few years as he had basically lost interest in the car. In the course of going through the car I decided to pull the radiator to clean it out and as I suspected it was quite clogged with debris.

Another thing that I've never been happy with from my previous S4s was the poor performance of the a/c and living in Florida, it is a necessity. After quite a bit of research and suggestions from an auto a/c forum that I frequent, one thing led to another and I decided to try to improve the efficiency of the cooling and a/c systems. Since these systems work together along with the charge cooler system, several steps were necessary to try to achieve my goals.

First I had the radiator recored and added a third cooling row in place of the oem 2 row core. The core is a little thicker but still works with the original tanks and frame. Also notice the more open spacing on the cooling fins to hopefully allow more of the debris to go through the rad instead of plugging it up.

Lotus rad:

New core:

Now we need new cooling fans to replace the antiquated units along with a new shroud. I started out to fabricate the shroud out of aluminum but then decided to try my hand at laying up a fiberglass piece. This is my first try at actually making a grp part and I'm quite pleased with how it turned out.

This is the side of the shroud that faces the rad and although hard to see in the pic, there are vertical dividers between each fan opening to create a separate air chamber for each fan. With the shroud mounted, the dividers are about 1/8" from the rad coil. This was following a suggestion by the old gentleman I purchased the fans from and sounded like a pretty good idea even if it was more work to fabricate.

Shroud mounted to rad with 3 Spal fans rated at 970 cfm each, so should move significantly more air.

Next is to deal with the a/c condenser. For some reason when Lotus went to R134-a on the 1995 models, they decided to use 2 smaller coils linked together, in parallel no less. Linked in series would have been more efficient. (according to the a/c gurus mentioned earlier) They are also god awful expensive if you have to replace them.

oem condenser:

I pitched the 2 smaller coils in favor of a single off the shelf parallel flow high efficiency condenser ($135 US). Although it has slightly less surface area (about 20 sq. inches), with more air flow and being one unit, it should be quite a bit more efficient.

Complete assembly:

Haven't been able to test it yet as I have a few other things to finish first, like putting the engine back in the car. Will post up the results once it's been tested.

Edited October 28, 2010 by lotus4s

[mike_sekinger]

Hi Jim,

Smart work there - I like the principle of improvement and modernisation.

Should stand the owner in good stead for next Summer.

What other tasks are on the list?

Cheers,

Mike S

[Rich H]

That short hose and joiner is a good idea!!

[lotus4s]

Yeah Rich, that bottom clamp is a bugger isn't it. I saw no reason to have to struggle with it again.

Mike,

So far I've replaced all the suspension bushings and would love to go with the new Bilstein/Eibach setup but funds are lacking for that at the moment.

Braided stainless brake lines will replace the originals. New pads to install and caliper rebuilds if needed.

The engine was pulled to do a complete C service and engine bay cleanup and while it was out I decided to check the bearings. A couple of the mains were

starting to show a little wear and although they would have been fine for a while longer I couldn't bring myself to leave it so a complete tear down was in order.

The engine is back together and ready to go in but need to flush the rest of the ac system first which means the dreaded Lotus position in the passenger footwell

to remove and replace the expansion valve. A new ac compressor and alternator are on hand.

One of Al B's stainless steel headers will mate to the existing Stebro exhaust.

Since I'm just a few more bolts away, I'm going to remove the lower valance and bumper and paint them along with installing new ss mesh in the grill openings.

No major performance mods for this one as I'd like to keep it fairly stock but have intsalled a chip socket to play with some other chips I have.

V8 Saturn wheels will replace the S4 wheels on it now. Wanted Novas but was unable to locate a set at the time.

The rest of the exterior and interior are near perfect so this car will be a really nice example when done.

Edited October 28, 2010 by lotus4s

[cjtpb13]

Jim,

Very nice work ! Curious to know what model of Spal cooling fan you choose. I believe I am going to do similar task this winter to correct issues the dealership could not / would not fix. I like the idea of the extension fitting in order to make things a bit easier. I am curious if you have had any experience with the Gates Powergrip hose clamps? I believe I am going to change out all of my current clamps for them after pulling the engine.

Hope all is well in Sunny Florida

[The Veg]

Never heard of the Powergrips so I looked them up...according to the description on Jeg's website, "Maintenance-free clamps that retain dynamic tension..."

Dynamic tension? Since when is Charles Atlas in the hose-clamp business?

But seriously, very nice work Jim! Keep us posted on how it turns out and works!

[lotus4s]

Chris,

The fans I used were these:

http://www.spalusa.com/store/main.aspx?p=itemdetail&item=30101500

They are the medium profile and are rated at 970cfm.

and I purchased them from here which had the best prices I could find anywhere for Spal.

http://www.the-fan-man.com/shop/spal-electric-fans-c-33.html

They list for $135 and he sells them for $89.

I was not familiar with the Gates clamps but like Ben I just looked them up. Seems like a good concept but I'm not sure I'd like the idea of having

to have special tools to install and remove them especially in an on the road repair situation. I can see where you might have a real

problem getting access to some of the clamps with a heat gun to install or soldering iron or other tool to remove them.

I use a 1/4" ratchet and extension and

don't have much trouble with access on most of the Esprit hose clamps.

[cjtpb13]

Jim,

Once again you are a wealth of information. I imagine too that the Spal fans you purchased are much quieter than the originals.

I had to laugh...one day I am in a gravel parking lot after a minor league baseball game waiting to exit in a long line of cars...the fans kicked on startling the people walking closest to me...worse yet the cloud of dust kicked up was tremendous...

Look towards your final results...

Side note...I should be down in the area after the holidays to begin prebaseball spring training maintenance. Will try to catch up in my travels...

[flowersrj]

Jim,

Can you give specifics on the replacement A/C condenser you used?

Thanks,

Rich Flowers

95 S4s ...SHF63000

79 S2 JPS#040

[lotus4s]

Chris,

Definitely be sure to let us know when you'll be in the area and we'll get together with a few of the other locals.

Sadly, I don't think these particular Spal fans are any quieter at least not comparing them out of the car. The curved blades available in

the same size will be quieter but don't move quite as much air. I'm curious to see what happens with these new ones in operation as well.

Rich,

The condenser is this one:

https://www.ackits.com/pc/12-0440C/Parallel/12-0440C+-+FSHE+PF+Condenser+%2812+X+27%29

[WEllison]

The Gates power grip shrinkable clamps are wonderful! They continue to shrink with each heat cycle as the hose shrinks and are great fot hard to reach places. Used them for my intercooler installation. You can look here.

http://www.thelotusforums.com/forums/index.php/topic/33622-intercooler-project-finally-finished/

Wayne

[lotus4s]

Pretty cool Wayne. How do you release them if you need to remove the hose? And I assume they are one time use only?

Also, it looks like we may have used the same fans. How have yours performed and how is the noise?

Edited November 4, 2010 by lotus4s

[sailorbob]

Jim, did you check the current draw of the fans? I ask because I was concerned when I replaced my fans due to the very thin wiring Lotus used and ended up using 5.6 amp fans.

[WEllison]

As you surmised, the Power Grips are a "one time" use. You can either cut them off or burn them off with a soldering iron. For hard to get into places they are perfect and they don't cut your hands! I used Spal 30101500 11" fans with straight cut blades. They are more noisy but their air flow rate curve is flatter for an increasing static pressure drop. You really know when they are running! Another reason I picked these fans is there current requirements, well below the 15 amp, each, fuse rating and below the 70 amp capability of the relay. They work fantastic! 1st, they almost never come on due to the improved radiator. I've been trapped in friday night traffic out of San Fransisco, bumper to bumper, for 2 hours in 85* F. temps. They come on about every 15 minutes, for 3 minutes and drop the ECT back to 95* F.

Wayne

Edited November 8, 2010 by WEllison

[sailorbob]

When it come to fuse sizes and fans be wary, the start-up current draw is a lot larger than the constant running draw which is why the fuse(s) are apparently larger than needed.

[WEllison]

Fans do have a large in rush current. A fan drawing 7 amps while running can pull 20 amps during start up, but most fuses (unless they are fast acting) will take the short term high current level.

[hilly]

For Automotive blade fuses (ie one of these ) then they do have an in-rush spec.

From the graph below you can see that a 7.5A fuse will be able to carry 20A for about 200milliseconds before failure, so most likely OK

For reference I have individually fused my 3 Spal fans with a 10A fuse for each, howeverI have used an illuminated version of the blade fuse so that you can instantly see which one has gone if a problem arises.

Hilly